It's done and made it's first cut! #93 - Clarksville TN USA

[Darin]

Miguel,
I only have one connection in my box prior to the main door switch, that's a ground bonded to the box. I guess my green wire grounds going through the contactors are redundant but I don't see how they can cause any harm. The ground going through the main contactor continues to the ground screwbconnections on the power supplies, although the power supply case is physically mounted to the bonded case. I also ran the earth ground through the other two contactors supplying my router motor and dust collector that green wire will connect of course to the cord wiring. Any metal on the router motor will be bonded also but the dust collector is physically unattached so its only earth ground will come from that ground wiring. My heatsink has its own bonding ground and the box is also bonded to the control mounting. I have isolated the computer ground from the equipment ground by insulating the parallel connector from the case. I plan to bond the control cabinet to the machine and also bond the gantry and car.

Your input is very appreciated and if you or anyone sees a fault after the explanation lets please discuss further.
Darin

[bradm]

Darin, I think it would raise some red flags for anyone looking in the box. The key characteristics of ground wires are that they never carry current under normal conditions, and that they provide a solid path to ground under all conditions. If there is a switch, then that ground does not provide a solid path under all conditions, and is thus, not, er, a ground. The problem with treating it as okay since it's redundant is that some future modification might render it critical, and it would be difficult to test to prove this point if it's controlled by a switch.

Or more simply put, this just isn't done, and I'd bet any inspector that saw it would react negatively.

[TechGladiator]

The way I think about a contactor is just as a bigger Home light switch. In your house all ground wires are tied together regardless of the switch being ON/OFF.

When we wire our motor control centers we do no connect the ground wire through the contactor and we have always passed inspection.

I am no electrician....

[Darin]

I see your point guys. Im contemplating how to make it right. I have a ground buss bar here left from somthing else. Im considering mounting it and pulling all my grounds to it. I've never noticed it done here on the forum like that. I have the two power supplies and two aux circuits that need ground. I guess I could just attach them all to the metal of the box.

[TechGladiator]

Ground bar sound like a good idea. I would probably read this thread anyway. I have not connected my grounding (Which I plan on doing tomorrow) but I will take some pictures when I do. What I plan on doing is running all my ground/earth wires to a terminal block and then use a "jumper" to connect them all together. I got the jumpers from Mike (MetalHead) since I purchased my terminal blocks from him.

[Darin]

I got the grounds straightened out and started running cables on the table. It only took a few minutes to change the grounds once I got the bus bar in. Thanks for pointing out my error I learned something from you guys!

[Darin]

I finished all the wiring! Everything is working. It's amazing to finally see it moving! I'm working on fine tuning the motors and tested out some fast jogs. I air ran some cut files I wrote for my little hobby machine. Everything seems about ready for a test cut.

I was surprised that the inertia of the movement easily overpowers the motors ability to stop and hold. I probably just need to slow it down but its pretty cool watching it run at 1500++ inches a min. What do most people set the max speed at for jogging and rapid moves?

I tried to adjust the Gecko tuning pots while I still had everything on the table but they really seemed to do nothing. I'm not sure what to listen for or if I need to try to tune them now. I will do some reading on that, could someone send me toward the right thread?

The motor springs are making a lot of noise. I think I will try to dampen them somehow. Anyone else dealt with that.

I should be able to make a test cut and post pics tomorrow.

Thanks everyone for the help along the way, especially Metalhead Mike, and a special big Thanks to Gerald for sharing this fantastic design! I'm thrilled with what Iv'e built and learned along the way.

[bradm]

The inertia of the movement should not overpower the motors stopping power. I suspect that your acceleration values are a bit too aggressive. 1500 IPM is also wicked fast. I'd recommend that you back down towards 600 IPM rapids and 100 IPM cutting, check your accel tuning, and then once you have the machine cutting accurately, you can explore just how quick you can get your rapids without any untoward effects. As for cutting speeds, you're gonna want to factor in your spindle speed, bit size and bit geometry in order to get the right chipload. Your bit manufacturer should have tables or calculators to help with this.

[Darin]

Brad,
I will slow her down to the numbers you suggest. When you get a sports car you just have to drive it fast the first time out
If I jogged to full speed at 1000 ipm and reached the soft limit it would coast past the correct stop point by a 1/4" or so while the motors growled and protested loudly. It would travel at around 2000 ipm before it started loosing steps on a straight run without a stop.

I tried turning the acceleration way down thinking it would give a more controlled stop (thinking deceleration was controlled the same as acceleration) that did help a fast stop in the middle of the table. I also tried adjusting the slow zone. The slow zone seemed to have no effect on that full run into the soft limit but I could tell it was set if I crept up on the limit. I ran out energy and will look at it closer tomorrow.

I did some reading and I'm thinking the tuning pots on the Geckos will reveal some smoothing effects if I actually feel the motor while its turning. I was thinking it was something you heard. I remembered the thread but didn't remember the hand on the motor requirement.

[Darin]

I had a little snag with the computer speed once I picked a slower speed in Mach it was smooth and very impressive.

[/IMG]

material is 3/4" veneer core oak face plywood. I cut shelves for a cabinet project. I used a 1/2" straight bit and started the cut at 30ipm and increased gradually to 150ipm only minor issue was slightly rounded corners.

[MetalHead]

Congrats on your build !! We are clickin right along !!! You get #93 !!!

[Darin]

Thanks mike! I'm really proud to be a member of the serial number club.

[jhiggins7]

Darin,

Congratulations on completing your MechMate and earning Serial # 93.

Here is the Updated Builder's Log.

True to your word, you completed the construction quickly, actually one month. But, since you completed a machine begun by Cordell, I arbitrarily set the build time to 3 months. It looked like Cordell spent at least 2 months on building the machine in 2010. It didn't seem right to indicate that you built the machine in 1 month. This is not a big deal, but if you want to change it let me know.

Please review your entry and let me know any changes you wish to make.

[darren salyer]

Man I hope (wish?) I can get done that fast.
Congrats sir!!

[TechGladiator]

Congrats Darin!.... Good Job!..

[domino11]

Congrats!

[Darin]

Thanks guys! Having it ready to cut is a fantastic thing. I'm anxious to show off some cutting build my planned computer station and dust foot but right now I desperately have to complete a bunch of stuff I sidelined to do this build.
Here's an open invitation. Send me a pm anytime anyone who wants to come by and see it cut.

[Darin]

I made myself a sign. It's the first major thing I've cut. It worked fantastic!

[IMG] [/IMG]

[MetalHead]

Sweet !! Great looking sign !!!