A benchtop cnc lathe build

[S_J_H]

Hi everybody, I thought I would share my current project which is a cnc benchtop lathe. After seeing the great work by other members and their custom machine projects I was motivated to try and build myself a nice little benchtop lathe. I already have a import 9x20 and I really have no interest in converting it. I wanted to just start fresh.
The lathe is a work in progress, I started on it about a month ago.
I adapted a mini lathe spindle and a mini mill spindle base to form the headstock for this project. Nice cast iron parts. I discarded the mini lathe plastic gear drive and built a new belt drive using a HTD primary and dual 3mm polyflex to drive the spindle. It will use a mini mill dc motor with a variable speed DC controller. The headstock is mounted through the bed with four studs. It's very solid.

The bed is made from 1" thick ground steel with 1/2" thick sides and boxed in underneath by welding. The bed is 5" wide and 24" long.
I mounted the z axis rails(Hiwin 15mm) today. I have them nice and parallel at around .0002" variance.
The tailstock will also be mounted to the z-axis rails on 2 blocks. The threaded holes in the bed are for locking the tailstock in place.
As shown in the pics it weighs about 100lbs right now. I'll be making a turret toolchanger. I figure the little feller will come in at around 150+lbs when done. So it'll be fairly easy to move around.
Well here are a few pics of my progress.
Steve

[bigbunny5]

That is Nice Man, I'm a Huge Fan of well made, Shop Made tools. Any FOOL can go to harbor Freight, and start laying down $100 bills for Mediocre at best tools, But it takes a real Craftsman to Build a finely honed piece of Shop made tooling! I look forward to following your build. Please post lot's more pictures!

[WilliamD]

Very Nice!!! I can't believe you did that in a month! Did you have the steel ground for you, or pick it up stock? Nice idea with using the mini lathe and mill headstocks. I want to build one a lot like it.

[Al_The_Man]

Look like a fairly large (DC?) spindle motor, what are using to control it?
Al.

[S_J_H]

Thanks guys. I'm just having fun building it "on the fly" without any real plans.
I won't be able to work on it for a few weeks as I'll be to busy. I'll start up again on it in August. I'll get the x axis finished up next and then mount the ballscrews.
The steel is precision ground flat stock. I figured I could save myself some machining by starting off with nice ground stock. A bit more expensive but worth it to me.

Al, I'll be using a Minarik DC drive. I was going to use my old mini mill dc drive but some goofball without much electronics knowledge(me) smoked it by accident.
I'll use a proximity sensor to index the spindle to mach3.

Steve

[FPV_GTp]

hi

I have to agree with the guys very nice job so far SJH

Minarik DC drive ??? never heard of this brand , why not concider Gecko G-REX G100 , USB or Ethernet communication connection.

cheers

cheers

[S_J_H]

FPV_GTp,
Thanks, I think Al was asking about the controller for the spindle motor, not the axis stepper motors.
For the spindle motor which is a 100volt dc motor, I will be using a manual DC drive for spindle speed, probably a Minarik drive.. For now anyways but that could change.
For the axis motion control and future tool changer l'll use a spare Xylotex 3 axis drive and 269oz steppers I have on hand. I will be using those with Mach3 Turn. Should work great with this machine.

Steve

[digits]

That's looking great Steve

I bought a mini-lathe headstock to do a similar thing, but rather tediously it isn't flat based like the mini-mill headstock - it has a dovetail groove cut into it. I think you've got it spot on by mixing and matching the spindles and castings from the mill and lathe

Do you mind me asking how you're going to synchronise the motor with the X-axis for thread-cutting - are you going to add an encoder somewhere?

Cheers.

[S_J_H]

digits,
My mini lathe headstock did have a dovetail but I machined it away completely.
Same thing with the mini mill base. The cast iron in these 2 parts is quite good. Machines beautifully and is free of voids.
The motor is not indexed. The spindle gets indexed with a sensor. Mach will read how fast the spindle turns and adjust the axis speed to match the spindle for threading.

Steve

[bigbunny5]

SJS when you finish that lathe I'd love to commission you to build me one about 1/8 scale. That has been giving me Ideas that I shouldn't dwell on. but suffice to say as a model builder I've felt the need for a lathe about 1/4 scale of shurelines something like the Clisby but not as toy like or foreign! something Very accurate yet portable that can be carried out to the race track.

[zephyr9900]

Originally Posted by S_J_H My mini lathe headstock did have a dovetail but I machined it away completely.

Steve, didn't you write that up somewhere? I've searched the forums here but haven't run across it.

Sweet looking build so far. Is your base material that oil-hardening stock that MSC sells? I see that it's +/-.001 on thickness and squareness. Almost certainly better than I could square up material on my Tormach...

I've been considering something similar. I have a whole box of Thomson 10mm profile slides with preloaded carriages, so was considering using 6 carriages each on the Z and X axes (I've read about using 6 carriages anyway for "tolerance averaging" and that would get the allowable load up also).

Is there a reason that you are looking at a turret rather than gang-slide? There actually seem to be good reasons behind both, so I'm curious to know what swayed your decision.

Best regards,

Randy

[S_J_H]

SJS when you finish that lathe I'd love to commission you to build me one about 1/8 scale.

wow that would be small! Sounds like a fun project though.

Randy, I am not sure if I ever talked about machining off the dovetails on the 2 bases. I may have mentioned it at the HSM site.
I am using Starret low carbon and oil hardening ground stock. It is very accurate dimension wise but the longer pieces do have some warp or Bow to them. So I did needed to flycut the z axis risers after it was all bolted together to keep the rails nice and even. What I could really use is a surface grinder. My x3 is fairly accurate though and I did not need to shim the rails at all.

The main reason I am going with a turret vs a gang slide is because I want to be able to use a tailstock if needed. Plus I think the designs for the pneumatic/stepper driven turrets are neat and I want to make one.


Steve