BOB recommendation for 36V system?

[rlrhett]

I am not having luck with break out boards. I started with a C-10, but after a few years it stopped working properly. I don't know what happened to it, but I do know that when I swapped it out for another BOB, my CNC was back in business. I replaced it with the "Upgraded" Chinese board as seen in picture. Unfortunately, that cheap Chinese BOB seems to have pooped out also. I have bought two other Chinese BOB's, but one was DOA and a second required 12-24V supplied in order for the limit switches to work. I have a 36V power supply. I'm getting tired of messing with mystery boards from eBay or AliExpress.

I am tempted to just buy a G540 integrated system, but I have 4 perfectly good drivers (3 DQ542MA drivers and one surviving G251X that has been with me for a decade). Also the G540 is pretty expensive for what it is and is long in the tooth. A related question would be is there a better alternative to the G540 for an integrated board available today? If a modern and reasonably priced integrated solution doesn't exist, back to my original question. There must be someone that sells a quality BOB. I prefer the ones that have a USB plug for 5v supply, and that have 4 terminals per axis as opposed to 3 with a common ground terminal. Is there one that won't just crap out on me? What do people recommend today?

Mine is a 3 axis (dual drive Y axis) aluminum extrusion DIY machine. I have 36V power supply, limit switches on all three axis, e-stop, probe. Manual router spindle, so no spindle control. Step generated by a UC100 dongle and UCCNC on a Windows10 machine.

Thanks!




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[rlrhett]

Crickets? That is really weird to me. No one has thoughts on a quality BOB? How about a reasonably priced alternative to the G540?

I guess I'll keep buying cheap Chinese boards and hope for the best. I would buy the USB Smoothstepper, but I like UCCNC. As far as I know nobody has a plugin that would make it possible to use the SS with UCCNC.


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[Mellis88]

I'm sorry I dont have much experience with Bob's in general, but why not just get a 24v power supply for the bob?

[john-100]

are you powering the BOB and motion controller from the PC's USB ports ?

did the breakout boards inputs fail or the outputs to the stepper drivers ?

how long did the C10 and Chinese BOB's work for

Do you still have the C10 ?
the old version has sockets making it easy to replace the C10's IC's

both BOB's have a direct connection between the switches and the 5V logic IC
a stray connection applying more than 5V to the BOB's input will damage it

what kind of limit switches do you have ?
1) mechanical micro switches
or
2) electronic proximity switches - if so what is the supply voltage to the proximity switch

the Chinese BOB has a design error
(see the top left hand corner of the circuit diagram)
the 74HC14 IC that connects the inputs to the 25 pin printer port connector
has no 5V power to the supply pin 14 !!!!
this can result in incorrect logic levels to the PC printer port or motion controller

I reverse engineered the BOB to see why the BOB did not work as expected

John

[rlrhett]

are you powering the BOB and motion controller from the PC's USB ports ?

did the breakout boards inputs fail or the outputs to the stepper drivers ?

how long did the C10 and Chinese BOB's work for

Do you still have the C10 ?
the old version has sockets making it easy to replace the C10's IC's

both BOB's have a direct connection between the switches and the 5V logic IC
a stray connection applying more than 5V to the BOB's input will damage it

what kind of limit switches do you have ?
1) mechanical micro switches
or
2) electronic proximity switches - if so what is the supply voltage to the proximity switch

the Chinese BOB has a design error
(see the top left hand corner of the circuit diagram)
the 74HC14 IC that connects the inputs to the 25 pin printer port connector
has no 5V power to the supply pin 14 !!!!
this can result in incorrect logic levels to the PC printer port or motion controller

I reverse engineered the BOB to see why the BOB did not work as expected

John

1) No, the BOB is plugged into a wall wart for the 5v.
2) The c-10 lasted about three years, but the Chinese BOB only about one.
3) On the c10, one axis just stopped sending signals. The Chinese one kept getting phantom input signals, usually a break on pin 10. It began to show the same on other input pins. But I pulled it when it actually arced with a flash, pop, and smoke. I can't see anything now, but I happened to be looking at it when it happened. It looked like it came from the input terminal block.
4) Mechanical micro switches wired NC.

I thought the c10 wasn't available anymore. When the first one gave out I went back to a web store called CNC4pc, but they seem to be out of business. They never responded to emails or phone calls. A recent Google search turned up the same web store, but with a very different looking BOB. Given that my C10 lasted three times as long, I'm planning on rolling the dice on them again. I just wish they were available elsewhere. Not sure I trust CNC4PC. OTOH, they can't be worse than some anonymous Chinese eBay vendor.

I hope all this didn't fry my UC100.


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[rlrhett]

I'm sorry I dont have much experience with Bob's in general, but why not just get a 24v power supply for the bob?

Because it is wasteful of money, electricity, and won't fit in my enclosure.


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[john-100]

is the 5V wall wart a 5V power supply or a 5V charger ?
the output of some chargers can be too high to power devices like your breakout boards
its worth checking the output is no more than 5.5V

the first C10 BOB I looked at was like this


the latest C10S uses surface mount IC's like this

not easy to repair your self

John

[rlrhett]

I never thought to check the voltage on the USB charger. Thanks for the tip! Hopefully that will be the answer to keeping these things alive.

My old c10 looked like your first photo. Alas, it went to recycling a year ago.

I’m going to go ahead and order a new one. It’s really no different in price than the ubiquitous Chinese ones. I did find a more expensive one sold by probotix.com. It is “RF” isolated. Don’t know if the UC100 needs to be isolated. Also don’t know that paying extra will actually get me a better made unit with better quality components.


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