coozer
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 posted on 19/6/12 at 05:37 PM |
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Which electric motor?
I'm after a 3hp motor and Machine Mart list two...
One is 2 pole and the other is 4 pole. What I need to know is the difference in this? I know 4 pole goes at 1500rpm and the 2 pole at 3000rpm, but,
what exactly does this mean? Is one more reliable, better duty cycle??
Want to build a saw and need the blade to go round about 4500rpm.. so a 4" pulley on the motor, 2.5" on the arbor...
Any thoughts electrical boffins??
Ta,
Steve
1972 V8 Jago
1980 Z750
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iank
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| posted on 19/6/12 at 06:09 PM |
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Neither have a commutator so should be reliable.
speed=(120 x freq)/no. of poles where freq is 50Hz in the UK.
So the 4 pole will have double the torque of the 2 pole assuming they have the same power rating.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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rf900rush
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| posted on 19/6/12 at 07:51 PM |
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As you state 4 pole 1500rpm 1400 rpm in real terms and 2 pole 3000rpm (2800 rpm).
If you use pulleys to drive your blade at 4500rpm both will be the same.
The main difference will be the pulley sizes.
On important thing, is the smaller the (blade) shaft pulley to deeper cut you can make.
My father has made 2 diy bench saws and I fairly sure both were 2 pole.
Just remember these machines must be used with care.
Seen a 6mmx6mm piece come off the blade and put half way through a fire door. 
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coozer
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| posted on 19/6/12 at 08:08 PM |
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quote:
Originally posted by rf900rush
As you state 4 pole 1500rpm 1400 rpm in real terms and 2 pole 3000rpm (2800 rpm).
If you use pulleys to drive your blade at 4500rpm both will be the same.
The main difference will be the pulley sizes.
On important thing, is the smaller the (blade) shaft pulley to deeper cut you can make.
My father has made 2 diy bench saws and I fairly sure both were 2 pole.
Just remember these machines must be used with care.
Seen a 6mmx6mm piece come off the blade and put half way through a fire door.
Its basically a rip saw to tear up pallets for the fire, more or less 1/2" by 4" planks, the occasional bit of 2x4..
1972 V8 Jago
1980 Z750
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I predict a Riot
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| posted on 19/6/12 at 09:18 PM |
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If you just want a basic set up I would go for a four pole on a DOL (direct on line starter) for the extra torque. There are a lot of knots and nails
in that type of wood.
If you can afford it use an inverter as your motor controller that gives you the option to tune the motor and can provide motor braking.
Don't forget to wire in some type of volt free relay or E stop.
A word of caution if you are wanting to use this pallet type wood in a log burner, lots of manufacturers don't recommend its use, don't
know why though.
"Honesty is a very expensive gift. Do not expect it from cheap people ". Warren Buffet on Expectation
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coozer
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| posted on 19/6/12 at 10:11 PM |
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quote:
Originally posted by I predict a Riot
A word of caution if you are wanting to use this pallet type wood in a log burner, lots of manufacturers don't recommend its use, don't
know why though.
Yes, I know why, my installer said not to use pallets.. the reason being they cost money to produce, are designed for re-use and its not ethical to
burn them.. however I couldn't give a monkeys about the 'environment' and where I work throw them out, and then they rely on me and
another bloke to take them away to avoid disposal costs. So, we both win
Oh, and the installer broke the pallet up to test the fire to make sure it burned ok with no leaks in the chimney.....
1972 V8 Jago
1980 Z750
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dmac
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| posted on 19/6/12 at 10:16 PM |
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Pallet wood is full of nails which will jam in your grate and are a real pain to remove.
Duncan
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coozer
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| posted on 19/6/12 at 10:19 PM |
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Dont worry about the nails chaps, I've been burning this stuff for 2 years now and as you say there are more nails than ash.. however, she
doesn't complain about lifting them out as the heat is free!
1972 V8 Jago
1980 Z750
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daviep
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| posted on 19/6/12 at 10:35 PM |
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quote:
Originally posted by coozer
Dont worry about the nails chaps, I've been burning this stuff for 2 years now and as you say there are more nails than ash.. however, she
doesn't complain about lifting them out as the heat is free!
You have to love free wood 
Keep us posted on how the saw performs, I'm in the same boat but I currently use a small electric chainsaw to "reduce" pallets,
I'm always on the look out for a more effective method.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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