Yet another iron in the fire...

[BobWarfield]

It's been taking me so long to finish my CNC lathe conversion, that I broke down and ordered Aaron's CNC kit for my IH mill. He has them on sale at a decent mark down until end of the month, so I couldn't resist.

The lathe really isn't that hard a project, but between how little time I find to get into my shop, other projects (like getting the IH mill stand built and the mill running) and my usual over engineered approach (fancy control panel, GRex, and the works), I thought a short cut on the mill conversion might be a good idea.

Will keep you posted after I get the kit and get going installing it. Just so you know, I am not likely to start on it until after the lathe is finished. I just wanted to cash in on the good sale deal.

Best,

BW

[Switcher]

.

[Ron111]

Bob,
Do finish the lathe, I want to CNC maybe a Lathemaster Mill (which is simular to the IH), I don't think that I am knowlable enough to do it with the servo motors, so I'll most like stick to the stepper motors. Has anyone put together a good tutorial on servo motors? Maybe I could study up, and venture out on new ground. But I guess I should be asking questions like the advantages of using Servo's over steppers. Is it only speed and possible the fear of loosing steps with stepper motors, or are servos more accurate?

Anyway, do you have an active thread on the lathe or is it on your webpage and is it your lathemaster or are you building one from scratch?

Look forward to whatever your building.

Take care,

Ron

[BobWarfield]

Ron, you can track my CNC Lathe activities on my blog:

http://www.thewarfields.com/MTLatheCNCBlog.htm

as well as the home page for the conversion:

http://www.thewarfields.com/MTLatheCNCHome.htm

The project moves in such fits and starts (especially compared to your recent rapid progress!) that I don't think it's worth a thread here. Last guy that was so slow got chewed out over it, heh. I'll send up a flare when I get it done so people can check it out.

My latest activity today was to design an optical limit that I'll be testing for potential use with the lathe. The biggest holdup is I like to open way too many cans of worms at once. But what the heck, its a hobby, eh?

That Lathemaster ZAY mill is almost identical to the IH mill I have. Just a little smaller travels. Go through the IH web site carefully, as most of what is there is well documented and totally applicable. You can even install the same kit Aaron sells.

As to the advantages of servos over steppers, whew boy, there has been a lot written about that! First thing you have to do is separate out the encoder as a servo advantage. You can add encoders to steppers, and in fact Mariss over at Gecko has a very cool project underway whereby you will be able to do exactly that and tie it back into the GRex motion controller to make what he calls an "unstallable stepper". No more lost steps!

Probably the second big advantage is a much broader torque curve. Steppers peak out at 1000 rpm for the most part and then decline pretty fast if you try to go faster. You will want to design your drive ratios so the max torque is happening at your fastest likely feedrates. You may get a little more speed on rapids, but going for the really high speed rapids can be hard due to the limited and peaky torque curve of the stepper.

A big disadvantage of servos is they are just not as standardized as steppers. That means you've got to do a lot more research and fooling around to work with them. A cool thing about the Gecko products is they all work on step + direction signals. Depending on what driver board you by, you can run steppers or servos. I suppose you could even mix them.

I don't know if I'll ever get to messing with servos or not. Steppers are a lot cheaper, and the unstallable step drivers seem like they kill nearly all the stepper warts. We'll have to see.

Best,

BW

[widgitmaster]

Just returned from your Blog!
That's a nice setup you have there Bob!
I can only dream of having that much floor space!
Oh yea, and a heat-treating oven too!

Eric

[BobWarfield]

Thanks Eric!

No heat treat oven as of yet--it's just a gleam in the eye. I want to build one, and it doesn't look terribly hard since the PID temperature controllers are cheaply available on eBay.

Widgit, there is surprisingly little floorspace in the main shop, actually. It looks just about identical to the space of your shop. The downside is I could never have fit that big knee mill you've got through my door. It's a normal sized door, but only 2/3's height, and there is a 2 step drop followed by an immediate sharp turn. The IH mill is what fit, and I'm very happy with it.

The welding would be impossible if I wasn't using the top of a car lift as a hide-away workshop extender.

Eric, I had a thought for you. I know you make the nice T-slot tables and offer them on eBay. You should put together a fixture plate setup. I've been making notes on one here:

http://www.thewarfields.com/MTMillFixturePlate.htm

You could offer the big plates in a size that makes sense for commonly available mills, as well as accessory plates of a size for Kurt Vises and rotary tables. A T-slot plate would also be handy to drop onto the main fixture plate from time to time. It would need to be done from cast iron to avoid the electrolysis messing up your mill table, but I'll bet you would get some takers for these, especially among the CNC'ers.

As you can see from that page, I'm planning a design similar to what Anvil uses. Still debating 3" versus 2" hole centers.

Best,

BW

[Ron111]

Bob,
Did you buy the kit from IH that just has the mechanicals? And are you planning to use steppers? And allow me to ask, I read where the guys are lapping the ways of some of the mills. I remember lapping valves, when I was a kid fooling with cars and motorcycles. Exactly what does lapping the ways do for us. The reason I ask, I have a shopmaster 3 in 1 and I having a unusual sound coming from the ways on the Yaxis(which is the long axis on that machine.) I think that I saw where some one recommended removing the gib and sanding it down a bit, but havn't run into the post again. So, when I read that some were lapping ways, I thought that maybe this would work for my anomoly.

Thanks,

Ron

Ron

[Mcgyver]

lapping with a cone shape will work, but not with a flat UNLESS you are using a lap, ie you know and control the shape of one of the surfaces - lapping is a specific process requiring methodology and some skill, it is not putting abrasive compound into mechanical works and hoping for the best. lapping machine pieces to each other would be like pouring lapping compound into your crankcase....yes it will definitely loosen things up, but its only doing so by creating slop, and we don't want that in the bearing surfaces our engines or machine tools!

this subject came up a while ago and is covered at depth here, hope its of use.

Way lapping, Scraping, Gib adjustment and Lock screws

[BobWarfield]

Ron, you have a unique talent for asking the controversial questions in such a matter of fact way.

Which is better, servos or steppers?

What about lapping your ways?

Both have been the subjects of long and somewhat acrimonious threads here in the past. I see McGyver is getting the gloves on early with respect to lapping. As he points out, lapping, at least in this case, is not about getting things flatter, straighter, or truer. In fact, if you look at the amount of activity Aaron recommends in his lapping instructions (i.e. grit versus number of strokes), it couldn't possibly move that much metal to make a profound difference there one way or the other (and here is where I'd best have my mouth guard and helmet in place!).

A short conversation with Aaron will quickly get you to the bottom line on why he advocates lapping these mills. In his view, it allows you to run the gibs tighter, which he says will result in greater accuracy. For the manual machinist, it lets you run tighter and still maintain smooth motion. For the CNC machinist, it allows you to really tighten things up and let the torque on your steppers or servos still be able to deal with it.

I have ordered the lapping kit along with the mechanicals only CNC conversion from Aaron and I do intend to lap per Aaron's advice. He knows these mills inside and out and swears up and down that it improves their performance, which is good enough for me.

I am sorely tempted to measure this machine according to Tormach's QA spec both before and after lapping to see what the measured difference is, if any. I think that spec provides a pretty complete accuracy work up on the machine and the result would be fascinating. At the least it would move things from the fight between, "Trust me, this works," and "Lapping will always make your machine less accurate and must be avoided like the plague, period," to something were there are real numbers to determine the real impact.

There is just one little fly in this ointment. I really hate the thought of tearing the machine down twice, and if I don't compare pre and post lapping while the machine is manual, the results won't be nearly as meaningful. If nothing else, per Aaron, I will be able to operate in CNC mode with the gibs really tight. Some will still say the proof is in the pudding, while others will argue that any increased accuracy came from a switch to ballscrews or some other source and the numbers are therefore meaningless. This would mean I've got to tear the thing down twice to get objective numbers done and do the CNC conversion. First I go through the measurement regime Tormach uses. Then I tear it down, lap it, reassemble, and measure all over again. Then, I tear it down, convert to CNC, reassemble, and probably measure that again too.

This all seems guaranteed to completely stop all forward progress I'm making on any other projects, so I am not exactly sold on doing it yet.

Best,

BW

[Mcgyver]

no gloves Bob, and no malice or acrimony. I was trying to share knowldedge, how one proceeds is up to them - it doesn't make or wreck my day good luck with it.

[BobWarfield]

Quite allright McGyver, I don't take offense at any of it, I just know these topics spur strong feelings on the boards and was more letting Ron know than anything.

BTW, I've come across several of your projects lately that looked really cool. for example, your sharpening jig projects and some of your CNC work. Please keep up the great postings. I'm very inspired by it all.

Right now I'm tied up with Widgitmaster's Kurt vise stop gizmo. Fussed and fumed for a bit before deciding I had to make one. I note that you use the collet-style clamps on some of your projects. I've wanted to try making some, so that's what I'll be doing for my vise stop.

When I get done with that, I will probably start building a sheet metal pan brake (I told you I had come across your postings!). I like the picture you posted over on HSM so much I tracked down the book the brake originally appeared in. Looks straightforward to build, and I've got the steel ordered already. Guess what I want to use it for? Enclosure work for my CNC. Now having seen your enclosure post, it does seem like this is a small world that just turns round and round on very similar thought processes!

After seeing all these common threads I finally just looked through all the posts you and Widgitmaster had made. Just trying to get some ideas and knew you guys tend to make high quality posts. Thanks!

Have a great weekend all,

BW

[Mcgyver]

thanks for the kind remarks. which brake? I think i know the one you mean, wasn't mine though just posted the pic. beautiful build none the less.

The split cotters are easy to make and a functional way to clamp, you'll like using them. If you're not sure of the process let me know

I to have toyed with building a brake, I keep flip flopping between buying a good one (used) and making one. I've a 4' 16 gauge brown boggs shear that must weight 1000 lbs and a home made pinch roller, all I need is the brake and spot welder and I'm good to go with sheet metal. well at least until i want to make a fender or some bloody thing