Y skipping

so tonight while printing my Y axis started grinding/skipping after about an hour into a print. The last time this happened was when i first build the printer and i was told to up the current of the trimmer by 1/8 turn and it never did it again until today. And i have printed for many 6+ hour days with no issues. I have a 40mm fan blowing across the ramps and the drivers have heat sinks on them. Is my driver bad? does it need to be turned up a bit more? oh and belt is ok not too tight not too lose

Any advice would be appreciated

I had to readjust motor current last week, too.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Where is your ramps mounted?

Ramps are underneath. I think i may have solved the problem. I am almost positive that the molex for my y was loose. (Probably from vibration) After slightly spreading the pins on the ramps and reinstalling the molex to a tighter fit I was able to print just like I was before. I really wish that they were made with locking molex connectors instead of plain loose header types. if it happens again i will have to come up with a more permanent fix maybe unsolder the cheap molex and find a locking type molex as a replacement.

"I am almost positive that the molex for my y was loose. (Probably from vibration) "

Gold star for quick thinking. Yeah, that's why I asked. vibration is a pita.

hint born of ~20 years experience in electronics design and support for high vibe environments: Vibratite. Connectors AND trimpots. for connectors, right at the joint on each side. only takes a tiny amount to make a big difference. trimpots, right where the adjust screw meets the trimpot body, of course once it has been cal'd.

Thanks for the info. I think this will be used on my current reprap and right from the get-go on my next machine

One word of warning. I noticed that the older pololu boards use open frame trimpots, so if you have those, be warned that it will need to be applied very carefully in order to avoid altering the resistance characteristics of the voltage divider. Do not just grab any old goo to secure the trimpots, and whatever you use, PLEASE don't get 'clever' and use superglue. It's simply not an appropriate solution for this purpose, any more than it is as a bonding agent for heat sinks.

If you happen to have the newer driver boards, it shouldn't be an issue, at least from the promo pics they have up on site, where they're finally showing sealed trimpots (tg for common sense...their largest customer is people building CNC machines!)

on a side note: I like Loctite for mechanical assemblies as much as anyone, but for electronics, I prefer real Vibratite (specifically VC3, the pink gel). A bottle will set you back about $20, so it's not exactly cheap, but the INVESTMENT is well worth it, since $20 is roughly 20 minute or less of your time as even a junior engineer (and at least double that for your employer if you work for someone else in that capacity for a living) . AFAIK, you can also get VC3 in a little tube now, but I still like the small bottle that has a cap help brush. Little tubes always seem to dry up far quicker than a properly closed bottle.

lecture over Hope this saves you some time downstream. I was offered that advise over and over back in the late 1980s and well into the early 1990s by a variety of senior design engineers, veteran techs, machinists and journeymen with whom I worked everytime I forgot to employ it.

ok, dull lecture over. happy printing!