CNC router build from Adept robotic cartesian slides.

**PJs** · Oct 18, 2015, 12:53 PM

Hi Bob, First I misspoke yesterday on the total quad count for the drive I was using. The encoder had 4096 counts/rev or ~3060 counts/in travel and had ~242 of travel which equates to ~740k counts (3060x242) for full travel, not 36000...must have been thinking of something else from back in the day.

I don't have any experience with Mach3 tuning. I went back and read the entire thread again and couldn't find any entry about the controllers you are interfacing with through the centipede breakout board. From what I have seen on the various CNC forums and Mach3 Help, you may run into some issues with tuning and may need a "smoother" interface depending on your controllers. Although I saw some stuff about auto-tune...it's only to get you in the ball park, IMHO but M3 does have a scope popup tuning window. Did your controllers come with any tuning stuff? CNCCookbook has a bit of a write up on the basics but think YT is your best bet to get you started. There is a ton of stuff out there on PID tuning just takes a bit of digging.

IMHO, the best advice I can give is to do only one drive at a time (others unplugged). I pre-tuned the Parker servos on the bench first as a base point. Then put them in the linear drive, re-tuned, then under load (min-Max) again. Lots of strategies out there...this is mine. P(proportional) is the most important, D(derivative) second and only mess with I(integral) in very small steps after you have decent movement and minimal vibration/oscillation. Start with very minimal velocity and acceleration and work your way up. But before all of this you must establish your home, and limits, in quadrature counts (to be accurate), although the built in DRO will give you an inch value. Seeing the curves will give you the best information on how your tuning is working. As far as velocity based on the 20mm pitch...you don't have to and Probably Don't want to run anywhere near Max velocity of these drives for your application...like I say above start with minimal velocity and work up to a mild velocity and medium acceleration (Unloaded)...once you put a bit in and start whittling you will need to continue to dial it in some more. It's a long process, take your time, take copious notes, and be patient with yourself.

Happy to help if I can along the way but it feels kind of like describing the taste of lemon meringue pie to someone....how bitter is the lemon or creamy is the meringue and the texture of the crust, but if you eat it too fast will you get indigestion?...best experienced in person...almost an analogy for PID.

May the force be with you! ~PJ

**machiningfool** · Oct 18, 2015, 02:59 PM

Oh boy, looks like i'm in for it. The Centipede manual gives me some info. and the Mach 3 does also, I will just have to dig in and learn it. Thanks for your info. Bob.

**PJs** · Oct 18, 2015, 03:32 PM

With all you've done to date with the build and wiring, you'll be fine!!

Just another learning is all and you'll benefit in the long run with more intimate knowledge when it goes into operation. Which reminds me, have you included a physical E-Stop or two? I had 3 on my machine only because it was 35' long and could be reached quickly no matter where the operator was. Also you didn't mention the brand/model of the controllers?? Happy to help if I can. ~PJ

**machiningfool** · Oct 18, 2015, 04:49 PM

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The control is Mach 3, the drives are Granite VSD-E, and the pci board in the computer is Centipede and a centipede brk. board. I have installed the Centipede driver and the Mach 3 program, all of the wires are installed, so tomorrow I will start the configuration and tuning. I am a little nervous about pushing that first button, but someone has to do it. I have soft stops, limit switches and an E-stop next to the controls. I will have a million questions tomorrow, so get ready. KSI labs provided many pages of docs., geared for more experienced persons than I, but I will trudge through it. Also there are some good videos on YouTube, I will be watching them also. I am not ready to post eating popcorn yet, when I get the axis' to move, I will be devouring popcorn. Bob.

**machiningfool** · Oct 19, 2015, 07:26 PM

Thank you PJs. Well I got off to a rocky start. I had a neutral wire crossed with a ground wire, think I blew a capacitor in the power supply, going to replace them. I think I have it whipped now, good lights on the brk board and the servo drives. I hope that is the only mistake I've made and I will be happy. Bob.

**machiningfool** · Oct 20, 2015, 09:19 AM

Well, I found out that capacitors don't last long without use and since this one has sat for a few years, that might be why it failed or it was because of my crossing some wires, so I have ordered so more, will be a week or so before I get them. Bob.

**PJs** · Oct 20, 2015, 12:21 PM

Too bad about the caps. Did one or both blow - pop up the vent or swell up? Would be best to replace both in either case. Your findings about sitting cap lifetimes peaked my interest because my use and understanding is that they will typically have a lifetime service of ~150khrs (7+yrs) at max spec but should be changed at about 50-60khrs due to leakage and electrolyte & film degradation. Hi heat (above spec) will kill them faster, but never heard of sitting on a shelf too long, so I looked it up. Wiki has a bit on it but the white paper I read really talk about it. Thanks for peaking my interests and learning a bit.

I looked back at the pictures of the PS...is that homegrown? The transformer seems an odd shape- toroidal? Surprised it would take so long to get the Caps. I've used Digi-Key and Mouser for years and typically only a few days and prices are good, generally.

Overall-great progress!! Thanks for the update, look forward to seeing your machine run!! ~PJ

**machiningfool** · Oct 20, 2015, 04:32 PM

OK, Sergey Kabashian says that they will last for 30 years on the shelf, but try to buy one at the local distributors. I called 8, trying to find one and they all said that they don't stock them because of shelf life. In my instance, it could have been both because my project has sat since Feb. of 2012. Only one blew, the vent blew and it also swelled at the bottom. I am replacing both. I found another ground that I mixed up with the neutral, so I think I have it solved now.I have about 2 wks. to get it right. Yes, the power supply is mine from plans from KSI labs, he sent me the diagram and I bought the parts and put it together. It supplies 120VDC to the drives and servos. The caps are 4000u farads, 150 volt dc, max 200vdc. Thanks for the encouragement, I will get it right yet. Bob.

**machiningfool** · Oct 24, 2015, 03:52 PM

OK, I received my capacitors and installed them. Here is what happened. Too many wires. I got mixed up and twice hooked a ground wire into the neutral circuit. I found them and corrected it. I also rewired the ground system as was on the diagram. I guess you are supposed to follow the diagram. Tomorrow I will fire the whole system up, today I fired up the power supply and got 143 volts DC., with no smoke, so after going over the whole diagram tomorrow, I will again fire it up. I am confident there will be no more smoke this time. Here are some more pics. I installed a power strip so that all of the components can get power. I also added a folding shelf for my laptop. It will come in handy for videos for the tuning. This Centipede pci card is designed for Mach 3 and by reading the setup procedures, it sounds like there is no setting up. It appears that I only have to "check" the axis that I want to use and that is it. The driver knows everything else except tuning. I am not running "home", so I don't "check that, but I will be checking "limits". If anyone out there has setup Centipede, let me know. I setup a wifi extender so that I could have wifi out in the garage and it works fine, spent 40 bucks on it, a Belkin, just plug it in to a wall outlet, and of course the security code. Bob.