…build an entire project 😦
So the only thing left to do is throw the switch and watch the thing start to rotate, right?
I did this with some trepidation, a little for my own health and safety vis a vis the electrics and a little around the general physics of spinning an extremely heavy, “nearly completely circular” wooden block embedded with 74 stainless steel screws at over 800rpm.
The switch threw, no one died, the motor started up, the belt drove the pulleys, the bearings held, the wooden block span like some evil dervish, the screws were an unsettling grey blur over its surface. I was feeling very pleased with myself and shut it all off.
As the scratter was slowing I noticed that it was spinning in the wrong direction… bugger. Now, I was under the impression that this would just be a simple case of reversing the live and neutral terminals on one side of my switch, but that just goes to underline that I’m living in blissful ignorance most of the time. I did this but the motor span in the same direction as before and it turned out that this assumption was one of the worst I’ve made on this project.
A little bit more research let me know that direction of spin can be overcome in a single phase motor by changing the internal wiring to reverse the start-up winding circuit of the motor. Again this isn’t beyond me so I took the back off the motor but there was very little in the way of accessible circuitry to alter and even more Googling let me know that on some single phase motors you can’t change it because the implication is it’s not to be changed. I had one of those motors. Clockwise only. Arse.
The short story is that yesterday afternoon I had to strip the whole thing down and rebuild the boxed in scratter the other way round as some of the mods I’d done (like drilling holes into the aluminium bar, wedging the drum etc) meant I couldn’t disassemble the thing without damaging the bearings etc. I basically had to pick up the bar/bearing/drum assembly and rotate it though 180° refit it, realign it and re-box it in before re-doing the work of mounting the motor on the other leg of the scratter. It turned a 2 day build into a 2-and-a-half day build and when I was looking at my once-fully-working machine in almost total bits again it was a very low point indeed.
The message from this is either “don’t be me” or “check which way your motor turns and if it is reversible before you decide which side to build out to”. Annoyingly I remember almost at the start of all this think that I wanted to mount the pulleys et al on that (now notoriously “wrong”) side because I thought it “looked better”. What a knob.
Still, it’s all back together again, a mirror image of its former self but no less lethal to the integrity of apples for all that. Switches flipped, the thing rotated in its now predictably frightening manner, this time towards the stainless steel scratting face.
Now it’s time for a road test.