Stepper Driver Problem, and Resolution

This caught me a little by surprise. The RAMPS board does its thing, tucked away, as it is, in the bowels of my Delta printer. Since I’ve had this printer, it has always had an issue with being noisy. I thought it would be cool to move it to its own box located somewhere else, and add a bigger, quieter fan. So that’s what I did. I made a temporary box with a lid, hoping to make a better “Steam Punk” type box as a future project.

I fitted it all in, and the difference in the noise level, was evident, yipppeeee. Anyway, all was fine, then I started printing little things with the Delta, and I marvelled at the deathly silence that was now emanating from the ramps box. A contented smile crept across my handsome, chiselled features. Then I decided to print a plinth for some work I have planned in a month or two. To show off some prints I wanted to highlight. The plinth was about 200mm x 80mm and about 5mm thick. I started this print which was going to take about 2 hours.

It had been going about 15 minutes, and I noticed that the hot end had moved over about 2mm, so any subsequent layers were going to be slightly off from the rest. I stopped the print and shook my fist at God, and decided to give it another go. Restarted the job and within 10 minutes the same sort of thing happens. This time the hot end had dropped and was merrily ploughing into the lower layer. WTF, I thought.

I left it alone at this point, I had other things to do, and thought I’d look into it later.

Yesterday I decided to finally sort this annoyance out, once and for all. I printed off a calibration cube, as a test. It went wrong half way through. The hot end, shot over a little bit so that the cube was looking good till half way up. Then the cube was printing 10mm over to one side. I thought I would flash the board with my “safe” version of Marlin.

This is a version I have, that’s plain vanilla, does nothing special, like bed leveling, or anything like that, just gets the printer working. I like to have a control version, that I can load, in cases just like these. Once I had flashed this I tried again. Same issues, well this time the hot end dropped down two or three millimetres, and was then knocking the hell out of the cube. I cancelled the print and quickly checked the belts, and all the other joints that I thought may be slipping, or loose. Then it occurred to me that the timings of the faults were roughly after 10 minutes. Thinking cap on. I started going through what might be happening. I fired the Delta up again, printing the same cube and waited. By the way, since the last print, and my checking everything, plus some “thinking cap” time, about an hour and a half had passed.

Sure enough, the print failed, the hot end just got plan crazy. Swinging, way off its path and doing all sorts of stuff. This time I decided to check my magnificent RAMPS box. I took the top off and suck my finger in different places. Not sure what I thought I would find. Then I put my finger on one of the heat sinks, located on the top of the stepper drivers. That made me take notice! It was very hot, and had I, had a small enough egg, I’m sure I could have cooked it. Obviously, the fan I incorporated into the top of the box wasn’t up to the job.

I went back into Tinkercad, and made some changes. I added the old fans from the first design back, into the side of the box. So, they were blowing directly across the stepper drivers. When I imported this new Mk2 box into Cura, it told me, it would take 11 hours to print. Not having the time for that now, I decided to hack the box, temporarily. Until I could get some time to do it properly. With the two fans blowing across the stepper drivers, I tried a new print. Success! Lot more noisy, but successful

Moral of this story? Don’t shake your fist at God. He doesn’t care, that you didn’t consider the air flow over the heat sinks. Heat sinks are there for a reason. If you have any, make sure you have the air flow to cool them.

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