[alan_3301]

I've stated building a metal lathe for myself. Funny enough, it started out because I needed a way to cut delrin rollers to roll in extrusion for a delta 3d printer I want to make.
We'll see how soon that get's built, but I'm excited about lathe stuff now.
So far I've got some 15mm rails for Z axis, and 25mm rails for X that will be mounted upside down.
I was planning 15mm and 20mm rails, but found a good deal on the 25's, and now after seeing how small the 15s are, I might look for some 20's to replace them
Everything will be build off of 30mm aluminum plate, that I am cutting from an unused table top I have.
Ballscrews are 1605 chinese ebay ones, which I am dissappointed with so far, but we'll see how they do.
some pics and a video, I still have some stuff to figure out, and the z rails and ballscrew will definitely be covered, I will try to make a telescoping metal cover.
If that doesn't work out, I look at other options.

some pics and a video

[pippin88]

I'll follow with interest. I'll planning a similar design, but using a large steel tube as the base frame.

What are you going to use for the spindle / headstock?

I'd think that the z axis ballnut connection is a weak part of your design.

[alan_3301]

The headstock is off a harbor freight 3 in 1 mill/lathe model 5980. Max speed 1600 rpm. with 20mm through hole. it came with a 370W motor.
I will probably try to find a bigger motor depending on how stiff the rest of it turns out.

I wasn't sure about how to secure the ballnuts to the carriage. What do you think about this, same style as the X mount.
Attachment 231882

[DSpeck]

I think you will regret putting the X stepper up above the plane of the tool plate - it would definitely be in the way there.

The second style of securing the Z-axis ballnut is better, but best would be to make the Z-axis plate stick out further over the ballscrew, and make the ballnut mount a solid block that bolted directly to it from underneath. That would give you the most solid connection between the plate and the ballnut. Rigid is going to be key here.

[alan_3301]

I am still looking for another place to put the X stepper, but where I have it now is the easiest way I can think of. I can see how it might get in the way if I have a really long boring bar, with only a little coming past the front of the tool holder, but other than that It might be ok where it is.
I'm trying to find a shape for a carriage that will extend over the ballscrew mounts, than I can cut out of what's left of my 30mm plate. It's now a zig-zag shape, so I'm having to see what fit's.
Otherwise I will just try to use the largest block I can between the carriage and ballscrew mount.

I finished up the risers for the bed, and have them attached with 6 m12 bolts
I'm trying to decide if I want to get it surfaced. The whole table top was surfaced with a huge flycutter I'm guessing. (blanchard ground?) the swirl marks look like 24" in diameter.
However I don't know if it has warped any between cutting it free from the table top, and bolting the risers to it.
I don't have a precision straightedge so I'm not sure how warped it may be, and I feel the cost of a straightedge will be half of what it costs to get it surfaced.
If I do go to a machine shop I will probably get them to cut the pocket that I will insert steel strips to act as the rail reference edge.

Anyways here are a couple pics, hopefully I can get some more work done on it soon.

One question for everyone..
The 15mm rails are bolted down with dinky m4 screws, and the recommended torque is like 5 newton meters.
Is this going to be able to hold the rail down tight enough? I'm guessing the rails are rated for way more than they will see, it just seems like they could have squeezed an m5 in there.
Attachment 234068
Attachment 234070

[alan_3301]

I will try to find a machine shop to square up and flatten all the critical surfaces.
I probed the bed surface and it has a 6-7 thou cup on one end. I will probe it again after it's surfaced.
And some more mockup shots.

Attachment 234144
Attachment 234146
Attachment 234150

[CRO-WD40]

This is not stiff, compared to the rest of the construction.
Either reduce the lever or widen the part in the axis of the ballscrew.

[alan_3301]

Thanks, I am still working on it, and that is one thing I know I had to figure out.
What I have done so far is space out the X rails as far as possible, and I will squeeze the X ballscrew in the middle.
For the Z ballnut connection, it is still going to be an indirect link, but a lot sturdier, hopefully.
Here is what I have now.

[CRO-WD40]

much better...

[alan_3301]

Getting closer.

I finally got my bed/base back from machine shop. I did probe the surface again and it was within 0.004 which I is probably my machine being out that much.
Also I got around to mounting the Z rails. I got them parallel to 0.00025 and coplanar to 0.001 over the full length. X rails are around 0.001 parallel.
It was suprisingly easy, I thought it might be a pain since I left out the reference surface on the Z. It took only 10 minutes to align all the rails.

Unfortunately I forgot to measure the bed and update the model after then machine shop surfaced it, so my rail spacing isn't even on both sides of the bed.
It is only cosmetic, as long as I remember to account for it later on.

Attachment 241948

Attachment 241950

Attachment 241952

[LeeWay]

Great work so far. Look forward to your progress. Should be a very nice one.

[alan_3301]

Making some more progress
I got the larger carriage finished.
Pay no attention to the single screw holding down the part, it worked fine
I used the router to drill the holes to 0.5", which was about as deep as I could go before the spindle started slowing down too much. It has no torque at 6000 rpms.
I went ahead and drilled the holes all the way through to make tapping easier. Still I broke a tap off in one of the holes for the X blocks.
I decided to just leave it. 15 out of 16 isn't bad.
Also the worst part of cutting aluminum on the router is the cleanup, my whole workshop is filled with shavings, and I had to stop in the middle and clean the machine rails.
I started losing steps because of chips caught under my bearings. Because of this I had to drill some holes out a little larger, but everything still lines up good.

I have everything mounted right now except the headstock and the Z ballscrew. No pics of that yet.
I still need to cut out the bracket that will attach the carriage to the Z ballnut mount.
I was worried about getting the pocket for the X ballnut mount cut to the correct depth, But I think I got it right. I still need to mess with the alignment a little, at the last .25" of travel on one end, the screw starts to bind a little. Hopefully enlarging the holes for the support ends will fix that problem.
For some reason my cutout for the belt and pulley to clear the carriage didn't line up quite right, not sure why that happened. I had to finish it off with a hacksaw and file.

Attachment 242412 Attachment 242410
Attachment 242406 Attachment 242408 Attachment 242404

[alan_3301]

1 more pic

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[alan_3301]

I made a stand out of aluminum extrusion, also mounted the Z ballscrew.
I need to figure out some way to square up the ballscrew end of the carriage to be parallel with the ballnut mount. Then I can mount the bracket which joints the two. (after I cut it out).
After that is taken care of, I can mount the headstock. I want to do it last so I can get it parallel to the Z axis travel.

Electronics have been ordered, g540 with nema 23 380 oz-in steppers for X and Z.
I got the g540 thinking I could use the extra channels for a rotary toolchanger if the gang lathe setup wasn't working for me.
I have a DMM 750watt servo and dyn3 drive coming for the spindle motor. The idea there is to have a C axis setup for broaching, and maybe a live tool in the future.
The motor is 3000rpm max speed which will be geared for around 1500rpm at the spindle. I may change that to 1:1 if I ever change out the headstock bearings for something faster.

Attachment 243410
Attachment 243412
Attachment 243414

[alan_3301]

Also I need to find some timing pulleys for the servo motor and spindle shaft.
I have looked through so many websites and it looks like I will have to pay a lot of money, and then bore them out to the correct diameter, 14mm with 5x5mm keyway for servo and 34mm with 10mmx3.6mm keyway for spindle shaft.

I am thinking about making my own pulleys, just trying to figure out how to draw them up. thinking of using htd 5 or 8mm pulley 16mm wide.
any suggestions on timing pulleys?

[LeeWay]

You might check out some of the threads by Hoss. Do a search. He has made some of his own pulleys.
I have bought a couple pulleys from Mcmaster Carr, but over the top pricing.
This is where I normally get them from.
Small Mechanical Components: Precision Gears, Gear Assemblies, Timing Belts, Timing Belt Pulleys and Couplings - SDP/SI

I have had to bore out several of mine for both the mill and lathe. I just used a manual 7/12 mini lathe and it works great.

[alan_3301]

Thanks, I think I found the gears I will buy on that website.

I got the carriage leveled to the Z ballnut mount. The easiest way was to mount the whole lathe to the end of the router table.
I couldn't reach the whole surface with a small end mill, but a 2" cutter would reach.
I ended up using a Magnate 2706 Surface Planing 2" bit, and tilting the spindle a couple of degrees for a flycutter effect.
Conservative settings were 0.005" DOC, 20 ipm @ 10,000 rpms, left a nice finish.

Also I cut out my bracket to join the carriage and ballnut mount. Just need to drill the holes, and tap the carriage.
Things are going smoothly, just a few more things to finish.

Attachment 243600
Attachment 243602
Attachment 243604

[alan_3301]

I'm still working on this.. The holdup now is trying to figure out how to true up the chuck faceplate before bolting the headstock down.
I wanted to measure a long bar held in the chuck, to align it with the Z axis, but I've found out the faceplate is not running true.
I'm amazed it worked as well as it did when it was mounted to the harbor freight 3 in 1.

I guess I have to get the axes under power ( a whole project by itself, decided to sell the stepper kit and go with 400w AC servos), then clamp the headstock down, and machine the faceplate.
Then mount the chuck and a test bar, and align the headstock to the Z axis. Then finally I can drill and tap the mounting holes.

Hopefully I'll have something to show soon!

[alan_3301]

I've been working on the electronics the past few weeks, only get a few minutes each day to work on it.
Control cabinet is mostly finished, and it ended up much larger and heavier than I had hoped.
I used 4040 metric extrusion and 3/8" acrylic panels, because I have a whole bunch of them, but they are very heavy.
I got a bunch of chinese din rail goodies off of amazon, cheap breakers, contactor, terminal blocks, and a cool voltmeter / ammeter display.
The computer is a junk model I found, hacked up the case of fit. I would have just used the motherboard, but I wanted some support for the 5i25 in the pci slot.
The 5i25 is connected to a mesa 7i77 that will handle all the inputs and outputs between linuxcnc and the servo drives.
I got on ebay 2x Delta asd-a2 400w servo drives and motors for a nice price, wish I had money to buy the other 2 that were available also.
Also I have the DMM 750w driver mounted in there, having a little trouble figuring out the I/O on that one, waiting for a response from tech support.
I did end up with a nice little empty space that a VFD would fit in if I decide to dedicate the spindle servo for C axis work, and use a larger motor for general turning.