The Coote is Completely Finished Almost - - -

R

rlinger

Joined
Mar 29, 2002
Messages
4,591
I want to put an electrical socket on the motor leads and a plug on the DC controller leads so that I can remove the grinder from the table without having to drag the DC drive around with it, but !!! its finished!! Except of course I still need to attach the graphite strip to the flat platen - but IT'S FINISHED!!!

pics are here: http://riflestocks.tripod.com/coote.html

And again; thanks to Itrade for his sharing DC motor and DC drive info with me and to Rhino for leaning me toward the Coote and to others for advising me on drive wheel size.

Roger
 
Congrats on the new addition to the family, er uh shop! I can't wait to hear how it performs. I'm sure it beats the heck out of my home made 2 X 48. Mine didn't cost me anything, but then you get what you pay for (it won't track worth a damn). Some day I too will have a real grinder. I thought it would be about two or three years ago but at least I can still dream of the day.

I like your setup, it looks like it will be a real space saver. Keep us updated with the performance.

Rick
 
Hey rlinger, buddy.

I was thinking my pulley setup (I'm at 1:1 with a 4" drive wheel) was a little laking for top speed. But, before I bought a new pulley I thought I'd see where I could adjust the controller.

As you know the controller is set for 90vdc at 120vac. However, the motor is rated for 120vdc and 4800rpm. So I started cranking it up. As it came the top voltage was set to about 87vdc. The controller in fact does adjust up from there. In fact it adjusts up to 120vdc! So cool.

I backed it off a bit to 117. So it's running below rated voltage, but boogies.:D:D:D

While I was at it, I adjusted the bottom speed too. Now I have crawl to scream.

FWIW,

Steve
 
Itrade,

Get that DC drive back down to 90 volts output max.. Go with a different ratio on the pulleys if you want more RPM at the drive wheel. You may over power the SCR's on that drive. As I recall that drive is rated at 1 1/2 HP at 90 volts output. At any rate, if you do run its output high check the heat sink by touch, while running under load (grinding steel).

I adjusted my max. speed pot for no more than 90 volts output.

You can buy inexpensive pulleys of various size from Sheffield Knife Supply.

Roger
 
Roger,

RE: Overpowering the SCRs

Hmmmm. could be. However it is also rated for 180vdc output - with approriate input. So the output circuitry can handle it. The supply side might belch.

I'll take half your advice and back it down to 110. That's probably fast enough. I did monitor the heat - none - so far so good. If I burn it out - so be it.

For me this is living on the edge - it is about all the adventure I get in life ;)

I did buy some pulleys from Sheffields. Not gonna do that again. The ones from MSC were more $$, but more better.

Thanks again,

Steve
 
Itrade. I guess from what you say your controller can be jumpered for either 110 or 220 volt input. Yes on what you say about the 180 volt output when wired for 220 input. I guess you're running at 220 in. Sorry for jumping to conclusion.

Roger
 
Nope you didn't jump anywhere. I am running at 120 input.

We'll see how long it lasts at my levels.

Steve
 
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