Thread: Carbatec CTJ-650 motor upgrade

Why not just replace the start capacitor? Cheers.

I suppose I could. As it happens I had an electrician (family member) with me when the capacitor blew. She reckoned that there is probably something wrong which caused the capacitor to blow, like it seemed that it wasn't switching over from the start cap to the run cap. So replacing the start cap might just buy me some more time but won't fix the underlying issue. It also doesn't get me the bigger motor that I want.

Originally Posted by WoodyNZ

I suppose I could. As it happens I had an electrician (family member) with me when the capacitor blew. She reckoned that there is probably something wrong which caused the capacitor to blow, like it seemed that it wasn't switching over from the start cap to the run cap. So replacing the start cap might just buy me some more time but won't fix the underlying issue. It also doesn't get me the bigger motor that I want.

Fair call. I've had caps just go so it could be an easy fix. If you have an electrician in the family its pretty straightforward to change the cap and also test the motor. Good luck with it.

So for anyone who read this and wondered where I got to, I have now replaced the motor and pulley with the ones I posted the links to. The new motor is a bit bigger but fortunately there is some flexibility with placement on the table saw. So I can still get the pulley to line up nicely with other pulley at the blade.

I had to remove the piece of metal sticking out the back that used to hold the blade guard because the new motor was hitting it. But the blade guard was a PITA so I haven't used it in years anyway. And I dont think it was really making it any safer. A riving knife would be good, but I'm probably best off making one myself. I also decided to remove the cover over the belt. That has already chafed and ruined one belt. And I've made a box for the motor to sit in anyway, so it's not hanging out in fresh air.

The motor does just stick above the table a tiny bit when doing 45 degree cuts, which is a bit annoying. But I dont often tilt the blade. And it will only be a problem cutting boards wider than about 250mm.

Also got an electrician in the family to help me run new plugs and cabling. Being a 3hp motor and rated at 12A, it really needs to be on a 15A circuit. Which means bigger cable from the motor to the breaker and the breaker to the wall, including 15A plugs.

So far I'm very happy. Blade spins about 30% faster based on the size of the new pulley. Makes a notably higher pitch sound. And cuts through big chunks of rimu without skipping a beat.

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Originally Posted by WoodyNZ

Also got an electrician in the family to help me run new plugs and cabling. Being a 3hp motor and rated at 12A, it really needs to be on a 15A circuit. Which means bigger cable from the motor to the breaker and the breaker to the wall, including 15A plugs.

Really requires a dedicated circuit from switchboard to wall outlet, plus beefed up cables, plugs, switchgear from the wall outlet to the motor, at least in Oz. 15A circuits are supposed to be a dedicated circuit to eliminate a load of twisted wire and clamped connections that can be found behind 10A GPO's. You are allowed multiple 10A GPO's on a single circuit, provided that the total current draw for the circuit does not exceed the cable/breaker ratings. If you treat the last outlet in a circuit like a 15A outlet, you are faced with accumulated voltage drops from all of the preceding wire joints in the circuit.

Two possible causes of destroying the cap on the original motor are natural decay of the cap over time, and excessive voltage drop in the supply, limiting the available motor power and causing the motor to slow and engage the centrifugal start switch to try and get back up to speed. The difference would be that the motor would be running hot in the second case, and emitting a burnt varnish odour. The second case is quite possible if the saw is heavily loaded and has been for some time, e.g. cutting a large batch of timber in one session.

It is also advisable to minimise the number of interconnects in the system where possible by direct wiring the motor terminals to the switch, and the switch to the 15A supply plug, as this again reduces voltage drops and allows the motor to operate more efficiently. The plug and socket by the motor in the pick really is not required, particularly with a family sparky to assist in wiring the unit.

Good points re GPOs. I should have clarified that I have 2.5mm TPS running from the sub board straight to a 15A socket, and then on to another 15A socket in case I want to plug the saw in at another location.
So no 10A connections between the sub board and the saw. And at most one connection behind a 15A socket.


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