The other day I was watching a 'This Old Tony' video and discovered that he made a small welding turntable (https://www.youtube.com/watch?v=ny5Xxwwpkxs). Looks like one of those occasional use but very useful when needed items. He made his with a worm drive gear box and a 24V DC motor. His design is simple and seems to work (at least as far as the viewer can see) but raises some questions about how he has done things as well as whether there are other ways to do this. I'd be interested in other's thoughts -



  • For starters, he runs his platten axis straight through the worm drive gear box. I always thought that stray welding current was disastrous for rolling element bearings - so should some insulating sleeves be between the metal shaft and the bearings? Given the low speeds involved, would plain plastic bushes work just as well (mount the plattern shaft in bushes and drive the shaft with a chain from the gearbox/ motor). On the other hand, what about stray heat?





  • Similarly, his earth clamping method is the earth clamp on the other end of that shaft and as the plattern rotates, the (spring) clamp slips on the shaft. Other weld turntables I've seen locally use a bit of welding cable, stripped of insulation and then wrapped around the shaft (with a little bit of tension) to get the contact. The clamp is cheap and I guess does the job, but not sure it's all that good for the shaft or the clamp.





  • He has used a 24V DC motor with a speed control board to drive his rotator. Nothing wrong with that, but looking around there do not seem to be many of them out there. As alternatives, perhaps a 1/4 or 1/2 Hp motor with VFD (and speed reduction gearboxes too - his rotator speed seems to be 0 to around 20rpm, so something is needed). The other option was a beater of a battery drill - 12 or 18 volts. The advantage of the drill is that there is already a speed control mechanism in there. Would a drill run as 0 to 600rpm and then through a 20:1 gear box (I just happen to have collected one in Tas while there) have enough torque? If I had one of these, it would be used for small parts with the plattern being say 6 to 8" diameter. The other alternative for motion would be a treadmill motor but I would have to find one of them as well. Are any of these options better than any other given the strong electric fields that welding currents would generate?





  • Lastly (for the moment), his rotator can drive both ways. Is that a feature worth chasing if it is not already in the control circuit? I've been trying to think why rotating both ways would be necessary and as it is used for circular welds, can't see why there would be a need to change hands.



Anyway, my questions/ thoughts for the moment.
Michael


Read the full thread at metalworkforums.com...