# D.I.Y CNC Lathe



## Analias (Nov 9, 2012)

I recently built a CNC Router Parts CRP-4848 CNC router table.  Having done so, it has whet my appetite for building more tools for working with aluminum, plastic, and steel.  To that end, I want a benchtop CNC mill and lathe.  Converting a new or used commercial unit (RF-45, G0704, or a Grizzly lathe) would be nice, but in this economy I don't think I can swing the $5K to $7.5K I need to purchase and build what I want, the way I want.  I need to be able to tackle this at the $10 to $200/purchase/month range.  So, I'm exploring alternatives - notably building it myself.  My CNC table can handle aluminum (and probably light steel), but I don't have any tools for turning and so I think the lathe would be first on my list to build.

To be truthful, I know nothing - I am a complete and absolute newbie.  Up until this summer, the only tools I owned were a Delta drill press, and enough hand tools to work on the car, computers, electronics, and my ham radio equipment.  Other than a new 10" table saw, 15" radial arm saw, and the CNC table not much has changed.

I was watching a video from a well respected custom CNC mill machine maker on CNCZone.  I only know his first name as Dave or David.  I was surprised to hear him say his beautiful new, seriously cool, CNC mill was built on top of 6" x 1/4" steel square tubing.  It got me thinking about building a RF-45 class vertical mill or a 10" x 22" lathe using steel tubing and using  25 mm or 35 mm linear rails for each axis.  I have a box of dozen SBG 35 SLL-C linear bearings but need the rails for them.

Since I expect the lathe would be a good second tool to supplement my CNC table I started thinking about how to do that.  I expect this to be an incremental project.  First relying on recycling pieces from eBay, like spindles, tail stocks, ways, etc. until I can fabricate what I need to improve the design.  Looking at eBay there are plenty of Atlas, Logan, and South Bend spindles, pulleys, carriages, and even complete heads in the price range that I can do this step wise.

I'm sure I'm not the only person to consider this - dumpstercnc has two lathe designs he did.  Does anyone know of any others?

I would like to hear from you folks on your opinions for this approach.  If it is a good one - which surrogate parts (manufacturer/model) would be the best to pick from the standpoint of availability, usability, and ease of conversion?  

The target range for the lathe would be something like the Grizzly G0602 (10" x 22"), an 8" to 10" chuck with a 20" to 30" bed - it needs to sit on top of a 60" x 40" bench.  I don't necessarily want to duplicate manual controls then have to convert them to CNC later - I would like to include the CNC conversion or the foundation for the conversion from the beginning and take advantage of ballscrews/steppers for power feeds.  For manual use, I would like to integrate manual pulse controllers and switches into the design to mimic traditional manual controls.  A servo for spindle control is tempting option.

The same incremental design approach could be used for building the mill, although I will have to rely on myself for manufacturing more of the parts since there are fewer parts to draw from on eBay for surrogate parts.  It's even hard finding R8 spindles to use, but I will have the lathe to turn one.

I look forward to your comments.  If I'm crazy, I've been told that before, go a head and tell me again.


-Freeman (analias)


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## tsull (Dec 31, 2012)

Do you have any CNC Router projects you can post? I almost started with a CNC router table after decinding to hold on the 3D Printer, but I finally bought a small lathe so I can learn basic machining first ( I have a bad tendency to think I can do anything and although - eventually - I make it happend, the cost and frustration is unbelievable/especially to my family!).

Thanks
tjs


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## David Kirtley (Dec 31, 2012)

I like the CNC Router Parts stuff. I bought a pair of linear bearings from them to study. If you already have the 4x4, why not just build a 4th axis for it to get started?

If I wanted something that large, I would just go ahead and jump on a structural steel with concrete filler frame. 6 inch C-channel metal roof purling comes to mind. 20mm supported rail linear rails would be under $200. I would have gone that way but I have an extra bed because I upgraded my 7x10 to a 14" bed.

Parts for a little SIEG mini-lathe are dirt cheap and readily available.  Minimal cost option would be a $40 spindle with a pair of pillow blocks. I went that way as I already have a little mini-lathe and already have chucks for it.  30mm pillow blocks at Surplus Center were like $9 each. I started out that way but actually just bought another whole headstock for $100 that had the bearings and everything already. I put the new one on my lathe but might swap them later once I get around to upgrading the old spindle to tapered bearings. I had already picked up the spindle and pillow blocks but decided to use that for a 4th axis on my (not yet built) CNC router eventually. I grabbed a 60 tooth #25 roller chain sprocket to drive it.

Since I am just playing, I have not been messing with nice ball screws. I bought a 1/2-10 Acme tap and Acme rod is cheap. Delrin leadscrew nuts only take a few minutes to make. I am going with two opposing nuts for anti-backlash like the Sherline stuff uses. Could also go with a slitted one like Dumpster-CNC makes. Add a box of a hundred 608 skate bearings and I can make just about any configuration screw support I want.


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