7 x 10 project started

[cut more]

I Found it! My appologies to who-ever posted this previously. I can't remember who it was. Here is some more info on spindle pulse for lathe threading. This is the wiring diagram I used that works.

Regards, Cutmore

[samco]

Nice work!

Have you decided on the machine control? (mach/emc2/turbocnc/other)? Emc allows you to use an encoder with index. (you would want to look at around 100 line or so if you are counting thru the printer port. Then the top spindle speed is determined by how fast your computer can count) A decent computer with a 100 line (400 edges) should be able to count up to 3000rpm. (yes emc can also do single index threading) Some have also made their own encoders with index.

People thread on mach all the time. (The same as you - I wonder how well )

some have switched from mach to emc have have said it is much better but I have not used mach. They say the threads come out better and think it is neat that they can lean into the spindle to slow it down with no change in the thread finish.

http://article.gmane.org/gmane.linux...athe+questions

[blades]

Wow, exellent info cutmore! Just one question about this: you mentioned that Mach will automatically recognize how many tabs you have (after calibration). Why do you need the shorter tab? Is that to give Mach a positional reference for the spindle? Probably a premature question, as I haven't yet looked at the PDF you attached.

Samco, I haven't yet decided which controller to use. I was thinking about TurboCNC, but I have not yet looked at Emc2, so I will certainly give that a look before I decide.

[blades]

More done today, to the extent that it's mechanically complete. YAY!
LOL, honestly, I don't know if that was the hard part or the easy part. It was probably the cheap part though.
Got the Z-axis limit switches mounted, the lead screw end support, and the optical gate on the spindle.

The lead screw end support is not really a support, but is more for anti-whip and to protect the screw from getting accidentally tweaked. Because of how my setup is and how short the screw is, it doesn't really require a bearing support on the other end.

The optical gate also required some tweaking after I got it installed, because the tab did not clear the end cover supports when I tried to put it on, so I had to shorten the tab and raise up the gate a bit.

The limit switches are tripped by two .060 dia. pieces of hard spring wire coming down from the carriage block, not seen in the pics. I didn't put limit switches on the X axis yet, and I honestly don't know if I will. The Z-axis is more prone to over-travel than the X-axis. I may prove myself wrong and end up putting limit switches on it as well.

I don't know if I will be using my control board or not, since it only supports unipolar mode on the motors, which seems to run about 30% lower power when wired that way. Think I need to wait for some funds to become available so I can get a legitimate Gecko controller.

[Teyber12]

it all looks good! real good

[blades]

Thanks Teyber! I must say, I'm pretty happy with it thus far.

[Starleper1]

I like the reverse mount on the Z axis. Very creative. Nice work.

[Farasien]

Just outta curiosity, what motors did you use for this? They look like NEMA 17 frame, but other than that, its hard to tell by your photos...

-Farasien

[blades]

Just outta curiosity, what motors did you use for this? They look like NEMA 17 frame, but other than that, its hard to tell by your photos...

-Farasien

Trust me, if I could have found 17's with enough torque, they would have been my first choice, but I've never seen any. The motors I used are 23's that I got from Keling, model #KL23H276-30-8B, which are 282oz-in motors.
http://www.kelinginc.net/KL23H276-30-8B.pdf

I'm still really leaning towards not using my existing controller I have on hand, mainly because it will only work in unipolar mode, which reduces the motor torque to 200oz-in. Still really leaning towards Gecko controllers, and really like the G540 unit, even though I only need 2-axis control. It costs a bit more than 2 of their G201 controllers, but I like it's compact size and it's all-in-one package with it's built-in DB25 printer port connector as well as the DB9 connectors for the motors. It's a neat package.

Would really appreciate any input regarding this unit as compared to the G201, in case my judgement is misguided here.

[NEATman]

With the two extra axes on the 540, you could add a turret tool changer and a screw driven tailstock - but I guess you are keeping this simple... :-)

I've thought about a screw driven tailstock for quite a while, it could have an independent leadscrew and a limit switch to stop it before it crashed into the carriage if I forgot to program the carriage out of the way before moving the tailstock.

Just a thought. I have never used Gecko products, but I do have some centent drives that Mariss had designed long ago before Gecko existed, and they are very reliable.

Keith

[blades]

A screw driven tailstock? That does sound interesting, and very do-able. The 4-axis controller would certainly give me options and room for expansion.
I've also never used any Gecko products, but I don't ever recall hearing anything negative about them on this forum. They seem to almost be the defacto standard for motor controllers, from having spent some time on the bench mill forum here. I'm open to suggestions, but still leaning towards one of the Gecko controllers.

[NEATman]

I have spoken with Mariss on a couple occasions as well, as I had sampled his products about three years ago for my job at the time. All excellent quality, and very reasonable cost. I am not sure if it ever resulted in any business for Gecko, as I had voluntarily left that job shortly after speaking with him. I have still been building all of my projects from
discarded "dumpster finds" from that job, but I have long thought that I would buy a 540 for one application that I have in mind.

As far as the lathe, a simpler option instead of a independent screw driven tailstock is simply to make a way to couple the tailstock to the carriage. So when you have a drilling operation, you can just drive the carriage with the tailstock in tow, and do a peck drilling cycle, etc.

And along the lines of a turret, I had found a really nice high capacity roller clutch a year ago, and I have had in the back of my mind that a stepper could simply drive it one way to index to the next tool, then drive it the opposite way to lock the clutch. It would be designed so that the cutting forces were all in the other direction against the locked clutch. For $5 at a surplus center, I figured why not.

Keith

[blades]

I have not yet given any amount of thought to a turret, but that would be the next obvious choice when expanding a simple 2-axis lathe. I no longer have access to misc. tooling components like I once had, which would have made fabricating something like that a lot easier.

Also like the idea of towing the tailstock with the carriage, I think that could be done fairly easily. However, I would not trust my current screw/delrin nut setup. I just don't think the delrin nut is up to the task. But it's definately something I would look into doing after switching to the ball-screw.

That reminds me Keith, I need to P.M. you regarding that. Will do that a bit later today.

- Bill

[Farasien]

G-540 is a really nice controller- easy to wire in, idiot proof (or else I'd be lost) and has a good return policy. Also, its hard to beat with tech service- Mariss is ON CNCZone and answers questions directly- try that with anyone else.

With 4 axis, you could to an auto-turret. There is a thread or two out there in the lathe group here talking about them. If you can't find them, I can email you the two sets of plans I found online. Also, someone said you could put a screw-driven tailstock on the mill... You could also just automate the feed of the tailstock itself. If you make an adapter plate that fits in between the casting and the heavy washer, all you have to do is make some spacers and bolt a motor on.

I figure having too many axes is alot like having too much money- not really a problem!

-Farasien

[blades]

Thanks for the input on that Farasien, I'm all about having expandability. Plus, you had me at idiot-proof. I'm there. ;-)

[blades]

.

[yang_cnc]

Blades:

impressive mod and neat. I especially like the idea of removing all underlying stuff of the carriage block(if my term is right)

one question, so did you throw away the old leadscrew?

[NEATman]

yang cnc-
Are you in need of a leadscrew? I've just removed one from my "speedway" (blue 7x10 or 7x12) lathe. It is the exact model on page 6 of this user guide:

http://www.littlemachineshop.com/Inf...UsersGuide.pdf

I have also removed the front apron (broken handwheel, good halfnut), cross slide screw & nut, change gears & Mount, end cover, thread dial, etc. I have no use for any of it, as I am replacing them with ballscrews on both axes.

Keith

[Farasien]

Hey Blades-

Did you have a print of where the holes need to be drilled in the end of the lathe bed to line up the screw where you have it? I was working on making the same setup as yours, but had a few other ideas for the end mount...

Thanks-

-F

[blades]

No buddy, I sure don't. I mounted the motor to the plate and then clamped up the plate to the end of the lathe bed, then transfered the holes once I had it positioned exactly where I wanted it.

I hope to be back on this project in another month or so. I am in the process of moving, and have a laundry list of stuff to get done before I can focus on this again.