'Lil Linistepper Lathe

[epineh]

Here goes what I hope is a short and sweet little project, I have a small lathe that was built by a friend during his apprenticeship, the original plan was to use the headstock and convert it for a 4th axis to put on my router, but I decided it would be better to retrofit it with a couple of steppers instead and use it as a lathe.

I have two specific purposes for the lathe, one is to make small "bobbins" that are used for lace making, I will post a pic of one as soon as I can, and the other is to make small chess pieces for a friend that wants to make boards to sell at the markets.

As such the lathe will be made with those specs in mind, mainly meaning that I am not too worried about backlash, there does not seem to be all that much anyway, and I don't think chess pieces and bobbins need sub micron accuracy

Now for a few pic's, I didn't take any before work started but you can see what it looked like, it has been sitting in various shed's for the last 20 or so years so don't expect it to be all shiny and new

Russell.

Similar Threads:

• Need Help!- linistepper over heating need help
• Linistepper in C
• Need Help!- Linistepper troubleshooting
• My linistepper-a true GEM
• Linistepper

[epineh]

I have to give all credit to the machining side of things to my good friend Chich, who has kindly donated his time and machinery to fast track this build, he had done in a couple of day's what I would have taken months to do... good on ya mate

First up is the tailstock, not too much to do on this, possibly it will get treated to a live centre, but a little trial and error will find that out.

Next is the cross slide, you can see where Chich has drilled and tapped out the end of the leadscrew and fitted a small bolt, then turned it down to suit the stepper motor coupling.

Last photo is the Z leadscrew, that Chich has turned down the end to suit the stepper.

[epineh]

Now for the X motor mount, a simple piece of box section steel, the pics tell the story...

[epineh]

Now for the Z stepper motor...and both motor's are mounted ready for couplings.

[epineh]

That is it for the mechanicals so far, now for some electronics, I am using Linisteppers for the drivers, easy to make at home, cheap and have some very nice features, linear microstepping, and a really good high torque half step mode, which is probably what I am going to run on the lathe.

The background on the drivers can be found here :

http://www.cnczone.com/forums/showthread.php?t=13267

Credit to Posix for his board layout, it worked well for my needs. Credit to the Linistepper project as well, Roman Black for the design and James Newton for maintaining information and troubleshooting. It is one great open source driver.

I thought I was a bit clever and in the spirit of recycling and saving the world I pulled apart an old dead UPS frame and mounted the electronics, they fitted quite nicely, but not for long... First couple of photo's are the before photo's, and the rest are my "enhancements"

The UPS enclosure was a good idea, you can see in the photo's how I was going to use the power input for the AC mains in, it already had a fan mounted at the back and a convenient sheetmetal base in the middle to fix everything to... only one small problem...

[epineh]

I managed to get hold of this, and it just will not fit inside the existing enclosure, I thought of mounting it beside, on top... you name it, but I just had to let the UPS enclosure go. 1.1 KW, single phase to 3 phase VFD, this is just too nice not to put on the lathe.

[epineh]

That is about it for now, I am going to rip apart the electronics enclosure and find something bigger, probably a PC tower and fit everything inside that.

I have got a good price on a 0.5 KW 3phase 2pole motor so as soon as I have the funds I will purchase that and fit it to the lathe, I am thinking of bolting the lathe to a thick piece of ply, this will make the spindle motor easy to mount (foot mount).

Stepper drivers are all tested O.K. the linear microstepping is VERY smooth, I only used a 17Vdc power supply and there was a surprising amount of torque, I also am running the steppers at about 70% of their rated current for now, until I can get the correct current sense resistors.

Russell.

[epineh]

Spindle motor turned up today, and I got a little inspired and mounted the various parts inside a PC tower, it is not an exact fit but it will have to do.

Now just have to wire it all up and should be ready for some testing on the machine, I still have to ramp up the current on the drives but I will wait until later, I want to see how they go as they are.

Russell.

[LeeWay]

Very nice. Looks like this little project is moving right along. Nice snag on the spindle motor and controller as well. Now that your motor is green, can I guess what color you will paint the lathe?
I am interested in following the completion of this.
I am just now considering what to do on my lathe. Just a 7/12 from Cummin's. but it really needs some cnc.
I have most of the stuff already. I think I will simply throw the motors on there for now. The brass bushings I make are less than an inch long and 9/16" OD, so the travel on it is fine. I am going to have to motorize the tailstock for drilling though.
The parts right now take about 3 or 4 minutes by hand. Just really tedious when I have to drill and turn 50 of them at a time. CNC would eliminate the right hand work and most of the hot bits and finger pinching operating the carriage. I turn then just using a cutoff tool, so no tool changes. I do make two different lengths of these though.

[chich2]

Hey Russ! Great thread! Cant wait to see your lathe running. I like your spindle motor. Is it brand new? It looks great. Are you going to put a spindle speed encoder on it?

Chich

[epineh]

Hey Lee, to be honest I hadn't thought about painting the lathe, but as you say - the motor is a nice shade of green The lathe was just going to be a little workhorse for a specific task, but I guess this doesn't mean I couldn't dress it up a little

I am in the same situation as yourself, I have simple parts to make but LOTS of 'em so while the setup of the machine will take a little effort the end result will make my life a lot easier.

I was thinking of setting up a little gang tooling setup but the cross slide just wasn't setup for it, my thinking was to have a second tool on the opposite side for finishing or maybe parting off but I would need a second toolpost, and decided against it.

Russell.

[epineh]

Hi Chich, yup the spindle motor is brand spankin' I was thinking of an encoder but I may just calibrate the VFD properly so I just include spindle speed in my G-Code, I have a tacho circuit based on a PIC chip, the same one used on the linistepper (no coincidence) so I may still use that, it would be very nice to have an illuminated LCD readout fixed to the lathe.

This little lathe is certainly getting its fair share of technology thrown at it !

Russell.

[LeeWay]

They call that making a silk purse out of a sow's ear. Nothing wrong with putting some nice features on it.
I built a mill using 80/20 extrusions as a base. I threw ground ball screws, cast iron Z axis and nice THK rails on it with some 203V's, 495 oz motors and a 72 volt 12 amp power supply on it. I used a nice treadmill motor and driver on it and it really turned out to be a fine little machine. Same thing. Silk purse from a sow's ear.

[epineh]

Yeah, you have a point, maybe a gang tool rack isn't such a bad idea

Seriously though, I have been following the laser edge finder and zero setter threads and I do like the sound of that for my lathe !

Russell.

[epineh]

I have started the wiring on the electronics, no pics yet but I hope to have it all finished over the weekend, have found a nice solid lump of plywood to mount the lathe and spindle motor, I have to get a pulley for the motor, hopefully next week and it will be mostly finished, the plan is to have 1:1 pulley gearing, and use the VFD for the variable speed.

I am aiming at spindle speeds from 2000 RPM to 10,000 RPM if it holds together as one of the jobs will be plastic turning at 3mm dia. I am unsure if I will be integrating spindle speed from the controller, I will put a trimpot on the electronics enclosure to start with, this coupled with the PIC based tacho LCD readout should be fine for initial testing, if it works well enough then I will add spindle speed to the controller.

Here is the link for the Tacho circuit I will be using if anybody is interested... :

http://www.jeffree.co.uk/pages/revmaster.htm

Russell.

[greybeard]

Hi Russell.
Thanks for that link. One of the best pages I've seen for a long time, very clear explanations and photos.
I've had a quick look at his home page and that is now bookmarked for future exploring.
Looking forward to the next instalments of your progress

Cheers mate.
John

[epineh]

Hi John, no probs on the link, I found it very helpful, and was sure others here would as well. I am thinking of making my own board to suit my needs a little better, shouldn't be very hard as it is a very simple schematic, I think I probably should email him and check he doesn't mind.

I did a little more wiring tonight but I left all of my tools at work so I cannot drill any holes through the lathe base for cabling so I will have to wait until after the weekend to tidy up the loose ends. I have the drivers wired except the motor DC, all that is left is to bring power into the VFD and the 3 phase to the motor. Too tired for photo's but I will have some tomorrow

Russell.

[epineh]

While we are on the subjects of handy links, here is another that I am thinking of using for spindle speed control via G-code :

http://www.cncathome.com/vfd.html

While the board itself is simple enough, I am going to use TurboCNC for the lathe (at this stage) and I am not sure if it supports PWM output for spindle speed, if anybody knows if it is possible in Turbo I am all ears

Russell.

[epineh]

Hooked the VFD up tonight and gave it a test run, all is good. It has a little switching noise at the motor that I will try to reduce by changing the drive's switching frequency but for now it is working fine. Spindle motor is nice and smooth, as it should be being brand new. Finished most of the stepper driver wiring, I just have to wire the steppers' power supply and it is ready to power up.

I have to make a gland plate where the PC power supply was to run the cabling to the lathe, again I have to wait until I am back at work for my tools
Russell.

[greybeard]

Looks like more people are going the 3 phase/vfd route, so I'd better do some more reading.
John