How do we know if the belt is too tight or loose on a mill?

[oskar]

My mini mill headstock is a Taig ER16 and it’s driven by a Sherline DCV motor. The distance between the 2 pulleys is 3.5” and when I press lightly on the belt at midpoint the belt deflects about 1/8”.

When the motor runs the belt wiggles more than it should (to my opinion) but I don’t want to tight it more in case the applied force will wear the belt prematurely.

So are any tricks here to know when your belt is too tight or not?

 

[Alittlerusty]

If it slips or stalls while taking a reasonable depth cut snug her up abit

 

[P. Waller]

I do not know how the collective "We" do it.

A belt tension gauge, used in many industries that employ belt drives, I have never used or even seen one.

https://www.grainger.com/product/OTC-Belt-Tension-Gauge-2TVU6

If you require a fixed limit of parameters as many hobbyists do this is for you, it has a white zone and a red zone on the dial.

The white zone is for loading and unloading only.

 

[markba633csi]

The 1/8" deflection is probably about right for that size lathe and belt
mark
edit: I meant mill

 

[oskar]

Thank you guys, guess I will just have to play with it and find the correct tension. Good to know that 1/8" is about right

Nicolas

 

[Bob Korves]

If it is not slipping it is tight enough, the belt will eventually be damaged if it slips. Too tight and the bearings and belt will suffer.

 

[mikey]

Depends. Are you using a Sherline cogged belt? If so, just pull it tight and lock it down. My belts move about 1/8" with moderate pressure. The cogged inner surface grabs well but it will slip if too much torque is applied, which is what it is designed to do.

 

[oskar]

Yes Mike I use the Sherline cogged belt and also I have a spare one just in case. Looks like the 1/8” slack is the right number and I will leave it there

Nicolas

 

[4ssss]

If the spindle turns, the belt is OK. If the spindle doesn't the belt is too loose.