Official Luthiers Forum!

I think everyone around here agrees that Zlurgh knows his way around CAD/CAM about as well as is possible, and his advice in this thread has been excellent. Depending on your experience with CAD you might consider finding some courses at a local community college or university. While no two CAD environments are identical, the general concepts of how to design a part hold true. After picking up the basics, your skill will continue to grow with practice. Unfortunately, quality and ease of use tend to come with a high price tag. Out of all the software I have used, SolidWorks feels like a bargain at $5k because I can work complex designs quickly and easily.

CAM will have the ugliest learning curve. I've given an earful to a few people in the past who assumed CAM worked exactly like a printer and that user involvement is minimal. Design is the easy part. While a CNC router is technically a big fancy printer, it is dumb like a computer and will do exactly what you tell it to do. The good news is: Once you have a cutting path perfected you can replicate the part quickly and with little effort from then on. Most good CAM software will include a simulation mode, and you can learn a lot from using it.

With those skills mastered, running your router is the easy part. I worked up a design with my business partner and when the parts arrived he had the gantry assembled within a few hours.

Last but not least: if all else fails, this forum rocks!

For software, I ordered Rhino 5 and madCAM (old version with free upgrade to the new version). I've been playing with demos to get comfy with the environment. I do have a little bit of CAD experience with various packages. A couple of years back, I actually modeled a complete guitar in SketchUp just to get an idea of the complexity involved. I haven't done any CAM. Incidentally, SketchUp is a FANTASTIC package for simple, and even some complex, design work. It's to CAD what Visual Basic was to Windows programming. Yeah, I can't build a driver in VB, but sometimes all you need to do make a couple of buttons and a text box. I'm feeling my way through Rhino...slow and steady.

re: KStep
I'm still on the fence. I want to place an order soon. What I see that I don't like is:

1) 16X micro stepping. Maybe not a big deal. 10X is probably better for the application
2) no midrange band resonance settings, though I've read that KStep does fine without this. I'm not sure I believe that.
3) Current settings are funny...there is no 3.5A setting, which means that I either overdrive or under drive the motors a bit OR upgrade to 5A motors. That's a possibility....more cost.
4) There is no idle current reduction, but I can easily program that in.

I suppose I could program a filter into KFlop to fix the lack of midband resonance suppression, but that's starting to feel too much like my last job. There's a reason I quit. I love that I'm bringing some aspect of guitar building back into my true comfort zone, but I want to build guitars, not control systems. At some point I'll start fiddling, I'm sure, and I'm even open to the thought of bringing some automation products to market in the future, but just not now.

KFlop is a slam dunk, especially if I skip Mach3 altogether (which is the plan). The only real question I have left is KStep vs Gecko. That motor/drive package that everyone recommended is maybe not the ultimate in performance, but it is solid and well understood. If I want to upgrade later, I can simply do the upgrade and sell off the old motor/drive combo and not be out very much money. I'm very strongly leaning towards KFlop/Gecko and will likely just order it today.

Andy, with microstepping, is the XZero repeatability +/- .005" or .0005"? Also, do you find the 381/3.5A motors/drives underpowered for the machine?

A little more info on KStep (Edit: John, I see I posted just after yours):
Microstep selection: fixed at 16 according to: http://www.cnczone.com/forums/1142925-post1.html That post says Tom K finds no benefit to less than 16. I had thought (from other sources) that torque decreases with each higher microstep (2, 4, 8...), and beyond about 8 has little real resolution benefit. (?)
Midband resonance control: yes, according to: http://www.cnczone.com/forums/dynomotio ... epper.html
Over-current or short-circuit protection: Not really, according to post #8 of the first link.
So, it looks like the G540 is more sophisticated, naturally at more $.

John, that fast-slow homing routine makes great sense -- I wish Mach3 had it. I've been manually jogging the machine near home, then homing. But I just found this for Mach3: http://www.cnczone.com/forums/mach_soft ... peeds.html

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David Malicky

re: extra set of hands
That was a BIG decider for me. I've been thinking for a long time how great it would be to be able to concentrate on all the repair work I have to do here instead of the boring, repetitive work of new builds. There's no value in me pushing a router around. I'd much rather be working on that smashed to bits ES350 I have, or any one of a zillion other projects that need to get done. Repairs take priority, so new builds just sit idle and that's bad news.

Let me preface this by saying that I haven't done a rigorous test and my best measuring device is a Starrett 1" dial indicator. Moving in one axis at a time, I can get it to return within .0005" most of the time, .001" all of the time. The basic testing I've done has always had the error in one direction too so I would confidently say I can get repeatability within .001". Everything I've read on micro-stepping is that you can bank on holding a half step, everything else is gravy. As far as overall accuracy goes, I'm probably in the .003" range over the whole table but I have no way to measure that. I say that because when I mounted my rails I did my best to get them under .002" compared to my profiles but those are only so good too.

The long axis might be a little under powered as I can't get the rapids or accels up as high as the other two shorter axes. The long axis has a 2510 ballscrew which is just gigantic and I could probably get slightly better performance with either a bigger motor or a faster lead - George offers a 2525 screw which apparently can do 700ipm rapids easily with a 381. I think the machine could run faster with bigger motors and a matched driver but, at 400ipm it takes around 4.2 seconds to traverse from one side to the other. A little extra acceleration would be nice but the machine already jerks around a lot as it is!

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

I'm really surprised how few people do that, actually. One of the last projects I worked on before I left had something to do with steppers, actually. The original homing routine took over a minute, I think, on a cycle of maybe 4 minutes. When we redesigned the controller, I did optimize some of the logic and since I also wrote the stepper control software, I was able to do a couple of tricks to make things go just a tiny bit faster. The big difference is that my home routine took about 5 seconds. LOL. Customer was very happy, though I'm not sure they ever really realized that the biggest speedup came from such a mundane place.

I left a question on the CNC board about the current limits. I'm assuming that adding jumpers just engages sense resistors, so there's probably a way to simply solder a resistor across on of the jumpers to get 3.5A. Based on that, and that there doesn't appear to be a midrange resonance problem, I may go to KStep yet. Honestly, I think it's a tossup and I'm just going to choose one and go for it.

I do also wonder about the lack of full step morphing (though this is a relatively new stepper driver feature), though I'm not sure how important that will really be. We'll see.

It's really not that big a deal though. Before I turn off my machine, I simply jog it over to near the home position. When I power back up, it takes 2 seconds to re-home. If I forget (my park position is clear on the other side for the Y axis) I just pull the Y axis over near home before I power up.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

That's pretty much exactly how most people do it, actually.

Well, it's all said and done except for figuring out a computer to run the KMotionCNC control software. I'm sort'a leaning towards a laptop right now, just for convenience especially during initial setup. I also think it will hold up better to all of the dust. If I can find an old laptop for $200 or $300, that's where I'll go.

What I ended up with is:

32" Raptor

Those motors you suggested, Andy (the 381 in-oz steppers) but I grabbed the bigger 12.5A power supply in case I decide to add another axis or maybe upgrade the gantry motor.

Same Teckno spindle that you have except I grabbed the dual ball bearing. I don't know what the difference was when you priced it out, but my difference was only $200 I think. I also grabbed the big Hitachi VFD to run it. Not sure what size you got. I got the biggest one that would run without 3 phase.

KFlop and KStep

Rhino with madCAM

I've pretty much stayed within budget so far, and I think I have a far better system than I would have had if I had gone with a turnkey product...at least in my price range. I would have made some pretty big mistakes if I hadn't had all the guidance and help from you guys. It was invaluable.

The KFLOP has been around for awhile, and it's very mature. The guy designing it (Tom Kerekes) is, in my opinion, probably over qualified to work on this sort of stuff. He designed it as a hobby project because he thought doing a full laser sintering system would take too long. He designed a motion controller on par with a modern Fanuc control as a hobby project...that's like designing a functioning jet from scratch for fun. There's nothing comparable in the budget of a hobbyist or even a small job shop.

If you can find bugs then they've gotta be pretty obscure at this point, and he's added a lot of really advanced features since I started using it (many at my request / heckling- the test toolpath on the website for the path smoothing is one I designed to test it on my machine). A lot of the really neat stuff doesn't really apply to steppers, but some of the path smoothing and such might still help cancel out mechanical issues. When on to servos, the actual motion control loop, tuning, and filtering is sort of peerless and all the software to do it comes free with the hardware. I do believe you can servo steppers on the KFlop, though I'm not sure whether it requires a user program or if it's sort of built in at this point. That'll at least help with accuracy errors, though I'll say again that it's easier to just go with servos in the first place.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Well good luck with Xzero. George seems to be a nice enough fellow, but he does have a big problem with delivery. I have been waiting 15 months for my machine, and there is still no sign of anything. The original estimate was 10 weeks for manufacture, 4 weeks shipping. I dare not mention CNC to the other half or I will get the "I told you so" thing. It may help if you can drive across the border and harass him, but I can't since I live on the other side of the world. Fortunatley I did not buy the motors and electronics from George, but got those locally, and they have been sitting in a box for more than 12 months gathering dust. I read reports that the wait is worth it, but then when other Xzero customers get their machines in less than 12 months, I am less than impressed. It does make me feel better when someone says that he is slow but has never failed to deliver, but at the moment I am frustrated. The last email from George was an estimate for air shipping, but I just wish he would get the dang thing shipped by whatever means. Be prepared for a long wait. Good luck.

Everybody thinks they can just hang out a shingle and it all just magically happens from there.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I think that Xzero's delivery issues, like a whole lot of small businesses', have been largely due to cash-flow problems. George has been adamant about keeping prices affordable to the masses while still producing the best product he can--a very noble goal. But, that idealism has kept his margins so low that I think he's had a hard time balancing the guzzintaz and guzzoutaz from a cash-flow standpoint.

George makes a heck of a machine for the price. I think he would do himself well to charge more, which would still be a good deal and might help him improve his deliver times and make him a few bucks to boot. But I think he's been undercapitalized and has done the best he can to keep things in balance between his customers and his suppliers. Running a small business is tough--especially when your vision goes beyond your capital.

I couldn't be happier with my Raptor machine, especially for what I paid. It did take a long time to get everything--it wasn't sold as "turn key," and it took some time and frustration to get all of the parts. If you're in a hurry to get up and running, Xzero isn't the place to go (at least it wasn't when I got mine). But, the Xzero machine is way more solid than any of the other similar-type/priced machines I've seen. If bang for the buck is your goal and you're patient, George sells a darned nice semi-DIY solution at a price that is hard to beat in today's market. I hope he is getting the delivery-side issues under control. He's a basically honest guy who seems to be doing his best at a balancing act between his suppliers and his customers and who genuinely does seem to be committed to providing the best machine for the dollar that he can.

Dave

The machine I bought happens to be complete, as far as I know, and we're just waiting on rails which should show up tomorrow or Monday. I don't think the machine I bought is one of the popular sizes. From what he's told me it's been sitting around for quite some time, so I may be just getting lucky because the long wait happened before I purchased. I don't know. It's not here yet, but we've talked about it some and I can't do anything but assume that it will all go smoothly until it doesn't.

I would be lying if I said I didn't take all of the negative comments into consideration. I probably would not have moved forward if I hadn't gotten assurances that nothing was missing and it was ready to go. He's got my money. I'm confident this will go smoothly. I've been wrong before but I'm not going to worry about that just yet and I'm going to assume that everything was honest and in the open.

Andy, Thanks for the clarification and details on the repeatability. It's remarkable they are similar to the K2, given the fast 10mm lead screws and steppers (vs the K2's 5 mm screws and servos/encoders). On speed, I guess it's one of those things we can never have enough of! I'd be ecstatic to go 400 ipm, but once there, maybe I'd want more too!

Bob, Thanks for the helpful info on KFLOP. Looking into it more, it's very impressive and I see what you mean about the great features for servos.

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David Malicky

That may be true, but from following cnczone he seems to be spending a lot of time on developing new machines and making improvements to the existing designs rather than concentrating on getting them out the door and off to customers. If he could just get them out the door and shipped then the cash flow problem would improve, and he would have less unhappy customers. A policy of first come first served would also help. If John gets his machine before mine is shipped I won't be terribly happy (sorry John) since I have been waiting for 16 months for nothing. I ordered a standard configuration with some standard options, so why can't he get it made and shipped in a time frame that bears some resemblance to the original quote? This is the sort of problem we face when the waiting list gets too long. Good communication (non existant from George) would help as well.

Don't think that I haven't thought about that. I may end up getting screwed too. I don't know. Honestly, I'm just looking for a solution. I didn't really mean to get involved in all of this other stuff that's going on with him. Now I'm sort of starting to regret having gone public with my decision because there is obviously a lot of unresolved problems with other people here (and elsewhere) and George, but honestly I just can't really worry about that. I was just trying to get some advice from people here that have gone through it before. The waits you guys are putting up with are absurd, IMHO. Honestly, I don't know why you're putting up with it.

I'm curious. What parts are you guys missing?

Everything I ordered.

I'm not sure I have been screwed, I still have not not completely given up hope something will arrive eventually, but there is nothing I can do about it from the other side of the pond.

Just got a couple of emails from George. He is putting things right. My machine is ready and hopefully will be shipped soon. Apparently it is much improved on the model I ordered so the wait should be worth it. I am much happier now, you should be fine.

I'm sincerely happy it's getting resolved. The more I look around, the more it's clear that he makes a heck of a nice machine. It's really too bad he's getting out of the small machine market.

Any opinions between 2010 and 2525 X ball nuts? I'm not sure it really makes sense to me to have a different pitch between Y/Z and X. I'm thinking it would be odd to have one axis just a little less accurate than the other two.

Unless you really need more than 400ipm, I'd go with the 2010. A 25mm lead will have ~2.5x less precision and repeatability, and magnify microstepping non-linearity.

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David Malicky

That's what I decided also. .10" lead comes out to .0005" per full step. .25" lead is .00125" per full. If he has 2510 screws, I'll go with that...if not I'll stick with 2010 and then just upgrade to 2525 if I ever add encoders and/or upgrade to servos.

edit: luck on my side. 2510 available....yippee.

Glad to hear it! My machine was the same way--upgraded from when I ordered. I think part of George's delivery problem has been his constant upgrading of the design rather than getting to a point and stopping saying, "that's good enough." I'm very pleased with the early Raptor I got off of ebay, but the later model that I got from George shows some significant improvements. They're both very solid machines, but the newer one is a bit more refined. It was worth the wait.

Dave

Well, I just got back from Toronto and I have most of a Raptor sitting in my car. I'm glad I went up there to get it...there was a lot of, "What about this? What about that?" going back and forth, and a lot of little parts here and there that we had to gather up. The only things missing is the table top (which should be getting mailed out) and the Z-axis plate, which should also be en-route already. I was planning on leaving the table top off for a while anyhow, so that's not going to hold me up. I have to be honest, though, that I'm really not happy about this. After a 18+ hours of driving, and after assurances that the machine was COMPLETE, it's not complete. It's close, but there was absolutely 0 communication indicating missing parts, and 100% communication indicating a 100% complete unit, so that took me completely by surprise and leaves a very bad taste in my mouth. Anyhow, of all the things that could be missing, at least the Z plate is something I could machine myself if I had to. I have all of the rails and screws.

The 2510 ball screw on X is massive. This thing looks like it could jack up a car. The SBC rails are very nice too. Like I said before, I don't know anything about CNC but I know my robots and automation stuff pretty well, and I can tell this thing is going to be very stiff and precise. Overall, I don't think there's anything else like this out there for anywhere near this price. I'm glad Dave and Andy steered me in this direction. I think it's absolutely the best choice I could have made given anything even close to my budget for machine + software.

George seemed like a pretty nice guy. He spent quite a bit of time with me showing me how everything goes together and it looks like I could practically toss everything in a box with some bolts and hex wrenches, shake it up, and a machine pops out. I suspect once the Z plate show up that It won't take me but a day to build it, align it and run all of the wiring.

So we'll see how it goes. I really really did wish I could come here and report that everything went smoothly, and a bit more communication BEFORE I spent two days going to Canada and back would have been helpful. I most likely would NOT have gone to pickup the machine until the "missing" parts showed up and I would have used that as my barometer for deciding if I was going to be left waiting for months and needed to pursue a refund. I would much rather have waited a few days, and then I'd be smiling right now. That said, it looks like it's going to be a kick ass machine when it's done and I'm still pretty optimistic that the rest will show up in a couple of days...and then I'll relax and smile.