Importance of Belt Tension

mksj said:
Use of linked belts does help in some cases, but technically they are not bidirectional per the manufactures recommendation. They were originally designed as temporary belts. Harmonics and vibration nodes can be more of a problem with VFDs because there is always some harmonic frequency point for every system, one reason why VFDs are designed with skip frequency bands so one can bypasses those frequency ranges. The 1340GT always seemed to be a bit more sustainable to some excitation frequency, partly because it is "relatively" light weight wise, sits on a tall cabinet, and has a high center of gravity. Small weight imbalances in the chuck can also cause problems. Belt tension is just one factor in the equation, along with better quality belts (that are more uniform in dimensions and less likely to take a set) that individuals need to evaluated. Tighter is not always better, but I also reacall a 1440GT owner complaining the spindle speed was dropping when he was cutting, and his belts were too loose. So the porridge needs to be just right, not too hot and not too cold.
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Is there a particular brand of belts that you find to be of better quality?

Thanks

Howardd
 
I have been using the Gates Tri-Power belts, used them in various lathes. They are notched belts so fit well around pulleys and so forth. I had one for 5 years on my last lathe and showed almost no wear or rubber coming off on the belt cover vs. the stock which was terrible. Gates Tri-Power belts are also commonly used in automotive applications. Be aware that the belt size are not interchangeable between brands, you need to measure the outside circumference and match to the belt specifications for the particular brand/type. I already made that mistake a few times. If multiple belts, higher quality ones should have closer tolerances from belt to belt so more even tension between belts.

Mark
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Dual belts, the motor pulley is quite small. Standard belts tend to take a set, so you can get more thumping, vibration.
290853
 
mksj said:
Use of linked belts does help in some cases, but technically they are not bidirectional per the manufactures recommendation. They were originally designed as temporary belts. Harmonics and vibration nodes can be more of a problem with VFDs because there is always some harmonic frequency point for every system, one reason why VFDs are designed with skip frequency bands so one can bypasses those frequency ranges. The 1340GT always seemed to be a bit more sustainable to some excitation frequency, partly because it is "relatively" light weight wise, sits on a tall cabinet, and has a high center of gravity. Small weight imbalances in the chuck can also cause problems. Belt tension is just one factor in the equation, along with better quality belts (that are more uniform in dimensions and less likely to take a set) that individuals need to evaluated. Tighter is not always better, but I also reacall a 1440GT owner complaining the spindle speed was dropping when he was cutting, and his belts were too loose. So the porridge needs to be just right, not too hot and not too cold.
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I recently 'discovered' the two belts I bought shortly after buying my 1340GT and decided to replace the link belt that I've been running for years with one.

On a couple of occasions, I'd get ready to use the lathe and turn the chuck slightly to get the pinion on top, only to have the chuck try to move back to where it was. Apparently, the belt can develop a 'memory' and I'm not sure I like that. I'm seriously thinking about going back to the link belt because I've never experienced that phenomenon using that belt, and I can't remember the last time I cut in reverse. :)
 
wrmiller said:
I recently 'discovered' the two belts I bought shortly after buying my 1340GT and decided to replace the link belt that I've been running for years with one.

On a couple of occasions, I'd get ready to use the lathe and turn the chuck slightly to get the pinion on top, only to have the chuck try to move back to where it was. Apparently, the belt can develop a 'memory' and I'm not sure I like that. I'm seriously thinking about going back to the link belt because I've never experienced that phenomenon using that belt, and I can't remember the last time I cut in reverse. :)
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I can relate. When I got my lathe the stock belts had already developed memory. Also due to the stock 1 phase motor, at certain RPMs when facing aluminum I would get harmonics leaving a swirl pattern finish. Loosening the belts helped. After switching to the Fenner Power Twist link belts the swirl pattern completely went away. I do cut in reverse sometimes & never had a problem but it's never heavy cuts. The twist belts are just a bit noisier in reverse, I don't mind.
 
I'd not heard of the Fenner belts, so I'll check them out.

Oh...which belt profile would I need? Thanks. :)
 
We also use Fenner Power Twist on much of our equipment. Lathes and mills, forward or reverse has never been an issue. No belt set and reduced vibrations and you don’t have to take the spindles apart to change a belt!
 
wrmiller said:
I'd not heard of the Fenner belts, so I'll check them out.

Oh...which belt profile would I need? Thanks. :)
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The red colored Fenner belts are the only link belts I'm aware of. I'm sure there has to be other brands but the Fenner brand is the one I thought is most common? Fenner makes different styles, Power Twist is the model I'm using. They're sold in common belt profiles, I forget but I think I'm running A/4L on my lathe. I'm also running one on my air compressor (air compressor didn't benefit from it, I just needed a slightly longer belt).

Edit: My mistake, I just remembered HF used to sell green link belts but only in one profile. I believe those green belts were good too, made in the USA.
 
The Fenner site shows blue belts now. :)

They have 3v, 5v, spa, spb, and spz. I assume this is the width of the belt?
 
I have a green link belt. Must have bought it from HF right after buying the lathe. It's worked great so far, so I'll just put that one back on for now.
 
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