mbrown

I recently borrowed a portable fretsaw from a friend, in order to make a wooden puzzle. After completing one puzzle with no problems, I began a second, but half way through a longish cut, it stopped working - every time the wood was pushed against the blade, it caught and stopped moving up and down. I guessed that the blade was blunt and changed it, but this made no difference. I then took the saw to pieces, thinking perhaps a stray bit of wood was stopping it from moving, but there's nothing obvious. Does anyone have any ideas? The saw is a Shapercraft Model No 1000, and I believe it's around 20 years old, or possibly older. It's made by Spiralux Handtools Ltd, Gillingham, Kent (in the UK). The design is an electromagnet which is turned rapidly on and off, pulling a metal plate up and down, to which the blade is attached. The top of the blade is attached to a sprung arm.

Thanks.

Paul K

Interesting problem. I don't have a lot of experience with fretsaws, but from what you describe, sounds like you might have overloaded something, on the "longish cut"? It still turns and looks like it might cut, but the pressure of the wood against the blade overpowers the power of the magnet, is that correct? I assume that there is a cylinder or shaft which houses the piston that the blade is attached to? I would have also guessed that there was an obstruction in there, but if it goes up and down before the wood is pressed against the blade, then that is out. Might also look at this piston and see if the pressure of the wood is deflecting it. Maybe a guide bushing popped out and it is no longer in that bushing? Sorry not to be of much help. hopefully someone here knows a bit more about these saws.
regards
pk

MrRodeoCC

I'd like to see a picture of the machine, sounds interesting. But if what I am envisioning is correct, it operates like a tattoo gun. Clean the electrical contact points, if they are dirty/corroded, it wont get a good electromagnetic pull therefore no strength to cut, it will have enough force to make it move and the return spring helps rebound. Also check all the solder joints, thermal expansion and vibration can cause the joints to crack, poor conductivity once again. Let us know how it goes.

mbrown

Thanks for your help.

With a bit of fiddling around, we discovered that it still cuts fine if the top cover is removed, but doesn't when it's in place - so presumably it's something on the cover dampening the vibrations of the plate to which the blade is attached.

Anyway, I finished making what I was making, and the owner of the saw says it's not been used for a good few years, so I won't waste too much time trying to diagnose the problem!