Yet another motor question…

I recently purchased an 8x12 C&P and previously had a 7x11 Pearl. I always operated the pearl by treadle and went to the trouble of fitting a hern ironworks treadle to the C&P (which came motorized). After printing one job, my knee was sore and I realized that just the weight of the castings on the C&P made using the treadle very difficult for me. I have oiled like crazy, double checked the oil diagrams to make sure I didn’t miss anything, but the press still seems a little stiff.

So I thought I’d use the old motor that came with the press. It was pretty rough, so I took it to the motor repair shop to be checked over. It was shot, so they found me a new motor that is 1725 RPM 1/2HP - similar to the other motors people here have discussed. My old motor had a stepped pulley system on the shaft, so they installed that as well.

Well I wired the switch/plug on it yesterday, and set it up with the belt tonight. When I switched it on I gave the flywheel a little push and this thing started flying. I had the belt connected to the smallest pulley (which in my mind would be the slowest?).

There is absolutely no way I’m printing like that, so now that I own this new motor can I limit the speed? It is not a three phase motor so the VFD that is recommended here won’t work, but is there something similar for my motor? What happens if I put a rheostat on it?

I just want it to move the speed of what a normal treadle speed would be.

Thanks-

Leslie

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First of all, we should figure out whether you have it hooked up to give you the slowest speed. With stepped pulleys, you should have the belt connected to the smallest wheel on the stepped motor pulley and the biggest wheel on the stepped pulley closer to the press. With the pulley closer to the press, this will probably have to be on another intermediate shaft. Then a very small pulley from the intermediate shaft will have to go to a large (maybe about 2+ feet diameter but this is just an estimate) pulley on the other end of the flywheel shaft from the flywheel. This last will give you more speed reduction.

The foregoing is just an estimate. Could you upload a photo so we can see just how things are hooked up on your press. Then someone can give you more concrete details on what to do.

Whatever you do, remember to guard everything and be sure to create a completely safe working environment. Exposed belts and pulleys, as well as all other moving parts, are very dangerous. Follow all applicable safety guidelines in all areas of your work and/or hobby.

Well, I guess that’s part of my problem - I have the stepped pulley on the shaft of my motor directly belted to the 24” diameter pulley on the flywheel shaft. When I’ve seen other motors work they have always been a direct connection like this. I really would like to have more control over the speed.

Will have to figure out how to guard everything once it’s working, since the press came with nothing. I have attached pics - I know there’s a lot of oil on the chipboard around the press, but I kept thinking that the more I oiled it the more it work its way in and make the treadle usable. I still can’t imagine how anybody treadles them with as stiff as mine is.

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Nice pretty clean press. I see some oil stain on the floor. That is good. We used to say if there was no oil on the floor, you were not oiling it enough. Keep wiping up the oil. I would like to see some guard over the bull gear.
You speak of stiff. You also say the motor runs the press too fast. The too fast is easy to see and we can work on that. I think you should look into the stiff part to make sure you are not going to have excessive wear. Take the belt off and disconnect the treadle hook from the crankshaft.
Grab a lower spoke and give the flywheel a big strong turn. Keep your hand on that spoke and follow it around to the bottom to complete the first turn and then pull up hard and let it go. Depending on how strong you are, the flywheel should turn 3-5 more times at least before the machine comes to a halt. Any less says something is binding. If the rollers are on the press and you turn the flywheel by hand very slowly, you should feel it get harder to turn as the rollers go over the top shoulders of the rails. That is normal. With the rollers removed and the press turned by hand there should be no hard spots. If there is one or more hard spots, something is binding.
I will take some pictures of my double reduction speed reduction and describe how I get the speed down to a very sedate speed for students. I will send these to you by private email.

Inky

Inky-

Thank you so much for the comments. You always have useful feedback. I spent about a month of evenings after I got the press de-rusting it and going over it to clean it up as it had been sitting for awhile. All of the “silver bits” like the large cam gear and all of the shafts had been painted black, so I took that off as well.

I did as you suggested, and with the treadle hook removed, the press went 8 turns. However, with the hook installed there are some sticking points, so I may re-evaluate the fit of the hook. Because of the cleanup, I feel like I know the parts of the press pretty well, so if you could advise me about other sticking points to look for that would be great.

I feel comfortable running the press at speeds I’ve seen in other shops, but if you saw it now you would laugh. Honestly, if I can get the treadle working more easily I would probably only run the motor for larger jobs.

Thanks again-

Leslie

I’m running my 12x18 from a 1725rpm, 1/2h motor. I’m running a belt from a 2” pulley on the motor around the flywheel of the press and it runs about 12 impressions a minute, which is pretty comfortable for me.

How fast is yours running?

Modernman-

I just ran it and counted - impressions are 36 per minute. Not sure why they are so different.

Inky-
Took the hook, after what I realized this morning, to a friends metal shop today and they put a round sanding wheel inside the hook and went to town. Voila! The press is now running nicely with the treadle, so at least that solves that problem, and takes the urgency out of getting the motor adjusted. Now I can tackle that.

Leslie

Leslie,

You have a 2” pulley running at 1725rpm belted to a 24” pulley.

The 8x12 C&Ps required 4 revolutions of the flywheel per impression.

24/2 = 12
1725/12 = 143.75
143.75/4 = 35.9

Larger presses will run a little slower as the flywheel requires more revolutions per impression.

If you want to slow down your press you’d need a bigger pulley on the flywheel shaft or a smaller pulley on the motor shaft. Or you can just belt the motor to the flywheel directly and reverse the direction of the motor.

I know you just bought that motor, but I can’t recommend the VFD solution highly enough. I can get my 8x12 down to 10 impressions per minute—very slow and safe for those just learning how to handfeed a motorized platen press.

Hope this helps.

Brad.

@ Brad
You need a 3 phase motor to use that VFD right??

I have an older single phase, 1/2 horse power motor (1725 rpm). And I am wanting to slow down the press, I already switched the motor to run on the fly wheel instead of the other wheel on the other side, had to remove the brake but it did slow it down some though I would like to slow it down more.) I am considering a treadle but I want the motor for long runs (thoughts on having both?)

Thanks
Angela