[stefang]

Mahogany Kitchen Stool Project

Well, here we go. I have been working on the design and preparation of this project for 3 years. The final prototype was just completed.



This is my second prototype. The first one was a quick (that is a relative term) mock up to see if I had the size correct. I built this out of scrap 2×4s and screws. Pieces were only roughly shaped. After building this, we determined that it was about a half inch too tall.



The second prototype was built as a prelude to actual construction. Each stool has 42 mortise and tenon joints. Several of them are angled and others are on curved parts. By making a full prototype, I have a scale pattern to verify the layout of each piece before I cut into my lumber.



Also, I get a chance to make mistakes and learn. I ended up missing on three or four dimensions and had to patch parts up. I have chosen to form the curved parts by laminating thin strips. The two curved boards on the back formed very well, but the 5 slats did have some spring back. I'll need to adjust the form or move to thinner strips. Stay tuned on that one.

Finally, I get one last chance to check my design choices. In this case, my wife and I felt that the slats on the back were spaced a little too far apart. It ended up crowding the gap to the legs. I changed the design and moved the slats a little closer together.

I'll outline how I intend to proceed with this blog. I'll post updates on the construction as I go. Woodworking is a spare time activity for me. Weeks may go by with only a little activity. I'll post a few "flashback" entries where I will cover my design process.

I'll also keep a log of construction hours. This will not include design or prototyping time.

Cutting rough stock : 2 hrs
Cutting legs to width and thickness: 4 hrs 20 min
Cutting thin stock for seat back laminations: 3 hrs

Total so far: 9 hrs 20 min

Very Nice. I like the curved pieces a lot and they all mesh real well with the design. Looks like a winner all the way around. Great approach with the prototype. I still have a prototype of Rodel's arts & crafts chair in pine in my loft, but haven't come further with it. I'm looking forward to seeing your blogs on this project.

 

[stefang]

Begin Rough Cutting

Back in early November, I went to my favorite lumber yard and started looking at what kind of wood to use. I was interested in mahogany, but wanted to check out my options. They had some very nice ribbon mahogany. I went home and gave it some more thought. The next weekend, I made the plunge.



I had only one problem, I kept seeing pieces that looked too nice to pass up! I ended up with way more than I needed for this project. I can rationalize it that I saved gas by not making an extra trip You can see 3 fir 2×4's on top of the stack. They ended up being the material for my prototype.

Even though I had plenty of material, I took it as a challenge to try to get the most use out of each and every board foot. I spent way too much time on this, but I packed in the pieces in the most compact cut layout I could. Here is the result after 3 or 4 iterations on my CAD system.



I'm hopeful I will end up with only small blocks of scrap and a big pile of sawdust!

Fast forward to last weekend. I finally was able to start cutting the legs. Here is where I ended up.



I got the width and thickness rough cut and then ran them through my planer. I learned something about my dial calipers. I bought a nice one with resolution down to 0.001 inches. The resolution makes it nice to know exactly what dimension I am at. On the other hand, I don't need to worry about being off by 0.001 or 0.002 inches. If I can't see the difference when I hold two pieces up to each other, I am happy.

Current time log:
Cutting rough stock: 2 hrs
Cutting legs to width and thickness: 4 hrs 20 min
Cutting thin stock for seat back laminations: 3 hrs 15 min
Prepping laminations: 15 min

Total so far: 9 hrs 50 min

Very nice wood Steve. I also buy Mahogany planks and it is a joy to work with. It seems to have most of the attributes one is looking for in wood. Beauty, stable, easy to work, easy to finish and probably others I forgot. Your chairs are going to be first rate. I'm especially interested in the seeing how you will be laminating the back supports (slats).

 

[stefang]

Preparing Lamination Strips

There are three curved parts in each stool. These are formed by gluing up thin strips to create a thicker laminated part. The three parts are:

1. Seat Back - 7/8" thick (formed with 5 or 6 strips)
2. Back Rest - 7/8" thick (formed with 5 or 6 strips)
3. Slats - 3/8" thick (formed with 3 or 4 strips) (5 per stool)

As I plan the construction, I start to realize that I have 6 stools with 7 curved parts each. That works out to 42 glue ups. Each one requires a full day for the glue to cure. I do have three different forms, but this is still a lot of time - 30 glue ups are for the back slats. I need to get the glue up process started first. I can work on shaping the other pieces while the glue dries on the laminated parts.

The 7/8" thick parts were prototyped with 6 layers. They formed fine with no spring back. I prefer to use fewer, thicker strips and end up with one less glue joint. I'll be testing out the first glue up with 5 strips and see how it goes.

The 3/8" slats were prototyped with 3 layers. There was some spring back that made it difficult to align parts for assembly. I need to reduce the spring back. My plan is to try to modify the form and test it with another prototype glue up.

The wood for the laminations was resawn off the Back Leg stock. I ended up with pieces about 1/2" thick and 3 5/8" wide. They were long enough to provide two pieces for the glue up. I then resawed these to give me 2 long strips. Now I am up to 4 pieces for the glue up.



I figured I would share some of the things I do when resawing. First I use a 7 1/4 inch thin kerf blade. The kerf is only 1/16". This helps me get the most out of each piece. If the board is too wide, I need to stay with one of my larger blades. I do not have a zero clearance insert (yet), so I use a long scrap of thin plywood and clamp it to my saw table. I raise the blade through the plywood and I end up with a temporary zero clearance solution. Finally, I use a marking technique to keep track of which board each pair of strips came from.

I use my hand saw and make a set of marks across the end of the board.



In this case I have marked this piece as belonging to stool number 4. By angling the marks, I can return the two pieces to the same orientation as before the resaw cut. Each stool has 2 boards (one for the Seat Back and one for the Back Rest). I mark the second board for stool number 4 with 4 cuts, but I place them in a different spacing.

I now have strips of wood that can provide 4 pieces for my glue up, but I need 5 or 6. Fortunately, my strips are wider than I need. When I rip them to the desired width, I have two narrow pieces left over. In the case of the Seat Back, these two narrow strips can be glued together. This way all the wood comes from the same board and I should be able to keep the colors matched.



Once I let the glue dry and clean up the piece, I have 3 strips of wood. Each is long enough to give me two pieces for a total of 6 parts for the lamination.



The strip on the right is the glued up one. The Back Rest is wider. As a result, my left over pieces are not wide enough to make the third strip.



In this case, I have added a third piece of left over stock to make the strip wide enough.



This entry is long enough. I'll cover more later.

Current time log:
Cutting rough stock: 2 hrs
Cutting legs to width and thickness: 4 hrs 20 min
Cutting thin stock for seat back laminations: 3 hrs 35 min
Prepping laminations: 2 hrs 20 min
Glue up Laminations: 35 min

Total so far: 12 hrs 40 min

Interesting process Steve. I like your idea about the thin kerf blade for resawing. Good color/grain match on the pieces pictured. You might get a little tired of glue-ups after awhile, but the design is so nice, once the laminate glue-ups are behind you I think you will be very satisfied.

 

[stefang]

Setting laminations to final thickness

Once I have the 3 lamination blanks cut to width I thickness sand the strips to reach the final dimension. I have tried using my planer, but when the strips get this thin it is easy to end up with damage. I set my ShopSmith up as a disc sander and use a thicknessing jig. I first showed the use of this in a previous blog. There was some interest in a more detailed description so here it is.

Here is the setup.



Basically it is a 3 1/2 inch tall bullnosed block clamped to the fence. The block is set up closer to the edge of the table than the desired final thickness of the strip. In this case I want strips 0.175" thick so the block is set about 1/8" from the edge of the table. The disc is initially positioned from the block at the current strip thickness (just over 0.2 inches in this case). I take advantage of the quill advance capability of the ShopSmith and move the disc closer to the block after each pass.



The construction of the block is pretty staright forward. I cut a bevel on each end of a 2×4 leaving about 1/4" flat on the end. I then cut the beveled end off making sure I had enough length to accomodate the clamp I will be using. Make sure the cut is square. Then mount the beveled piece to a cross piece. The final step is to true up the edge. I clamped the block to the fence and set it up hanging over the table. I then advanced the disc against the block. This way I have the functional edge of the block exactly parallel to the disc.



Once this was done I marked the top side (see top two photos). If I were to flip this over, I might get tapered width strips (that would be bad).

A final set up element is to mount a dust collection hose underneath the table next to the disc. I don't always do this, but this project has a lot of strips to sand. In no time, I had my shop coated with fine mahogany powder. The hose does a good job of collecting most of the dust. I took this shot while sanding a strip. You can see some of the dust in the picture.



Finally, here are a few operating tips.

1. Do not let your fingers touch the disc! Use long strips - they should extend 3 or 4 inches past each side of the disc to give you good finger access.
2. Set the block up to contact the disc on its downward motion. Setting block close to center can result in the strip being pushed back at you.
3. Feed the strip in until there is only 3 or 4 inches of strip left, then pull the strip out on the exit side.
4. Allow about 3 inches on each end as waste. The strips can taper a bit as you start the strip or pull it out.
5. Keep the strip feeding in as straight as possible. Letting it bump against the disc any where but at the block can result in gouges.
6. The exception to #5 is if you are sanding very thin strips. Then the strip can fall between the table and the disc - in fact there may be no table exposed past the block. In this case rest the strip on the table, bend it into the gap and bend it back onto the table once you can reach it safely. I have managed to sand strips as thin as 0.02"
7. Use light passes. I take off about 0.005 each time. You can force a bigger cut, but I worry about deflections and not getting a consistent strip.
8. One time past the disc will not remove all the material. I have made as many as 5 passes without changing the spacing.
9. You can control how much is removed in a pass by how quickly you feed the strip. This gets easier on the 2nd or 3rd pass at the same gap between the fence and disc.

I have been using this method for several years. I am able to set my strip thickness to within 0.004" (+/- 0.002").

If you have a conventional disc sander, you could shim the block closer after each pass - or get fancy and build an adjustable version.

The next entry will cover glueing up some curved parts. As always, comments are welcome.

Current time log:
Cutting rough stock: 2 hrs
Cutting legs to width and thickness: 4 hrs 20 min
Cutting thin stock for seat back laminations: 3 hrs 35 min
Prepping laminations: 3 hrs 20 min
Glue up Laminations: 1 hr 35 min
Trim Laminated Parts: 15 min

Total so far: 15 hrs 5 min

Good blog Steve. I made my own version of your jig a awhile back and it works great, thanks for this tip.

 

[stefang]

Laminating Seat Back and Back Rest

Once I have my strips sanded to thickness, I can cut them and get the five pieces I need for gluing. I have enough material for six so I'll have a strip left over. There are a couple of cases where I ended up with damage on part of a strip and that sixth piece was nice to have.

First, I sort my six long strips and find which end I want to have in the final part. I look for color, grain direction and any character that I might want to have on the outer faces. Then I mark for cutting. I use the inner form and rock it along the strips to get the length.



I then set aside one piece and cut the last two to length. Next, I spend a few minutes and sort and re-arrange the pieces. I am looking for the two nicest surfaces to be on the outside as well as have uniform color and grain direction on the top edge. This can take several tries before I find a combination I am happy with. I then mark the pieces to make sure I keep the orientation unchanged.

Now it is time to apply glue. I use yellow wood glue - it has a fairly slow set up time and that is a good thing for this operation. I just use a piece of cardboard to get an even coat.



I coat one face and make sure the entire surface is coated and fairly even. I can see wood grain through most of the glue. If I have too much, I transfer it to the next surface to be glued.



One thing that you do NOT want to do is glue your piece to the fixture. To prevent this, I use a piece of stretch wrap (from the kitchen). Then I put the stack into the fixture and start to draw it together.



The fixture has two arcs offset by the thickness of the part. These arcs were cut carefully to ensure that I would get even pressure along the glue joints. After the first clamp is at its limit, I add two more clamps. As I draw these two in, the first clamp comes off.



The outer form of the fixture is set up to be a jig for cutting the tenons. As a result, they are short and do not pull the ends in to the inner fixture. So I add C-clamps on each end.



After getting all 6 clamps tightened, I set the assembly aside for 24 hours. I have two fixtures - one for the curve at the back of the seat and one for the curve at the top of the back rest (you can refer back to a picture of the prototype here). The two pieces have a different radius.



I checked the spring back after when I unclamped the first part. There was about 1/16 of an inch at the center. I used 6 laminations in the prototype and there was less than half that much. I like fewer glue joints , so I will live with this much spring back.



My first glue up had a little too much glue. The squeeze out wicked onto the face of the part. I used less on the rest of the parts and never had this issue again. It only took a little sanding to remove the squeeze out.



On one piece, I had a swirl in the grain that looked cool. It was on two of my parts so by placing one on the inner face and the other on the outer, I could give the illusion that the swirl went all the way through the part. Unfortuantely, the part on the outer surface broke during clamp up. I had to unclamp, unwrap, remove the broken part, retrieve my spare 6th part, rearrange for grain and color, clean the glue off the new outer surface and reclamp. It was a bit of scramble, but it all worked out.





After unclamping, I trim the part to width and length. I am very pleased with how these parts are turning out. The glue lines are hard to find and the parts are very uniform.



Here is a shot of eleven of the twelve parts. It has taken a while to get this far, but I am pleased with my pace.



Current time log:
Cutting rough stock: 2 hrs
Cutting legs to width and thickness: 4 hrs 20 min
Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hrs 35 min
> Prepping laminations: 8 hrs 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min

Total so far: 24 hrs 40 min

Very good work Steve. I've never done any laminating/bending like that so I appreciate you including your thinking process about grain, features, etc. Thanks for sharing this with us. Very good blog.

 

[stefang]

Finding shop time in a busy schedule -or- Making slats & cutting pieces

The next step in this project is making the curved slats for the back of the stool. The process is the same as for the curved parts with a couple exceptions. First the pieces for each set of slats are cut from two blocks. These blocks were next to each other when cut from the large stock. Instead of marking with a saw cut as I did last time, I used a permanent marker.



By angling one stripe across both blocks, I am able to keep the strips in order. The total number of stripes tells me which stool this set of strips belong to.

The other difference is the clamping jig.



This jig has two curves and required careful adjustment to create a tight fitting result.

But, this is not what I want to write about for this post. I think it would be nice to share how I find shop time. We all have busy schedules and, at least for me, the woodshop takes a lower priority. I find that I can fit in shop time a little bit at a time.

I start out with a stack of strips to be glued up. This makes a good example of how to find shop time.



My shop is located off the back of my garage. Gluing up a set of 4 strips takes 10 to 15 minutes. If I can find that much time before I leave for work, I have enough time to glue one more set.



As the days go by, I find that the pile slowly shifts from only one done to only a few left to do.



And then the day comes when I have glued the last one up!



Then there are days when I have more time. That is when I can take the rest of the wood and start to cut it into final pieces.



In this case, there is a bit of prep work to make sure that the grain runs from one part to the next wherever possible. There were several 15 to 30 minute sessions where I just focused on marking the pieces.



Once again, cutting the pieces is done a little bit at a time. The longest session was less than 2 hours. Over time, the pile of big parts turns into a pile of smaller parts.



And once again, the day came when the last pieces were cut.



There is likely some extra time in this project that results from working in small sessions. For me the tradeoff is that I get to make progress and spend time in the shop more often.

The project is now to the point where all the pieces have been cut to thickness and width (well almost all … ). Next is cutting to length and then cutting mortises.



Current time log:

Cutting rough stock: 2 hrs
Cutting legs to width and thickness: 4 hrs 20 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hrs 35 min
> Prepping laminations: 8 hrs 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hrs
> Glue up Laminations: 6 hrs 5 min
> Trim Laminated Parts: 10 min

Lower rail parts
>Cut to width and thickness: 10 hrs

Total so far: 44 hrs (7+ hrs per stool)

A smart way to work Steve. I'm sure your blog will show others with limited time how they can get more done. Like they say; small streams make large rivers.

 

[stefang]

While visions of perfection dance in my head

I deal with correcting mistakes instead!

It has been quite a while since my last post, but I AM still working on this project. In addition to regular life, we have had a week long vacation, business trips (including 2 weeks in China), a family illness and preparing for RAGBRAI . The shop time has been hard to come by.

I figured this would be a good time to confess and share how I am dealing with this round of unexpected issues.

Dull Bandsaw Blade

I started to shape one side of the back legs. I knew my bandsaw had a dull blade, but I got lazy and told myself that I could just leave a little extra wood. Wrong. The blade took on a twist and curved right past my line. Stopped and bought a new blade (one with a better tooth profile) and the rest of the cuts went fine. But I was stuck with one leg that needed help.

My solution was to flatten out the damaged area and glue a patch on.



After the glue dried, I smoothed the sides. The grain matched quite well.



Once I did the final shaping, there is a faint glue line that I think willl nearly disappear once the wood darkens (sorry no pic)

Router Pattern

This one was an act of real poor thinking. I had been shaping several legs and always being careful to turn the router on and off only when it was stable on the template.

Except this ONE time.

I lifted the router while it was on and the bit cut into the pattern The solution here was automotive body filler (Bondo).



The filler was applied to the cut and then sanded smooth.



Chipout

The base of the leg flares out and it was not a surprise that I had some chipout. Most of the time, I could find the missing piece and glue it back in. One time I had to make a patch. I squared up the chipped area and flattened it with a sharp chisel.



I found a piece of wood with matching color and glued a block in.



Mortises and Tenons

This project has a LOT of mortises and tenons. I took extra time to draw each mortise and then I would check it against my pattern piece.

Foolproof - right?

Wrong!

Every once in a while, I would forget to check a piece against my pattern. As luck would have it, one time I skipped checking was on a part where I had shifted the mortise location 1/2 inch. Back to gluing patches… I came up with a fairly creative soution to apply pressure while the glue dried. Luckily, this particular joint has a tenon shoulder that will completely cover this patch.



I managed to cut a tenon or two a little thin. More patches. These are completely hidden inside the mortises. I should point out the black dot on the end of the tenon. This is my technique for preserving the orientation of each piece. The black dot is always in the top right front corner of each piece.



The Big One

When I first did the rough cutting of the legs, I had one kick back incident. The only damage was the blade dug into the side of one of the legs. I saved the scrap from shaping the leg to get a good color match.



I used my laminate trimmer to create a pocket of even depth. Then I created a paper pattern by rubbing a pencil over the recessed area. I cut a thin slice off my patch piece and placed the pattern to match the grain.



It took a while to get the patch shape to match the cutout area. Lots of hand filing.



I glued the patch in place with just a little extra thickness. A little sanding and this is what I ended up with. I had hoped for a little better color match, but it is down next to the floor so hopefully it won't be too big of a distraction.



I have been cutting a lot of motises and tenons. Not the most thrilling blog material, but I'll try to show where I am with my next post.

Current time log:

Cutting rough stock: 2 hrs

Legs
> Cutting to width and thickness: 4 hrs 20 min
> Cut to final length: 3 hrs 30 min
> Shaping: 5 hrs 50 min
> Mortises: 10 hrs 35 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hrs 35 min
> Prepping laminations: 8 hrs 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hrs
> Glue up Laminations: 6 hrs 5 min
> Trim Laminated Parts: 10 min

Lower rail parts
> Cut to width and thickness: 10 hrs
> Cut to length: 1 hr 30 min
> Tenon: 13 hrs 20 min

Total so far: 78 hrs 45 min (13+ hrs per stool)

Very professional looking fixes Steve. I have been through this myself (many times) and though I feel I can adequately fix almost any mistake I make, oh the time it can suck up! But anytime spent making corrections on those beautiful stools will be worth it, and someday your kids will probably inherit them.

 

[stefang]

Seat backs

Q: What goes slower than my progress on these stools?

A: My blog on these stools!

I have been making progress. Other projects and Christmas gifts provided distractions. And woodworking is still a hobby and has to wait for when there is time after everything else. I find that I am quite able to let a bigger project like this sit to one side for a few weeks and come back to it when I can.

Next up are the seat backs. The last entry covered fitting the top and bottom rail of the seat back. Now I need to cut the slats to length. I used an insert from my glue up form to align each slat.

Each piece has been numbered for color and grain direction. As I cut them to length I need to transfer the numbers.

To put the mortises in the upper and lower rails, I used the glue up form and fixtured it in the mortiser. The rail is positioned in the form to locate the mortise. The form can slide between two stops to give me the correct width.

Now I need to form tenons on each end of the slats. Again, I use the insert from the glue up form - this time in the tenon jig.

Now I can put the back together for a test fit. Looks good!

BUT - the tenons were a little tight. I did not think much of it until I tried to pull it apart. Not happening. I knew the "use a hammer until it gives up" option was not a good one. It took a while (like a couple days) to figure out out to pull it apart, but I came up with a solution.

After adjusting the tenons for a better fit. I now have seat backs!

There are a lot of angles in this project, but I think the most interesting part is the back. Every part is curved and makes for a very inviting appearance.

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 10 min
> Mortises: 5 hr 5 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 3 hr 50 min
> Tenon: 23 hr 30 min

Total so far: 108 hr 10 min (18+ hrs per stool)

Making chairs is a pretty slow process Steve, except maybe for those that do every day. So I'm not surprised that this project is taking awhile, especially considering all the curvy complexity involved. You have accomplished quite a bit in only 108 hrs. I know these are going to be fantastic stools when they're finished and you will never want to get rid of them. Great work so far and a wonderful blog too. Can't wait to see them completed.

 

[stefang]

Shaping and sanding

Shaping and sanding is pretty easy to figure out, so I'll just share a few of the techniques I used on this project.

The back legs still needed to be cut to final shape on one remaining side. The template was clamped onto each leg.

The shape is traced onto the leg.

Cut on the bandsaw with about 1/16" left.

A router with a guide bearing and straight bit made the first pass using the template.

Even with multiple passes, I still had an occasional blow out.

Repairs involved gluing pieces back in place and then routing very carefully. After this one, I used the disc sander to get very close to the line before using the router.

Nearly every exposed edge has a radius routed on it. Radii of 1/16, 1/8, 1/4 and 3/8 were used. Here is example of the bottom of the front leg. I sand the surfaces to 120 grit before I add the roundover routing. The smooth surface helps create a cleaner roundover.

The larger radii caused me some concern. I set up the fence on my router table with a spacer strip.

This allowed me to make a first pass with a partial depth cut.

Then I flipped up the spacer strip and made a full depth cut. If you look closely, you'll see that the bit is not flush to the fence. This way I could get the first and second passes to be the depths I wanted.

The next thing to cover is the sanding. I have put in LOTS of hours sanding. Not that I mind. I kind of enjoy feeling how each grit makes the part more smooth. The hours are from the fact this project has lots of parts.

And those are just a few of the parts. Remember there are 6 of these!

I do my sanding by hand. I use a block for the flat surfaces.

A piece of an old mouse pad for the radiused edges.

And a curved block for the inside curves.

I step through each of the grits - 60, 80, 100, 120, 15, 180, 220, 320.

Finally, here is an update on the hours.

=================================================

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min
> Sand & radius edges: 19 hr 35 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 40 min
> Mortises: 5 hr 30 min
> Sand & radius edges: 6 hr 10 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min
> Sand: 7 hr 35 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 4 hr 35 min
> Tenon: 28 hr 30 min
> Sand & radius edges: 15 hr 35 min

Corner Blocks
> Cut to size: 1 hr 50 min
> Shape: 1 hr 50 min
> Tenons: 35 min
> Holes: 1 hr

Total so far: 168 hr 50 min (28+ hrs per stool)

A daunting challenge Steve, just in terms of the huge amount of parts not to mention all the machining and sanding. I like your approach to the work. I think your hinged router fence spacer is brilliant. Can't wait to see the glue-up part and the final stools. Keep up the good work!

 

[stefang]

Oxidizing for color

Yes - oxidize. Not stain. Not dye.

Alin Dobra posted a very informative blog on using potassium dichromate to cause wood to darken the same way it does when exposed to sunlight. I'll let you read his entry to learn about the technique. These stools will eventually be sitting around the island in our kitchen. The sun will only land on the top part of the backs and I don't want them to develop "tan lines".

This was my first experience with the technique. I coated the surface twice to make sure I had uniform coverage. You can see how much darker the mahogany is after treatment. The two pieces on the right were just coated.

After the surface was dry, I sanded each surface with 320, 400 and 600 grit.

This process caused me to lay out all the parts at once. These next pictures give a pretty good view of the number of pieces in this project. I had to clean off my workbench just to find space!

The total is 156 pieces of mahogany.

And 24 pieces of maple.

=================================================

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min
> Sand & radius edges: 19 hr 35 min
> Oxidize and Final sanding: 3 hr 10 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 40 min
> Mortises: 5 hr 30 min
> Sand & radius edges: 6 hr 10 min
> Oxidize and Final sanding: 1 hr 20 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min
> Sand: 7 hr 35 min
> Oxidize and Final sanding: 1 hr 30 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 4 hr 35 min
> Tenon: 28 hr 30 min
> Sand & radius edges: 15 hr 35 min
> Oxidize and Final sanding: 3 hr 40 min

Corner Blocks
> Cut to size: 1 hr 50 min
> Shape: 1 hr 50 min
> Tenons: 35 min
> Holes: 1 hr

Total so far: 178 hr 40 min (~30 hrs per stool)

Very interesting Steve. Something I've never heard about before. Where do you buy the chemicals? This is a big project which would be very taxing on most small workshops, but you have really done a lot of great work with it so far.

It looks to me that you will soon be into the glue-up stage. I can imagine that you will face some challenges there as well, and I look forward to seeing how you do it. The blog and the work is so well organized that it should set an excellent example and show folks a very good way to produce high quality multiples.

I can't wait to see the finished stools in your kitchen!

 

[stefang]

Mask & Prep for finish

I have decided to finish each piece before assembly. The benefit is it will be easier to get an even coat all the way to the end of each piece with no internal corners to catch finish.

The challenge is in keeping the joints clear of finish and eventually working with finished parts during glue-up.

For now, I only need to concern myself with keeping the mortises and tenons free of finish. The tenons were the easy part. I just masked off each one with blue painter's tape. If I counted right, I ended up taping 264 tenons!

Some of them are pictured here…

I did not concern myself with taping the shoulders of the tenons as the glue joint strength is mainly from the tenon.

I spent some time trying to figure out how to protect the mortises, but I REALLY did NOT want to mask the inside of 264 mortises. Since I will be wiping on the finish, I decided to see if I could just be careful and not let the finish run into the mortises.

The next step was to set up the pieces for finishing. I needed to support each piece such that none of the finished surfaces would be in contact with anything.

For the pieces with a tenon on each end that was pretty easy - just set each tenon on a support rail.

The legs are a little different. They do not have a tenon on the ends. The front legs were set up by screwing a hook into the top. The top of the front leg will eventually be covered by the seat.

The back legs were more of a puzzle. All surfaces are exposed. I guess I could screw a hook into the bottom of the leg, but I did not care for a hole there. It took me a while to figure this out, but I ended up creating a set of stands that supported each leg in the bottom of each of three mortises that run along the inside face. I forgot to take a picture of this during the setup, so these show a preview of the finish work under way.

Now I'm ready to apply the finish. I still need to figure out how to assemble pieces with finish already on them. I have some time to figure that out. It's all part of the fun.

You'll notice that the total hours went up by almost 7, about an hour and a half was spent setting up supports for the legs. That leaves about 5 and a half hours for taping tenons. That works out to a little over a minute per tenon!

=================================================

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min
> Sand & radius edges: 19 hr 35 min
> Oxidize and Final sanding: 3 hr 10 min
> Prep for finish: 1 h 25 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 40 min
> Mortises: 5 hr 30 min
> Sand & radius edges: 6 hr 10 min
> Oxidize and Final sanding: 1 hr 20 min
> Mask & Prep for finish: 20 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min
> Sand: 7 hr 35 min
> Oxidize and Final sanding: 1 hr 30 min
> Mask & Prep for finish: 40 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 4 hr 35 min
> Tenon: 28 hr 30 min
> Sand & radius edges: 15 hr 35 min
> Oxidize and Final sanding: 3 hr 40 min
> Mask & Prep for finish: 2 h 30 min

Corner Blocks
> Cut to size: 1 hr 50 min
> Shape: 1 hr 50 min
> Tenons: 35 min
> Holes: 1 hr

Total so far: 183 hr 35 min (~31 hrs per stool)

I wish I could be as well organized and exacting as yourself Steve. I do greatly admire your approach to this work and I'm sure those are going to be smashing stools when finished. You are teaching us how to work properly with your excellent blog. I usually stuff mortises with paper towels to lock out finish. Works well for me.

 

[stefang]

Finish is on - all 9 coats! Plus 2 buffing, wax and polish

After getting everything set up, the next step was put the finish on! I really like this step, each coat increases the gloss, depth and color.

I use a two finish process, both parts are from General Finishes. The first finish is their oil based coat.

I wipe the finish on with a piece of cheesecloth. The first coat basically soaks into the wood.

Areas where the grain is very tight, even the first coat shows a little gloss. I add more coats until the wood shows a uniform gloss. On average, it takes 5 coats to get there.

After that, I buff each face with 600 grit and 000 steel wool.

Next up is the top coat.

Since these stools will see heavy use, I wanted a heavy finish. When looking for a heavy finish, my rule is "add coats until you don't want to add any more". That took 4 coats. I'm pretty sure that I have a good durable finish on these parts.

After the top coats, I buffed each face with 000 steel wool and the applied a coat of paste wax and polished each face. I figure the wax will help with any clean up when I do the glue up.

I am really pleased with how the pieces look at this point. The appearance is great and the polished wax gives a really nice feel to each part.

Now I have to get ready for glue up. I have to confess that this step has caused me a great deal of pondering for the duration of this project. The main choice I have is do I glue up sub assemblies or do I glue up an entire stool at once? I am interested in your opinions on this one…

Gluing assemblies has the benefit of allowing the use of wood glues with shorter open time as well as less confusion and stress during glue up. The down side is if any assembly ends up a little out of square or twisted, it will be very difficult to correct it later on.

Gluing the entire stool is a much more complex process. I would expect to use epoxy to allow a sufficient open time. It would also require a really good fixture and clamping technique to ensure the stool is aligned.

=================================================

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min
> Sand & radius edges: 19 hr 35 min
> Oxidize and Final sanding: 3 hr 10 min
> Prep for finish: 1 h 25 min
> Finish: 12 h 15 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 40 min
> Mortises: 5 hr 30 min
> Sand & radius edges: 6 hr 10 min
> Oxidize and Final sanding: 1 hr 20 min
> Mask & Prep for finish: 20 min
> Finish: 2 h 45 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min
> Sand: 7 hr 35 min
> Oxidize and Final sanding: 1 hr 30 min
> Mask & Prep for finish: 40 min
> Finish: 4 h 35 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 4 hr 35 min
> Tenon: 28 hr 30 min
> Sand & radius edges: 15 hr 35 min
> Oxidize and Final sanding: 3 hr 40 min
> Mask & Prep for finish: 2 h 30 min
> Finish: 12 h 5 min

Corner Blocks
> Cut to size: 1 hr 50 min
> Shape: 1 hr 50 min
> Tenons: 35 min
> Holes: 1 hr

Total so far: 215 hr 15 min (~36 hrs per stool)

More than up to my high expectations Steve.The finish looks top notch. I can think that the glue-up will be a challenge. I would try to determine which parts, if any, can be glued up separately without the danger of misalignment, or at least where slight misalignments might not be a significant problem.

I would also rehearse a full all at once glue-up. I can see that the pre-finishing is a big advantage in terms of clean-up and good coverage, but it may make clamping a bit difficult due to the possibility of messing up the finish, so you need a really well thought out plan.

I did have one idea that might help. Have you ever thought about using cargo straps with ratchet fasteners to clamp with? These are easy to pad where they contact the wood and the ratchet can produce a huge amount of clamping pressure. I have used them myself with excellent results and they are safer than steel clamps with regards to the finish. You might have to use angled pads to prevent slippage on angled areas.

Having seen how you work, I have no doubt you will have success with the glue-up, and I don't think you really need advice on this, as you will figure it out yourself. I am looking forward to seeing your stools finished. I'm sure they will be very beautiful.

 

[stefang]

Jigs for glue up

This last weekend was spent setting up the process for assembly and glue up. I had not expected I would spend this much time coming up with a glue up solution. Still, this was a fun puzzle to solve.

The first step was to remove the masking tape. It took a while to peel of tape from all 244 tenons!

One concern I had with clamping pre-finished parts was damaging the finish. In past times I have had the texture of any padding end up imprinting into the finish. I decided to use a smooth surface to line the inside of my clamping jigs. I used masonite hardboard to line the jigs. The assembly of the jigs took all my spring clamps!

I went through a couple iterations to arrive at my final solution and clamping sequence. I chose to assemble the entire chair in a single glue-up. I used my prototype to develop the clamping sequence.

One of the fun parts about this step is I had to go buy more clamps!

The first step is to clamp the seat back assembly. This step is optional and is only done when the assembly resists being fully compressed. The jigs look like this.

And is used like this. The trick was the top rail and the bottom rail do not line up so I needed a way to get the clamp force to pull the parts together without causing the clamp to slide off.

Next are two pads for the top of the back.

The angled wedges on each side are used to let a clamp pull the two back legs together at the top.

Then there are two sets of clamping pads to pull the back legs together at the middle and bottom rails.

Here is a view of the bottom pads in action. The middle pads serve double duty and will show up a little later…

The next set of pads are for the front legs. They have a top block so they rest on the legs and are long enough on the outside faces to cover the lower rail.

The first clamping step is to pull the two front legs together at the top and bottom.

Then the front leg assembly is clamped to the back leg assembly at the top. Here is where the middle pads for the back legs show up.

The last set of pads are for the bottom rails.

Two more clamps finish the job.

Here is the final solution.

I promise the next post will show assembled frames!

Finally a note on the hours. I only added the time to remove the masking tape. I have not included the time to build any of the jigs and I chose to stay with that precedent.

=================================================

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min
> Sand & radius edges: 19 hr 35 min
> Oxidize and Final sanding: 3 hr 10 min
> Prep for finish: 1 h 25 min
> Finish: 12 h 15 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 40 min
> Mortises: 5 hr 30 min
> Sand & radius edges: 6 hr 10 min
> Oxidize and Final sanding: 1 hr 20 min
> Mask & Prep for finish: 20 min
> Finish: 2 h 45 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min
> Sand: 7 hr 35 min
> Oxidize and Final sanding: 1 hr 30 min
> Mask & Prep for finish: 40 min
> Finish: 4 h 35 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 4 hr 35 min
> Tenon: 28 hr 30 min
> Sand & radius edges: 15 hr 35 min
> Oxidize and Final sanding: 3 hr 40 min
> Mask & Prep for finish: 2 h 30 min
> Finish: 12 h 5 min

Corner Blocks
> Cut to size: 1 hr 50 min
> Shape: 1 hr 50 min
> Tenons: 35 min
> Holes: 1 hr

Frame assembly
> Remove Masking Tape: 1 hr 30 min

Total so far: 216 hr 45 min (~36 hrs per stool)

Amazing Steve. You certainly have my respect. This looks like an excellent and well thought out setup. It appears that you used a mockup stool to do your glue-up rehearsal, smart. This is bound to work out well. I look forward to seeing the grand finale!

 

[stefang]

Assembling 6 stools with pre-finished parts

After I got the parts all finished, I was really excited to do a dry fit and see how everything looked. I didn't even bother to change into any shop clothes!

As you can see, tongue position is important when dry fitting pre-finished parts.

Before I actually glued up an assembly, I dry fit the stool. The corner blocks are then set in place. The tenons on the corner blocks needed a little fitting to get them into position. Pilot holes for the screws were drilled and then the stool is disassembled. Then I set the parts out to make sure I have everything ready to go.

I also make sure the clamps and clamping jigs are in order.

Gluing up an entire stool at once requires a glue that has a loooonnnng open time. I am using epoxy. I learned about epoxy assembly from building kayaks a few years ago.

This epoxy needs to mixed in a 2:1 ratio (resin:hardener) by volume. You can use pumps to meter out the portions. Others use scales that account for the ratio and density differences. I find it much easier to measure out volumes. I use old pill bottles to do this.

I mark the left one to measure out a single part of the mixture. I then pour water to that level and transfer two parts into the right container and mark that level. I then add one more part and mark that level. I then empty the water out and dry it well. I then add resin to the first mark and hardener to the second mark.

The epoxy needs a structural filler to create strong joints. I also added a little mahogany sanding sawdust to tint the mixture. The entire tub of sawdust was collecting from sanding all the parts . I reserve some of the epoxy to pre-wet the joint and the rest is transferred to a cup and the fillers are added.

I use an acid brush to pre-wet the tenon and the mortise. This is a very thin layer as I do not want to deal with a lot of squeeze out. As I understand it, the pre-wetting allows the wood to absorb some epoxy and helps prevent epoxy being wicked away from the joint.

I then spread the thickened mixture on the walls of the mortise.

The assembly sequence is the same as described in the gluing jig post just before this one. After the parts are clamped, the corner blocks were glued and screwed into position.

The masonite surfaces on the clamping pads worked very well. I had no marks from clamping. There was very little epoxy squeeze out. When this did happen, ithe wax on the parts made clean up quite successful. The final results looks very nice.

I paid close attention to making sure all four legs were in contact with the floor after clamping. I unclamped it and it was rock solid on the shop floor. When I brought the first stool into the house and tried to rock it, there was a slight "tick-tick-tick" as I wiggled it. Rats - not perfect, but close. Shop floor must not be flat. With the next stool, I made sure I found a perfectly flat spot on the shop floor.
The second stool was dead square - even when turning 90 degrees. Brought it into the house and it was rock solid. Then I put it in place the first stool sat - "tick-tick-tick".

Ah- HA! My kitchen floor is not flat!! The rocking is really slight and goes away when I put my weight on the stool.

They look really nice and are now ready for seats.

They all look good sitting in their final home.

The finishing process took about 11 hours.

=================================================

Current time log:

Cutting rough stock: 2 hr

Legs
> Cutting to width and thickness: 4 hr 20 min
> Cut to final length: 3 hr 30 min
> Shaping: 5 hr 50 min
> Mortises: 10 hr 35 min
> Sand & radius edges: 19 hr 35 min
> Oxidize and Final sanding: 3 hr 10 min
> Prep for finish: 1 hr 25 min
> Finish: 12 h 15 min

Seat Back and Back Rest
> Cutting thin stock for laminations: 3 hr 35 min
> Prepping laminations: 8 hr 40 min
> Glue up Laminations: 3 hr 50 min
> Trim Laminated Parts: 2 hr 25 min
> Tenon: 5 hr 40 min
> Mortises: 5 hr 30 min
> Sand & radius edges: 6 hr 10 min
> Oxidize and Final sanding: 1 hr 20 min
> Mask & Prep for finish: 20 min
> Finish: 2 h 45 min

Back Slats
> Cutting thin stock for laminations: 1 hr 55 min
> Prepping laminations: 3 hr
> Glue up Laminations: 6 hr 5 min
> Trim Laminated Parts: 30 min
> Tenon: 2 hr 50 min
> Sand: 7 hr 35 min
> Oxidize and Final sanding: 1 hr 30 min
> Mask & Prep for finish: 40 min
> Finish: 4 hr 35 min

Lower rail parts
> Cut to width and thickness: 10 hr
> Cut to length: 1 hr 30 min
> Mortise: 4 hr 35 min
> Tenon: 28 hr 30 min
> Sand & radius edges: 15 hr 35 min
> Oxidize and Final sanding: 3 hr 40 min
> Mask & Prep for finish: 2 hr 30 min
> Finish: 12 hr 5 min

Corner Blocks
> Cut to size: 1 hr 50 min
> Shape: 1 hr 50 min
> Tenons: 1 hr 15 min
> Holes: 1 hr 30 min

Frame assembly
> Remove Masking Tape: 1 hr 30 min
> Dry Fitting: 4 hr 20 min
> Glue up: 6 hr 50 min

Total so far: 229 hr 5 min (~38 hrs per stool)

Well worth the efforts going by the look of them Steve. A beautifully completed project. I will bet that besides being such a good woodworker that you are also a talented engineer. This is pretty apparent from the way you work and the wonderful results you get. Thanks so much for taking us along on your stool building adventure, it was very enjoyable and educational too.