[LeeWay]

LeeWay, I noticed they have some 3 & 3 1/2hp treadmill motors at the surplus. I wander if the bigger controller will run one of these. I know you would have to at least go 220v (no problem there) but even with a heat sink the controler only claims to pull 2hp worth of load. I was thinking if a person made a better heat sink and used a good fan system the bigger motors might run on those controllers.


If not, what controler could one get to push those bigger motors ? I would really like to run that 3HP 4100rpm motor on my big mill.


I have my parts gathering up for the CNC conversion. I went with 850 servos,Gecko320's, CNC Brain and Rockford Ball screws. I really need that extra power for my spindle and the RPM also. I could just go for one of the 2 1/2hp motors, I think they have one that has some very nice RPM. A belt drive and this would be sweet. I guess if worse come to worse I could put a encoder on that big motor and run it with a Viper servo drive but thats starts getting into some funds. I have a lot of work to do just to get this thing going, but as far as design and parts my spindle is all thats holding me back.


BTW, a 3rd machine, no wait is that the 4th ? Cool, your mill works so good I think a lathe of this design will rock also. Between you & Hoss (plus many others) you guys are what keeps my motivation up to keep me going with all this. Thanks You.


Jess

Thanks, Jess. I have three completed and two in the works. I built a router, mill and converted a little lathe. I am about 3/4 done with a trailer mounted plasma cutter and still need time to get this second lathe built. The plasma is now on permanent hold though. I never expected the mill to do so well. As it is now, the plasma really isn't needed. That may change and if it does, I will complete it then.

I hadn't seen those motors before.
You won't have any trouble running these motors with the drive I used on my mill. You won't get more than 2HP though. I find that is plenty on my mill. There ain't any bogging down. At the low end, I cut steel at 3300 RPM and 6600 on the high side. I spot drill and engrave at the high speed on steel and use it also for all my aluminum cutting. It just works better than I expected.

I looked on the Minarik site and the two drives they have to handle this sized motor are both well over $500. I think I would go the servo route or use an AC motor and VFD instead.
Good luck with it and post a link if you have a build log.

[LeeWay]

Leeway,
This is my first post to CNC Zone. I am also contemplating building a mini lathe very similar to yours. This all started back in March 2008. I googled looking for info on linear motion devices to use for each of the axes and ended up here.

Before going to far with the Headstock and Spindle have a look at this site and eBay Item 150312130102

http://www.arceurotrade.co.uk/projec...ges/index.html

I will be using tapered roller bearings as the bearings for the mini lathe headstock casting.

I need a favor from anyone that can measure the mini lathe casting. I need the foot print dimensions to make some detailed drawings for the build.

I did find all the info I needed for the linear motion stuff, here and your mill build thread. What a fantastic example of DIY. You should be very proud of your accomplishement.

Al

Hi Al and welcome aboard.
I actually considered going with the taper rollers, but chose new sealed bearings instead. Lower maint. on those. If these ever wear out, I will likely go the tapered route, but I would want to seal around the bearings well so that a grease fitting could be used to pump grease into the bearings.
They could also be sealed and an oil bath type lube used. The lower maint was more appealing to me than the smoothness it might get. My parts don't need model engine precision. At least not yet.
Good luck with it and start a biuld log so we can see what you are doing.
Thanks.

[LeeWay]

A little progress on this. I hope to at least get it running in the next day or two.

[S_J_H]

It's looking good!
I would not worry about the tapered rollers. The deep grooves are plenty stout in these head stocks. No way your machine will notice the difference.
I was taking a pretty good cut with stock bearings let alone better replacements.

Steve

[LeeWay]

Thanks, Steve.
I just put the new bearings in the spindle yesterday. I had to turn the opening in the timing pulley to size. It all seems real nice. I haven't powered the motor yet. Likely this afternoon.
I did seal the head up when I put this back together. I used set screws and aluminum plugs to fill all the holes. The only opening now is the little relief on the base where it is milled out for the rack on an X2.
I can easily seal that then as well. Then if later on, I decide to use the tapers, I can use an oil bath just like the rear end on my truck.

I do think these I have now will work great though. It was all perfect fitting. All nice and snug, but not too tight.
More to come later.
Thanks.

[LeeWay]

Here are a few more pictures. I had the motor running yesterday with this smaller controller. I had to turn the POT down because at full power, the board would go into over speed and knock the RPMs back down about 1000 RPM's or so.
Rather than fool around with this little controller, I sprang for another just like I have on the mill. I will only run it on 120 VAC to start with. May not need more. If I do, it is available to me. I have already worked out the nuances of this bigger controller. It has a lot more onboard adjustments and really plays well with the Homann spindle control board.
This motor isn't quite as powerful as the one on the mill, but should still do the trick on this lathe. That's the plan anyway.

[sergizmo]

Lee,

Great stuff! You don't mess around, it's getting built quick! I guess after so many builds you've learnt a few things.

A few questions;

- Runout of the spindle before and after new bearings? Also, what was used for diss-assembly and re-assebly, one of these?
http://www.littlemachineshop.com/pro...ory=1687114045

- What are you using for bearings? (brand and grade)

- Motor HP at 120V with that controller?

The mini mill spindle I got for the mill project has .0008" of runout, measured in the spindle taper. Not too hot. I'm thinking of buying the above kit when it is in stock, taking the spindle apart and bearings off and putting on some Japanese/German/etc... Abec 3's. I'd like to go Abec 5, but I seriously doubt the case is machined precisely enough for that to matter or even for them to run properly. Good 3's should still be a huge improvement over the stock crappy Chinese 1's. Plus it will be able to run at 5K RPM no sweat. Do you have any spindle thoughts/info/etc... to share that may be helpful?

- Why did you go with rolled screws instead of ebaying some ground ones?

- Are the steel plates that your z-rails and head mounted on some kind of ground stock cut to length?

Thanks again for posting up your builds. Very interesting and lots of great info.

Serge

[The Blight]

This is turning out to be a truely beautiful machine! So nice and clean!

[LeeWay]

Great stuff! You don't mess around, it's getting built quick! I guess after so many builds you've learnt a few things.

There are some short cuts, but what really helps is having most of the parts on hand and having a decent mill and a functional lathe to make parts. I did deviate some from the initial drawings. I knew they would not be spot on. Just an idea how it could bolt up.

A few questions;

- Runout of the spindle before and after new bearings?

Not sure what it was before. I just don't recall. This head was on my mill to begin with though, so it wasn't too bad.
I checked the spindle hole this AM. My dial gauge only measures to .001", but the run out is about .00025" or so. .0003" at most. This is both rotating by hand and with the motor slowly. I doubt I will get the chuck mounted that close.


Also, what was used for diss-assembly and re-assebly, one of these?
http://www.littlemachineshop.com/pro...ory=1687114045

I do use that kit. I bought mine when it was $49.95 IIRC. Mine is all steel and it has a very nice black oxide finish. I use 7/16 20 threaded rod with mine. I think 1/2" will work as well. It really is a nice kit.

- What are you using for bearings? (brand and grade)

I just used some ABEC 1 grade bearings. Mcmaster Carr has most grades availabale, but I went with part number 5972K47.
A little better bearing would be 6661K107. They are about $19 as opposed to $11 for the ones I bought. The trade number for these bearings is 6206.

- Motor HP at 120V with that controller?

This motor is 2.5 HP @ 130 VDC. This controller does run the motor okay up to about 4000 RPM on the spindle. I do have it geared down about 1/3rd from the motor.
It is rated @ 4500 RPM itself. I'd say I am getting just over 1/2 HP out of it now. With the newer MC, I expect to get around 1 HP. Maybe 7/8 HP. It should do fine.

The mini mill spindle I got for the mill project has .0008" of runout, measured in the spindle taper. Not too hot. I'm thinking of buying the above kit when it is in stock, taking the spindle apart and bearings off and putting on some Japanese/German/etc... Abec 3's. I'd like to go Abec 5, but I seriously doubt the case is machined precisely enough for that to matter or even for them to run properly. Good 3's should still be a huge improvement over the stock crappy Chinese 1's. Plus it will be able to run at 5K RPM no sweat. Do you have any spindle thoughts/info/etc... to share that may be helpful?

See above for the bearings and thoughts on that kit.
I really don't think I will have enough machine to warrant better bearings than the second one I showed. If these give out, I will upgrade. I did a run in for about an hour yesterday.
@ 4000 RPM spindle speed with the cover closed and no fans, not even on the motor, the head only got to 125 degrees F. This is no load of course. I also ran it for 1/2 hour before that at 2000 RPM to loosen it up.
This is a little warmer than my mill head, but I think it may be because these bearings are closer tolerance. Just using stock bearings on the mill.


- Why did you go with rolled screws instead of ebaying some ground ones?

I actually did check out Ebay often for screws.
I still do. If better ones pop up, I can always retrofit. I was really pleased with the double nut setup on my router with rolled screws. I just went ahead and bought these so I would have at least something suitable for not a lot of cash when I got time to finish this up.

- Are the steel plates that your z-rails and head mounted on some kind of ground stock cut to length?

These aren't ground. Just cold rolled plate. I figured I would put everything together first and then concern myself with the flatness and alignment.
As far as I can tell right now, everything is nice and flat and aligned. I did make judicious use of all my measuring tools when putting it together. Most everything also has some slight adjustment capabilities as well. Worst case, I tear it back down some to grind it. Shimming may be needed, but as far as I can tell, it is very close to just right.
I seem to get pretty lucky like that with this 30/60 80/20. Good stuff.

Thanks again for posting up your builds. Very interesting and lots of great info.

Thanks. I am having a blast with these. What a great hobby/business. Dang sure blew out the cobwebs in the old noggin.

[Hack]

Where did you get the spring that is between the ballnuts? I assume these are for anti-backlash reasons. What size ballscrew? I am looking for a spring to complete an asembly like this for my mill and haven't had much luck.

Thanks

Dan

[LeeWay]

Springs are from McMaster carr. Part number 9657K17.

Ball screws and nuts are also from there. There are the 5/8" size.

[LeeWay]

I started to install my chuck yesterday.
Arrg! The seat on the spindle is too big. Not by alot, but enough so that I have to turn it down a bit. Since this chuck fit my other lathe just fine, it is the replacement spindle that is wrong. This is the type thing you cannot plan for.
I have to make an extension tool holder to do this. Not too difficult, but aggravating. I mention this in case some of you decide to order a replacement lathe spindle. If so, you may need to tweak it as well.

[Jason3]

Hi Lee,

Just checking in to say it's looking great, and the fast progress is impressive too. Well done.

Turret or gang tool is still a big question for me - my machine is a real baby one, so the limited travel might mean it has to be a tiny turret... Have you had any further thoughts on this?

What capacity do you expect to have over the cross slide on this beauty?

Best regards,

Jason

Edit - I take that question about the turret back - just read your posts on the small lathe turret thread My lathe will only have 100 mm cross travel, guess it'll need a turret unless I only make pretty simple or small parts...

[LeeWay]

Thanks, Jason.
The cross slide has 5" travel. That should be plenty I think. The key will be setting up the gang tooling just right. Also the QCTP I ordered should give me more flexibility for non production stuff.
I am still waiting for some of the new parts I ordered. I ordered a couple 495 oz motors from Keling along with another C-10 BOB.
I will upgrade the controller to the 72 VDC PS I bought when the one on my mill had issues. Gecko 201's on this machine. Should all work fine.

I also ordered that bigger DC motor controller. While I am getting good power and speed from this one @4000 RPM spindle speed, when this one shuts down, it is very slow to stop. The other one has pots to adjust spin up and down along with some other pots like for torque, max and min speed etc.
Plus I know that one now.
I will still keep this little one around. I am thinking about installing it on one of my drill presses. Probably my small 9" benchtop. Just a cheapy, but it does the bulk of the work in the shop. I also have a radial DP and a floor model. I have the X2 table mounted on the floor model with a real nice chuck. It does all the precision drilling.

[LeeWay]

Here are a few more pics.
I did turn about a thou off the mount on the spindle. Now the chuck fits, however it is out of true by about 17 thou low to high. Not acceptable. I will turn the rest of the seat down so it runs true. It appears to now, but may be off a hair itself. I think a thou will work. I just used a brazed carbide square cutter initially, but will use a carbide insert tool to finish the rest.
Then I will get it as close as I can. My goal is to get it centered below a thousandth.

[LeeWay]

This chuck was scaring me at first. I thought I could not get it to do right. I placed my old 3" chuck on it and had the same discrepancy. Nearly .03"
That is no good.
I did get my two old steppers mounted temporary. I have bigger ones on the way from Keling.
I then mounted a nice little carbide insert tool on my temporary tool holder. I then faced the entire spindle face. I just shaved a tiny amount off. Then went to align it again. After about 45 minutes, I now have it mounted within .003".
It now runs nice and smooth as well.
To get it any closer, I think I would have to grind the jaws a bit.
I will rig up a tool post grinder at some point, however this is now closer than my old conversion was. It was about .006" out. I can live with it for the time being.

I have now ran through the little stock of parts I had when I started getting this going. It is imperative now that I complete it or at least get it quasi functional soon.

I can still turn some parts by hand on the other machine, but instead will put that effort into completing this.
This machine should produce a much better result than I have been able to achieve thus far.
Stay tuned.

[LeeWay]

Here are a few more pics. The two motor mounts. And then a shot with the initial gang tooling for my production parts. I will have to learn how to do offsets now. I'll just code them by hand at first though. I want to learn to use Dolphin turn so that I may be able to do more complicated stuff in the future. I imagine this lathe will be with me a while.

I need better holders for the drills. I will probably use some Tormach tool holders that take a chuck. Use some 1 1/4" plate and the slot the holes.

This setup as it sits now will do my parts. I will add a couple motor covers. The start the coding and turning of a needed supply of these bushings.
It will probably take me some time again to install the larger motors, PS, DC motor controller and computer control for the spindle. It will earn some money in the meantime though.

[sergizmo]

The 270's aren't strong enough? What will you be making that you need 495's Lee?

Can you run collets in that spindle? That would give you much less runout but would be a big limit size wise. Then again if you do the whole part in 1 setup I guess it doesn't matter too much if you have a few thou runout.

[LeeWay]

The 270's seem to be okay for now. They have been on each of my builds so far and have always done a fair job. I was wanting to redo this control box anyway. No need for the third Gecko to stay inside the old one. I have a new BOB and that computer spindle controller as well as the spindle feedback to install. All a little later though. I haven't yet decided on limit switches yet. Hard stops on the ends of travel seem to do fine with steppers anyway. I only use one at the top of Z on my mill. No problems with it.

I did bore a few deep holes in the brass yesterday with them plunging by hand. Jogging actually. Just checking the drill bits set. The bigger motor on this one didn't bog down much. I did hit on plunge a little fast and it threw the motor controller into a lope. That ain't good.
Especially if it was under machine control.

The new motor controller will go in as soon as it gets here. I also want to install permanent oilers. Basically just a small tube that I can shoot a few drops of oil onto the screws near the ball nuts. The trucks have grease fittings, so maint on those will be about every three months or so. I may just wind up using a small oil can with a long flex spout. I have one, but the hose is a little short.

On the way covers, I just decided to use what I had. These will be no problem at all past the cross slide. Not sure how well the one under the chuck will do. Brass chips tend to pack in and they have a little weight to them. I may wind up building a telescoping one for the front. I wouldn't loose as much swing with one of those either.

[LeeWay]

I did get to make some chips today. That's cool. I still need to do some more tweaking pretty soon, but for now, I can at least make some parts again.
I had to remove the big plate I had on here for tool holding. I will likely make a dedicated plate that I can slide into place with all three tools I use for my production parts. This will allow me to remove the whole plate and it would stay lined up. I would use other tooling for other odd jobs.
At least I can now get some product out the door again.
These are the most accurate parts I have ever turned now. No backlash to speak of.
I will post more later when I get more progress on this.