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Longer belts and 2nd idler for G0602???

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Mark Stonich

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Sep 24, 2016
Has anyone tried longer belts and a 2nd idler for the high speed belt? My belts, 800mm (31.5") & 686mm, (27.0") are so tight that I need tire levers to move them from pulley to pulley. They snap into place with a loud BANG! At least I doubt they will slip :adore: 1/2" longer belts are available, which should make changing them much easier.

I've seen Fabrikator's quick change setup, with one relocated idler. http://www.projectsinmetal.com/forum/general-discussion/diary-of-a-new-g0602/ If it didn't work well, he wouldn't have posted it. But I'm somewhat OCD about stuff like this and feel idlers should always be pushing inward for more belt to pulley contact. And that they should be on the return run, not the tensioned side.

I have all the materials I'd need to build such an idler on hand, including suitable bearings. It seems like a good 2nd project, after a reverse tumbler.


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Jan 29, 2017
If they are that tight, lengthen them by one inch. You should have sufficient adjustment to absorb that. Try a metric belt, which is what should have come with the lathe. There may be one in between imperial sizes. Also, if you have that much tension, what's happening to your spindle bearings? Too much tension creates alot of friction in your outboard bearing. If this gets too hot then heat transfer will lengthen your spindle a minute amount and all of a sudden your finish will suffer. I'd be checking temperatures between them just in case.
I had a look at the link you posted and what Fabrickator has done is still feasible. I reckon he was annoyed at the lack of belt adjustment when in high speed mode, that's why he shifted his tensioner.
You can't keep a good man down I say.

"feel idlers should always be pushing inward for more belt to pulley contact" - agree with you here, thats standard power transmission practice.

"And that they should be on the return run, not the tensioned side." - agreed again, but not too tight, just enough to stop slapping and maintain tension. Remember, centrifugal force throws a belt out at speed and if slightly loose, slaps about. This tells us it is slightly undertensioned. Another place you'll see this is on a multibelt pulley where the belts are not matched.

I've just checked my G0602, and i have the same belts except now I only use the 686 because I have variable speed drive. I still use the idler that drives the spindle. Note my belt tensioner, its above the belt taking up any slack by guiding it in, between the pulleys. Yours should be the same.
As I have variable speed, when in normal rotation during turning, the tensioner is on the return leg but when I choose reverse its on the drive leg of the belt. Unfortunately I have to leave it as is, but I see it as a positive because I'm not always running in reverse. Also, my belt tension is such that I can still push the lower leg in about 10mm (3/8") by finger. I have no issues with bearing temps.

Upper drive pulleys.jpg
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