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.

This project sounds freakin interesting!

Ok the stroke is one thing but you can reposition the piece itself. Getting it clamped down and secure and keeping it perfectly straight is what’s gonna be fun. Couldn’t a regular shop sized drill press handle that? Get the hole started, go as far as the press can go, lower the platform holding the part, change to longer bit? Keep going until it’s through?

Give Deep Hole Services in Houston Tx a call at (713) 896-1121 or Cobor at 713-467-4837. We used to send or deep drilling jobs to them and it was amazing what they could do.

Sorry folks...I posted this question on two forums, then forgot to check back here.

Error on my part. Its a 42" diameter plate, with a 18" hole in the center.

We obviously need to get a drafter to create a set of drawings for this.

Here is a pic of a table that gets close to look. The 42" plate, with the 18" hole in the center is the top.
It will sit on a base made by cutting a similar 36" plate in half, and nesting them together.
In the 18" hole in the top plate, we will suspend a 18" diameter "dished" SS plate, to form the fire pit bowl.

The complexity comes from the desire to have "magic fire", with no visible tubing providing the fuel.




After discussing this with multiple folks, we realized we do not need the hole all the way from the center cut-out to the edge. We need it from the center outward about 6", to where the top sits on the base.

A better suggestion may be to cut a groove into one side of the flat surface, about 2/3 the thickness of the plate, then hide a piece of tubing in the grove, capping with with a thin piece of ss that we can weld and grind down. As long as you cannot feel this work underneath, it will achieve the desired effect.

being only 1/2" thick, if you drill a 1/4" hole for gas you end up with only 1/8" on either side and I would think this would compromise its structural integrity.

why not figure out some way to incorporate tubing into the build, maybe as the legs in the table picture?
maybe mill out some channels on the bottom side and weld tubing in so only half is exposed, you could use 3//8" and have 3 orifices at the fire end etc.

The above seems to be the way its leaning now. The totally hidden gas supply thing just got too complicated and too expensive.

The project is getting put on hold for a while. We accepted an offer on our house on Saturday and I started a new job on Monday. I've got to focus on that stuff for a while.