Hi, I am new to faceting and have acquired a gemmasta gf4 secondhand. I can hear a knocking sound when it runs and the top of the 240v motor gets hot along with the belt pulleys. ( THE EMPTY ONE ).
I have changed the belt twice. Sprayed silicone oiled and cleaned what I can get to. It runs at uneven speeds, stops for no reason and starts again on its own.
I imagine this means I should change the bearings and look at the wiring which visually looks intact and sound. i fully intend to swap over to 12v and have most of the parts but I am longing for a technical diagram with part names and instructions. Can anyone direct me to these? I have googled but without success.
I am in the sticks so its easier for me to fix it myself but I have to send away for parts. I have the gf3 manual as photos but it doesnt address bearings. I would also like to know what theyellow light on the front of it is for.
Might pay to check the brushes in the motor. Worn brushes can cause many of the symptoms you describe. Could also be the control pot (speed controller) has bad contacts.
Take the belt off the motor pulley and run the motor. The lap spindle should easily spin by hand, if not, then it may be a bearing issue, also you will find out if the motor still runs hot or not.
The stop start sounds like the bushes in the motor are worn out. My electric drill did that when it wore out.
dont run the motor until you replace the bushes or you could kill the speed controller.
Gemcuts do 12v conversions for the GF4. Brian bought the rights to GemMaster and last I heard (at the Muster) he was working on bringing out a new model.
I would ring Gemcuts in Ballina. Brian may be able to help.
otherwise Motion Dynamics sells a range of 12v & 24v dc motors and speed controllers. Look online.
If you don’t mind waiting 2 months you can get a decent switch mode power supply ( get one that delivers more than twice the current draw of your motor as the motor will draw more current at startup and slow speeds) say 15 amps at 12v (180w) for a 60w to 90w motor and a 40A pulse width modulator. My 40Amp PWM and 25A 12vdc supply cost just over $50 about 3 years age for the package.
But you’ll need to work out a mounting plate. Hence, contact Brian at Gemcuts.
Try & pinpoint where the knocking noise is coming from. Place a screwdriver up against your ear & touch it on the bearing housings at the motor, speed belt splitter & the turntable spindle. Just like a doctors thethescope. As previously mentioned, slip the belts off underneath one by one to isolate where the noise may be coming from. Check the belt for lumps & hard spots especially where the join is and if the machine hasn't been used for awhile the belt goes hard and as it goes around makes a knock noise.
My GF4 has a belt splitter on the top & the shafts move up & down in the bearings causing a knock noise. I know there's a bit of play there. The original bearings & shafts had bearing lock light on them to stop any free play but occasionally I have to retighten the pulleys to take the slack out.
Bearings are cheap compared to a 12v conversion and I'd only go down that path if your motor or controller needed replacement.
Only replace the bearings with High Precision" bearings as normal bearings have a lot of play in them.
Thanks for the replies. The motor just stopped working do I am going to do a 12v conversion since I already had most of the gear. So the machine decided for itself. I have learned a lot from the replies. Thank you.
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