Recommendations/Limitations

[netmage]

Greetings, totally new to machining, fairly decent mechanical aptitude, CAD experience, looking at some fairly simple (I think) projects related to diving/rebreathers for myself and friends, materials initially will be type 1 PVC, later on delrin.

Been browsing the internet and Sherline seem to have complete packaged solutions. My initial projects probably only require a lathe, but future ideas would require milling, so I'm wondering if a mill w/ rotary table would be all I need to look at. (or maybe CNC ready and upgrade later)

The tricky parts to my initial projects I think are size. Future projects would require some threading (internal and external).

One project involves machining 6" dia. from a sheet of 1" PVC, a fairly narrow slot just shy of the outer circumfrence, a few cutouts, and three tapped holes.
(Detailed sketches here - http://www.rebreatherworld.com/megal...-scrubber.html)

A future project would involve machining a rebreather lid, 7.25" dia. from Delrin, adding some grooves to house o-rings.

The video's and docs regarding rotary tables havn't painted a clear picture how they are used, other than as a lathe mounted horizontally.
I'm wondering if I'd be able to work with these larger pieces?, but I'd think fixing the Y axis, I'm really only bound by what will clear the and the X-travel, and even then that would only limit the radius? (i.e. half the piece could overhang, since the rotary table moves it under the tooling...)

The Sherline 2000 w/ it's adjustable headstock looks like it would accomidate my sizes...

This leves me w/ the following: can I accomidate a 6" or 7.25" dia piece on a 4" dia rotary table....? The guy who put together the plans I'm working from used a 3/4" mandrel, I imagine the same could work vertically....

Is this do-able? Thanks for reading...

-Tim

[Stepper Monkey]

You are thinking in the right direction, rotary stages can be used either vertically or horizontally. For many uses they are flat on the table as you propose, and you can indeed get a larger radius cut out of them than the Y movement suggests.

There is a company called A2Z out of Colorado that sells extensions kits for both of a Sherlines axes, the Y-axis extension brings it up to 9" or better of travel! I usually think this to be a very, very bad idea for most uses as it removes almost all of the machines already low rigidity, but I have seen one so modified by an artist cutting plastic and hard wax quite effectively. If it is a dedicated single-purpose machine this might be a way to go, but it would be dedicated solely to soft materials.