Series 2 BOSS 6 Axis motion problem

[braidmeister]

Craig,
That sounds great! I bet you are pretty stoked right now!

I too have been considering the new 202/212 drives for my BOSS5. It seems that with the extra protection of the drives, it should prevent anyone else from reporting a smoked Gecko...plus boost sales. As you know, plenty of us are on the fence about steppers vs servos. I have some suitable DC motors for servos...but since Rutex is still farting around with the much awaited 2000 series...I am leaning towards the 200 series Geckos to just use the machine!

Any particular reason why you went with the Pico board? It would seem to me, given the limits of the motor and gearing, that Mach2 on a decent computer should be more than enough to generate a good data stream. Have you tried running without the board? Just the 202s?

-Brady

[craig96us]

Hi Brady--

I went with the Pico board for a couple of reasons. The first was the ability to run encoders for closed loop. My old shoptask CNC conversion had step loss problem that I never did get ironed out! The second reason is the Pico board generates the step pulses with a microprocessor. There is no way a PC can generate as smooth a pulse train as a dedicated microprocessor does. The board is also capable of generating about 300K steps/sec! I am currently driving the board with a really old, slow PC. I guess the more I investigated the available parts options, the more I was drawn to the Pico board. I don't think there is anything else like it out there right now. Geckodrives is working on a similar technology device that may be a bit more capable... Or not... The only downside to the Pico board that I could find is that it is not supported by the MACH controller software. I downloaded the MACH2 software, and spent some time reviewing it's features. It is definately a nice system. I was considering it all along, but decided to go with EMC because I am kind of partial to Linux, and MACH doesn't support the Pico board. etc. Initially I had a problem with the startup pulsewidth of the Pico board not being wide enough to trigger the G202's, but Jon Elson worked through the problem with me, and we fixed it within a couple of days! Jon ended up making some modifications to his EMC driver software which will eliminate the problem for other users as well. I am quite happy with the end result! Better than anticipated!

The reason I went with the Gecko 202's is mostly due to economy. Comparing the price of three G202's to a set of three servo motors, three encoders, and three servo drives sort of makes the G202's with the factory steppers the economy answer!

The G202's get warm when moving at slower speeds, but nothing to worry about. I have them mounted to a .125" thick aluminum plate which is in turn mounted to the bottom of the huge heatsink that takes up much of the rear door of the control cabinet. This location allowed me to use the original stepper wiring! I didn't use any cooling fans for the G202's because I felt the big heatsink would do the trick... It works fine! I just used heatsink compound on the back of the G202's, and along the areas where my mounting plate contacts the big BP heatsink.

The motors run really smooth with this setup! At times I can't hear the steppers at all when they are moving!

If you decide to run the steppers with G202 drives, be really careful about how you wire the steppers! In order to get the maximum speed/performance from them they need to be wired parallel. There are several wiring diagrams on the web, but of the ones I found, only one matched my motors based on reading the winding resistance at the motor terminals...

The steppers on my machine are the 900 oz-in Superior motors.

/Craig

[braidmeister]

Craig,
How did you determine the 900 Oz/in rating of the Superiors? I have them on my BP as well...but thought that they were a higher rating than that...Would be interesting to find out if mine are the same @ 900.

I like all of the features that the Pico board has...except it's incapatability with Mach2/3.

-Brady

[craig96us]

I have a nameplate from the end of one of them!

[braidmeister]

Hmm....Mine doesn't have that; Instead it has a wiring schematic...

-Brady

[craig96us]

Yup. Saw that one too. On the backside of the outer cover that is screwed to the heatsink there is a wiring diagram for the boss stepper drive. The cover in the photo came from the stepper motor itself and was under the cover that had the boss diagram! the cover was only on one of my motors, and I didn't put it back due to wire clearance! I imagine that there are a lot of covers that were not replaced by bridgeport techs over the years! I must have gotten really lucky to have one I guess...

/Craig

[machine_nut]

I know this is an post,but I bought a BPT Boss6 which has been sitting around for a couple of years and had the same problem with the transistors,( blew one on each axis). When I checked it out there wasn't any two that were the same make or number so I pick one (NTB53) I bought 12 which is enough for each axis from NewakInOne(www.newarkinone.com) and they work fine. Just another source for transistors In case someone needs them.

[machintek]

I noted that the motor end plate says 3.9 volts at 6 amps yet the machine feeds them 8 amps at 9.5 volts static which at rapid goes to 2.5 amps at 56 volts.
Interesting.

George