More help

[digr]

I want to drill 1 1/16 holes in 4" and 6" thin wall tubing to except the two pieces of pipe one on either side and cut the 3/8 slots also. I know that I will have to build a fixture to hold the pipes which will be quite a job in itself. I will have to have something that I can drill one side and turn it over, index it and drill the other side and the same with the slot. I have many of these to do so a jig is a must. The slot is not a problem but as far as the 1 1/16" hole what options do I have such as a core drill or what. And I am open for ideas on the fixture also. I used a hole saw before I got this mill ,but doing it that way is quite slow. I plan to leave the slots closed at the ends until done than grind the remainder away.

[sbi1]

http://www.acetoolonline.com/Champio...SAW-s/8182.htm

This is what I have used to drill holes that size in sch. 80 pipe for heavy jack stands. Worked very well for that application, should work on thinwall too.

[GWIZ]

How long is the part ?
What material is it ?
Why do you say grind ?
Can you give us an idea of what tolerance you want ?
Is it a thru 4", 6" hole?

"thin wall tubing " how thin is it "

[GWIZ]

Here's a start. see picture.

Don't forget you need room for clamps that hold the part.

You will also need to use a jack-screw or tail-stock (aka center).


Don't drill the 1-1/16" hole thru the fixture if you don't need too.
If needed to can add a clamp in that hole.

[digr]

Originally Posted by GWIZ

How long is the part ?
What material is it ?
Why do you say grind ?
Can you give us an idea of what tolerance you want ?
Is it a thru 4", 6" hole?

"thin wall tubing " how thin is it "

Large pipes are steel tubing and the small pipes are welded so the fit can be loose, the slots can be anywhere from 3/8 to 1/2 and is about 1/16 wall and 15 long. If I don't leave the bottom of the slots closed there is a problem with distortion when the top, bushings, and gussets are welded on.

[digr]

This is what I had in mind, I think it will work but the only draw back is that it will take some time to get another part ready to go,

[GWIZ]

If you don't clamp the part to the index hub, the part is not going to turn with it.

Assuming your good with sharpening tool bits.
I was going to say use a circle cutter for the 1-1/16" holes, but without support for the holes a sharp hole saw is about it.

[digr]

Originally Posted by GWIZ

If you don't clamp the part to the index hub, the part is not going to turn with it.

Assuming your good with sharpening tool bits.
I was going to say use a circle cutter for the 1-1/16" holes, but without support for the holes a sharp hole saw is about it.

I thought about that right after my post. Maybe I will have a small tab on the hub and grind a small slot into the pipe and fill it when the top is welded on. I am going to order one of those carbide hole saws and try it out.

[OLD MAN]

I use a pilot hole all the way through, and then a step bit to the size needed, works very well.

[GWIZ]

"I am going to order one of those carbide hole saws and try it out."

Its a tough call on that saw in the post.

It doesn't appear to have alot of teeth. your going to be cutting thin metal on a curve, the teeth may catch as you break thru and continue to catch until you finish.
My thinking, the large amount of teeth on a regular hole-saw and shape and width, will lessen the catching.

Adding more supports will help keep you out of trouble.

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For your slots, I would use a 4 flute end mill.