My pitch is off...
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My pitch is off...
I just recently got my lathe going, and I have tried a couple of cuts. I am having a issue of the pitch being slightly off during playback on another record player. I just had my motor rebuilt could this be the issue, or do I need to look at the idler wheels? Its seems to be just a few cents off of pitch(slower).
Hi,
The idlers have no effect on speed. If you are correct that its only off by a few cents, you are being way too picky. That's very accurate for a lathe of this type. Assuming the speed is off more than say 25 cents (about 1%), I would first look to see if there is a mechnical adjustment to set the pressure of the motor shaft to the idler. If this is set too high it will slow the motor down. There is usually some way to move the motor and or idler by loosening some screws and sliding the motor in relation to the idler. You want only enough pressure to avoid slippage, but not so much as to increase the loading. The adjustment should be detailed in the service manual for the lathe.
If that's not the problem, you would need to use a strobe to check the shaft speed of the re-built motor. If that is the problem, you will have to either change the shaft diameter by having something custom made, or use a variable freq drive with the motor so that you can run it at a line freq that is other than 60hz.
Mark
The idlers have no effect on speed. If you are correct that its only off by a few cents, you are being way too picky. That's very accurate for a lathe of this type. Assuming the speed is off more than say 25 cents (about 1%), I would first look to see if there is a mechnical adjustment to set the pressure of the motor shaft to the idler. If this is set too high it will slow the motor down. There is usually some way to move the motor and or idler by loosening some screws and sliding the motor in relation to the idler. You want only enough pressure to avoid slippage, but not so much as to increase the loading. The adjustment should be detailed in the service manual for the lathe.
If that's not the problem, you would need to use a strobe to check the shaft speed of the re-built motor. If that is the problem, you will have to either change the shaft diameter by having something custom made, or use a variable freq drive with the motor so that you can run it at a line freq that is other than 60hz.
Mark
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cuttercollector
- Posts: 431
- Joined: Sun Jun 11, 2006 4:49 pm
- Location: San Jose, CA
Re: My pitch is off...
Obviously, don't forget to check the player you are comparing with with a strobe also. Perhaps they are both slightly off.monoplex wrote:I just recently got my lathe going, and I have tried a couple of cuts. I am having a issue of the pitch being slightly off during playback on another record player. I just had my motor rebuilt could this be the issue, or do I need to look at the idler wheels? Its seems to be just a few cents off of pitch(slower).
Analog is not like digital in that respect. Always close - never perfect.
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aussie cutter
- Posts: 67
- Joined: Thu Sep 18, 2008 9:51 pm
hi there,
I seem to have a similar pitch problem to you and maybe your problem is the same... The pitch problem on mine seems to stem from the physical weight of the lathe and cutterhead creating a liitle drag while cutting...
I'm using a Stanton STR8-150 turntable to drive my lathe, it has 5kg torque which is supposed to be the strongest availble on the market
(technics sl1200 has only 1.5kg)
i speed up the turntable to while cutting to compensate for the drag and then set back to 0 for playback the problem's solved
I seem to have a similar pitch problem to you and maybe your problem is the same... The pitch problem on mine seems to stem from the physical weight of the lathe and cutterhead creating a liitle drag while cutting...
I'm using a Stanton STR8-150 turntable to drive my lathe, it has 5kg torque which is supposed to be the strongest availble on the market
(technics sl1200 has only 1.5kg)
i speed up the turntable to while cutting to compensate for the drag and then set back to 0 for playback the problem's solved