South Bend 9 Motor Pulley And Belt Hot

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mordamer

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After getting my new to me South Bend 9a set up in my shop I have been going over it thoroughly. This is an underdrive 9a with the countershaft assembly in the cabinet below the headstock.

Going over it I noticed the V-Belt from the motor pulley to the countershaft was causing a bad vibration because of a damaged spot on the belt. I took that belt off and got one that very closely matched from the auto parts store. I installed it at a tension that felt about right and ran the lathe for a minute or two. I then felt the belt and it was warmer than I would have expected for that short of run time. I then felt the motor pulley and it was too hot to keep my finger on for more than a second or two. I re-adjusted the tension tighter because I assumed the belt was slipping. Same issue. I have the belt pretty tight now. If I pull or push on the belt I can only move it about 3/4" between the pulleys. The motor shaft is not hot and the motor bearings are not even warm. The countershaft pulley and bearings are not warm. This lathe is very difficult to adjust belt tension on and I cannot figure out what is causing it to get so hot. No belt squeaks at all.

Please instruct me on the proper technique for setting correct tension on this machine.
 
mordamer said:
After getting my new to me South Bend 9a set up in my shop I have been going over it thoroughly. This is an underdrive 9a with the countershaft assembly in the cabinet below the headstock.

Going over it I noticed the V-Belt from the motor pulley to the countershaft was causing a bad vibration because of a damaged spot on the belt. I took that belt off and got one that very closely matched from the auto parts store. I installed it at a tension that felt about right and ran the lathe for a minute or two. I then felt the belt and it was warmer than I would have expected for that short of run time. I then felt the motor pulley and it was too hot to keep my finger on for more than a second or two. I re-adjusted the tension tighter because I assumed the belt was slipping. Same issue. I have the belt pretty tight now. If I pull or push on the belt I can only move it about 3/4" between the pulleys. The motor shaft is not hot and the motor bearings are not even warm. The countershaft pulley and bearings are not warm. This lathe is very difficult to adjust belt tension on and I cannot figure out what is causing it to get so hot. No belt squeaks at all.

Please instruct me on the proper technique for setting correct tension on this machine.
Click to expand...

You need to get the right belt for it automotive belts have different widths and angle to the vee portion of the belt.
 
Take the belt off and run the motor. Is the pulley hot? This would isolate if the issue is with the motor (possibly bad bearings) or the belt.
 
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The belt is too tight. And yes a automotive is probably not the correct one to use. The original SBL belt is a 5L section belt. The last one I bought came from Tractor Supply.

Sent from my SAMSUNG-SM-G920A using Tapatalk
 
4gsr said:
The belt is too tight. And yes a automotive is probably not the correct one to use. The original SBL belt is a 5L section belt. The last one I bought came from Tractor Supply.

Sent from my SAMSUNG-SM-G920A using Tapatalk
Click to expand...

You were correct. I found the section in "How to Run a Lathe" on tensioning this belt. It says to have 1" of movement between the pulleys. I went and actually measured how much I could move it and I could only move it 1/4". I tensioned it to where I could move it a full 1 inch and it feels pretty loose, but works great. Ran it for about the same time as before and the belt and pulley were both just barely warm. The belt may not be an exact match, but I'll run it for now and monitor it. Thank you for your help.
 
I just got a vintage South Bend 9 I think it's an A ,Flat belts with the motor and pulleys behind the lathe. I'm still getting it setup, but the old belt it came with was flat leather with the ends wired together usable to test at purchase but cracked.

My question is, I found a supplier on ebay of leather flat belts should just measure the length and order it or is there an other type or material I should get?
 
Assume you are referring to the belt that drives the cone pulleys, not the motor? If so, try one of the new link belts, sold at Harbor freight, or purchased on line. Seems to be the go-to upgrade to replace flat belts. These are commonly used as drive belts on new machines.

Gpb

Edit- see post below. Yep, can't use link belts as a replacement for old flat belts. I was mistaken about some advice I got regarding rebuilding my old Dalton lathe - set me on the right path with the Dalton as well. Thanks Andre!

Gpb.
 
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I like the flat leather belts because they slip. I have them on two SB 9s and a small horizontal milling machine. I'd rather the belt slip than I damage a tool or part when (not if) I make a mistake.

I got a tool like this off of ebay:

s-l500.jpg

And I ordered some of the clips and stays like these:

http://emurdock.com/532to316156to187beltthickness.aspx


I also discovered it was less expensive to order an XXXL fat guy belt than to order an industrial belt. I just have to scuff up the side that rides on the pulleys.

The pin system makes it easy to install them without having to remove anything.
 
outoftimedreamer said:
I just got a vintage South Bend 9 I think it's an A ,Flat belts with the motor and pulleys behind the lathe. I'm still getting it setup, but the old belt it came with was flat leather with the ends wired together usable to test at purchase but cracked.

My question is, I found a supplier on ebay of leather flat belts should just measure the length and order it or is there an other type or material I should get?
Click to expand...


It is really pretty easy to pull the spindle and the countershaft and put an automotive serpentine belt (uncut) on your SB9. They work much better than the flat leather belt IMO.
 
Glenn Brooks said:
Assume you are referring to the belt that drives the cone pulleys, not the motor? If so, try one of the new link belts, sold at Harbor freight, or purchased on line. Seems to be the go-to upgrade to replace flat belts. These are commonly used as drive belts on new machines.

Gpb
Click to expand...
Link belts are not a replacement for flat belts. You would need to replace the flat belt pulley with v groove pulleys

Sent from my XT1053 using Tapatalk
 
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