I have an 8x12 c&p. I currently have a 1/4 horse power (1725 rpm, single phase) motor running it on the 32” flywheel (it was way way too fast when I had it on other big pulley.
On the motor I have a 2” pulley.
It is currently doing about 23-24 impressions a minute, good for some work but a bit to fast in general for me at this point.
How big of a pulley to do I need for the Speed reduction pulley? Any one know the formula? Have any good pictures of your solution?
I would love to get it back on the other side of the press so I can put my brake back on but that wheel is smaller than the flywheel (it is 22inch)
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I’d recommend spending the money for a new motor and variable frequency drive. This way you can run the motor on the 22 inch pulley and still get down to 8 or so impressions per minute.
Just let me know if you need a walkthrough.
New motor and VFD is the way to go, but can be pricey.
The main shaft turns 4 times on an 8x12 for one impression I think. It’s 6 on my 12x18s.
You’ve already got the math done, though…
2” pulley/32” flywheel/4 revs per impression = 0.0156 reduction.
Multiply that by 1725 and you’ve got your 28/29 impressions per minute.
Not sure how your speed reduction pulley will work, presumably the motor will feed a pulley and a second pulley of a larger size will drive the flywheel. The ratio between these two pulleys will affect your speed proportionately.
If you get a 2.5 reduction between those pulleys you’ll be running about 12 impressions a minute which is fairly slow. At that speed I’m comfortable feeding full 11x17s on my presses which are larger, so you may want to go a bit faster than that. At that speed you’re still above 700 impressions an hour, and if you’re doing lots of runs that large you may want to invest in an auto-feed press. That’s the only reason I might say it’s not the biggest deal to not get the VFD motor—you won’t want to do many jobs by hand that will take you more than an hour no matter what, even if the press is running painfully slow.
Hope that makes sense.
Think of the pulley system as a gear reduction. A 2 inch pulley driving a 4 inch pulley reduces the speed in half. If you get a 2 inch pulley and a 4 inch pulley on a 1/2 inch intermediate shaft with pillow block bearings on each end, mounted on a frame of some sort, and drive the 4 inch pulley with the 2 inch on the motor, and drive the 22 inch wheel on the press off the other 2 inch pulley, you should wind up with about 20 impressions per minute (88:1 reduction compared to the current 64:1 reduction). It should also start easier since there will be more mechanical advantage between the motor and press. All those parts should be available off the shelf at any decent hardware store.
Thanks everyone — does anyone have a photo of there system? Bob??
Where can one buy the pulleys with several sizes on them?? that way maybe I can adjust and use a different pulley to go a little faster or slower?
And any good affordable sources for a small v-belt? And I might get a new one to run the press so I can move the motor closer to the press (I am going to move the press into a 10x12 space — so space is a premium!) And the belt I have is very long the motor mounts way out in front of the press.
Would love a new motor and a VFD.. but im putting all my money right now in to the space to move the press so I don’t have to make a 30 mile commute one way every time I use my press.
many have commented on this, and i was thinking. why could you not buy an old used drill press, take the “head” off the stand, lay it on its side and build some sort of mount. i see drill presses for sale alot locally and for 50-125 bucks. they are well configured for quite a range of speeds.the drive pulley could be mounted on a shaft, then simply “chucked” into the drill. it seems it would be cheap enough, and self contained.
as for belts,,, ACE hardware, NAPA, FARM and FLEET, or a local air conditioning/heating contractor
Angela, if you don’t have a good hardware store (which should also have the stepped pulley) nearby you can order all the parts, including belts, from McMaster Carr (www.mcmaster.com). They are very well stocked and fast. I am about 3500 miles from my own shop where I could photo the parts you would need — sorry. If you were in Richmond VA I would send you to Pleasants Hardware, who would have everything you need. Just be sure all the pulleys you get for the intermediate drive have the same shaft diameter bores, and get a shaft for them as well as the pillow block bearings all at the same time. You could have a mounting for all this made by any good welder if you show him/her what you need to do. I would also suggest making the frame an extension of the motor mount base so the motor and reduction system are mounted together.
Angela, why don’t you take your current 2” pulley off, bring it to a local machinist and have them lathe it down to 1.75” outer diameter? And if that’s still too fast, then bring it back, lathe it down to 1.50” if your pulley allows for it. That might be the cheapest and easiest solution. And if your pulley isn’t solid where you can lathe it down, you can get something like:
I believe that has enough meat to lathe down to the diameter of your liking.
One more tip to keep the belt on the pulley is to take a bastard file and rub the pulley while running to put a very very slight concave crown on the center of the pulley to keep the belt from running off. And I mean very as in not visible to the naked eye, but that’s all you need.
There are also such things as 1140 and 850 RPM fractional horsepower, single phase motors. The 1140 will run you around $250.00 new. The 850 about double that.
Years ago i had the same press and it ran too fast, we bought something that reduced the power to the motor slowing the press down, can’t remember what it was called but it had a dial on it that you could turn to speed up or slow down, it worked well. Dick G.
Where a variable speed motor is not practical or possible and when the speed of the driven shaft must be reduced beyond what reasonable sized pulleys can produce, speed is commonly reduced by placing an intermediate shaft and pulleys between the motor pulley and the drive pulley on the press as mentioned by AdLibPress above.
A compound drive system is fairly simple to make and requires a few, relatively inexpensive parts. I have a variable speed motor on my 10x15 press but when I had an 8x12 I used a 3/4 hp motor with a compound drive that reduced the speed to 14 ipm. I’ve posted a photo below of that setup. Note that I was fortunate to have an old cast iron motor mount that had an intermediate shaft with bearings built into it. But a similar one out of wood and/or angle iron, etc. could be put together. Note also that although the shaft is physically behind the motor, it is still considered an intermediate shaft as it is in the middle of the drive train.
My motor was 1725 rpm with a 2” pulley on the shaft connected to (I believe) a 6” pulley on the intermediate shaft using a V-belt. On the end of the intermediate shaft was a 2” flat belt pulley that connected to the 24” flat belt pulley on the press.
You will notice another wide flat belt pulley under the belt. That was an idler pulley I set up to keep tension on the belt and force the belt to contact more of the surface of the flat belt pulley on the intermediate shaft. It probably wasn’t necessary but gave me the assurance that the belt would not slip and would provide enough power. If I hadn’t have had that old pulley laying around I would have done without it,.
Front Room Press
8x12 Motor cropped.jpg
Angela, hi. I have the same problem as you. My 8x12” C&P operates way too fast with a direct drive belt…or used to until yesterday. I asked my neighbor to come over and take a look at my situation. He is a factory mechanic and understands machines. Sure enough, he explained to me the math of size and rotation given the different diameters of the flywheel and the 2” pulley. And as expected, it was way over my head being a right brained person. He understood and simplified it for me. Basically, a smaller pulley would yield a slower machine. He looked at my pulley and found it was a variable sized one that could be adjusted in width by a set screw so the belt will sink into the pulley. Sure enough, when he widened the pulley, the belt sank into it and the press operates about a third slower than before, very manageable. If I want the press to operate faster, I just narrow the width of the pulley. Problem solved. You can see my pulley setup in the attached picture.
The slack in the belt is because it now rides lower in the pulley. Even with this slack, the press runs just fine. Hope this helps. It was a simple fix.