# hp for electric saw?



## Leroy in Kansas (Jul 20, 2008)

I'm building a modified version of the Logsol. I'm considering several options for powering the blade. Can anyone help with hp requirement for electric power? Also which speed motor would be best? Looks like the choices are 1750-3400 rpm. Is Direct drive a consideration? or is it going to be necessary to change speed with pulley's? So Many questions, This is a great bunch of guys. I've learned so much just by reading your response to questions ask. 
Thanks Leroy


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## weisyboy (Jul 21, 2008)

get the highest speed motor you can. and as bigger hores power as you can.

the power needed will depend on the length of bar. will it be 2 or 3 phase?


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## Backwood (Jul 21, 2008)

Hey Leroy, you never hear people complain about having to much motor. Not enough motor sucks though. I think the biggest motor you can use on single phase current is 10hp. A 10hp single phase motor will use somewhere in the ball park of 50 amps of 220 current. So you need to make sure you have that available. Also consider weight, my 10 hp weighs 140 pounds.
Not many people have 3 phase current but if you are lucky enough to have 3 phase the sky is the limit as far as hp is concerned. If you want something bigger than 10hp and only have single phase you could use a phase converter.
I dont know which motor speed would be better or if it would make a difference???? I do know you can change pulleys to get the speed you want.
I would think a belt would be a good idea incase something goes wrong the belt can slip.
I have never heard of 2 phase current??
Good luck


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## Leroy in Kansas (Jul 21, 2008)

*Some Pic's of the slide if I can get it right?*

This is what I've came up with so far. I have more pic's of details if your interested Leroy


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## slabmaster (Jul 21, 2008)

The hardest part is getting to the proper R.P.M. Electric motors don't have alot of rpm compared to a 2stroke engine.Some major gearing will be in order for it to work good.Mark


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## lmbeachy (Jul 21, 2008)

Obviously it will work, as Logosol sells an electric version of their mill, I forget what the horsepower is, but if you look on "logosol.com" you can find out.
BTW that is a real nice mill that you are making.


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## Mike Van (Jul 21, 2008)

Just for a ballpark figure, the older 1960's era Homelites ran 6000 rpm under load.


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## Marklambert61 (Jul 21, 2008)

*Ohm's Law*

Single phase electric motor's just are not going to make the grade just no torque....

Just ohm's law guys.

Also be careful with some Single phase to 3 phase converters they will run the motor but lousy performance.

Mark


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## woodshop (Jul 21, 2008)

Marklambert61 said:


> Single phase electric motor's just are not going to make the grade just no torque....
> 
> Just ohm's law guys.
> 
> ...



This discussion pops up here every so often... and as an electronics tech, I know just enough about this to get me in trouble, but I have to agree with the above. As he said, it's ohm's law, pure and simple. Power equels current (amps) times voltage, and power is what you need to pull a chain through hardwood. You just can't make a silk purse out of a sows ear, period. Milling takes lots of torque, raw low end power. Sure, you can configure a single phase motor to mill, but you better have a lot of patience, and how much will that thing bog down as soon as it has to really work hard, even if you gear it down. I'm sure under the right circumstances (like a power cord the size of a garden hose coming right from your 400 amp service in your house) you can mill with a huge single phase motor, but I think that lack of torque will get real old quick. But hey, if you're somewhere that you have to use electric, it might be the only horse in town.


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## Leroy in Kansas (Jul 22, 2008)

Well, sounds like electric isn't the way to go. Sooooooooooo the next option I have available would be the hydraulic power supply. I've found a vain motor that will turn in the 2600 rpm range and puts out around 20-26 hp. The cost is about what a lesser expensive saw will cost. Has anyone tried using hydraulic and what was the do and don't.


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## KiwiTony (Jul 23, 2008)

Your fabricating skills look pretty good to me.
Have you got any pics of the method you have chosen to adjust the log
height.?

One recurring thought I have got is of having the top rail adjustable from
the horizontal axis to the vertical.I know it is possible.

This way,I reckon you could do the top slab cut/s, then turn the rail & saw 90* , and do a vertical cut. Some simple method of moving the log inwards to the cutting head would be required though. Nothings impossible.


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## weisyboy (Jul 23, 2008)

just remember if using hydrolics yuo also ned a hydrolic pump and petrol/electric motor to run it.

i reckon the speed streight off the saw would be heaps the lucas/peterson sawmills have the chain driving streight off the petrol motor and an electric runs mutch faster that one of them.


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## Zodiac45 (Jul 23, 2008)

Nice looking work Leroy,

The electric motor that Logosol offers is a 3 phase 220V 30amp motor. They state it at 15hp with a phase converter. It runs a guide bar with the pmx chain they use and has an oiler system built on. It's about 70 lbs and big money at close too 6G.


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## Leroy in Kansas (Jul 23, 2008)

KiwiTony said:


> Your fabricating skills look pretty good to me.
> Have you got any pics of the method you have chosen to adjust the log
> height.?
> 
> ...



here are the pic's of the lift mech. It's rather simple to build. I used 1" sq. tube with a 1 1/2"x 1 1/2" angle for the slide mechanism. and the winch is a 5/8" cold roll round that sticks through holes on the angle. 

I haven't given much thought to an adjustable horizontal axis to the vertical. I'm sure there would be a way to do it. I'm sure one would certainly want some sort of wood on top of the lift mech. just to attempt to save a chain. 

Well I'm having difficulty with the attachments? Will see if I can post the pics seperate? Leroy


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## Leroy in Kansas (Jul 23, 2008)

*pic's of the lift mechanism.*

will try this again?


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## woodshop (Jul 23, 2008)

Very nice job Leroy... where are you when I need some serious welding done? Lots of talent on this forum, that's for sure. Can't wait to see this rig in action. What color are you going to paint it? I pic John Deere green. (or IH red if you're a Farmall guy)


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## Leroy in Kansas (Jul 23, 2008)

woodshop said:


> Very nice job Leroy... where are you when I need some serious welding done? Lots of talent on this forum, that's for sure. Can't wait to see this rig in action. What color are you going to paint it? I pic John Deere green. (or IH red if you're a Farmall guy)



How about neon green?


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## ttoberer (Aug 20, 2008)

leroy, how many amps do you have available? this seems to be the determining factor on wether electric is an option. you dont need that much hp to run a bandmill, but a chainsaw mill is going to take at least a 7.5 and probabaly a 10 hp three phase and bigger probably still better. rotary converters are nearly as good as the real thing. im also checking into variable frequency drives. I think im coming from a similar place. all the mills ive been designing in my head are electric. Ive been trying to work out what size generator id need to run a a 10 hp three phase to make portability a possibility.


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## Backwood (Aug 20, 2008)

ttoberer, If you are just going to use a 7.5 or a 10hp why bother with 3 phase? You can do either of those in single phase.

Leroy, I am hoping for some neon pictures.

I wish I had more power, I am using a 10hp ( with a piece of wire the size of a garden hose ) and wish I had more. If I went to a 20hp 3phase is there a way to make it varible speed? So I could maybe turn the dial down and slow or stop the Blade? Had a guy a while back told me I needed a DC motor for that ??? I dont know ther difference between AC and DC when it comes to this.


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## excess650 (Aug 21, 2008)

Has anyone tried a liquid cooled motorcycle engine?


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## ttoberer (Aug 21, 2008)

im going to use three phase because they are cheap. I picked up a 10 and a 15 for 150 bucks, both never used. there is a 15hp converter kit on ebay for a little more than $100. I figure the 15 can be an idler. I have to think a 10 hp three phase motor has at least as much muscle as a stihl 090, although I could be wrong on this. available power is my main limiting factor, so ill have to run some bigger wires.


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## ttoberer (Aug 21, 2008)

backwood, look at variable frequency drives for variable speed on three phase motors. ive seen some big ones on ebay for reasonable. what type of saw are you running?


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## Backwood (Aug 21, 2008)

I am running a homemade sawmill. I have 28" between the guides, but my 10hp saw dont really like cutting anything over 20". I would like to one day switch to a 20hp, figure then I could push it as fast as I wanted to.


Seems like a static converter ( the cheap kind ) will only give you 2/3rd's of your power so if you ran a 15 motor through a static converter you should get only 10hp worth out of it. 

If I had a variable frequency drive would I want to hook it to a 20hp AC or a 20Hp DC ? I was thinking a 20AC but somebody recently said I should use DC?


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## ttoberer (Aug 21, 2008)

im guessing when you say homemade mill, you mean some kind of bandmill.??? I have heard of people using 3 and 5 hp electrics on bandmills that size. it seems you may have some other problems going on here. on the diybandmill site, a guy uses a 220v 5 hp compresser motor from harbor freight on a mill larger than yours with little difficulty..he has a youtube video, check it out http://www.youtube.com/user/67fastback428 . they make vfds for single and 3 phase motors, dc motors use controllers. both allow variable speed. with a static converter say a 15 hp one, you would get about 10 hp if using it to do the work. it would also be really hard on the motor, but if you wire in the 15 as an idler, you have a rotary converter which will clean up the third leg and you get much cleaner 3 phase. if you have the patience you can balance out the voltage with capaciters to generate almost perfect three phase. 2 phase is just another way of saying 220v... the problem with using dc motors is the need to rectify the direct current to alternating current, or you could build a huge battery bank and charge it off solar panels and run the dc motor off of that.( wish I could afford that!) they make some aftermarket golf cart motors that seem well suited for the task. search stealth stalker. if you can pull it off electric is the way to go in my opinion.


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## Backwood (Aug 23, 2008)

ttoberer said:


> im guessing when you say homemade mill, you mean some kind of bandmill.??? I have heard of people using 3 and 5 hp electrics on bandmills that size. it seems you may have some other problems going on here. on the diybandmill site, a guy uses a 220v 5 hp compresser motor from harbor freight on a mill larger than yours with little difficulty .



My mill is the same size as woodmizers big mills? 28" between the guides. ( for this size saw woodmizer uses a 25hp electric ) And I like to use the chainsawmill to whittle big trees down to where they will fit on the mill and cut wide stuff. IMO a 5hp compressor duty motor is not enough to cut 28" wide white oak. it would take forever. I imagine some people like riding mopeds though.


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## ttoberer (Aug 23, 2008)

I agree, its almost ridiculous to think of that little motor on that saw. I think hes burned one up also. my point was only that it does work. I think a 10 hp 3 phase should be plenty, not sure about single phase. I looked at the woodmizer page and the LT 15 which has a 28" cutting max. it comes with 10hp single or 3 phase electric, 10 hp diesel, 15 or 25hp gas. id be interested in seeing a picture of your mill if you get a chance. did you follow a set of plans? Tim


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## Backwood (Aug 24, 2008)

I dont think a compressor duty motor is made to run for long periods of time , make sure you get a continous duty motor that will hold up.
There is a difference between log capicity and distance between guides. Seems like the l-15 only has @ 23" between guides but saw will handle 28" diameter logs. L-40 has 28" between guides and 36" log 
I ordered a couple sets of plans from ebay , looked them over then built a saw. Didnt actually follow plans, they just gave ideas.


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## dallasm1 (Aug 25, 2008)

Keep in mind if you are going to use a Variable Frequency drive to convert single phase to three phase, the VFD must be rated for TWICE the HP of the final motor. If you have a 3ph, 10hp motor, you will need a VFD rated at 20hp. You might also consider using reluctors at this size to prolong the life of the motor. Reluctors are large inductors used to soften the output pulse.VERY expensive proposition at this size of motor.


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## Mike Van (Aug 26, 2008)

I run a 10 hp three phase on my bandmill, no converter, true 3 phase. It gets the job done - 4800 fpm on the blade. I was up at 5400 fpm, slowed it down & it worked better. I have a 15 hp I'd like to put on it, but it won't fit in the frame, and I'm not going to cut it apart at this point.


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## Backwood (Aug 26, 2008)

I didnt realize band speed would make a real difference. I just guessed on pulley sizes when building my mill and recently I found out my band speed is 7700. I will try slowing it down. Thanks Mike


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## ttoberer (Aug 27, 2008)

what size pulleys are you running to get these speeds? what is the motor speed?


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## ttoberer (Aug 27, 2008)

found this, so this would only run a 5hp motor? the ratings on these things are confusing! seems they got them with the wrong voltage. http://cgi.ebay.com/Trane-Dan-Foss-...39:1|66:3|65:12|240:1318&_trksid=p3286.c0.m14


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## dallasm1 (Aug 27, 2008)

ttoberer said:


> found this, so this would only run a 5hp motor? the ratings on these things are confusing! seems they got them with the wrong voltage. http://cgi.ebay.com/Trane-Dan-Foss-...39:1|66:3|65:12|240:1318&_trksid=p3286.c0.m14



Yes, this would run a 5hp 3phase motor from a single phase 240 volt source.


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## ttoberer (Aug 27, 2008)

some of them I looked at specifically state that they will run any motor up to the hp they are listed at. others dont say what size motor they will run. it seems strange they would call it a 10 hp drive if it only ran 5... I have read many conflicting descriptions of what size idler motor you need when running a rotary converter also. some say the idler must be the same size as the motor run, others say it must at least be 2 times as big. seems to be some confusion around this subject.:bang:


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## Mike Van (Aug 28, 2008)

Just off the top of my head, the motor's 1730 rpm, about a 6 1/2" pulley on it driving a 14 1/2" one, the bandwheels are 24" dia.


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## dallasm1 (Aug 28, 2008)

It is a rule of thumb in the field. The units documentation will indicate the exact load rating for a single phase input. The unit will indeed power a 10hp 3 phase motor from a 3 phase source and provide Variable Frequency (Speed Control). When used as a phase converter it has to be derated as all of the three phase load is now spread over only two input phases. The same energy is flowing through only two wires instead of three. The exact derating would be indicated by the manufacturer.


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## Backwood (Aug 28, 2008)

ttoberer said:


> what size pulleys are you running to get these speeds? what is the motor speed?



Try this http://www.##################/members/donp/bandspeedcalc.htm

Well for some reason I dont think this link is working ??? Ok here is what I have. 8" pulley, 1740rpm, 10" pulley, 21" bandwheels, gives 7652 feet per min.


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