I know this question has been asked before, but I can’t find it, so here goes… What RPM’s am I developing?? Motor speed 1725 RPM Motor pulley diam’s (Top to bottom) 5,4,3,2 (inches) Quill pulley diam’s (Top to bottom) 2,3,4,5 No idler pulley to mess up the math. For the longest time I’ve been using the ‘that looks about right’ system, but I should know the speeds. Any help would be greatly appreciated. Thanks in advance SawdustSteve Long Island, NY (E of NYC) and…. waiting for the snowstorm on Wednesday
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Replies
Steve,
According to this calculator I found:
http://www.csgnetwork.com/pulleybeltcalc.html
Top = 4312.5 RPM
2nd = 2299.424
3rd = 1293.75
Bottom = 690
The belt information is irrelevant.
Back in the old paper and pencil days it was.
VD=vd or Velocity X Diameter = velocity X diameter.
Aren't computers great.
Steve,
Even when you know pulley size things can be less than accurate. There are other things like variable speed routers--what speed is that? It can be pretty important with routers and shapers.
In our shop, we've gotten into the habit of checking speeds. We have two similar milling machines and both had the wrong spindle speeds on their boiler plate labels. One had the speed ratios reversed.
If you look, you can find digital non-contact tachometers very inexpensively these days. A search of Amazon with that description returned results with prices ranging from about $20 to $30. We don't use the one we bought often but it was inexpensive and we do check things with it a few times a year.
Thanks guys for your time and anserrs. I know I can depend on you for correct answers. So... now I have the proper website to go to for other machines I own, I have the answer as to RPM without having to find my calculator, and a place to go for a digital tach.
SawdustSteve Long Island, NY (E of NYC)
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