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27th June 2011, 11:39 PM #1Novice
- Join Date
- Aug 2010
- Location
- Sydney
- Posts
- 8
Bosch sliding mitre compound saw - intermittent running
Hello all.
Im having some problems with my Bosch GCM10S Professional SCMS.
It seems to be intermittantly shutting down - when the saw is lowered, under load or not.
Before I worked it out this far, I changed the blade, took the brushes out cleaned them with solvent, still have pleanty of wear to go. Opened up the body and inspected the capacitor for signs of damage (couldnt see any burn marks. Cleaned the commutator.
I dont think it has had that hard a life. Still on the first set of brushes and has cut mainly pine with a Jarrah table thrown in but noting to arduous.
Sometimes it just seems like something "trips out" then it has no torque, an initial ping then nothing unless you realease the trigger and try again.
After the cleaning, it did seem to pull hard initially even if it did cut out when lowered.
Anyway my current thinking is maybe it is the switch that is malfunctioning, but I thought I would throw it out there to see if anyone else has experianced any problems with this model or something similar and what you had to do to fix it.
Any comment would be appreciated.
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28th June 2011, 08:32 AM #2Awaiting Email Confirmation
- Join Date
- Sep 2007
- Location
- Northern Brisbania...
- Posts
- 637
Dear Mhunter,
The problem certainly sounds "switchish" alright. Sometimes just a retightening of the little screws that hold the wires in the switch-assembly is all that is needed in such a case. But going by my brother's experience with that same model of saw, it might also pay you to have a closer look at the Commutator, to see whether any of the individual slip-ring segments have delaminated from the Armature. Symptoms are a little different in such a case - in so much as total-shutdown doesn't occur, but intermittent speed and power does. Brush-wear would be much higher than normal, and there would be telltale signs of caked black deposit at one spot on the inside of the transparent blade-guard. But your situation certainly sounds more switchish at this stage.
Best Wishes,
Batpig.
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28th June 2011, 09:23 AM #3
Is there a cable that is flexing as the saw is lowered?
There is a chance that the copper inside has fatigued & broken & it is only the insulation that is holding the ends together until it is moved.Cliff.
If you find a post of mine that is missing a pic that you'd like to see, let me know & I'll see if I can find a copy.
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28th June 2011, 05:53 PM #4Novice
- Join Date
- Aug 2010
- Location
- Sydney
- Posts
- 8
Ahh yes! I will see if it is the cord, switch (or hopefully not other) and let you know.
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2nd July 2011, 11:58 PM #5Novice
- Join Date
- Aug 2010
- Location
- Sydney
- Posts
- 8
We have a winner!!!
Looked at cable continuity from 3 pins into the machine - all good.
Checked connections into terminal blocks - one was a bit loose and came out with a small tug.
I thought that might have fixed it, but no.
I went in again, continuity test on the switch, yep it seemed suspect. Took the switch out, and pulled it apart. One of the copper switching plates was making a poor connection on activation, had some small "burns" and the copper was pitted. A little bit of wet and dry, then moving round a bit of the internal grease and its all good. I know its a temporary fix, but at least I know that the switch is on its way out.
Thank you both for your help.
PS the cleaning of the brushes and commutator seems to make it go harder so it wasn't a waste - well thats what it seems like anyway.
Cheers Woodys!!!