Vince's BP CNC conversion

[N4NV]

Originally Posted by CNCfun&games Vince, Also are a couple of pictures of the Z Quill/Leadscrew Mtg Block and my Y axis plate. Regards....Will Smith

Where did you get your timing pulleys and belt? I am going to have to have to do my Y axis like you did. My servo motor is too long to place under the knee.

I talked to Hiwin today (they are in Fremont now) and they could not figure out what I needed. I have the Bridgeport power feed on the X and this changed the length of the screw. Looking through their documentation, I could not find a diagram that would fit the power feed. Rockford did have a screw specifically for the power feed.

Vince

[CNCfun&games]

Vince,
I buy my HTD Pulley's and Belts from: www.sdp-si.com
Pulley's 5MM-15 mm wide(28 tooth) A 6A25M028DF1508
(56 tooth) A 6A25M056NF1512
Belt 6R25134150 ( yours may vary)There are belt /pulley formulas
in their Catalog.

Since you are discarding the power Feed why can't you use the standard
HIWIN CORP B3205X-42 Ball Lead Screw? (see enclosed invoice)
Regards....Will Smith

[N4NV]

I ordered my timing gears and belts on Saturday and picked up some 1/2" aluminum plate for the motor mounts. Hiwin is sending me a quote for their ball screws. I spent Saturday and Sunday putting my power supply into an enclosure. I solved the encoder connector problem. Using a microscope, I was able to solder the wires from a Cat 5e cable to the connector. I hooked up my Gecko 320 and the parallel port break out board and started up Mach 3. All seemed to work fine as I went through the start up procedure in the Gecko manual. When I hooked up the motor, something is wrong. The motor jumps back and forth about 1/32 of a revolution continuously causing constant faults on the 320. It is not making a "singing" sound like the manual says it might, but more or a low growl. The gain, current limit and damping trimpots are set to the suggested positions. Adjusting them has no effect. I disconnected the printer cable to see if it was coming from the computer but nothing changed. A call to Mariss is in order, until then, any suggestions?

Vince

[jdelaney44]

I had a similar problem but it was from the VFD noise finding it's way back up the mains, through the PC power supply, and then out LPT1. Fixed it with ferrite beads as you have read.

I see that you are missing the capacitors on the power side of the Geckos. Very important. I had issues without these as well.

Is the encoder wire shielded? CAT5e is good, but shielding is still needed and the shield needs to be grounded on one end only. Usually the control end. The shield needs to end as close to the G320 as possible in my experience. Marriss posted something about this at DIY-CNC.

My motors don't sing either. They are totally silent. Singing is dithering. Growling is either BIG dithering or some other kind of periodic error compensation or interference.

Does the growling sound anywhere close to 60hz? I'm looking at that big old magnet you got going with that tranny and thinking it's messing with the Gecko.

These reliance motors I have, have some indexing at low voltage as you suggested with your motors as well. So, I'm thinking it's not the motors.

-jd

[N4NV]

Mariss said that cat 5e was supposed to work for the encoder. He also said that I may or may not need the cap. I am online ordering the cap from digikey now. I have the motor leads in shielded cable. I don't have a VFD in the enclosure. The growling sound (and movement) is random and not at any particular frequency. Sometimes the motor is turning slightly forward and sometimes slightly backward.

Vince

Vince

[jdelaney44]

Hmmm, he said otherwise on the DIY-CNC post. He said shielded cat 5e on that one. In theory the twist should do it.

OK, well, what you are describing was EXACTLY what I was experiencing. It took a combination of the caps AND the ferrite beads to nail it. I also shielded the wires from the break out to the G320. But, every set up is different.

Cool. Well it will be interesting to see if the same things fix your problem that fixed mine.

Best,
-jd

[N4NV]

I called Mariss today. He said since I ran Cat 5e cable to the encoder, the most likely cause of my problem was I ran the A&B channel down the same pair. He said that Cat 5e is as good as a shielded cable. He added that since I just replaced the brushes, the motors need to be run for 20 hours in both directions.

When I got home and checked, sure enough both the A&B channels were on the same pair. I had to chuck that connector and make up another with the A&B channels on separate pairs. I hooked up the drive and motor and tried again and it really helped. The motor was still hunting back and forth a little, but not as much as before. I ran the motor on straight DC and tried again. It ran a little better. I am now letting it run over night.

It has been 20 years since I used and oscilloscope so I don’t know if it is my scope or how I set it up, but I could not get the screen to look like the sample in the tuning section of the manual. I played with the gain and damping a bit, but without the proper display, I could not tune the motor. I will try again tomorrow after the motor has run for a day.

I have been holding off using my mill until I can get the oil system installed. The machine came with zerk fitting which someone in their great wisdom filled with grease. Disassembled the mill, cleaned it, reassembled it and installed my own one shot oiler. I did not know about metering device then. I ordered some Bijur meters, pn B1114 to install on my oiler manifold. These are a size 2, which D&L said were the size to use. When they get in, I can finish assembling the mill and start on the drive mounts.

While I am waiting for all the other things to come together, I spent some time fabricating the mount for my Gecko’s. I am using the same type system as JD. When I get something worth pictures I will post some.

Vince

[N4NV]

After spending an hour on the phone with Mariss, I think I found the problem getting the motor to work with the drive. My computer has 3.5V logic and the parallel port interface card I am using is made for 5V logic. I don't want to spend much for an interface card because I am going to change to a Grex 100 as soon as Mach 4 is stable. Does anyone have a suggestion for an inexpensive interface card that will work with 3.5V logic?

Vince

[N4NV]

It seems like all I can do is wait. I am waiting for my timing pulleys and belts, and my metering valves for the lube system. The big wait is to solve my motor drive problem. I want to make sure the motors and encoders I purchased are going to work before I go through all the trouble of making mounts for them. I have spent 15 hours over the last week trying to get my Gecko 320 to run my motors, plus almost 3 hours on the phone with Mariss over the course of 4 phone calls.

At this point I have ferrites on the AC power, DC power, and +5V power for the breakout board. I have the 470uF cap on the motor input, shielded 22 gage cable running to the encoder (I tried a cat 5e cable as well). All three motors behave the same, no matter how I set the pots on the drive. They seem to be randomly hunting for position and when I command a rotation, they sound like they have rocks in the bearings. The motors have run for over 24 hours since installing new brushes, they look fully seated. I have a clean signal from the break out board, 0V to 5V. I have a perfect signal from the encoder on both channel A and B (I ran the motor from a separate power supply while monitoring the channels). The motor is grounded; there is a shielded power cable to the motor. The encoder cable is grounded on only one end, the drive end. I changed the printer cable. The printer cable, motor power cable and encoder cable are separated by at least 1' until they get to the drive. I have tried several motor tuning combinations in Mach 3. I tried feeding the drive with a function generator. The only thing I have not changed is the drive. I ordered a couple more. I will try them when they get here.

I sent the drive I have back to Gecko for evaluation. I hope it is the drive because I am at a loss as to what else could be the problem.

Vince

[N4NV]

My timing pulleys came in yesterday. The small ones have 5/16" bore and I need 1/2" for my motor shafts. I just happen to read in another thread about a way to bore the hole larger and keep it in the center of the pulley. The flanges of the pulley are pressed on and not turned with the pulley. If you try to hold the pulley by the flanges, the bore will not be true. Besides which, the flanges did not look that strong to clamp in a chuck. WhiteTiger suggested turning a piece of pipe so the inside diameter was the same as the outside of the pulley. Then turn the outside so it is true with the inside. Cut the pipe into three pieces and place one under each jaw of the chuck.

I found a brass fitting on my wife’s plumbing truck (she does high purity process plumbing and pipe fitting) and turned like the suggestion. Placing it between the jaws and the pulley kept the jaws from clamping on the flanges and held the pulley true. From here it was just a matter of boring the hole larger. Both pulleys came out great.

Vince

[RotarySMP]

Thanks for saring those photo Vince. I have to the same thing on some flanged pulleys I have.

[N4NV]

After over 20 hours of trouble shooting and changing every component in drive system, I finally got my Gecko 320 to turn my motor properly. Everything change I made helped a little. The last thing I did that fixed the problem comptetely was to add ferrite beads to the motor wires.

Vince