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DRilling holes in end grain of plywood.

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Forum topic by MrRon posted 04-29-2013 05:42 PM 1453 views 0 times favorited 11 replies Add to Favorites Watch
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MrRon

2859 posts in 1929 days


04-29-2013 05:42 PM

Topic tags/keywords: question

I build large scale locomotive models. They can get quite large, like 5’ long x 15” wide x 16” tall. I build them following metal working techniques, but out of wood mostly. I have a situation where I want to drill 1/8” holes parallel to the plies of 1/2” (12 mm) Baltic Birch plywood (11 ply). The holes will go through 1/4” thickness , but centered and parallel (not perpendicular) to the plies. Machine screws will go in the holes to tie it to something else. This is something that I would normally use a metal for, but due to the size of the material, a metal would be too costly. The bolted joint won’t see any great stress. I could use glue, but I want it to be able to be disassembled. Do you see any problem with drilling those holes as I’ve depicted?


11 replies so far

View 404 - Not Found's profile

404 - Not Found

2544 posts in 1655 days


#1 posted 04-29-2013 05:50 PM

I don’t see any problem with what you are proposing, especially since the BB ply is void free. The wise thing to do would be try it on a scrap piece first and see how well it works.

View DS's profile

DS

2131 posts in 1106 days


#2 posted 04-29-2013 06:02 PM

The drill bit will want to wander before it gets started. The plys will influence the bit some.
Best to use some kind of jig, or clamp your work into a drill press setup to get the holes drilled just where you want them.

A smaller diameter pilot hole will help a larger bit stay on course too.

My $0.02

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View Loren's profile

Loren

7718 posts in 2333 days


#3 posted 04-29-2013 06:10 PM

Best way to do it is use a bushing to control flexing of the
bit so it drills on center.

Have you considered threaded inserts?

A threaded insert is bigger so you can use a larger, stiffer
brad point drill which will stay on center better than a little
wiggly 1/8” drill.

-- http://lawoodworking.com

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DS

2131 posts in 1106 days


#4 posted 04-29-2013 06:18 PM

Threaded inserts are slick—and a true machine thread.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

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MrRon

2859 posts in 1929 days


#5 posted 04-29-2013 06:31 PM

Thanks for the replies. I had thought about threaded inserts, but I can go either way; insert or screw and nut. I will experiment and see which works best. I’m thinking an insert would tend to split apart the plies; looking at a 6-32 threaded insert with an OD of 1/4”. There wouldn’t be much meat left. I made a mistake. 12 mm BB is only 9 ply.

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Loren

7718 posts in 2333 days


#6 posted 04-29-2013 07:10 PM

Also, check out cross dowels (barrel nuts).

-- http://lawoodworking.com

View casual1carpenter's profile

casual1carpenter

353 posts in 1161 days


#7 posted 04-29-2013 08:30 PM

Not sure about this myself but I wonder why no one suggested coating the drilled hole with CA glue to sort of harden the area that will form {accept} threads?

View Dan Lyke's profile

Dan Lyke

1485 posts in 2810 days


#8 posted 04-29-2013 11:20 PM

Completely different wood, completely different project, but this weekend we won the Bodega Bay Fisherman's Festival Wooden Boat Challenge with a boat where the seams were joined by drilling and screwing into the center-ply of cheap 3/8” construction ply.

I’d use a proper-sized taper bit and you should have no problems when the center ply is end-grain, it’ll be a challenge when the center ply is side-grain.

-- Dan Lyke, Petaluma California, http://www.flutterby.net/User:DanLyke

View Lee Barker's profile

Lee Barker

2169 posts in 1536 days


#9 posted 04-30-2013 04:29 AM

I like Loren’s barrel nuts idea. That allows for a little oversize holes, in case the bit wanders, but positive attachment. Brilliant.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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MrRon

2859 posts in 1929 days


#10 posted 04-30-2013 03:47 PM

Here is a sketch showing what I want to do. This detail takes place in 18 places on the model. The model is of an electric loco used by the New York Central RR. I posted this because barrel nuts won’t in this case. The CA glue is an idea that I can try. The BB is for the frame of the loco which measures approximately 6×50. Alum would be too expensive to use.

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MrRon

2859 posts in 1929 days


#11 posted 04-30-2013 04:01 PM

Dan Lyke, Thanks for the pictures; sure looks like fun. I lived in San Rafael from 1966 to 1998 and used to boat on the Bay area waterways. It got to be too expensive for me, so here I am in beautiful Vancleave, South Mississippi.

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