[How do I?] How do I Line Bore Square Tubing?

I have NOT used an annular cutter, but that makes sense....why turn the entire circle into chips, it's more work.
I was going to suggest a hole saw.
11 gauge is only about 1/8", perhaps a step drill would do it quicker.
-brino
 
I've used Blair Rotabroaches to do exactly what the OP is proposing. I've used drills, hole saws and Unibits to do it, too, and the Rotabroaches are the fastest and cleanest way to make large holes in steel tubing in your home shop. A drill press jig makes it easy to work with precision and you can duplicate the hole location on both sides of the tube easily. I own sets of these cutters but you can buy them individually to cut costs. These cutters beat a S&D drill or Unibit, hands down.
 
I would do that with a drill jig that locates from the previously drilled hole and straddles the tube snugly and use the annular cutter. A drill would wobble in the hole unless tightly restrained in a hard bushing, and the annular cutter would give you a clean accurate hole.
 
RonRock said:
So my son wants to build a weight machine. Should be a good project, we'll work together and both learn some skills.

First thing is figuring out how to bore series of 1" holes in a 90" length of square tubing. Six times! Similar to what would have to be done for an adjustable shop press, as well as other items.

The "Machine" will have 6 legs (uprights) that will have different styles of pegs or standoffs that need to be adjustable in height. So the holes have to be very accurate positioned with each leg.

The material is 11 gage 2 x 2 mild steel. Would prefer to not drill/machine clear through. Might need to do front and side on corner legs.

I have a Bridgeport with a dro and of course a stand up drill press. I figure that the BP will be the machine to use, but the length of the tube is going to be an issue. The DRO may not be the best help in this instance because of the number of holes, and the need for 6 pieces to match. I'm thinking some kind of jig to locate a series of holes after the first one is done. Then the lengths could be adjusted to match. Or simply accurately drilled the first hole.

Any thoughts?

As a little kicker to the project, he has mentioned Keyholing the holes if possible. That would compound the project, so not sure on that.
Click to expand...
I had to make a series of parallel 1" holes in several pieces 1 x 6 aluminum that were approximately 4 feet long (see photo). These were going to be used to construct an assembly table so they had to be exact. Here's a photo:
288494

The project was time-consuming and a little cumbersome but conceptually, not difficult. I'll do the best I can to explain how I did it.

  1. You won't be able to use your vise for this project. You'll need a piece of metal or wood to make a fence for your milling table. I don't recall exactly, but I think I used a piece of 5/8"x4" aluminum a few inches shorter than the length of my mill's table (49"). After a little tweaking, it fit very snugly into the rear T-slot on the mill.
  2. Block and clamp the piece you're going to drill both against the fence and onto the milling table. If you are not milling all the way through, it won't be necessary elevate the work piece. Otherwise, you'll need to block up for drill bit/mill/reamer clearance. Make sure you allow yourself a method to exactly indicate your work piece on the first cut so that all pieces will be uniform. My recollection is that I used the edge of the fence to do that. If you do it that way MAKE SURE YOU DO NOT MOVE THE FENCE UNTIL THE ENTIRE PROJECT IS FINISHED. If you do, you'll lose your reference point.
  3. Lock the y-axis, and use your DRO to mill as many of the holes as possible along the x-axis in the normal fashion.
  4. Now comes the tricky part. IN THIS ORDER, (a) turn OFF the DRO; (b) keep the quill down so the cutter is STILL IN THE LAST HOLE; (c) loosen the clamps on your work piece; (d) HAND TURN the x-axis all the way back (so you're sliding the table, but not the work piece); (e) re-clamp the work piece; (f) turn ON the DRO; and (g) start milling again. If your DRO is like mine, it will still measure from the last reading. Alternatively, you could simply re-set the DRO to zero and still arrive at the desired result. Repeat this process as many times as is necessary to mill all the holes.

There are some drawbacks to this method: First, it is definitely time consuming. Especially, as was my case, if more than one step is required, such as drill first/then follow with a reamer. Second, if you're working with 90" pieces, you'll need a lot of clearance on both sides of your mill to accommodate the length. Third, you need to be very careful that the fence fits tightly into the T-slot and is clamped rigidly. If it flexes or wobbles, your holes won't line up perfectly. My project required 23 pairs of holes, plus two mounting holes on each of fifteen pieces. Counting drilling and reaming, that's a total 1,380 independent operations to complete the project. It took a lot of time and patience, but it turned out great! Didn't need to re-make a single one. (I consider that a miracle.)

Hope this helps.

Regards,
Terry
 
If I were doing it I would have a piece of plate and weld a pin the same size as the hole you want on the plate in a spot where it can still be easily clamped to the table.
Then I would cut the tubing longer than needed.
Drill your first hole roughly at the end . It could be 3" 4" whatever doesn't matter at this point. Just make sure its centered width wise and you are able to drill all pieces.
Remove your vice
Clamp your plate to the table with the correct spacing for the holes. You can move the table back and forth to get it exact.
clamp all axis
insert the first hole in the pin and start drilling. Keep moving after every hole.
Then mill them to length after
I would also use an annular cutter

Hope this is clearer than mud
Cheers
Martin
 
Martin W said:
If I were doing it I would have a piece of plate and weld a pin the same size as the hole you want on the plate in a spot where it can still be easily clamped to the table.
Then I would cut the tubing longer than needed.
Drill your first hole roughly at the end . It could be 3" 4" whatever doesn't matter at this point. Just make sure its centered width wise and you are able to drill all pieces.
Remove your vice
Clamp your plate to the table with the correct spacing for the holes. You can move the table back and forth to get it exact.
clamp all axis
insert the first hole in the pin and start drilling. Keep moving after every hole.
Then mill them to length after
I would also use an annular cutter

Hope this is clearer than mud
Cheers
Martin
Click to expand...

Thanks guys. I think this is what I'm going to try. I plan to use a piece of angle clamped to the mill table another on the opposite side of the tube. With a strap with a locating pin bolted to them. Maybe spring load the pin, maybe not. Just thinking that a spring loaded pin might be faster and easier than removing the bolts that the strap will have.

Well as I was typing I got to thinking, took another look at the quoted text and it makes more sense to have the pin clamped to the table. Since I am drilling clear through I can have the locating pin on bottom. That takes out a lot of possible slop in the setup. And raises the tube off of the table at the same time. Should be easy.
 
Well this project has been slowed to a stop. Damn winter!

But things have changed in the design also. So now the holes are going to be either 5/8 or 3/4" holes. Either will be plenty strong for the shear strength needed, and should be easier to drill. Still plan to use 3" square 11 gage tube. So now I have to figure out how to drill a 5/8" or 3/4" hole through 3" tube. Still leaning towards a annular cutter if I can find one that will go that deep. I'd buy or make an extension for the extra length, but I think that the "hub" that locks onto the cutter shank would be larger than the hole. So by dropping down in hole size I have another problem.

Any thoughts? Have I missed the annular cutters that will go deeper? Or one with a smaller shank?
 
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