LumberJocks Woodworking Forum banner
4K views 18 replies 11 participants last post by  KTNC 
#1 · (Edited by Moderator)
I was working on a technique for joining long 2×6s together. This requires drilling two perfectly alinged holes into the faces. I found I could not get it straight enough using a hand drill. I set up my Craftsman radial arm saw for drilling and it worked very well. Below are some pictures of the set up.

In the pictures, you'll see some short pieces joined by all-thread. These are samples. The actual boards I'm joining are 12 foot long 2×6s. Since it's too long to clamp, I'm using the 3/8 all thread and nuts to apply pressure to the glued joint.

I thought you fellow RAS users, would be interested in the horizontal drilling application.

Kerry

Sewing machine Sewing machine feet Household appliance accessory Wood Creative arts


Wood Automotive tire Gas Hardwood Engineering


Wood Gas Rectangle Wood stain Hardwood


Brown Wood Rectangle Gas Hardwood


Eye Helmet Plant Wood Organism


Wood Gas Circle Metal Concrete
 

Attachments

See less See more
12
#2 · (Edited by Moderator)
How fast does the saw turn? I am a little concerned with how safe it is to use a 3/8" drill bit at the speeds that RAS typically turn. I doubt the chuck is designed to be used at those speeds either?

Edit: I just looked up the manual for your RAS and apparently you can using it for horizontal drilling. Drilling at 3400 RPM. Yikes.

Also, glue on endgrain is not going to add much strength to the joint. What are you planing to use the longs spans for? I am not sure that this joint, even if you leave the bolts in, will even be able to support their own weight much less any additional load.
 
#3 ·
Also, glue on endgrain is not going to add much strength to the joint. What are you planing to use the longs spans for? I am not sure that this joint, even if you leave the bolts in, will even be able to support their own weight much less any additional load.
I would definitely consider adding some long dowels to this joint. It shouldn't be too difficult, and it will be much stronger than end-on-end gluing.
 
#4 ·
How fast does the saw turn? I am a little concerned with how safe it is to use a 3/8" drill bit at the speeds that RAS typically turn. I doubt the chuck is designed to be used at those speeds either?

Edit: I just looked up the manual for your RAS and apparently you can using it for horizontal drilling. Drilling at 3400 RPM. Yikes.

Also, glue on endgrain is not going to add much strength to the joint. What are you planing to use the longs spans for? I am not sure that this joint, even if you leave the bolts in, will even be able to support their own weight much less any additional load.

- Lazyman
The motor spins at 3450 RPM.

Motor vehicle Font Gas Auto part Automotive wheel system


I checked my hand drills and one has a range of 0-2700 RPM and the other 0-1900 RPM. I also checked the chart on my drill press. It recommends 3100 RPM for a 3/8 bit. The chuck is sold as an accessory for the radial arm saw, so it's designed for the RPM.

Thanks for the tip about end-grain joints. I didn't know they were inherently weak: just thought it was difficult to clamp. I'm making a 21 foot long beam out of four 12 foot long 2×6s. The butt joints will be offset 3 feet from each other and I will bolt and glue along the length. There will be only about 10 pounds of load under normal conditions. This beam is used to support a canopy. The canopy will collect some water from the rain, but I'm providing a 2" diameter drain. I think this will be strong enough for the application even if those butt end joints aren't very strong. Below are some pics of the 2×6s arranged in the way I will use them.

Wood Track Railway Working animal Metal


Wood Plant Grass Tarpaulin Automotive exterior
 

Attachments

#5 · (Edited by Moderator)
Years ago I used my RAS as a horizontal drill press and it worked great. As with all power tool applications due caution needs to be used. For instance you would not use a Forstner type bit at those RPMs.

In the application you illustrated to join the long 2X6s the but joint will fail; possibly just under the weight of the boards. I would suggest you use a lap joint, glued and screwed.
 
#6 ·
Years ago I used my RAS as a horizontal drill press and it worked great. As with all power tool applications due caution needs to be used. For instance you would not use a Forstner type bit at those RPMs.

In the application you illustrated to join the long 2X6s the but joint will fail; possibly just under the weight of the boards. I would suggest you use a lap joint, glued and screwed.

- LesB
Hi LesB:
Could you possibly provide a sketch of your suggestion. Maybe I can incorporate it before going further. Thanks!
 
#7 ·
Under your uses I doubt the end grain attachment of any kind will add to strength. I had a pole barn in Montana with scabbed out to 16 feet of 2×4 rafters (like you are proposing) that lasted many years under heavy snow load. Fasteners (especially carriage bolts) at and around the lap joints will add more than the end bolts, et.al.
 
#8 · (Edited by Moderator)
Hmm, seems like a whole lot of extra work for laminated butt joint on framing?

+1 butt joints have very low strength in tension, and typically only used with design that has joint in compression.

In some past volunteer work framing barns and such; we used connector plates on butt joint framing? They come in many forms; bolt, nail, screw on types. My favorite was nail on plate:
https://www.strongtie.com/trussplates_platedtrussconnectors/trussplates_productgroup_wcc/p/truss-connector-plates The integral nails make it thinner, and better for laminating short boards to make a long beam.
Set planks end to end, and hammer them the down.
Some building codes required minimum fastener length on connector plates, and had to use kind with holes for nails, but nail gun makes those easy too - even you miss the hole. :-0)

YMMV
 
#9 ·
For that laminated beam the glued end butt joints will not add any strength. If anything, the holes for the nuts on the end of the threaded rod weaken the beam. Skip the end glued joints. Your big overlap of the joints with adequate bolts through the beam should be plenty. Lap joints would add even more, but are probably not necessary.
 
#10 ·
Skip the end-to-end connection; totally unnecessary; will not add any strength. The 3' lap will do the work. I doubt that glue between the boards will help. The boards will not make good contact due to wood irregularities unless you can pull them tight together with C-clamps You will need a whole lot of C-clamps. Sandwich the boards between (2) 1/4" steel plates, approximately 4" wide x 24" long and use grade 8 hex head bolts and nuts spaced 3" apart staggered. Torque the bolts down. Carriage bolts would tend to loosen up with weather changes.
 
#11 · (Edited by Moderator)
I think a 21' long 3" wide and 5 1/2" high beam will sag without any load. THat's the actual dimension you will have after joining two 2×6 side by side. Don't think it would break, but I'd be very surprised if it stayed straight for very long.

Glue that does not creep is important on laminated beams, and I would consider resorcinol glue. If you can't come up with enough clamps, the boards can be glued and then screwed together. I've done a 16 long 4'x14" load bearing curved laminated beam for a bridge that way.

A common way of joining long pieces is by use of a scarf joint. Way easier and probably stronger than what you are proposing. A lot simpler than getting steel fabricated. That's how most carpenters would approach the problem, I'm guessing. Just make sure the scarf joints don't line up. Google the term and you'll see how it works.
 
#13 ·
Here's another variation on my previous suggestion that simplifies things even more: Just screw the boards together. One of the boards will need to be cut so that the joint of one board don't line up with the joint of the other board. Keep the joints of the board 4 feet apart. Use a lot of decking screws.

I remember doing a couple of framing projects where we took out an interior bearing wall on a two story building. "Sistering" up the floor joists (in this case 2×12's) is done all the time in framing and the code-approved method is simply to connect the two joists by nailing them together. I don't remember the required spacing, but lets say every 4" in two staggered rows. Those 2×6's connected this way by decking screws will never come apart.
 
#14 ·
UPDATE:

When my sample (two six inch pieces bolted/glued in picture above) dried I put it across two small boards and stood on it. It didn't break. Next, I drove my truck onto it and it broke. I thought … it can take 200 pounds but not 1000 pounds so I'll go ahead and use this technique in the long beam. By the way, I tested a similar length piece of 2×6 by driving the truck onto it and it did not break. See pictures below

Tire Automotive tire Tread Chair Wood


Automotive tire Leg Wood Road surface Asphalt


Wood Road surface Flooring Wood stain Floor


I took one of the 21 foot beams with the butt ends glued and joined with threaded rods and put it in place. I pulled down on the middle and the joint opened up after applying around 20 pounds.

Plant Wood Ladder Tree Shade


Wood Brick Wall Line Building material


CONCLUSION: GLUED BUTT END JOINTS HAVE NO STRENGTH - JUST LIKE YOU ALL TOLD ME

I proceeded with bolting and gluing the boards together and then bolted the finished beam to the tops of the two vertical posts. I hung my full weight from the middle. It didn't break and my wife said it looked like it sagged down an inch or two.

Wood Grass Denim Tints and shades Electric blue


Plant Shade Tree Tints and shades Wood


Finally, here's a picture of the finished project. It's a canopy under which I park my truck.

Plant Shade Tree Wood Fence
 

Attachments

#16 ·
If you had placed the posts inward a few feet you would have less unsupported span.

Also less racking, as you could put support braces on either side of the post.

No offense in intended but by any construction standards "sagging" and "holding a big load" are counterintuitive. That fact the beam is already sagging tells me I would go ahead and relocate the posts now before it gets worse.
 
#17 · (Edited by Moderator)
No offense taken. Totally agree that support braces are a good idea, to provide resistance against racking i.e. sideways motion, and also help lock the posts to the beam…and of course would add to the strength of the beam by effectively shortening the span. Couldn't tell from the photo how the beams are attached to the post. That might be the weak point in the OP's design. Don't know.

This is not the structure that I would have built. It begs to have the posts locked together by cross pieces, which could be 2×4s. A simple addition that would reduce stress on the joints which are the weak spots. And as you say, Robert, support braces are called for, because it doesn't quite look right without them, and historically that's how structures should look, and such architectural features have a reason. Overkill? Maybe. But its how I would do it.

Wood is quite flexible and will bend a lot before breaking. Sag looks bad, but doesn't indicate imminent failure. So when I say could support a big load, I mean vertical load. Certainly enough to support shade cloth and a few people hanging on it. I wouldn't use it for an engine hoist. If the beams come off the posts, then you've got major problems.
 
#18 ·
Why have a 21' span? Put 5th & 6th supports in the middle of each side and your span drops to 10'6" - you can buy 2×6x12's so no splicing required. The cost of the bolts and extra labor will be saved probably wiping out the cost of the 2 extra posts.

Also I agree that the end poles should move in a couple of feet to reduce the span.

M
 
#19 ·
Hi Madmark2:

Good question about the span, intermediate posts etc. I have the need to remove and reattach the tarp pretty often. There is a travel trailer (not visible in the pics) that is behind the canopy. The trailer is about 4 feet higher than the tarp. So to pull the trailer out, I stow the tarp. The tarp also can't handle snow which we do get here occasionally. My plan is to stow it if the weather prediction is for snow. I'm explaining all that because my design is for the tarp to wrap completely around the front beam and then I use ropes in tension to hold it in place. If there were intermediate posts, I'd have to have some custom made tarp that had slots in there to go around the vertical posts. The 21' overall span is because that's about how long my truck is. It also makes the horizontal beams clear for the 20×16 tarp I'm using. More reasons I didn't want intermediate posts are
- I hate digging post holes
- I didn't want any of my truck doors to hit a post upon opening.
- When I maneuver the travel trailer into place those extra posts would potentially be in the way.

Hi Sark:
I didn't use crosspieces because they would get into the way of pulling the trailer through. I was prepared to add some crosspieces if I had to though. They would have needed to be set up so as to be easily removable. Happily I've found I don't need the crosspieces.

I wanted to build a very tall permanent roof to park both the trailer and truck under. I checked with the county building department. To satisfy their requirements, it would have been a tremendously disruptive project as I already have a finished manicured lawn with mature trees, built in sprinklers and an already in-place gate. So instead I compromised by using a cover on the trailer and this canopy for my truck.

Below are pictures of how I stow the tarp when I need it out of the way. It's pulled up higher in the middle than on the ends so that rain will not accumulate.

Plant Shade Building Tree Wood


I found it was inconvenient and time consuming go keep moving a step ladder to attach these ropes so I added that scaffold/bench next to the fence that you can see in the picture from my previous post above. The horizontal beam on the grass side is 1 1/2 feet lower so I can reach that while standing on the ground.

Kerry
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top