[nicad]

I am new to CNC lathes (but not CNC mills).
I am wanting to build my own CNC lathe, and the main part that is not clear to me yet is where to source the spindle/headstock.

I want to be able to use 5c collets, as well as have a threaded spindle nose (2 1/4"-8tpi, 2 1/2"-8tpi?) so I can also mount a chuck adaptor plate.
Is there anything already available like this? The closest I have found is a 5c indexer with a 2 1/4"-8tpi threaded nose here http://www.wttool.com/p/1709-0005 (other places have the same basic thing for slightly cheaper). I have read where a guy here made a lathe spindle from the guts of a 5c spin indexer, but the overall length of this indexer "spindle" is pretty short-- too short? Also the lip where the 2 1/4"-8 adaptor plate seats up against is not very big (http://www.reliabletools.com/itemima...lyV06/v01o.jpg)-- is that enough for a plate to reliably seat up against? I want to use a 6" plate and chuck.

any input is appreciated.
Thanks-
Colin

[NC Cams]

Check Grizzly Industrial.

They make a 5C collet closer/adapter thingie system that fits on most lathes.

It comes complete with collet holder and lever arm doofus thingie for external release of the collet. I bought one when I bought my lathe from them and have never got around to using it.

[KDN Tool]

Check Dunham Tool
http://www.dunhamtool.com/precision_...headstock.html

It will definitely be a big part of your budget though!!

Ken
KDN Tool

[nicad]

Well I jumped in and bought a Dunham 50M 5C spindle with air collet closer. Good news is, it was used, so a fraction of new price. Bad news is, well, it is used-- Suppose to be in good condition tho.

Are these robust enough to have a long life? Or do they require re-building often?

I have a big 240v 16a DC "servo" motor with encoder which, if I can find a powerful enough DC servo controller for it, might have to turn this headstock.

I am thinking on mounting everything to a granite plate. For some reason I like the idea.

[jdr]

nicad,

Any update on using your Dunham spindle as a lathe headstock with your servo motor?

[nicad]

I have been working on a layout in CAD on and off for the past few months.. I was just even looking at again today. Right now I have it based on a 24" long x 8" wide x 4" thick granite plate (might have to be custom cut??). From my little bit of experience in the past with building machines I have learned- plan the coolant and chip guarding into the design. To cover the rails and ballscrew between the Z table and spindle I plan to use an 8" bellows cover from mcmaster (not cheap but should be worth it) and metal skirting around the rest. The main key is to leave space for such things, instead of trying to fit everything too closely together.
I am pretty much copying the Omniturn setup with work envelope size, gang tooling, slant bed (60 or 75 degrees), etc.

Items gathered so far, other than the Dunham spindle, are some Granite Devices VSD-A drives and a small selection of 300 and 400 watt AC servos, the linear rails, and C1 (for X axis) and C3 (for Z axis) ball screws. I have no real experience with AC servos yet.. does anyone know if 300 to 400 watt (~100v ~7a, 16a peak) AC servos would be close to be matched for this size of lathe? By reverse engineering the Omniturn specs, I think they are using 400 watt motors (going by their axis force numbers and ballscrew pitch + typical screw efficiency).

There will be one specific part being run on this lathe that would require a bar feed. So, I have an idea for a crude, but functional feed mechanism idea for that. Mount a wedged shaped pair of sharp jaws on the tooling plate that can "grab" the end of a bar and pull it through the spindle (operating the air powered collet closer via a solenoid and Gcode). On the back side of the spindle the 8' long bar will be supported by a series of bearings.

So no, no physical progress has been made other than CAD and ideas.

[lerman]

Watch out for whipping on that 8 foot long bar hanging out the back. I think I would put the bar inside a well anchored tube.

As far as I'm concerned, an Omniturn design is on the top of my list to copy.

Ken

[nicad]

For the long bar support I plan on having simple ball bearings mounted every 12"-18" (for a 1" bar) with plastic grommets in them so that the bar has just a little bit of clearance to slide through, but not too much or else vibration will get too bad. This will assure that as the bar progresses through the bearings, it will only ever have a max of 12-18" of "unsupported" length to limit whipping. Will try to align all the bearings with each other and the headstock the best I can. Think that will work OK?

[BALLSCREWPRO]

I have the resources and equipment to manufacture the 5C spindle head assembly but i choose not to due to time consuming and i took the shortcut path & retrofit a Hardinge clone (Taiwan m/c) 2nd operation lathe 5C collet. I made the XY table and gang tools holder and have been running this machine non stop for years on turbo cnc software. The mahine can achive accuracy of within .01 mm easily and targeting on small volume turn part with 1" diameter & below.
click the link to view my videos
http://www.youtube.com/watch?v=T5lC4OoaTKw

[nicad]

Ballscrewpro- nice build, thanks for the video.
I would like to know more about the tool plate table you used on your lathe. I will also be needing one very much like that one. What are the dimensions of it? I will be needing 6" (or 8") wide x 22" long x 1" (or close to those dimensions). with T-slotting along the front edge, or dual T-slotting like yours has. What size T-slots are those? I would like to be able to use Omniturn/Cubic gang tool-holders (at 0.5" table height = 1" part diameter) which mount into a T-slot.

[lerman]

See: http://www.cnczone.com/forums/showth...light=omniturn
for a discussion of the Omniturn tool plate dimensions. It appears that: http://www.snkamerica.com/Prod-pdf/G...Dimensions.pdf is the drawing that you need.

Ken