CNC Mini lathe

[simso]

Okay for all those that dont know, I decided a little while back I need a cnc lathe to make some of my repetitive lathe work easier, I have a normal lathe at home a nuttal which ways 2 ton, now Im not going to convert it, its fantastic as a standard heavy duty unit, but I will purchase a small lathe purposely to convert and cnc.

Im step by stepping it so that way people who have no idea whats invloved can see whats happening and how the process begins,

This may take a few weeks to finish as Ive still got to to order some bits and pieces, but I will order them as I need them.

[simso]

firstly my old lathe, would cost a fortune to cnc this girl

[simso]

Step 1

Need a bench to store the lathe on, and to create some more room in my workshop, so here Ive welded up a bench thats on wheels so I can roll it up to the wall, I have also made it a bit larger than required so that way it can also house my wood lathe as you can see already on the bench, this allows me to throw away the crappy legs that came with the wood unit, it also allows me to store consumables underneath in the internal cavity of the bench. Ive simply cladded the steel frame with 6mm mdf sheeting. I also had a hydraulic press that was taking up floor space, so Ive fitted this to the end of the workbench as well.

Next I will pick up the lathe

[snowyskiesau]

What lathe are getting for the CNC conversion?

[simso]

I was looking at quite a few, but decided to go with the hare and forbes hafco al-50ag. its a small lathe for 995, for a few more hundred dollars they step up into some really nice lathes, but I decided I only want the smaller version becuase I have a large lathe already and convenience wise this will be more than ample for what I need

On top of this, rod who is a member on this board does a kit for the motor mounting, so instead of re-inventing the wheel, Ill give his kit a go, and let people see how it works etc.

But first I pick the lathe up tommorrow, it arrived today, Ive been waiting a few weeks for new stocks to come in, currently cant pick it up today due to work commitments but will squeeze it into tommorrows lunch break and pick it up

[crocky]

But first I pick the lathe up tommorrow, it arrived today, Ive been waiting a few weeks for new stocks to come in, currently cant pick it up today due to work commitments but will squeeze it into tommorrows lunch break and pick it up

Well where's the NEW piccy? :D

[simso]

Ask and yee shall recieve, isnt it just purty

[simso]

My first task is to get rid of the old toolpost and fit a quick change unit, I grabbed the 100 series from hare and forbes while I was there, there small, nothing wrong with the old toolpost but quick change units make life easy, I have one on my large lathe and I would be lost without it, it also will allow for easy tool manipulation when doing different profile cuts on the cnc, heres the old toolpost

Now that I have the lathe at home, I can measure up and place an order for the ballscrews and nuts, Im even tempted to do a trial run with the ariginal acme threads that come with the lathe, just so I can do a comparison check at completion

[simso]

Okay quick change toolpost is fitted, was a bit more of a drama than I thought it was going to be, to fit the item, I basically removed the old toolpost and threaded the top of the vise to accept the new toopost thread, unfortunatley these vises are cast, and when I tightened the bolt up it stripped the threads out of the vise, so I ended up milling the underside of the vise and mounted a nut inside the casting and then simply bolted the quick change toolpost from above, this will make life very easy when having to do toolchanges during the cnc operations

[simso]

Im ordering the ballscrews and nuts this weekend for the movement of the two axis's, but that being said I will be running the unit as well for a while with the original acme threads, as I am curious how much accuracy is in fact gained with ballscrews. Okay next step is to make an area for mounting the computer and cnc driver board and power supplies, Ive shown a picture of the back of the lathe and this is where I am going to box up and install these items

[rodm]

Hi Steve,
Lathe looks good. :)
Are you going to retain the tool slide in the conversion? If so you might want to make the 4 bolt tool plate to make sure the tool post is rigid. I can give you links for this if you need them.
If you are going to do threading you might want to consider a DC motor and tacho or a 3 phase motor and VFD. Just suggesting this now so you can leave room when you make the driver control box.

[simso]

Thanks rod, Ill take any links you have mate. Now that Im starting the process, its all starting to make sense again, yes I intend to be able to do threading, but like my cnc router and the fourth axis, threading is something I will attack after its all up and running.

The current toolpost/cross slide clamping system is rubbish, they use a circular ring to pull down around a round collar to hold the toolpost/slide solid, and gee surprise surpise it moves, not a little but a lot, under hand pressure you can deflect the toolpost a good 9-10mm.

Tommorrow Im starting on the computer cavity, hopefully Ill have that finished by the weekend

[rodm]

Hi Steve,
Here is the link for the 4 bolt clamp. Don't worry about yours as it is a common problem for this lathe.
Here (http://bedair.org/clamp/9x20clamp.html)
He has full instructions on how to make it and I made mine using his details. I have some steel the right size so don't go buying a length to do the job.
This fellow is a guru in the 9X20 lathe circles so spend some time looking over his other projects on the lathe.

The other Rod was over tonight for a workout in the shed and I talked to him about CNC threading. Apparently it is easy and all you need is a tachometer on the standard motor set up so I led you astray a bit on my last post. It only needs a single pick up (one count per revolution) on the spindle and Rod has worked all this out to feed back to Mach3. I probably have made it sound difficult because I don't fully understand this mumbo jumbo electronics. :-

Oh yeah you will laugh as umongst other things we mounted a QCPT to his cross slide tonight.

I am currently ordering ballscrews from that new link in China and will let you know how it goes. So far not as cheap as expected but still less that our previous supplier in USA. I still have to have freight costs confirmed so that might change things a bit. Will let you know how it goes.

I'll keep watching this thread with interest as I will do my lathe conversion one of these days. Before I start that I have two machines on the drawing board as well as one under construction so I might start a thread on that one.

[simso]

Okay well I got the Computer / Cnc driver cavity made up today, for those that dont know its important to set something up that is easy to access when in use, allows fine tuning of the circuitry and also allows easy changing of parts if necessary.

Here I have carved a hole in the back of the workbench behind the lathe, boxed it in, created an access hole and then wired a computers motherboard in, it all works fine, I hooked up a monitor and remote keyboard mouse and it works a treat. Now Ive just got to put the cnc driver board in "which is sitting on my desk here at home" and a power supply for the driver board and then its into motor mounting.

[WillyInBris]

Hey Steve its a wed one dat must be weely fast :2tsup:, why not triton orange it rods favourite colour :D

[simso]

mmm, Ill pass on triton orange , got to much of that one all ready. Im hoping being red it will be a fast one

[rodm]

Red's good. :wink:

Steve you may want to make provision for two MPG's. You can make your own or if you are lazy like me buy them ready made. You can then operate the lathe in manual mode using the steppers.
See attached photo.
You need a break out board and second parallel port. I fit a PCI parallel port and use the $25 CNC4PC break out board. They also have the MPG's.

[simso]

I did a small mod to the lathe today, as identified the cross sled mounting of the vise assembly is really sub-standard on these, fully tightened up they move a good 8mm realistically it should not move at all. Rod posted the link for those that are interested in carrying out the mod, basically it is removing the crappy 2 bolt fastening system and incorporating a 4 bolt system, can tell you now it works fantastic and is a must for anyone that has one of these small lathes

[simso]

Well, this little lathe has sat still since march. "Life and work unfortunatley got in the way"

Finally had some time and motivation to revisit this uncompleted job.

First on the weekend, I pulled the 3 axis driver board out of my router setup and fitted that to the lathe. I replaced the routers driver board with a brand new four axis unit

Three axis unit fitted behind lathe

[simso]

Just for the pic, four axis board fitted to the old router

[simso]

Okay, have pretty much gutted the lathe of everything it doesnt need, all the thread gearing has been removed the z axis slide is all gone, the quick engage and disengage on the sled removed as well.

Before and after

[simso]

All wired up, and running mach 3, even though the ballscrews and motor mounts are not made yet, I took it for a little cnc dance. Ran a program and watched the motors humm and do there stuff.

To finish I just have to get the ballscrews and make the motor mounts and wolla done.

So 6 months of sitting there collecting dust and then two days later, almost ready to carve its first job. Go figure

[simso]

Well, I must say, the new supplier of ballscrews is pretty good, ordered the ballscrews on the 31st, "day of the last post" and they arrived today 10 days later from china all machined up and ready to go. Got to be happy with that.

Now I just got to get my butt into gear and start making the motor mounts and supports

Okay picky time, new ballscrews

[simso]

and the motors which are all wired up and hooked into the computer and dancing along just fine, just waiting to be mounted

[simso]

Todays efforts, Z axis motor mounted, going to do the x on monday and then mount in the ballscrews

[simso]

Okay, still doing a little bit each day, today I made up the thrust bearing mounts for both axis's, I made two different styles, one open and simply reatined by the clamping pressue of being bolted up and the other rebated with a cover plate, why the different styles, simply for the sake of trying something new out, no more no less

[simso]

And z axis ballscrew fitted for checking alignment and clearances, taken some measurements and now have to make some mounts.

[rodm]

Nice work Steve.

[simso]

Well, I designed up a mount for the x axis which bolts up to the original spots, and also provides a surface for the nema motor, and it also incorporates holes to locate the z axis ballscrew

Decided however to get it laser cut,just got to wait a few days to get it, hopefully will have it for the weekend

[simso]

Well, got the bracket back from the laser cutters, didnt fit up as nice as I wanted, had to make a couple of small mods, but here it is bolted into place, Ill fit the motor up tommorrow and then make some ballscrew mounts to couple both slides and wolla its finished

[rodm]

Nice design - you have picked up two axes in the one bracket. :2tsup:

[simso]

Well z axis is all up and running, I havent put a rear bearing support on it yet, got to strip it down and machine the ballscrew down to do that, so a later job.

Runs nice and smooth under the computers control.

Have mounted the motor for the x axis, just got to make up a bracket for the ballnut, little bit more difficult, think Im going to have to mount the bracket on top of the cross slide instead of on the side, theres not much meat there and its a bit flimsy. So got to have a few ideas first

[Ch4iS]

Looking good so far.

So was it the laser cutting that was not as accurate as you would have liked or just a slight design flaw? Also was it expensive?

This would be the first one I have seen put together and it looks clean . . . AND NOW I WANT ONE :D

[simso]

Drawing flaw, the laser cut bit was like 20 bucks, I made the two location holes for bolting to the sled to low, it stopped the slide from coming out,I also had problems with the location of the ballscrew mount not clearing the slide, so I had to cut 12mm of the top and dredrill the two mounting holes,

revised drawing

[simso]

This is the z axis ballscrew mount I made up today

[simso]

and this is were it sits

[simso]

This is the one Ive got to now make for the x axis ballscrew mount

[rodm]

Hi Steve,
Coming together well there. Have you thought about cutting down the top of the Z axis mount a bit - the one you made today. You could then run a piece of angle slighlty above the bracket the full lenght of the lathe and attached to the side of the ways. This would protect the ballscrew from swarf, etc.

[simso]

Yep spot on rod, I was going to trim it down when I stripped the unit down when finished to paint the bits etc and make the rear z ballscrew support.

A piece of angle full length and over the x as well.

My biggest pet hate with the router is the dust and crap on the ballscrew, I think the router has gotten to the stage now it needs all new ballscrews, they all graunch when moving now, even after cleaning them out, I motor the z on the lathe and its quiet as, motor anything on the router and its crack groan crack groan etc, mind you Ive probably racked up a few hundred hours of cutting on it at least

[rodm]

I do a bit of brass on my lathes and that would be nasty in a ballscrew. I learnt through my builds that protecting the screws and rails is a must and doing it in the build stage is much easier than trying to retro-fit later.
As you know I have the identical lathe that has been sitting in the corner of my shed for at least two years and should have been converted long ago. You are motivating me so I am kean to see yours finished.

[simso]

Wll, I was going to make that x axis bracket as above but it just seemed to comlicated. I did a search of the net and everyone else seems to use the side of the cross slide, so I decided to drill some holes into the side and use a crappy piece of ally first,

Result - Moved no problems

So I drilled and milled a proper bracket works an absolute treat

[simso]

Oh yeh forgot to say, ITS FINISHED. Yayyyy

minus of course some ballscrew covers etc, but it works and runs, now still having problems with some simple software to run it

[John H]

Nice one :)

Have you tried Mach3? There are some built in wizards for the turning size of things.

[simso]

Hi john, thanks for that. The built in wizards in mach 3 unfortuanltey dont take into consideration the material size, they just simply take in your final co-ordinates and drive to almost that position and start facing, not good if you have to turn a 2 inch block to 1 inch, you almost have to create it by hand and then you can run the wizard to finish. I could be wrong, if I am please jump in becuase finiding software is frustrating as

Best so far is visual turn but 1250 usd for a version, I dont think so, mastercam leaves a lot to be desired etc. Frustrating, currently just doing things by notepad and g-code

[simso]

Also, got to do a few more mods, Im finding the locknut on the ballscrews to thrust bearing blocks are unwinding, so I might drill the ballscrew and use a casalated nut with split pin and shim for end play. Hev the same problem on my router for z axis

[rodm]

Hi Steve,
I have some 5/8 hex steel bar I can spare if you want to make a couple of double narrow nuts to lock them together - this is what I do and it works well. Also loctite might be an alternative.

[simso]

Hey rod, first in repsonse to your last comment, thanks, but I ended up running double nuts and on the second nut I drilled straight through the side and through the ballscrews and then split pinned them. Has been running sweet since

[simso]

Ended up having to do a mod on the lathe, becuase I wanted to have it shut down by itself when it finished the job, so Rod came to the rescue and donated two relays, one for my lathe and one for my router, basically power is controlled via your breakout board and mach 3 control centre. Works an absolute treat

Heres the relay if people decide they need one as well

[simso]

With the relay fitted, I needed a new control top for the lathe, this allows me to run the lathe stand alone without the cnc hooked up - hence the man switch on the right, and on the left is the cnc switch which when thrown allows complete control of power from mach 3. I put the switch in becuase I dont trust computers, imagine loading a job into the chuch and it suddenly came on. Scary.

Below that is the direction switch for the chuck and at the very top is the two wires coming in from breakout board to the relay which is fitted inside the cavity

[rodm]

Nice work Steve. The acrylic with the engraving makes for a tidy job as well as insulating it.

I got a 750 watt brushless servo and control box for my little lathe last night and I am told it will spin in both directions as well as brake and index. Sounds good until I unpacked it and found this - see photo.
Now how the heck am I going to work all that mumbo jumbo electrickery out. :-
I think this will be a job for the electronics wizard.

Stealing your thread a bit but I thought you might be interested to see what I was talking about.

Hah just got an email from a mate that knows all about them so looks like I can remain on the darkside.

[simso]

That will be on my to do list eventually as well rod, being able to put a thread on something via cnc is a good option. Mmmm thinking now, give us a buzzz when you eventually rig yours up with it, Ill pop over and have a gander