Running the SB9

hello.back after a hiatus of being a single parent whilst 'she-who-must-be-obeyed' was in the motherland.

I have been reading posts on the flat belt on the SB.

Here are the steps i use to run the lathe.
Belt is slack.
Put belt on pulleys to be used
Turn on motor
Push camlever over(tighten belt)
Take cuts.
Pull lever back(slack off belt)
Turn off motor
Measure work.
Repeat.
When i stop for the day I loosen the belt.

Is this right?


I read an article where a bloke had converted to a serpentine belt and commented that he could not use the cam lever and adjusted tension with the turnbuckle, so i assume he left the belt under tension all the time.

How tight should the belt be? How deep a cut on aluminium or steel before slipping is 'normal' for an SB9? That I think is the only way to see if the belt is tight enough. I am scared stiff of ruining the machine!
I have a leather belt, but am thinking of the serpentine route.

Cheers

Ant

Hi Ant,

I have just converted my newly-purchased 9A to a serpentine belt from flat leather. I never ran it with the original leather belt but did see it driven by the leather belt when I picked it up. According to HTRAL you should be able to push the belt down by 1" at the centre of the belt when the lever is in the down position. I think you will find that there is a lot more grip from a serpentine belt than a flat leather if you do decide to do the conversion.

Pulling the spindle and the countershaft is fairly straightforward as long as you are sensible but I also did buy the Ilion "Guide to Renovating the SBL 9" Model A, B & C Plus Model 10K" book before I started, which was very helpful.

I don't bother slackening the belt between cuts but I do release it when I have finished working on the lathe. I also have a 3-phase motor controlled by a VFD (inverter) so am not so concerned about stopping and starting the motor.

Regards,

Bruce

Tighten belt, then turn on motor. Yes, loosen belt when you stop for the day.

Converting to serpentine won't affect the functioning of the cam lever, the length of the belt, in that case, was probably not correct.

You can reasonably take 1/8" depth of cut on aluminum, 0.05" to 0.1" on mild steel.

Paul

I really don't understand the logic of loosening the serpentine belt up at the end of the day. Nobody loosens their belts up on their cars when parked for the night, do they?

You're probably right - with leather belts and belts that have joints, it's probably a good idea, but with a one piece serpentine, it probably doesn't matter. And as far as the countershaft and spindle, I doubt there would be any detrimental effects.

tommy1010 said:

I really don't understand the logic of loosening the serpentine belt up at the end of the day. Nobody loosens their belts up on their cars when parked for the night, do they?

Click to expand...

I seem to remember that water pumps in cars used to start leaking and go bad all the time. At least I fixed quite a few many years ago.

I'd still leave the tension OFF the belt when not working with the lathe. FWIW

-Ron

Loosening the belt after use was the standard recommended procedure for many years because of the use of leather drive belts, as it reduced stretching. The use of modern belting that use non-stretching materials probably reduces this requirerment somewhat, but it is still a good habit. Developing good habits in lathe use is very important in maintaining the lathes overall health and accuracy. My process is Lube machine, tighten belt, use the machine. After use, loosen belt, clean the machine and lube again.
Steve