[How do I?] Turn accurate parallel faces on a disk

[NC Rick]

Hi folks,
im in process of playing around with mounting an 8" 3 jaw Chuck to my rotary table. My plain back chuck needs an intermediary plate to attach to my table slots. I got hold of a Somewhat oversized 10" diameter disk of gray cast iron, assuming it would be a good choice for this.
the disk is sawn off but roughly turned. I would like to turn it to have both sides as parallel as I can get it. I haven't tried anything just like this before but have a picture in my head of what I want to do but am a little spooked to start it since I don't want to mess it up.

i made some stops for my 12" 4 jaw Chuck kinda using the idea I see Tom Lipton do. I'm no tool maker and the stops likely took me as long as it will to do the rest of this project. They certainly didn't come out as nice as his but I think they will serve me.

I wasn't sure if I should average the thickness before facing the first side? At this point, I just arbitrarily set the disk onto the stops which I set to equal length. Once I dialed in the O.D. The outside face to be turned is about 0.060" total indicated runout. I'm thinking I should true the face, then the OD and flip it around? On the flip, I may skim off the stops to try to achieve better parallelism.
Any hints, tips, tricks would be appreciated! I'm hoping to get this pretty flat and with in a thou or better? On thickness...

 

[Nutfarmer]

Nice job on the stops. I think you have most of the bases covered with your set up. The only thing that would go further to making both sides parallel is if you had access to a surface grinder.

 

[addertooth]

Soft jaws are the cat's meow for making two parallel faces. They don't make them for every size chuck.

 

[NC Rick]

Nice job on the stops. I think you have most of the bases covered with your set up. The only thing that would go further to making both sides parallel is if you had access to a surface grinder.

Yea, I thought of grinding... 10" wide would be a bigun I think. I have a friend with a 6x8 ... I may cut the middle hole on the rotary table instead of trepanning or making all the cast iron into dust on the lathe?

 

[NC Rick]

Soft jaws are the cat's meow for making two parallel faces. They don't make them for every size chuck.

I have a friend who makes fun of me for using my 4 jaw but sticking the 10" round in my 10" 3 jaw sounds sketchy? I could make some soft jaws for that 3 jaw (2-part jaws)... that's a new idea. Thanks.

 

[akjeff]

Those stops look great Rick! I think this is as good an excuse as any to buy a surface grinder! I'd definitely do the inside hole on the rotab, but I have a really flimsy lathe, and trepanning scares the poop out of me!

 

[NC Rick]

Those stops look great Rick! I think this is as good an excuse as any to buy a surface grinder! I'd definitely do the inside hole on the rotab, but I have a really flimsy lathe, and trepanning scares the poop out of me!

I hate to throw stuff out and a 3" x 3/4" hole could become something else, or help hold the building slab in place (as I heard on here).

 

[akjeff]

I hate to throw stuff out and a 3" x 3/4" hole could become something else, or help hold the building slab in place (as I heard on here).

That is the cool thing about trepanning, definitely less material loss/scrap. We use core drills a lot at work, wonder how that would do?

 

[NC Rick]

I have a hole saw... the biggest annular cutter I own is 1". I think a 2.5 in one would be costly. That would be the way to do it I think, if I had one.

 

[akjeff]

I have a hole saw... the biggest annular cutter I own is 1". I think a 2.5 in one would be costly. That would be the way to do it I think, if I had one.

Yes those annular cutters and diamond edge coring drills are crazy expensive. Glad the company is buying them, and not me!