What size hole saw do I need for 3/4" pipe?

chad22 · Jan 17, 2011

I've probably already answered my own question.

I'm kinda stuck on this. I'm needing to drill a hole to insert a 3/4" pipe to use as a bushing. What size of hole saw do I need to make this hole?

If my math is correct I'm thinking 1-1/2" is the size of hole saw I would need so the outer diameter of the pipe will insert into the hole? I just want to make sure I buy the right size hole saw.

Forgive me. I was staring at the pretty girls in school instead of my math book. So math isn't exactly my forte. :laughing:

Thanks

Chad

brandoro · Jan 17, 2011

1-1/8" hole saw is used for 3/4" electrical conduit. What kind of pipe are you using?

k0ua · Jan 17, 2011

It is a hard question. I am going to make some assumtions.
steel pipe sch 40. nominal should be about 1.050 inches. so use 1 inch hole saw if sawing in wood, then ream/sand as neccessary if you want an interference fit, if you just want a big hole it will fit into then maybe 1 1/8 or 1 1/4 would be fine. I will never forget the 2 girls that sat behind my row in math class. I needed to turn around a lot and check on them:laughing::laughing:

James K0UA

chad22 · Jan 17, 2011

I'm using 3/4" galvanized water pipe. I used 1" hole saw and it was too small.

k0ua · Jan 17, 2011

Then my 1.050 should be pretty accurate, put your dial calipers on it and find out... If you dont have any, you should get some, they are about 12 bucks. and then you will always know how big something is from 0 to 6 inches..:thumbsup: Harbor freight ones will be ok.. or any machine tools store. if you want good ones. There are just certain things a man should own in this world, and an inexpensive set of 6 inch dial calipers are one of them.

James K0UA

Jw5875 · Jan 17, 2011

Hope this helps!

Pipe Chart

JW5857

k0ua · Jan 17, 2011

yes it should be 50/1000 too small, thats why I said ream/sand to get and interference fit, if you use the next size up 1 1/8 it will be to large, at 1.125, and I understood you wanted to use this as a bushing..?

James K0UA

k0ua · Jan 17, 2011

you should be able to ream a piece of wood with the 1 inch hole saw by running the hole saw back and forth while "wiggleing" the hole saw some in the hole to "ream it out some. in other words make the hole a little larger by 25/1000 on each edge, for the total of 50/1000 of an inch you need for a tight fit in the wood..if that is what you are looking for. if you just want the steel pipe to fit through the hole then 1 1/8 or 1.125 is what you want, but it will be a very sloppy fit.

James K0UA

k0ua · Jan 17, 2011

By the way, maybe if you told us what you are building, we could reply better, I assumed you wanted a tight fit of the pipe in the wood, since you mentioned bushing. you may be able to just drive the 3/4 pipe into the 1 inch hole, if the wood you are using is strong enough, by greasing the pipe and hit the end of the pipe with a hammer.

James K0UA

chad22 · Jan 17, 2011

This is for my backhoe I'm building.

I want to stick the pipe through a piece of steel square tubing, weld it in there and put a bolt through the pipe. So I guess if the hole is a tiny bit big I can weld around it.

I might be able to force the pipe through the 1" hole but doubt it.

I have another question. Which is bigger and which is smaller?

The 1-1/4" hole saw, the 1-1/8" hole saw?

Chad

k0ua · Jan 17, 2011

The 1 1/4 is the larger, the 1 1/8 is the smaller.
in decimal the 1 1/4 is 1.250 inches and the 1 1/8 is 1.125 inches

I guess I just assumed you were putting the 3/4 pipe into wood not metal. so the 50/1000 or in decimal .050 will not be so easy to achieve in metal as wood. so yes I see your problem... use the 1 1/8 hole saw. of if you can find a 1 1/16 inch hole saw that would be better, but I am not sure they make one..

James K0UA

Willl · Jan 17, 2011

chad22 said:
I have another question. Which is bigger and which is smaller?

The 1-1/4" hole saw, the 1-1/8" hole saw?

Chad

OK, where's the cameras ?, it's a trick question ain't it ?

Buy both saws and do a test hole. Regardless what it says on the bit, it's not what your going to get. (holesaws only)

CurlyDave · Jan 17, 2011

The 1-1/8 hole saw is smaller and is the right clearance hole for the pipe.

Most people would use a piece of DOM (Drawn Over Mandrel) tubing for this application. The ID is much more precise and is also smooth compared to a piece of 3/4" pipe.

k0ua · Jan 17, 2011

1-1/16" Hole Saw by Lenox - K17L - More Hole Saws at doitbest.com

Well looks like Lennox makes an 1 1/16 hole saw. I dont have one, but looks like they exist. this is what you want.
your pipe should be 1.050 nominal size, and 1 1/16 is 1.0625. so the pipe should slip in and weld nice.
James K0UA

chad22 · Jan 17, 2011

Willl said:
OK, where's the cameras ?, it's a trick question ain't it ?

Buy both saws and do a test hole. Regardless what it says on the bit, it's not what your going to get. (holesaws only)

:laughing: Sorry I wrote a confusing question. :confused2: lol I guess I should have asked. Which hole saw is smaller? The 1-1/4" or the 1/1/8" ? :laughing:

Even though I got the answer to the question, is this question better worded?

I know the original question was confusing even to me.

Chad

k0ua · Jan 18, 2011

Well I think you got your answer, that the 1 1/8 is the smaller of the hole saws, and I think what Will was getting at is that a hole saw is an inprecise "hole cutter" at best, and that the stated size may not be what size hole you wind up with, and a lot depends on what kind of material you are cutting and the fact that the pilot drill kinda reams out its own hole making the hole saw uncentered after a period of time. In other words the longer you drill the wider the hole becomes. did that make any sense? if you are going to use a hole saw for drilling large holes in metal, go very slow, and use a lubricant (even wd40 will help) to keep the saw cool as you can, they burn up pretty easy. good luck.

James K0UA

mjncad · Jan 18, 2011

k0ua said:
1-1/16" Hole Saw by Lenox - K17L - More Hole Saws at doitbest.com

Well looks like Lennox makes an 1 1/16 hole saw. I dont have one, but looks like they exist. this is what you want.
your pipe should be 1.050 nominal size, and 1 1/16 is 1.0625. so the pipe should slip in and weld nice.
James K0UA

I was going to suggest 1-1/16" hole saw and I have one. You have to get them online from places that carry a good assortment like McMaster-Carr or MSC Direct. Home Cheapot and Lowe's don't carry hole saws in 1/16" increments.

Willl · Jan 18, 2011

If it don't say Bimetal, don't buy it.

Lube, lube, lube.

RPM. If you can't maintain 200+- R's or below, your going to smoke 'em.

k0ua · Jan 18, 2011

I am not sure what your situation is, but if you already have a 1 inch hole through the material you are trying to drill, you are going to have trouble getting a 1 1/16 holesaw to drill a hole over this hole. as you have no material for the pilot bit to go into. If you can get the part into your drillpress vise, and chuck up the holesaw into your drill press, perhaps you could get this done, but it wont be easy. Have you looked into getting a Silver and Demming drill set? These are large diameter drill bits with reduced shanks to fit you drill press. Perhaps you could find one of these. Another option is sanding drums and reaming carefully out the hole you already have. You have 50 thousanths of an inch to get rid of, and it is difficult to do with a sanding drum/drums but it can be done and is another option. Good luck and let us know how you come out.

James K0UA