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Adjusting Belt Tension
Posted: Tue Aug 10, 2010 12:04 pm
by mark2u
In searching the forums on maintenance of my Mark V, I frequently see references to adjusting the belt tension... but I have yet to find anything that tells me how to do so. I suspect my new belts are too tight and that is keeping my motor from having enough umph to start up. Please help.
Posted: Tue Aug 10, 2010 4:26 pm
by wa2crk
Welcome to the forum.
I don't believe that the belt tension can cause sluggish startup. I would look for another reason. Sometimes the belt can be squeezed between the two sheave halves and cause a bind but this a rare occurrence.
Can you turn the spindle easily by hand with the sanding disc on the shaft? If you can then the machine should start OK. If you can not then there is probably a mechanical issue such as bad bearings or some other issue causing a bind.
How good is your electrical supply? Are you connected to a 20 amp breaker?
Are you using an extension cord? If so what size is the wire and how long is the cord? The wire should be no less than 12 gauge and the length no longer than 25'. What speed setting are you at when you try to start the machine? You should be at the "SLOW" end of the range to minimize load on the motor.
If you do adjust the tension of the poly V belt be careful and DO NOT OVER TIGHTEN THE BOLT THROUGH TWO TABS UNDER THE ECCENTRIC BUSHING. Doing so could snap one of the tabs and this is a catastrophic damage.
Does the machine come up to speed at all? Motor problems could be anything from tight bearings to dirt in the start winding contacts or a bad or weak start capacitor.
One final thing, please post your location as there may be a forum member close by who can give you some direct help.
Bill V
Posted: Tue Aug 10, 2010 5:00 pm
by SDSSmith
mark2u wrote:In searching the forums on maintenance of my Mark V, I frequently see references to adjusting the belt tension... but I have yet to find anything that tells me how to do so. I suspect my new belts are too tight and that is keeping my motor from having enough umph to start up. Please help.
To adjust the belt tension on the poly v belt or gilmer belt you rotate the eccentric bushing. Here is a link to SS's instruction for belt replacement which also addresses the belt tensioning process: http://www.shopsmith.com/ownersite/prod ... cement.pdf
Posted: Wed Aug 11, 2010 11:44 am
by mark2u
Yes, I have a Mark V that has a Gilmore belt. I replaced both belts but they do seem to have a lot of play in them. You say rotating the eccentric bushing will adjust them? Can you explain. My extension cord is short and of proper guage so I don't think it is that. The belts do seem to be tightly squeezed between the two sheaves. Middle speeds seem to work alright, not happy at the lowest speeds and doesn't go to the very highest speeds... on a 15amp breaker... but the only machine on it. Always worked before I replaced the belts. There was a lot of belt debris (a lot) all over the inside of the casing and I thought I cleaned it real well but I didn't get down into the motor area very easily. Dirt in the start winding contacts sounds like a possibility... can you tell me more about how to remedy that? ...or other thoughts.
Posted: Wed Aug 11, 2010 11:51 am
by mark2u
I've read the reference you sent me which is similar to the instructions that came with the belts. However I'm unfamiliar with the section that says:
"If you are replacing the Poly-V belt in
a machine with a removable name-
plate (which is the case in my Mark V), position the Poly-V belt in the
third groove of the Poly-v pulley."
I don't know what they are talking about here with the third groove. Can someone explain that to me or show with a photo?
Posted: Wed Aug 11, 2010 12:01 pm
by mark2u
My new Gilmore belt has a lot of deflection to it... I am now suspecting it is not tight enough and therefore not allowing the machine to reach full power. Sound plausible? I have actually seen the spindle slip without the belt turning when I turn by hand as it offers too much resistance. Otherwise, I am able to turn the machine by hand while adjusting the speed dial. I appreciate the help people are attempting to give.
Posted: Wed Aug 11, 2010 12:10 pm
by SDSSmith
mark2u wrote:I've read the reference you sent me which is similar to the instructions that came with the belts. However I'm unfamiliar with the section that says:
"If you are replacing the Poly-V belt in
a machine with a removable name-
plate (which is the case in my Mark V), position the Poly-V belt in the
third groove of the Poly-v pulley."
I don't know what they are talking about here with the third groove. Can someone explain that to me or show with a photo?
On the poly v belt the grooves run around the circumference of the drive sleeve. You have indicated that you have a gilmer belt and the grooves, as you know, run axially. The cited instructions do not apply to a gilmer drive.
Posted: Wed Aug 11, 2010 12:16 pm
by SDSSmith
mark2u wrote:My new Gilmore belt has a lot of deflection to it... I am now suspecting it is not tight enough and therefore not allowing the machine to reach full power. Sound plausible? I have actually seen the spindle slip without the belt turning when I turn by hand as it offers too much resistance. Otherwise, I am able to turn the machine by hand while adjusting the speed dial. I appreciate the help people are attempting to give.
Did you follow the instructions for adjusting the belt tension while the machine is running? Speed set at G or H and increase tension until you hear the scream/squeal, then back off until the noise stops.
If tensioned properly, I don't think the gilmer belt likes to "slip". It is very hard on the cogs on the belt. The drive sleeve has a clutch that might not be properly adjusted allowing slippage.
Posted: Wed Aug 11, 2010 12:30 pm
by JPG
SDSSmith wrote:Did you follow the instructions for adjusting the belt tension while the machine is running? Speed set at G or H and increase tension until you hear the scream/squeal, then back off until the noise stops.
If tensioned properly, I don't think the gilmer belt likes to "slip". It is very hard on the cogs on the belt. The drive sleeve has a clutch that might not be properly adjusted allowing slippage.
Methinks you hit the nail squarely on the head!!!:)
See Mickyd's greenie restoration thread for insight into the clutch/refurbing/testing it!
Posted: Wed Aug 11, 2010 1:45 pm
by beeg
Welcome to the forum Mark2U. Have ya lube the Mark5 lately? Disregard the info about the Poly-V, you have the gilmer belt instead.