need to slow down C&P 8 x 12
My C& P platen is running too fast with a B-Line motor. At this point with a loosened belt the press runs slow enough for 3 closings and then the belt catches hold and the press speeds enough to snap and catch a piece of paper. Plate reads: 3/4 HP MS 3381 ES4130 Volts 115-230 Cycle 60 PH1 Amps 12/6 RPM 1140 Temp Rating 40cc 110-220 volt line. The electrician hooked it into 220V. The motor pulley is 3 1/4 ” in diameter while the fly wheel pulley is 14 3/4”. I located a 2” flat belt pulley on line at McMaster-Carr. Will this slow the press enough for me to put in my hand? That leaves me with the problem of shortening the belt. My electrician fears my spending money and not solving the problem for this is beyond his knowledge. The two contacts reached for electric motors will sell me new but can not suggest anything further. I purchased the press June 4, cleaned it then had the electrician wire the work space. I have been trying to solve the speed problem for a month.
Any thoughts are appreciated,
Elizabeth
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I’d recommend a Variable Frequency Drive. This may require a new motor, but the whole package should be under $200 and will allow you excellent speed control.
If you’re interested in going this route just let me know and I’ll explain.
Brad.
I am all ears Brad. The two quotes I got for a new motor with variable control were 500.00 and 700.00. Under 200.00 sounds fine.
Elizabeth
Hi Elizabeth,
Here is one way to calculate what you are asking. Time how many printing cycles your press completes in one minute. It’s probably over twenty if I were to hazard a guess. Your current drive pulley has a circumference of about 10.25”. A 2” diameter pulley has a circumference of about 6”. The ratio is therefore about .58 which is 6/10.25. Multipy this x’s current # of cycles per minute to get new # of cycles per minute. If your press is running at 24 impressions per minute with a 3.25” pulley, it will run at about 14 impressions per minute with the 2”. If it is running at 20, it will run at 11.5” and so forth. I cannot predict what speed you would find comfortable, but, I run at 14 and it is very comfortable for me, yet not boringly slow.
John
The variable speed motor solution is ideal, but does require cash outlay.
To take John F.’s calculation one step further, if you run the belt against the motor shaft without a pulley attached, assuming a 1” motor shaft, you could bring the current speed down to 30% of the current speed, so if 20/min, would now be 7/minute.
We just counted and we are running 50 impression per minute, so a 2” pulley will still run the press too fast - - - and I have endured the comment that I was just not used to the press!!
Elizabeth
I have been using a Variable Frequency Drive and a 1/2hp Baldor motor for running my 8x12 C&P platens. One of the presses already had a nice variable speed motor (with controller) from the 1950s, but it didn’t give the range of speed I was looking for when doing workshops. I like to run the presses very slowly when I am teaching anyone how they work.
A quality Variable Frequency Drive (VFD for short) will run anywhere from $85-150 depending on the horsepower of the motor and the voltage available in your shop. I am running on standard 110v power, so I am using this VFD:
http://dealerselectric.com/item.asp?cID=28&PID=998
You’ll need a three phase motor—even though you may not have three phase power in your studio. The VFD will convert to single phase. Look for something that’s 1/2hp and 220/230v. Try eBay for the best deals on new old stock motors.
You’ll want to make sure that the motor has a mounting plate on the bottom. This will allow you to secure it to either a C&P motor mount or to the pallet on which your press is sitting.
The wiring is pretty straightforward and shouldn’t take any competent electrician more than 30 minutes to complete. I wired my own in less time and my electrical experience is limited.
I hope this helps. Let us know what you decide to do!
Regards,
Brad.
I have purchased a 3 phase 1/2 HP motor and the variable frequency drive on ebay for under 200.00. I shall report on the press once it is installed. This forum is invaluable. Thank you,
Elizabeth