Drilling opposing 90 degree holes through round tube

This is really two functions, cylindrical workholding versus 90-degree indicating.

Vee blocks are one suitable workholding device for cylindrical things. Use the clamps provided, or pinch the work against a vise jaw with the vee.

Assuming you don't have a precision rotary workholder like a rotary table or collet holder, you can mark 90 degrees accurately one time on your lathe chuck and thereafter hold the work in that for scribing. Or at the least you can wrap paper around the tube and divide that as a template.

Sounds good to me.

Here's another grizzly item I noticed in their catalog the other day that could help with that set up...

If the tube is small enough so you can get it with a 5C collet, you can use one of the handy square 5C collet blocks held against a vise stop in the milling vise. When you're done with one hole, loosen the vise, flip the block, slide it against the stop, tighten the vise and do the other hole.

Like this one:

Cheap spin indexer?

Gunner

Political Correctness is a doctrine fostered by a delusional, illogical liberal minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Or simply drill/bore the proper sized hole for your tube, in the center of a rectangular block of steel, drill a hole in each of two sides, slide in the tube, drill, drop in a pin, turn the block over to the next hole and drill the second hole. Pull the pin, slide in the new tube, and repeat.

Cost is nothing to speak but about a half hour of your time

Gunner Political Correctness is a doctrine fostered by a delusional, illogical liberal minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Depending on the size and quantity of holes, use wood. It is cheap, easy and can hold tighter tolerances than you might think. To hold a tube, just drill a hole then cut a slit on the side of the wood that will not be in the vise, put a screw in for tightening. If you have trouble with the drill wobbling on the tube, go with a short bit or epoxy in a drill jig bushing. For small parts, I buy 2x2 hardwood blocks from Home depot, a cheap fix for holding parts that are easy to deform. Good for stand-offs as well.

A simple way is to clamp the tube into the vee of angle iron and locate off the two flat sides. You can find the center by lightly pressing the middle of a 6" ruler against the tubing with the point of a drill. The drill is centered when the ruler sits level.

That gives good drill-press accuracy if done carefully, but nowhere nearly as accurate as a milling machine and an index or collet fixture.

replying to Gunner Asch, The Grumpy Army retiree wrote: Wow, I just sent your quote to my wife and a few friends....I think you hit the target "spot on" ...you're making my ribs hurt over here from laughing too hard!