[How do I?] 7" Diameter Alumimum 'shell' - Mill Or Lathe?

[Dan_S]

Based on your description I would do the following.

1. change the design, and add some mounting holes to the top so it can be mounted to the face-plate.
2. toe clamp the part to your mill table.
3. rough mill the inside wall with the mill
4. mill the top to the correct thickness and mill all the mounting holes in it.
5. mount the part to face plate
6. bring the inner and outer faces to the proper dimensions as well bore your center mounting hole to dimension.

as a side note, you probably want to use cast aluminum plate, and not extruded round bar. Extruded bar has internal stress from the extrusion process that will cause warpage.

 

[cowanrg]

I can easily add some mounting holes, I'll look into that.

Dan_S, that's kinda what I was thinking. I can do a couple mounting holes and basically finish the inner and outer diameters on the lathe.

How does one get cast aluminum plate, versus extruded? I've not seen cast for sale anywhere.

Also, I've seen a lot of lathe chucks for sale, but not a lot of faceplates. Are they just not very common, or do people usually make their own? Why am I not finding any for sale at the normal places (Shars, Enco)?

 

[Dan_S]

How does one get cast aluminum plate, versus extruded? I've not seen cast for sale anywhere.

https://www.onlinemetals.com/merchant.cfm?step=2&id=309

Also, I've seen a lot of lathe chucks for sale, but not a lot of faceplates. Are they just not very common, or do people usually make their own? Why am I not finding any for sale at the normal places (Shars, Enco)?

Usually they come with the lathe, or are an accessory you can buy form the manufacture.

http://www.littlemachineshop.com/ might have one that fit's your lathe, and if not, you can definitely make one, or modify an existing one.

 

[cowanrg]

Cool, thanks. I can probably just use the one my current chuck is mounted to.

Regarding cast aluminum... Yeah, that's not happening. It's $200 for a piece that would work. I will just have to deal with warpage.

 

[Dan_S]

Cool, thanks. I can probably just use the one my current chuck is mounted to.

Regarding cast aluminum... Yeah, that's not happening. It's $200 for a piece that would work. I will just have to deal with warpage.

Just ask for "mic-6" or "jig plate" from where ever you buy metal, also look for drops at your metal supplier or on eBay. Online metals is expensive for everything, i just knew they would have it.

 

[gotogojo]

I can easily add some mounting holes, I'll look into that.

Dan_S, that's kinda what I was thinking. I can do a couple mounting holes and basically finish the inner and outer diameters on the lathe.

How does one get cast aluminum plate, versus extruded? I've not seen cast for sale anywhere.

Also, I've seen a lot of lathe chucks for sale, but not a lot of faceplates. Are they just not very common, or do people usually make their own? Why am I not finding any for sale at the normal places (Shars, Enco)?

what size plate you looking for and how thick?? mite be of some help to you or any one gotogojo

 

[RJSakowski]

I would get a round about a 1/2 or 3/4" thicker than required. Drill and tap four holes to fit the faceplate using as large a screw as will fit the faceplate. Mount the blank to the faceplate and turn both O.D. and ID to finished dimensions. Reverse the work and mount from the inside on a four jaw chuck. Dial in the work and face to required dimension. Pad the jaws to prevent marring your work. The shell will fit over a 6" four jaw chuck and if you reverse the jaws, you can get full engagement of the jaws.

It is a lot of material to hog out. It would make sense to rough out the internal feature on the mill. At least with the CNC, you can set up a pocketing routine and let the machine do the work.

Bob

 

[cowanrg]

I would get a round about a 1/2 or 3/4" thicker than required. Drill and tap four holes to fit the faceplate using as large a screw as will fit the faceplate. Mount the blank to the faceplate and turn both O.D. and ID to finished dimensions. Reverse the work and mount from the inside on a four jaw chuck. Dial in the work and face to required dimension. Pad the jaws to prevent marring your work. The shell will fit over a 6" four jaw chuck and if you reverse the jaws, you can get full engagement of the jaws.

It is a lot of material to hog out. It would make sense to rough out the internal feature on the mill. At least with the CNC, you can set up a pocketing routine and let the machine do the work.

Bob

Bob, that's kinda what I'm thinking at this point. I can do 4 large holes wherever I want and just use those for mounting. Then use a rougher on the mill to remove as much material as possible, then move it to the lathe and finish the inside and outside bore in one setup.