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Glue-up a Fence for a TS Crosscut Sled

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Forum topic by gmaffPappy posted 05-08-2019 12:35 AM 1096 views 0 times favorited 15 replies Add to Favorites Watch
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gmaffPappy

78 posts in 2511 days


05-08-2019 12:35 AM

Topic tags/keywords: jig question trick tablesaw glue-up

I’m making William Ng's crosscut sled.

In the video he says the key is to do the clamp the glued fence pieces to a surface that is absolutely flat. Makes sense! He doesn’t use the TS or Jointer top, as they are hard to clamp to. He used a jointed and planed 12/4 piece of Maple to make a clamping table. I know where to get that, and the lumber yard will joint and plane it for me. With that, he can put clamps on all 4 sides of the blue-up.

All sounds reasonable, until I realized that piece of lumber would be VERY expensive!

Other options?

I’m making two fences (front and back)

I was considering putting down some wax paper down on the table saw. Put the glued up Baltic Birch pieces (front and back fences) face up, side by side, on top of the paper. Then cover with another piece of wax paper and a couple larger pieces of Baltic Birch, to evenly spread the top pressure across the two fence pieces, then pile sand bags on top.

Would this provide enough pressure to create a solid and flat glue-up, or should I look for another method?

I know clamps will provide an enormous about of pressure, and that pressure can be spread by sandwiching the pieces between to materials. It would take a ton of sandbags to equal the pressure provide by the clamps, and a “Ton” of sandbags would just be silly. But is a “Ton” really needed? Math says the clamps are better, but would a few the bags be sufficient?

Or, should I just bite the bullet, buy two 12/4 Maple and dedicate them for glue-ups. Sandwich this and future glue-ups between them. If that’s the case, how wide should they be. What’s the average width of your face to face glue-ups?

Other suggestions for creating an “absolutely flat” glue-up, please….

-- If it's easy to do, you haven't spent enough time over engineering it.


15 replies so far

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BlasterStumps

1390 posts in 920 days


#1 posted 05-08-2019 01:54 AM

I doubt if I can assist with the question but am hoping you will share a picture or two of your finished sled when you get it done. I made my sled with mdf. The front fence is a single piece and the rear is two pieces. I haven’t noticed any problems with it but maybe baltic birch would be better and maybe lighter. However, I can’t find the good 11 ply stuff in my area.

-- "I build for function first, looks second. Most times I never get around to looks." - Mike, western Colorado

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MPython

163 posts in 292 days


#2 posted 05-08-2019 12:38 PM

Maple wold be great for the task; but, like you said, it’s expensive for such a utilitarian use. If it were me, I’d stack two pieces of good quality 3/4” plywood and add a top layer of 3/4” MDF. MDF is very flat. All you need is a reasonably flat foundation of some sort to keep it from sagging. FWIW, I’ve made several glued up sled fences. I laid down a piece of MDF on my workbench top and clamped the fence lamination to that. Worked fine.

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Robert

3516 posts in 1961 days


#3 posted 05-08-2019 01:18 PM

Well you can clamp to your table top. Place a board underneath to deal with the webs.

But I would also mention that IMO every shop should have an assembly bench with a perfectly flat top.

All this said, I made my sled fence out of solid wood and simply jointed it. If you have a piece of lumber that is nice an acclimated and preferably quarter sawn you won’t have an issue with the fence staying flat.

-- Everything is a prototype thats why its one of a kind!!

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Anth0ny

2 posts in 144 days


#4 posted 05-08-2019 03:13 PM

I agree with the comment about having a flat assembly bench or a dead flat workbench. I use my Roubo style workbench for clamping all the time. This bench is dead flat as I do lots of work with hand planes and it has to be dead flat.

If neither of those are an option I would devise a way to clamp to your tablesaw wings. I personally don’t think weights are heavy enough to get the right amount of clamping pressure. The hydraulic nature of glue will keep those parts separated unless you apply a good amount of force to them.

View CaptainKlutz's profile

CaptainKlutz

1761 posts in 1974 days


#5 posted 05-10-2019 09:45 AM

Creating a flat surface for glue up can be challenging, but IMHO challenge is only costs.

1) Make you own 3” thick laminated butcher block slab any size needed (sort of like small bench). Use any hardwood you get cheap. even old pallets. A board foot of lumber doesn’t change regardless of shape, but the out of pocket cost for 4/4 laminated wood is fairly low compared to premium 12/4 slab of maple.

2) Use a hunk of aluminum tool plate. Any decent metal supply offers nice 1-2” thick 6061 cast aluminum plates that are machined flat during manufacturing. My local place has remnant pieces up to 3 ft square sold by pound in scrap bins. I have a couple I use as base plates for vacuum bag work (veneer and epoxy composite lamination).

Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View gmaffPappy's profile

gmaffPappy

78 posts in 2511 days


#6 posted 05-12-2019 03:38 AM

So, here’s my solution. Use the TS as the base. Put a 30” X 60” X 3/4” Birch HW sheet down. cover in Saran Wrap. Applied glue to joining sides of 3 4” X 30” X .2” Birch HW. Covered that with Saran Wrap and stacked 3 more glued up. I surrounded the glue-up with stacks of scrap that equalled the glue-up. Topped it off with another 30” X 60” X 3/4” Birch HW sheet. The final sheet was totally supported and parallel with the first.

I then slid the assembly over the edge of the TS and clamped it all up. The final piece was to use 2” X 4”’s to protect the sheets from the clamps, and I started clamping in the center and moved outwards with 8 clamps. Then repeated with 8 more, starting from the middle. Finally, 24 clamps the job is done….I hope.

Hopefully, this will result in solid and flat fences.

Critiques….PLZ – Predictions on results…...How else will I lean?

-- If it's easy to do, you haven't spent enough time over engineering it.

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Woodknack

12890 posts in 2860 days


#7 posted 05-12-2019 03:40 AM

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RJweb

132 posts in 3113 days


#8 posted 05-12-2019 05:53 PM

In the video he shows how to make 5 cuts for aligning the sled, does he have a vide or plans for making the sled?
Thx RJ

-- Life Begins @ 190 MPH

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gmaffPappy

78 posts in 2511 days


#9 posted 05-12-2019 06:58 PM

No, I’m just following what he did in the vid. There’s only a couple things that’re really missing:
1. The height of the fences. I’m making mine 4” tall. It just needs to be tall enough to receive a full height through cut over the TS and still have enough left to be solid and hold the two base pieces together. The same with the front fence.
2. Thickness of the base of the sled. I chose 3/8”.
Also, I’m also not making my fences curved like his. I’m going to put T-Track on the top the back fence, so it needs to be flat.

-- If it's easy to do, you haven't spent enough time over engineering it.

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gmaffPappy

78 posts in 2511 days


#10 posted 05-15-2019 02:36 AM

It looks good, and is within 5/10,000 of an inch per inch. That’s pretty good.

I’m going to make a blade guard for the back and not do the clear plastic chip shield. That plastic is expensive…..but you know, not as expensive as a trip to the Dr. I’ll think more about it.

-- If it's easy to do, you haven't spent enough time over engineering it.

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therealSteveN

3625 posts in 1054 days


#11 posted 05-15-2019 05:21 AM

There is something to be said while building everything you will need in a shop to make a very well constructed pair of these You would want to locate them on a part of your floor known to either be dead flat, or build the saw horses dead flat to a spot in the floor.

Once you have these as your base, it’s nothing to use them to fabricate a torsion box top for them, so you have a quickly made flat surface to work on, until you get a decent bench made.

Even after you have a bench, these horses, and the top you’ve made are valuable for an extra flat, known surface to cut on, assemble on, whatever. Top off, and horses stacked they can be stored in a smaller footprint than a bike.

On the blade guard thing, remember you do NOT need to see the blade inside the guard, just know it’s there. Using some BORG 2×4 glued up to make a solid block works well.

-- Think safe, be safe

View Lazyman's profile

Lazyman

3876 posts in 1868 days


#12 posted 05-15-2019 12:33 PM

IMO, the curves in the fence are pretty handy. They make it a lot easier to clamp things down especially stop blocks for repetitive cuts. I didn’t put the plexiglass blade guard on it either. I thought it would be in the way most of the time and make it harder to use. Definitely put something on the backside of the fence, if nothing else as a reminder to keep your hands away from the where the blade exits. When you are holding something to the fence by hand, it could be easy to forget that a blade is about to come through the back. I simply glued a double thick piece of plywood there that extends far enough back so that when the blade is at maximum height it still does not come through when top of the blade hits the fence.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Monte Milanuk's profile

Monte Milanuk

11 posts in 4173 days


#13 posted 07-01-2019 05:26 PM

My first attempt at following his video, I figured ‘plywood is flat enough’, and didn’t use any kind of clamping caul or beam. The result… was a nicely glued up piece of scrap, after I put a straight edge against the front face :(

Second go around… I found that regular cold-rolled steel tubing is pretty straight, dimensionally. The individual faces may not be completely flat from corner to corner, but along the length, they are more than flat enough for this purpose. As luck would have it, the previous home-owner had left a ~3’ chunk of 4” square tubing behind (he’d had it secured to the ceiling joists to aid in rigging heavy pieces onto the table of his mill). I put my Lee Valley/ Veritas steel reference straight-edge down the face… not a hint of light peeking under.

The second glue up went flawlessly using that piece of steel as a clamping beam, FWIW.

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ArtMann

1425 posts in 1296 days


#14 posted 07-01-2019 09:04 PM

That is pretty good indeed! How did you measure that parameter? Table saw tables are nowhere near that flat.


It looks good, and is within 5/10,000 of an inch per inch. That s pretty good.

- gmaffPappy


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gmaffPappy

78 posts in 2511 days


#15 posted 07-01-2019 09:09 PM

It’s a simple formula. I used feeler gauges to determine how far out of square I was and made that part of the ratio from my set pivot point to the point at which the measurement was made.

If you take in the whole video, he goes into depth on all the calculations and application of the technique.

-- If it's easy to do, you haven't spent enough time over engineering it.

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