beats per minute

[Jason Fry]

Been reading a bit as I continue to work on my Rusty hammer about various BPM rates.  Help me understand if/what I'm missing.

The rate is driven primarily by the reduction in the RPM of the motor by the ratio between the drive wheel and tire diameter.  I'm using a 24" tire.  Math says:

2" drive  1750= 145 BPM 3200=266 BPM

3" drive 1750= 218 BPM 3200= 400 BPM

In addition to the max sustainable rate, there's some slip/friction/loss in the system, so that you won't necessarily get the calculated number of BPM, correct?

In addition to that, you have the limiting factor of the mechanics... some machines won't physically sustain too high of a rate without crazy vibration, failure, etc. 

My hammer has a 40 pound head and a fairly long leaf spring pack with four springs.

I'm thinking somewhere in the 200 BPM range is what I should shoot for?  Any help here?

 

[Frosty]

Jason: Without having a good idea of how skilled you are at fabrication and construction I wouldn't advise you on hammer speed on a bet. However I'll offer a little common sense advise. Start your hammer with the slowest BPM rate you can find a primary wheel for and GRADUALLY work your way up till you find out what it'll take. 

Were I building it I'd maybe start with a different cycle speed but I'm not. Start very slow and work your way up. How long have you been welding? Ever have them inspected, Xrayed or mag fluxed? Been welding high stress components for how long? 

Not much help I know, it's an ethics thing.

Frosty The Lucky.

 

[Jason Fry]

Indeed, Frosty, wise thoughts.  I'd love to find a 1750 and fab the smaller drive wheel.  Also the hammer has a tire clutch, so I won't necessarily have to ever run it wide open. 

[Jason Fry]

I had to give up on scrounging and go ahead and purchase a motor to meet the project timeline.  Went with a 1.5hp 1750 RPM that I'll likely wire for 220.  Now to shop for some stock from which to make the drive wheel... 3" likely, for a max BPM of 218.