I have a 36" diameter x 1/2" 316 SS disk, with a 18" hole in the enter (its a big Orifice Plate, for metering natural gas).

I need two 1/4" holes bored from the outside edge of the disk to the center opening...so each 1/4" bore will need to be 12" deep.

I'm in DFW. Any idea what kind of shop could do this and how much it might cost? I called a couple of local machine shops and they were WFT?

We are turning it into a Fire Table and the holes will be for the propane supply to the center. the burner itself will be an 18" bowl (a bowed orifice plate) and we need to get gas there "magically" with no visible lines.

This is a tough one.

I thought about it some more. I have what is needed to do it. But, I can't guarantee the bit won't walk toward the end of the cut. That's why this is so tricky.

Meaning the bit might end up out of the side of the plate instead of the center 18" opening.

Laser beams, we need freakin laser beams!

Tell me again how long the bore will be from the outside Ø to the inside Ø? I come up with 9"

Better off to TIG weld the two new stainless feeder tubes underneath, with fittings on the outside edges.. That's simple for any quality shop.

I get 9" cut too -
a good drill press with at least 12" opening and THREE passes with progressively longer 1/4" drill bits ( 4", 7", 10") assuming 1" in the chuck?

also assumes you can hang the bottom of the piece below the base, and might need a bit more than 12" opening depending on base of the press & inside curvature of the work piece.

Send two drawings to the shops that you have already talked to. One of the piece in it's current state, number it. Send another drawing of the final piece with the thru holes. Note on the finished drawing "made from ______" and fill in the number of the drawing number of the piece in it's current state. Draw it in 3rd angle projection. Let them know you will be providing the "made from" piece. Tolerances on the thru hole Ø to be -0/+ .010". The thru Ø should be > than the tubing by .010". Any machine shop can do this.


PM me if you want drawings, I'll tell you what they need to look like.

Machine shops see drawings like this all day long, they'll know exactly what you need.

I could do this in my shop, but I'm probably 7-8 months out on working it in. Welding tubing below would work unless you had to have it flat on bottom. If that's the case, another option would be to mill a slot for the tubes just larger than the tubing and tack them in there.

That's a job thats easier said than done. Keeping the hole straight is not a problem. The problem is finding a machine with 9" of stroke. My Bridgeport mill had 5" of stroke, drill press had 6". When drilling a hole that deep you have to be able to withdraw the drill in order to clear the chips and supply lubricant. I would suggest finding a shop with a horizontal mill or radial arm drill capable of drilling that deep. It won't be cheap.

Anyway to cut it in half, and pass from inside, and outside to complete? This reduces the bore to 4.5". Not knowing how this is going to finish out, or what surfaces will be visible it's hard to say.

That’s a big orifice plate.