lathe project

[Teyber12]

hey all!

i have a cnc x3 and have a lot of parts that i can do on my x3, but would be easier to do on a cnc lathe. I'm a unemployed high school student, so i can't justify spending $1,100 on a 10x22 then converting that. But i had the thought to build a lathe with the x3. I want it to be quite rigid, but not too big(not physical size as much as travel). I had the thought that for now, i will not be running both machines at the same time so just transferring the x and y steppers and my 1hp 3phase motor over to the lathe will be fine. Then using a different(lathe) profile for the lathe(mach3). The only question i have about this as i would want this lathe to thread is the indexing situation might get a little complicated won't it? maybe not. This literally takes out more then half the cost of the lathe which makes it so practical. my budget for the whole thing is quite low, since i would rather put more money into my main horse(x3). I was thinking around $500. I have already ordered some parts, 19" long linear ways(they arn't too bulky, the blocks are thk rsr20's i believe) for the z and will buy some 15" linear ways for the x. Thats about $175. I was going to do roton's for the x and y axis with double nuts on each. i have double nuts on my x3(x,z) and like it. I ordered a 8x12 lathe with bearings for $50 from harborfreight, it will take ~ 2 months to get here though. I will probably replace the bearings.

Something i would like some feedback on is size. the max y travel on my x3 is ~ 6.5", so parts can't really be wider then 6" without it being a pain in the arse and sacrificing a tiny bit of straightness (the machine is going to be more accurate then my setting up i would imagine). If anyone thinks that having the z axis rails ~ 6" apart is going to really hurt my rigidity over say 8", i will just do that. The overall length will probably be about 30" long, but i can't design the headstock until i have the spindle on hand so don't know the overall length. I also thought i would have flat bottom, this would save tons of work and $ in steel. If anyone thinks this is going to be an issue or hurt rigidity i will change it to a raised/boxed bed. The material is going to be hot/cold roll steel and will be bolted together (stepper mounts, ballnut mounts will probably be alu). The x axis is so large because i will be using gang tooling. i have no plans to make a tailstock at this point because im turning mostly 1.5" aluminum that is fairly short.

If i could get the granite drilled and tapped for not too much id be really interested in using a surface plate as the base.
http://cgi.ebay.com/18-X-24-GRANITE-...#ht_3059wt_939
Here are the sketchup designs. Its all pretty accurate exactly how i was thinking i wanted it, except i didn't bother with the details like fasteners and motor mounts because i know ill change it.

cheers

[RotarySMP]

Are you planning on doing production runs, or single one off jobs? For one off jobs, I wouldn't bother with gang tooling. Just get an Phase II AXA tool post and a bunch of Shars tool holders. Changing tools only take a couple of seconds, and you can set up a tool offset list in your software.

[wildwestpat]

Hi Teyber12

Just a thought why build a separate small lathe when you will not be using both the X3 mill and the lathe at the same time? Why not build a headstock that is driven as the fourth axis from Mach3 and provide a tailstock and possibly steadies as this would open the door to proper four axis machining. Hossmachines web site put together by Daniel E. Kemp, one of the most helpful guys on the CNC forum

http://www.hossmachine.info/projects_5.html#4th%20axis

Good luck - regards Pat

[fatal-exception]

Yeah, I agree with Pat, especially if your only using one machine at a time, building a headstock and tail stock would be simple compared to building a whole standalone machine, not to mention being cost effective...

Paul

[vlmarshall]

Pretty cool, Teyber. I'll be following this one whichever way you go with it. Everyone does have a good point though; if you're mostly turning short parts, using the mill as your main structure, and just adding onto it, might work.

[Teyber12]

hey gang!

i don't know why but i just want a lathe... Im a little turned off by how AWFUL the mill worked as a lathe by using a r8 3" chuck, it just marred the material or it would be so bad the material would fall out of the chuck. They are slightly different but that was a deterrent.

The lathe would be used for production work. As many as i can make TBH. With a mill, i need to use a slitting saw and work all the way around the copper being held in a chuck clamped to the table. With a lathe, i think i would be able to cut the time down with this lathe.

The gang tooling would be able to face the end, turn down a radius of 1.375", cut slits in the copper, part it off, then cut a second one the same way. This would be less work for me

If the lathe worked out i wanted i would definitely be open to investing more money in electronics so i could run the lathe and the mill at the same time.

Also i put this in the wrong section i was trying to have it moved tot he vertical mill/lathe build thread.

Best regards,

Reed Teyber

[vlmarshall]

Parting copper in a lathe can be... miserable.

[wildwestpat]

Hi Reed

Appreciate your concern after a bad experience of machining copper. Copper can be the devil to machine and requires special tool angles and great ridgidity to stop the swarf mounting the tool rake and dragging the tool into the work.

If I am reading you right the copper job was held in a 3" chuck mounter on a back plate using the spindle of the X3 which has in your case an (R8) tapper. This is going to be difficult - the X3 spindle is not the most rigid unless you take a lot of trouble to counteract the play in the quill. A more conventional way of doing this sort of machining would be to mount the part on a rotary table (indexing plate with a worm drive) and use a slitting saw with plenty of lubricant to cut away through the copper. The spindle being kept locked both on the quill and the slideways throughout. The work is brought to the slitting saw using the table rotary motion. The surface of the cut can be cleaned up with a suitable end mill if needed. Keep at least three teeth of the rotary saw engaged with the part right upto the last cut - this stops the work snagging in the saw gullet (gap between the saw's tooth points). I don't think there would be much time saving as parting off a copper part is difficult and high risk.

With a four or five axis machine all the tools are held in the X3 spindle and would normally be rotating. The turning being achieved by end milling whilst spining the work held in the headstock / tailstock if required both of which are mounted on the mill table for 'X' and 'Y' motion.

I don't wish to put you off making a lathe but think a four or five axis mill would be more for less. Kind regards - Pat