Thread: Recovering from the flood

Bob, I think I would be absolutely devastated if my shed / house was flooded. I'm not real sure how I would cope, if at all.

Congratulations on the positive attitude!

I second that - good attitude Bob.

what size is that motor ? , i might have a spare , just got a shipment in from ebay , 34 size , 600-800oz 8 wire ( yours is four wire ) , bought it for its 10:1 gearbox and 24volt brake , will be running servo's so the mortor is not needed , if it is the right size ill send it to you ,

Bob that's terrible news, very sorry to hear it. Just about all the bearings in RV's motors at Sumner Park were noisy or have become noisy, I rekon while you have them apart you might as well change the bearings. The water at least at Sumner Park has turned out to be very corrosive, it's incredible how etched metal parts have become. Best of luck with it.

Cheers
Michael

I thank you all for your concern and various offers of help.

At this stage I don't think I need any help, but if I do then I certainly know where to go to get it.

Thank you too for your kind offer of a spare motor SawDustSniffer. You are correct that the existing motor is a Nema34. It is a 1200oz motor from Ausxmods that I purchased in an effort to make my machine run at 10 metres a minute. This was before somebody pointed out to me that the top revs of a stepper was about 800 RPM and if I wanted to go any faster then I have to use a gear box of some sort. . I hope that the motors I have will work OK when I start up the machines again. If not then I will certainly take advantage of you.as the 1200oz is ridiculously over engineered. .

I didn't mention in the first post that when the room downstairs was dis-en-gyprocked, we found hoardes of white ants in the walls and ceiling. We called in the white ant man and he found four huge nests of the buggers. Three under my computer room (explains the cracked tiles) and another one in the roof. $3k and three weeks later and we are still getting dead ants dropping from various cracks in the house and around the windows. Hopefully that will end soon.

While the house was empty we took the opportunity to repaint the inside. We finished that and then the electrician came and started demolishing it all, so we had to start patching holes in the walls and ceiling and repainting again. Still, now it is all together again it looks very nice.

Bob

The two smaller motors seem to be working OK but I am having difficulty with the 1200 oz motor.

I initially cleaned it all up and reassembled it and it turned by hand quite nicely with just the normal amount of resistance.

Today, I tried starting up the motors to test them. The two little ones are (as I said previously) OK, but the big one seems to be binding somewhere.

I took it apart again to see if some rust had rebuilt since I last fixed it but there doesn't seem to be anything there. I wire brushed it all again anyway and also searched for any stray bits of wire brush that might have got stuck to the (magnetic) rotor. -- Nothing. I also made sure that the bearings were all free and turning easily. - they are. I reassembled it and it binds. Disassembled again. - Nothing wrong that I can see anywhere.

It is as if the field has swollen and is clamping onto the rotor. But that is ridiculous. The only thing I can think of is if the motor casing that houses the field has managed to retain some rust and is pressing onto the field and distorting it.

Does anyone have any ideas on what else could be wrong with it because I would much rather not have to buy another motor?

Bob

Hi Bob
I was thinking about you yesterday when drilling holes to secure the work table on my machine and all the holes you drilled on yours.
Maybe you could put some bearing blue or marker pen on the rotor then give it a spin and see if it is binding on the rotor anywhere.
Have you tried shorting the coils and turning by hand? If the coils are working there should be increased resistance when shorted.

Good luck with it.

Cheers
Brian

Hi Brian

As I said above, the rotor is binding on the field somewhere. it didn't before the water gave it a bath so why is it doing so now?

The coils do seem to be working. When I applied power the rotor turned but only very slowly due to the binding.

Bob Willson

Bob,
I have been told never to disassemble a stepper motor because of the close tolerances. Onya for having a go and maybe because of those close tolerances it just needs a tweak of the screws, motor caps and a few terse words to stop the binding.

I can help out with the terse words.

Yea I believe rods right on the money.

I've seen what you are talking about a few times but normally a strip and rebuild fixes the problem.

If you cant get it up and running you can send it back and I'll see what I can do.

I managed to get it running again.

Using the clues that you two provided I reasoned that if it was running before and these motors are as fussy as you say, then the only part that could have been reassembled differently was the front cover plate which has four possible positions. (The rear cover plate can only go in one position as it has to accommodate the wiring.) It was already in one of those positions and it wasn't working; so that left three more positions to try. So, take off cover, turn through 90 degrees and reassemble. Do this twice more (because of course it had to be the last possible position) and it turns again.

Hooked up the wiring and yahoo it runs like a bought one. - Hold on - it is a bought one.

Hi Bob,
Good news but it was the uttering of terse words from this side of the island that really fixed the problem.

OK, then utter a few more and I will see if the rest of the machine fixes itself up too.

Done