ThomasPowers Posted November 2, 2017 Posted November 2, 2017 If you are near farm country go to an implement repair place and ask about speed reducers in their bone yard.. If you know the correct sprocket sizes for using a chain you can calculate the speed reduction very simply as pi x diameter x rotations of one == pi x the diameter x rotations of the other---and you can divide out pi from both sides! Quote
Jspool Posted November 2, 2017 Posted November 2, 2017 I made the mistake of previously posting this in a sticky. Not sure if that was the correct thing to do or not. I purchased plans, and am in the process of having a Mcdonald rolling mill made. Rather than chain and sprockets I want to go with a motor and reduction gear box that I have seen others do. What I can’t seem to extract from the WIPs I’ve read is what HP motor and what speed reduction is required. Any help with that, and a good surplus source for motor and reducer would greatly appreciated. Another idea is to utilize a hydraulic motor as I have hydraulics plumbed in the shop. Would a system putting out 8gpm be able to power the rolling mill or is it better to stick with electric? Other thread moved/merged into this one., there is no reason to have 2 threads on same thing, Quote
ThomasPowers Posted November 2, 2017 Author Posted November 2, 2017 I believe I answered that other one on how to figure out the reduction and where to look for a reducer. Another suggestion for a reducer is for a motorized large commercial roll up door; check with the folks that install and repair such things. Quote
Steve Sells Posted November 2, 2017 Posted November 2, 2017 I suggest you read the plans you got from McDonald all this info in in there, with reasons why, I love my rolling mill Quote
Michael Cochran Posted November 2, 2017 Posted November 2, 2017 Steve did you ever get in touch with Mr. McDonald about distributing his plans? Quote
Steve Sells Posted November 2, 2017 Posted November 2, 2017 no response at all from him or anyone Quote
Jspool Posted November 2, 2017 Posted November 2, 2017 2 hours ago, Steve Sells said: I suggest you read the plans you got from McDonald all this info in in there, with reasons why, I love my rolling mill The info package I received didn't cover geared speed reducers. Quote
ThomasPowers Posted November 2, 2017 Author Posted November 2, 2017 Did it cover size of sprockets for a chain drive reduction? If it did you can use the information I posted and know what reduction you need to look for in a geared speed reducer. Quote
jeremy k Posted November 2, 2017 Posted November 2, 2017 I would rather have a chain break VS. a gear box in the event of a jam - chains are much easier and cheaper to replace. About all I have left to acquire for my rolling mill is the chain and sprockets and a little more assembly of the parts - then I'll be rollin' Quote
Steve Sells Posted November 2, 2017 Posted November 2, 2017 12 minutes ago, Jspool said: The info package I received didn't cover geared speed reducers. Mine mentioned those that used a gear box reduction system blew up. It seems the pulley/belt acts as a natural clutch and when a roller binds, and a chain will break, but a reducing gear box did not have this feature, but it said a 20 to 22 rpm is close to optimal and it should be simple math from there. It also covered the experiences of hydraulic methods for closing the rollers is not a good idea also, did your issue of the plans not include this information? Quote
ThomasPowers Posted November 2, 2017 Author Posted November 2, 2017 You could use a pulley and belt and a gear reducer... Perhaps a flat belt as they tend to slip a bit better than a V belt... Quote
Michael Cochran Posted November 3, 2017 Posted November 3, 2017 I hate to ask what's likely to be a stupid question but I can't help myself. Other than slimming down nonferrous metals, what use is there for a rolling mill? Is it good for drawing out billets? I'm sure I'd find a use for one on occasion if I had one but I don't know that I'd want one not knowing what they're actually good for. Quote
Steve Sells Posted November 3, 2017 Posted November 3, 2017 I use mine for steel billets and blades Quote
Frosty Posted November 3, 2017 Posted November 3, 2017 22 hours ago, ThomasPowers said: If you are near farm country go to an implement repair place and ask about speed reducers in their bone yard.. If you know the correct sprocket sizes for using a chain you can calculate the speed reduction very simply as pi x diameter x rotations of one == pi x the diameter x rotations of the other---and you can divide out pi from both sides! I used to figure gears like this but it's WAY easier. It's a simple multiplication or division problem. If the driven pully is 2x the master pully the rpm of the driven is 1/2 and torque is 2/1. There are a lot of "proper" terms for which half is which. At home I use Master, Slave. The "master": pully, sprocket, gear, etc. is the first in the train, "Motor" pully above. The "slave" is the one powered by the belt, chain or down the line in the power train. Write it as a fraction, Master as the Numerator, Slave as the Denominator. Master = 1" slave = 10" It's a straight fraction, 1728/10 = 172.8 RPM. It just came to me one day after spending a LONG time with a calculator determining what pully to change on a LA Abrasion machine, (tumbler) at work. I was following the directions in the book they give away at power train places. To do it right you have to measure the radius of the pully center to where the mid point of the belt contacts the pully, figure circumference, one book wanted you to calculate the belt speed even! Anyway, I was looking at my notes and realized none of that extra calculator time is necessary. A motor pully that's 2x the dia of the slave will turn the slave 2x as fast. Major head slapping moment. Frosty The Lucky. Quote
Jspool Posted November 3, 2017 Posted November 3, 2017 6 hours ago, Steve Sells said: Mine mentioned those that used a gear box reduction system blew up. It seems the pulley/belt acts as a natural clutch and when a roller binds, and a chain will break, but a reducing gear box did not have this feature, but it said a 20 to 22 rpm is close to optimal and it should be simple math from there. It also covered the experiences of hydraulic methods for closing the rollers is not a good idea also, did your issue of the plans not include this information? Hugh mentioned that, but that was his his dated opinion limited by not understanding that a VFD would simply kick out if the motor gets too stressed. Its a parameter thats easy to set up, and nothing blows up. I admit that a v belt drive is attractive as it would just slip. I have seen lovejoys that do this as well. When you suggested looking at the plans I thought I missed where he mentions what parameters to use if you go the route of a geared reduction. At this junction, with the feedback I am getting, and looking at other builds (my there are a lot of them) a 60:1 1.5hp 1725 3ph setup run of a vfd should do the trick. I can slow the 29rpm down to 22rpm with the vfd if needed. Frosty, as much as I appreciate your help, it just reminds me that I should have paid more attention in school! Wish I could understand that. I do know the torque requirements, and the target rpm for the 2” roller, so went with that. Quote
ThomasPowers Posted November 3, 2017 Author Posted November 3, 2017 How does the VFD affect torque? Quote
ianinsa Posted November 3, 2017 Posted November 3, 2017 i seem to be missing something here? on my mcd type mill you need to press down with your foot to create the "squeeze" and if you are breaking chains ???? the other mill "large version of jewellers mill" uses a chain and is a different animal entirely Quote
timgunn1962 Posted November 3, 2017 Posted November 3, 2017 4 hours ago, ThomasPowers said: How does the VFD affect torque? For speed reduction (i.e. any frequency below the rated frequency of the motor: 60 Hz or 50 Hz, depending on location), the motor gives constant torque. For increased speeds (above rated frequency), the motor runs at constant power. This means that there is no problem if the motor sizing is based on the torque requirement, but may be a problem if it is based on the power requirement. In Jspool's example, the VFD speed reduction to 22/29ths of the rated speed will maintain full Torque, but provide "only" 22/29ths of the rated power. Quote
Michael Cochran Posted November 3, 2017 Posted November 3, 2017 11 hours ago, Steve Sells said: I use mine for steel billets and blades Thank you for that quick answer. I might have to try building one now. Quote
jeremy k Posted November 3, 2017 Posted November 3, 2017 Ian - No - the chains should not break but with that amount of torque being made with the reductions...if there happens to be something that does cause something to jam a weak point that is built into a piece of equipment is cheaper to fix than major parts. Yes under normal circumstances the chains should not break under normal use, but incase for some reason something happened, I would rather replace a chain than broken gears in a gearbox. I would think that even with a huge amount of use the most maintenance to a rolling mill would be to lubricate the needed parts and possibly have to replace a chain due to stretching from lots of use. Although I would venture to say(my personal opinion) that most rolling mills built as Hugh did - would provide a great machine that will last the average persons forging sessions for many many years. Quote
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