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ROJEK SH1 MA lathe

R

Roy Ward

Joined
Jan 26, 2013
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Location
Ingolf Ontario Canada
I have a ROJEK SH1 MA copying wood turning lathe which was acquired used without any documentation. I need to replace the drive belt but I suspect the belt that was on it is not the right size as it did not run properly. The belt would flip over on its side as if it was too wide for the "V" grove on the pulley. Does anyone else have this lathe and if so could please let me know what "V" belt you are using.
 
There's not that many sizes of V-belts.
3L - likely too small for that machine.
4L - very common at automotive suppliers and the most used variety
5L - also easily available, but not that common on lathes.

Check your existing belts for any printing, which should have designations like these along with the length, either in inches or cm.
If not, these are cheap and easy to get. Buy a 4L and 5L, see which fits that gap. Bring the other back. Most stores are good about that.

I've had issue like you describe. It was a 5L belt on a 4L wheel

Then figure out the length.
 
Last edited:
Roy Ward said:
I have a ROJEK SH1 MA copying wood turning lathe which was acquired used without any documentation. I need to replace the drive belt but I suspect the belt that was on it is not the right size as it did not run properly. The belt would flip over on its side as if it was too wide for the "V" grove on the pulley. Does anyone else have this lathe and if so could please let me know what "V" belt you are using.
Click to expand...

There are not that many different V-belt cross sections and the belt that is on the lathe may be the right size. Measure the width at the inside top of the groove, the width at the bottom of the groove, and the depth of the groove. The width at the top of the groove is the most important. Search for a belt that is just a hair smaller than the width at the top of the groove. The height of the belt must be less than the depth of the groove. If there is a size printed on the belt, compare that to your measurements. There are numerous sources on the web that give the dimensions of belt cross sections.

There are several possible problems that can cause a belt to flip:
  • Belts run on their sidewalls -- NOT the bottom of the groove. If a belt is worn to the point that it starts running in the bottom of the groove. it can flip. Even if it doesn't flip, it will begin to slip and overheat the pulley and that can damage the pulley especially if it is an aluminum or zinc pulley.
  • Some things that cause a belt to wear out with the possibility of flipping include.
    • A belt can wear out from ozone cracking which causes it to get hard.
    • If a belt has been over tensioned that can cause fiber breaking
    • If a belt has been under tensioned that can cause slipping, heating, and accelerated wear.
    • If the pulleys are misaligned that can cause asymmetrical wear that can lead to flipping.
    • Continuing to use a belt past its normal end of life wearout can lead to flipping.
  • Pulleys can wear out. Improperly tensioned belts can accelerate this wear. Running the proper size belt in a worn out pulley can cause the belt to flip even if the belt is in perfect shape.
  • Misaligned pulleys can also cause a belt to flip.
  • A very long belt can lead to lateral whip and cause it to flip.
 
Bill Boehme said:
There are not that many different V-belt cross sections and the belt that is on the lathe may be the right size. Measure the width at the inside top of the groove, the width at the bottom of the groove, and the depth of the groove. The width at the top of the groove is the most important. Search for a belt that is just a hair smaller than the width at the top of the groove. The height of the belt must be less than the depth of the groove. If there is a size printed on the belt, compare that to your measurements. There are numerous sources on the web that give the dimensions of belt cross sections.

There are several possible problems that can cause a belt to flip:
  • Belts run on their sidewalls -- NOT the bottom of the groove. If a belt is worn to the point that it starts running in the bottom of the groove. it can flip. Even if it doesn't flip, it will begin to slip and overheat the pulley and that can damage the pulley especially if it is an aluminum or zinc pulley.
  • Some things that cause a belt to wear out with the possibility of flipping include.
    • A belt can wear out from ozone cracking which causes it to get hard.
    • If a belt has been over tensioned that can cause fiber breaking
    • If a belt has been under tensioned that can cause slipping, heating, and accelerated wear.
    • If the pulleys are misaligned that can cause asymmetrical wear that can lead to flipping.
    • Continuing to use a belt past its normal end of life wearout can lead to flipping.
  • Pulleys can wear out. Improperly tensioned belts can accelerate this wear. Running the proper size belt in a worn out pulley can cause the belt to flip even if the belt is in perfect shape.
  • Misaligned pulleys can also cause a belt to flip.
  • A very long belt can lead to lateral whip and cause it to flip.
Click to expand...
Thanks Bill. I have been advised by ROJEK that my lathe uses an "O" type 1250mm drive belt. Unfortunately nobody seems to have "O" type belts. Have you ever heard of an "O" type belt?
 
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