Geoff Keyes Posted January 8, 2015 Share Posted January 8, 2015 The motor on my hammer packed it up and while I'm searching for a replacement (the original came from a dead compressor with who knows how many miles on it, 15 years ago), I thought back to a conversation I had with Grant Sarver just before he died. Could you use a VFD as the speed control for a powerhammer? I'm thinking that you could run the belt from the motor to the drive pulley directly, with no clutch. The VFD would be controlled with a foot pedal. The more you depressed the pedal, the faster the motor would run, like a big sewing machine. Could that be made to work? It sounds to me that you'd have both speed control (from O to OMG) and maybe a single blow stroke. The hammer is a shop built mechanical, like a Champion, with a DuPont toggle arm setup, about 50#. Thanks Geoff Quote Link to comment Share on other sites More sharing options...
kubiack Posted January 8, 2015 Share Posted January 8, 2015 I had a VFD on my lathe before buying a large RPC. It took several seconds for the motor to go from 0 to 60 hertz. Speed changed after the motor was running were not instantaneous either. If I remember correctly VFDs were original created to lessen the inrush current when a motor is turned on by controlling the electrical cycle frequency. I don't know if other VFDs have parameters that can be changed so that speed changes happen faster but I would defiantly say it would not work with the one I had. There was a thread on Practical Machinist recently were some installed a 75lb Fairbanks hammer and removed the jack shaft and the old motor and replaced it with a higher HP but lower RPM modern motor. The new motor without the extra rotational mass struggled to get the hammer moving from a dead stop. Something to think about if there will be no line shaft or clutch pulley constantly spinning. Quote Link to comment Share on other sites More sharing options...
the iron dwarf Posted January 8, 2015 Share Posted January 8, 2015 Vfd / invertors here have loads of parameters, acceleration, deccelerat, braking force, current boost, on my hammer I set min freq to about 20hz, max to about 50hz, slow accel and fast decel, DC braking to max to stop motor in 1 rev max. here mains is at 50hz and 240v or 3 phase is 415v Quote Link to comment Share on other sites More sharing options...
Will. K. Posted January 9, 2015 Share Posted January 9, 2015 Check out Steve H's post & video at the end of his "New addition to the family" thread about his Beaudry hammer over at the NWBA forum. Quote Link to comment Share on other sites More sharing options...
Geoff Keyes Posted January 9, 2015 Author Share Posted January 9, 2015 I've got 30 hp of 3 ph converter, so I could go that route. I would like to try this, but right now I found a nice beefy 220 v unit an d I will go with that. Thanks for the replies. I'll check the NWBA thread as well. Geoff Quote Link to comment Share on other sites More sharing options...
basher Posted January 27, 2015 Share Posted January 27, 2015 I have thought this may work, and I went to the expense of buying a variable potentiometer foot pedal...However I was lucky enough to see a hammer in belgium that ran from a vfd with no clutch, it was pretty lame and had slow response time. I think lack of momentum was the issue, not much beats a fly wheel. I think it would work well with an oversized , over powered motor. Quote Link to comment Share on other sites More sharing options...
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