armymedic.2 Posted March 4, 2015 Share Posted March 4, 2015 I am planning a 2 x 72 and belt grinder I have on hand made 5 hp 3450 RPM motor. I plan to reduce the RPMs with a pulley system but have not seen anyone building with a five horse is that too much power or is that a doable thing?thanks in advance for answering my stupid question Quote Link to comment Share on other sites More sharing options...
armymedic.2 Posted March 4, 2015 Author Share Posted March 4, 2015 doerr emersion electric t63bxbyf1133 5 horsepower. This is the motor Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 4, 2015 Share Posted March 4, 2015 Way more than needed. Why? Quote Link to comment Share on other sites More sharing options...
armymedic.2 Posted March 4, 2015 Author Share Posted March 4, 2015 The only reason would be that i have that motor sitting on a broken air compressor in my shop, which means it would be free. The other free motor i have is a 3/4 1725 rpm. Anything else would have to be purchased Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted March 4, 2015 Share Posted March 4, 2015 Either will work. I got my scrap motor from a friend who pulled it out of an old mainframe computer system. It is a 1 hp, 240v single phase, cap start TEFC motor at 3600 rpm. Has run like a champ for almost 15 years. Quote Link to comment Share on other sites More sharing options...
armymedic.2 Posted March 4, 2015 Author Share Posted March 4, 2015 Have you reduced the rpm's via pulley on that motor Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted March 4, 2015 Share Posted March 4, 2015 No reduction, I put a 3" solid drive pulley on it so the SFM is high. I run belts over a 10" round caster as a contact wheel. It will hog material pretty fast and doesn't bog down. I'll try to post a couple of pics tonight after I get home from work. Quote Link to comment Share on other sites More sharing options...
arftist Posted March 4, 2015 Share Posted March 4, 2015 3/4 hp is enough for a 2" belt. Save the compressor motor for a compressor. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 4, 2015 Share Posted March 4, 2015 3/4 hp is enough for a 2" belt. Save the compressor motor for a compressor. Agreed, save it for something that can use the power though I'm thinking power hammer, that'd drive a handsome junkyard hammer. I'd make a 100lb mechanical dance pretty for you.Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Dodge Posted March 4, 2015 Share Posted March 4, 2015 FWIW, My home 2x72 bogged down easily, especially with coarser gits with a 3/4. I doubled it (because the price was right) and I can disintegrate stuff with little effort YMMVScott Quote Link to comment Share on other sites More sharing options...
arftist Posted March 4, 2015 Share Posted March 4, 2015 Agreed, save it for something that can use the power though I'm thinking power hammer, that'd drive a handsome junkyard hammer. I'd make a 100lb mechanical dance pretty for you.Frosty The Lucky.Yes, except for the speed. It could certainly be geared down but I would prefer to start closer to the needed speed and avoid expensive gear train parts. It could certainly be done though. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 4, 2015 Share Posted March 4, 2015 I'm not a big fan of 3456 rpm motors either but using one on a tire hammer is only a matter of making the drive wheel smaller and or the tire larger. Too small and the drive wheel doesn't have enough contact surface with the tire but most of these are easily solved on paper before starting the build.I'm an even smaller fan of complex home built gear trains unless the person knows what they're doing. Things like jack shafts unless carefully laid out and guarded are moving traps. Of course something getting tossed between a tire and the drive wheel is a B-A-D thing too. Guards are your friends in the right places of course.Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
JNewman Posted March 4, 2015 Share Posted March 4, 2015 I have a 1hp on mine and when using 36 grit belts I wish it were 2hp Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted March 4, 2015 Share Posted March 4, 2015 (edited) I suggest using at least 1.5 HP. I have bogged down many 1hp many times. Edited March 6, 2015 by Steve Sells Quote Link to comment Share on other sites More sharing options...
armymedic.2 Posted March 5, 2015 Author Share Posted March 5, 2015 interesting thoughts on a hammer off that motor. Sure could use one sometimes. But the grinder at hand...... Ill wait on purchasing products as my sister inlaw said i can come get her treadmill this weekend just a couple hours ago. Cant wait to see what motor it has in it, and make some decisions from there. From the way treadmills work i would think i could keep the button panel and have a variable speed that plugs into 110. Double bonus if it works out. Hoping is is 2-3 hp which seems standard from what i have read Quote Link to comment Share on other sites More sharing options...
WayneCoeArtistBlacksmith Posted March 5, 2015 Share Posted March 5, 2015 The compressor motor is probably not TEFC so the metal grindings would probably get inside and short the motor out pretty soon. Your issue is not the hp but the lack of TEFC and the speed of the motor. Using step pulleys will speed up the rotation of the drive wheel. I put a 3600 rpm motor on a step pulley ONCE for about 5 seconds. The amount of time that it took to hit the on switch, get my wits back and then turn the switch off. I did have it on the fastest speed when I turned it on, the same way that I had it set with the 1800 rpm motor. You don't want to be in the same room with a grinder running at those speeds.I agree that the 3/4 hp is not enough motor. 1.5 works well. That is what I have on my grinder with a VFD and I carry it to conferences and meetings and challenge others to bog it down. Quote Link to comment Share on other sites More sharing options...
armymedic.2 Posted March 5, 2015 Author Share Posted March 5, 2015 That motor is actually tefc. The 1.5 is not however. Hoping the treadmill one is. Wont know anything about that one till some demo occurs Sunday Quote Link to comment Share on other sites More sharing options...
KRS Posted March 5, 2015 Share Posted March 5, 2015 You could check if its possible to reduce the rpm by half with the dahlander wiring.I think it would require a new switch and some wire shielding. anyone knows if that is doable? Quote Link to comment Share on other sites More sharing options...
SJS Posted March 5, 2015 Share Posted March 5, 2015 (edited) I know guys who are using 2-3HP 3phase motors with VFDs and they are tickled pink. I would rather have more than I need, than barely enough. Hopefully the treadmill has a nice 1.5 HP DC with a variable speed controller that you can salvage. The speed on the 5 HP makes it less attractive, but it is doable. Though to be honest you might spend enough on buying parts to jackshaft it, that you should have just coughed up a bit more and bought at 1.5 or 2 HP motor. If you go ahead and buy the 3 phase motor and VFD now, you won't have to upgrade later;-) You can rebuild the grinder around those components, as you learn what works and what you don't like about what ever design you start with... DC motors with speed controllers are great but tend to be pricey to buy new, even more than the 3 Phase VFD combos... First let me say I love my belt grinder, and I want several MORE, bigger, better, with more options... But I have to say a knife maker's belt grinder is a deathtrap under the best of circumstances, most of them can't be OSHA approved for lack of adequate safety guards. (Yes there are belt grinders with guards that are used in industry like the Baldor, BurrKing, Wilton Square Wheel Grinder, and others, but most people don't buy those for use in a blacksmiths shop they are too expensive for most people to buy new, unless they are lucky enough to find one used for cheap...) But all belt grinders evaporate flesh even faster than they powder steel. That being said, you need to build it as well as you can, and try to build in as many safety features as is practical for you. A belt grinder is more versatile the less guards that are in the way, and the belt changing goes a ton quicker. BUT having belts explode in your face isn't fun at all, and contacting the belt or sometimes worse the edge of the belt can be painful and debilitating. You may think you can be careful enough, but who else might be in the shop with you who might get hurt? Having to build a guard box that you can still open and change/replace belts on your jackshaft arrangement, makes getting a 3 phase motor and a VFD with a dust proof enclosure a LOT more attractive... (Go ahead and buy the dustproof enclosure if the VFD can be ordered without one, it is much easier on you and on the VFD...;-) Variable speed makes a HUGE difference in what you can do with a belt grinder, if you JUST want to hog steel with a 24-36grit belt, you don't need variable speed, hard and fast will work fine. If you want to be able to use the full range of grits including the super fine 2000grit filament belt and the linen polishing belts you want the variable speed. Or if you want to "grind" wood, horn, or plastic you want to be able to crank the speed way down to reduce the heat build up. Edited March 5, 2015 by SJS Quote Link to comment Share on other sites More sharing options...
basher Posted March 6, 2015 Share Posted March 6, 2015 I see no problem with running a 5hp grinder. the only reason to go for less in my opinion is if you want to run the motor from a VFD with a single phaze input. I have grinders from 1.5hp to 4kw (5.5hp) Grinders defiantly work better with more power. Basic Industry minimum is 1hp per inch of belt width.perfect world would be something like the bader spacesavers and I think they are 5hp variable speed.its worth remembering that a lot of modern belts are designed to run fast for optimal removal of metal and belt life. Quote Link to comment Share on other sites More sharing options...
Dodge Posted March 6, 2015 Share Posted March 6, 2015 (edited) I'm with you, Basher. Just because you have the excess power doesn't mean you need to use it. But its there in the case you do need it. A 1725 rpm 5 hp doesn't turn any faster than a 1725 rpm 3/4hp after all. Maybe a bit of over-kill but if that's all ya had and you're on a budget. Kinda like a gas forge that gets "too hot" or a car that's "too fast" Turn it down, Son! Of course, You would probably disintegrate a belt and/or contact wheel before you ever bog it down, mind you YMMVScott Edited March 6, 2015 by Dodge Quote Link to comment Share on other sites More sharing options...
armymedic.2 Posted March 7, 2015 Author Share Posted March 7, 2015 thanks for the replies guys. i would have replied earlier but via mobile it keeps telling me fatal error when i try to go to log in.So I think the overwhelming majority say more vs less power, and i can roll with that. i'm hoping the treadmill is at least 1.5, but i won't know that till sunday morning. looks like worse case i'll be running pulleys off of a "free" 5 hp motor. not a bad spot to be in.SJS I know all too well what you mean about the grinders being death traps. i have lost many a meat chucnk to angle grinders and belt sanders already i will figure out gaurds that make sense, but i must say must of my mishaps have been where the metal meet the abrasive. push just a little too hard, lean just a little too bit. yada yada. I won't be running a vfd because i am on a budget ($400), so im hoping the treadmill control board gives me the flexibility i need, and if not ill be changing steps on the wheels. With some steel on hand, and a free to me motor plus wire laying around, I should come in just under, including the idler wheels for the platten attchment and one contact wheel. thanks for all of the constructive thoughts gents! Quote Link to comment Share on other sites More sharing options...
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