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Radial Arm Saw - horizontal drilling

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Forum topic by KTNC posted 09-20-2019 02:32 PM 454 views 0 times favorited 18 replies Add to Favorites Watch
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KTNC

119 posts in 769 days


09-20-2019 02:32 PM

Topic tags/keywords: radial arm saw ras horizontal drilling drilling with ras drilling with radial arm saw butt end joint butt joint long board

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


18 replies so far

View Lazyman's profile (online now)

Lazyman

3987 posts in 1901 days


#1 posted 09-20-2019 02:51 PM

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.

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

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theart

134 posts in 1068 days


#2 posted 09-20-2019 04:24 PM


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.

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KTNC

119 posts in 769 days


#3 posted 09-20-2019 04:32 PM



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.

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.

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LesB

2206 posts in 3956 days


#4 posted 09-20-2019 04:41 PM

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.

-- Les B, Oregon

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KTNC

119 posts in 769 days


#5 posted 09-20-2019 04:51 PM



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!

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Jack Lewis

494 posts in 1591 days


#6 posted 09-20-2019 05:22 PM

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.

-- "PLUMBER'S BUTT! Get over it, everybody has one"

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CaptainKlutz

1898 posts in 2007 days


#7 posted 09-20-2019 11:02 PM

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

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

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Kazooman

1364 posts in 2465 days


#8 posted 09-20-2019 11:18 PM

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.

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MrRon

5721 posts in 3757 days


#9 posted 09-22-2019 02:02 AM

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.

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Sark

200 posts in 873 days


#10 posted 09-22-2019 05:35 AM

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.

View KTNC's profile

KTNC

119 posts in 769 days


#11 posted 09-22-2019 02:14 PM

Thanks everyone for your suggestions! I’ll be finishing up the project this week and I’ll post an update here.

Kerry

View Sark's profile

Sark

200 posts in 873 days


#12 posted 09-22-2019 04:36 PM

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.

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KTNC

119 posts in 769 days


#13 posted 09-28-2019 02:30 AM

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

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.

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.

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

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Sark

200 posts in 873 days


#14 posted 09-28-2019 02:41 AM

Thanks for posting the results of your labor and design and testing! Looks great. Bolting the two pieces together surely makes the entire beam permanent. May sag a bit, but could hold a big load.

View Robert's profile

Robert

3541 posts in 1994 days


#15 posted 09-28-2019 12:34 PM

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.

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

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