Charnwood W575 Thicknesser Electrical Issues?

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5 Feb 2017
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Hello all,

A few weeks ago I purchased a 2nd hand charnwood W575 thicknesser from someone who didn't know much about it.

I tried it out and it seemed to work fine. New blades required as they were quite blunt and damaged. Digital read out wasn't working, so i took it to pieces and gave it a clean-it sprung back into life so all was well.

Screenshot 2024-06-03 081648.png

No blade setting jig with the machine, so i designed some magnetic blocks to set the new blades up.

First test cuts, machine works perfectly. Then I get to thicknessing some beech, it works beautifully. However, on the final pass, the motor decided to slowly ramp down to a stop and not restart again.

I am no electrical engineer, but I've tried my best to check things through. My hunch is on the NVR switch, but I do not know how to test it properly to see if it works. A replacement is readily available so my fingers are crossed for that to be the issue.

I have checked the fuse in the plug, and checked continuity from the plug to the NVR switch and that is all fine. Then there is continuity from the NVR wires to the motor brushes housing.
I have the machine relatively stripped down so i have decent access, but I have yet to figure out how to remove the motor/electronics cover to see the wiring inside.
Screenshot 2024-06-03 081539.png

I have a larger NVR switch which I tried using, but that just immediately tripped the breaker in the garage. I also tried bypassing the NVR completely and that also tripped the breaker.
The manual does not have a wiring diagram inside.
Screenshot 2024-06-03 081213.jpg

Before I try to strip the machine further, I would like to check the NVR switch. Does anyone have any recommendations for how this should be done?

First thing is to ensure everything moves smoothly and nothing is jamed or tight due to dust build up.

I have a larger NVR switch which I tried using, but that just immediately tripped the breaker in the garage.
That suggest either wired wrong or there is a motor fault , but you said you bypassed the NVR so power directly to the motor and it still tripped so that suggest the motor is at fault so disconnect the drive from the motor and see if that turns freely and then does it still trip ? Next will be an inspection of the brushes and commutator on the armature to see if that is clean.
Hi Roy,

Yes, I've removed all drive belts so the motor is spinning by itself freely. The bearings don't feel perfect, but they're in decent enough shape. The brushes are fine too, plenty left on them.
My only though is that it isn't tripping when the original switch is in, and it didn't trip the garage power when It initially stopped working.

I'm more free than I expected this evening so I shall have another go at getting the motor out. Will update, but any other ideas meanwhile are much appreciated!

After further playing, I think I have sorted it, but I still have concerns.
I used some logic and tested the spare NVR switch I have for continuity. The old switch does not have continuity in the same way, so there must be something wrong with it.
When trying the other NVR switch in the thicknesser, it worked this time. However, it is still tripping the breaker sometimes. This switch is rated slightly higher, i didn't check to see the rating of the breaker it was tripping, it could be a small one in the garage as there are a couple different ones depending on the socket (i think).

I've ordered a replacement NVR switch the same (as best I can) as the original.

I also took the original switch to pieces, to find a very melted contact and plastic part, stopping it from working-definitely beyond my repair.

So my final remaining question is, can this happen to switches by itself (for example if the plastic part wore out or something?), or has this happened due to an issue somewhere else in the machine? Not an easy question but just wondering what the chances are.

Hopefully when the new switch arrives it will just work and not trip anything, but with it tripping the breaker I am not convinced

What's the rating and class of the breaker? you might have class B but need class C to handle the startup current.
On the switch - my inclination would be not to worry too much. that's not what the manufacturers spend their money on these days. So just replace it with a better one. (It's quite a harsh environment - I had a similar-sized Axminster thicknesser, and the switch stopped working because it had filled up with wood dust).
I cannot remember which breaker tripped, i have a feeling it was the 3rd one in. However you are correct, they are class B so that could be the issue. It would also explain why the breaker always trips when i'm welding and do a few spot/tack welds.

I took the time last night to clean the roller gears and get the rest of the thicknesser back together for the switch arriving (hopefully today).


Much cleaner, and with new grease too. Was a little bit of a pain to fully disassemble, but went back together without too much fuss.

Will update once the switch arrives
New switch arrived on Friday, Installed and it seems to have cured the problem. It is still tripping the breaker occasionally, but i can live with that.

New switch coupled with the fresh set of blades is leaving a fantastic finish on the workpiece.
However, i am getting quite a significant 0.25mm step of snipe.

Any tips for reducing snipe on thicknessers like these?

Any tips for reducing snipe on thicknessers like these?
Make sure the infeed/outfeed tables are adjusted properly.
Gently support long pieces as they feed in/out.

See also:

Or, as I mostly do, just work with pieces ‘two snipes’ longer than they need to be, say 5”, then cut off the snipe both ends to get final length. A bit wasteful for valuable wood, but useful for kindling.