holes for black pipe (drilling odd sized holes)

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Forum topic by crossedout posted 02-25-2010 03:32 AM 5868 views 0 times favorited 9 replies Add to Favorites Watch
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6 posts in 3050 days

02-25-2010 03:32 AM

I am loving LJs. Lots of quick help out there. Here’s my next question:

I’m working on a franken – Rubo / New fangled styled workbench. It will have the pipe clamp workholdings like the new fangled with the thick heaviness.

I’m using a solid 5” thick top and want to drill holes thru the center at 6”/6”/6”/6”/12”/12”/40” to put in 3/4” pipe clamps. I’m trying to drill the right sized holes thru each layer of the lamination of the top. But the OD of the black pipe is just larger than 1 1/16 inch. I can’t find a drill bit that will make this fit snugly, but not tight. I used a 1 1/8 inch paddle and forsner bit, but they both are a bit sloppy.

How does one make a properly sized hole when there doesn’t seem to be a drill bit to fit? I’ve used the “wiggle the smaller paddle bit around in the hole to make it a bigger hole” method, but I don’t want it to be sloppy. Several layers with the same hole need to be glued together and lined up.

Thanks for your help.

9 replies so far

View jayjay's profile


639 posts in 3043 days

#1 posted 02-25-2010 03:55 AM

If you have a grinder, you could grind a little off the outer edges of the 1-1/8” spade bit. Those bits are relatively inexpensive, so modifying one wouldn’t be a big deal.

-- ~Jason~ , Albuquerque NM

View Dennis Fletcher's profile

Dennis Fletcher

467 posts in 3052 days

#2 posted 02-25-2010 04:03 AM

Do they make metric bits? If they do, I would think this would be the right way to go.

--, Making design and application one. †

View albut's profile


56 posts in 3689 days

#3 posted 02-25-2010 04:13 AM

drum sander on drill to over size hole a little bit,42500,42501

View John Ormsby's profile

John Ormsby

1285 posts in 3734 days

#4 posted 02-25-2010 04:17 AM

You can drill the holes a bit smaller and then use a router and jig with a template guide and long bit. You can then clamp the jig to the table top and make the holes cleanly. You can most likely reach to the middle of the table and flip it over and repeat the routing.

-- Oldworld, Fair Oaks, Ca

View jerseyshore's profile


15 posts in 3454 days

#5 posted 02-25-2010 04:24 AM

Try using a hole saw 1 1/8 ” is standard for a 3/4 pipe; make sure your pilot bit is sharp, use very light to medium pressure after you sink the pilot bit.

View crossedout's profile


6 posts in 3050 days

#6 posted 02-25-2010 06:42 AM

Wow. This is probably the most active forum (of any topic) I have ever looked at. In addition, the general attitude is very humble and extremely helpful. Many other forums it is “I know more that anyone” attitude. I love it.

Great suggestions everyone.

When I took another look i realized I had my measurements backwards (question still remains the same). Instead of being just a little over 1 1/16 it is just under.

I think I will try the suggestion of grinding down a 1-1/8” bit. Could be fun even. (It probably took a machinist to think of that one (Thanks JayJay)). I’ve tried the hole saw, but it was a little big.

View Gary's profile


9331 posts in 3430 days

#7 posted 02-25-2010 06:59 AM

You can buy 1 1/8 auger bits.

-- Gary, DeKalb Texas only 4 miles from the mill

View Westy's profile


6 posts in 3110 days

#8 posted 02-25-2010 08:18 PM

The OD for 3/4” pipe is 1.050 which is less than 1 1/16” (1.062), so the 1 1/16 dia should work.

-- I finally got it together, but now I can't remember where I put it.

View unisaw2's profile


209 posts in 3032 days

#9 posted 02-25-2010 10:32 PM

MLCS has a forstner bit that is 1-1/16” that I used to install rigid electric pipe. They are around $7 each and cut very clean holes. They have a good selection of sizes. (1-1/32” etc)

-- JJ - Northern Illinois

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