V-belt adjustment

[Evo160K]

Is there a rule of thumb on a Singer 45 for determining when a rubber v-belt is adjusted properly?  A search of this forum found nothing.  Thank you.

[Singermania]

I expect an engineer will give you some serious technical advice on this, however in our business we find that its rule of thumb.... ie if its too loose it slips and or flaps, if its too tight you and the machine will find the handwheel hard to turn (assuming the clutch is disengaged on a clutch motor) and you will stress the motor and burn out its bearings.

 

[Gregspitz]

should it be real easy to turn manually with a speed reducer attached to a servo motor...

I can move mine but it takes a bit of effort..maybe I have to loosen the belt from the motor to the reducer???

 it is sewing fine

[mikesc]

Don't "fix" what isn't broken..

[Evo160K]

Thanks Singermania, that helps.  Thank you.

[Singermania]

No, once you put a speed reducer into the equation the gearing, friction and inertia are working against you and it does become a bit more difficult to turn, however (depending on  how strong your are) it should still be able to get rolling.... again when its too tight it will be really hard to turn over.   We find on the box style reducer that the first thing to slip is the small reducer pulley as it doesn't seem to have the depth of other pulley wheels.

[Gregg From Keystone Sewing]

See attached.  I've never used this or needed to; after a while, we do it by feel.  But, if you don't know what is too tight or too loose, here is a baseline guide.

Too loose, the belt will slip.  This is not a timing belt or chain on an engine; you'll never damage the machine by slipping the belt on the pulley if it is too loose.  

Too tight, at the motor can jack rabbit start, as where you push down on the motor treadle and the motor goes from zero to 60 with no control in between.  This can also put excessive load on the machine and motor pulley and prematurely wear out these parts.  

Edited July 15, 2016 by Gregg From Keystone Sewing

[Art]

Gregg is correct about the belt situation.  About an inch of deflection with a moderate push sets things up just right.  Now with today's servo motors, a 1/2 inch is ok too.  In the days of the clutch motor (probably still that way in factories) you would back off the brake and set the belt loose.  A lot of folks used the balance wheel and their hand as a kind of brake so they liked the belt tension sometimes a little looser than nominal.  You're not going to hurt much setting the machine up a little loose, but setting tight enough to load the bearings other than the bare minimum is not going to be great.  After a while working with machines, they have a particular sound when the belts are too tight.

Art

[graywolf]

Rule of thumb for setting v-belts in general:

1/2" inch of slack.

That is on one side between the pulleys, of course.

Never, ever, less than 1/4 inch as you are likely to damage something.

1 (one) inch and it needs to be tightened because it is likely to slip. Actually if your belt has stretched to where it has one-inch or more of slack to ought to be replaced (assuming it started out properly adjusted).

There are exceptions to the above for very long or very short runs of belt, but if you shoot for that half-inch you are usually good to go.

[Art]

I'll stick with 1" for a clutch motor, and some of my servos are set-up that way too.  Never a problem, 1" isn't much given the length of belt.  

Art