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Thread: Number of belts vs hp

  1. #16
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    Josko, If the wiring was not upgraded to match the night motor, that may be why it still bogs down.


    John

  2. #17
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    Quote Originally Posted by John McClanahan View Post
    Josko, If the wiring was not upgraded to match the night motor, that may be why it still bogs down.


    John
    We did bog it down taking off 3/16" of 8" wide black locust. Seller wanted to show me what it could do. The motor slowed down, but the belt did not slip. Wiring seems to be 12ga throughout. Based on this thread, I plan to leave it as is. Still, as Ole noted, why are manufacturers now putting multiple belts on 3 hp machines?
    Last edited by Josko Catipovic; 10-17-2018 at 12:58 PM.

  3. #18
    dont know the jointer. An 8" jointer is still in toy land. (some brands exception) To take a very hard wood then take a pass of 3/16" deep on that machine is not to bright. I changed out the motor from the 1 1/2 Hp recmmended when I got a new general 8" jointer eons ago to 2 HP Leeson farm duty. PUt a piece of hard maple 8" wide and take a third as much off and it was still gutless.

  4. #19
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    Torque rating of a v-belt drive is based on the size of the drive sheave, driven sheave, center distance of the drive and belt being used. Cogged belts transmit more HP than the smooth versions and can be an easy fix, but they have their limit. Send me the info and I would be glad to check for you. Brian
    Last edited by Brian Runau; 10-17-2018 at 12:52 PM.

  5. #20
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    So, with 3 HP 1725 rpm motor, 6" pulley at the motor, 2 1/4" pulley at the cutterhead, do I deliver more power to the cutterhead with one A-size belt or two?

  6. #21
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    Quote Originally Posted by Josko Catipovic View Post
    So, with 3 HP 1725 rpm motor, 6" pulley at the motor, 2 1/4" pulley at the cutterhead, do I deliver more power to the cutterhead with one A-size belt or two?
    What is the center distance between the two shafts of the drive?

    Thanks.

    Brian

  7. #22
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    20" between shaft centers

  8. #23
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    I have the exact same jonter and mine came with a 1h.p. baldor motor. I thought it was a bit light and then decided to try for a while. It has worked fine for the last five years.Recently ...upgraded to a 16'' paoloni with a 5.5 h.p. and it is definitely more power. Maybe I just did not know what I was missing.Mike.

  9. #24
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    Quote Originally Posted by Josko Catipovic View Post
    20" between shaft centers
    Josko, sorry for the delay. I've been looking for my software program, too lazy to do it long hand. torque(ft lbs)=hp x 5252/rpm 3HP MOTOR HAS 9FT lbs of torque. You have a 2.67 ratio speed up drive. So at the driven speed of the 2.25" dia pulley you have a speed of 4672 rpm. Torque at the driven pulley is t=3x5252/4672 net is 3.37 ft lbs of torque. 3ft lbs/hp is the rule so you are delivering @ 1.123 HP at the cutter head.

    Let's say you changed the 2.25" pulley to a 6" to make it a 1:1 ratio drive. The A belt could deliver up to 7.42 HP with a single groove set up. Don't know what the original design cutter head sped should be, but I wonder if whoever put he 3HP motor on it changed the driven pulley size to speed up the cutter head.

    Thanks.

    Brian
    Last edited by Brian Runau; 10-25-2018 at 12:41 PM.

  10. #25
    Quote Originally Posted by Ole Anderson View Post
    So now I am wondering why they put triple belts on 3 hp table saws?
    When Delta designed the Unisaw back in the thirties, there were only cotton core belts. By using three belts, power transmission was reliable. Today's belts with synthetic cores can handle much greater loads. That's why you have a single serpentine belt to drive all the accessories on your car. PM only uses two belts on the PM 66 which could be had with a 5 HP motor

  11. #26
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    Quote Originally Posted by Brian Runau View Post
    Josko, sorry for the delay. I've been looking for my software program, too lazy to do it long hand. torque(ft lbs)=hp x 5252/rpm 3HP MOTOR HAS 9FT lbs of torque. You have a 2.67 ratio speed up drive. So at the driven speed of the 2.25" dia pulley you have a speed of 4672 rpm. Torque at the driven pulley is t=3x5252/4672 net is 3.37 ft lbs of torque. 3ft lbs/hp is the rule so you are delivering @ 1.123 HP at the cutter head.

    Let's say you changed the 2.25" pulley to a 6" to make it a 1:1 ratio drive. The A belt could deliver up to 7.42 HP with a single groove set up. Don't know what the original design cutter head sped should be, but I wonder if whoever put he 3HP motor on it changed the driven pulley size to speed up the cutter head.

    Thanks.

    Brian
    Thanks much Brian,

    I'm trying to follow your math but could use a bit of help: if the motor is generating 3 HP but only 1.123 HP is delivered to the cutterhead, where does the rest of the power go? If it's dissipated in the belt, that's almost 1.4 KW of heat generated in the belt, so it would surely melt before long. Does this mean that if i upgrade to two belts, I can deliver 2.246 HP to the cutterhead? Does this number (1.123) have anything to do with the pulley ratio? Thanks in advance.
    Last edited by Josko Catipovic; 10-29-2018 at 9:42 AM.

  12. #27
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    Quote Originally Posted by Josko Catipovic View Post
    Thanks much Brian,

    I'm trying to follow your math but could use a bit of help: if the motor is generating 3 HP but only 1.123 HP is delivered to the cutterhead, where does the rest of the power go? If it's dissipated in the belt, that's almost 1.4 KW of heat generated in the belt, so it would surely melt before long. Does this mean that if i upgrade to two belts, I can deliver 2.246 HP to the cutterhead? Does this number (1.123) have anything to do with the pulley ratio? Thanks in advance.
    Hi, your torque is 3.37 pound-feet at 4672 RPM as per the above.

    That's 3 HP, not 1.123 HP.

    3 pound-feet per HP is an approximation that only works at 1,800 RPM...................Rod.

  13. #28
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    Rod, thanks let me review on my end. I really did want to do this long hand!

    Thanks.

    Brian
    Last edited by Brian Runau; 10-30-2018 at 1:00 PM.

  14. #29
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    Coming in late and haven't read the whole thread, but thought I'd add that I have a big compressor that's supposedly pulling 5 hp at 3450 rpm on drive sheave through one belt...I'm sure it must be a "B" belt...

    @Brian Runau - Are you an ME? I'm getting ready to build a bandsaw mill and was curious whether I could get 22 hp through a single B belt with maybe a 4" drive sheave and 18" driven sheave...I found some tables online but I'll be darned if I can figure out how to read them...times like this I wish I had studied ME as planned, and dad ain't around to ask anymore...
    Last edited by Jacob Reverb; 10-30-2018 at 5:23 PM.

  15. #30
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    Rod:

    yes my thought to convert ft lbs to HP at the higher rpm is incorrect. The match of 3.37ft lbs of torque at the cutter head is correct though. So this drive is delivering @ 1/3 the force in torque that the motor generates.

    Thanks.

    Brian

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