# Craftsman 12" (101.07403) Belt Replacement



## ZZYL-Vulcan (Dec 19, 2015)

Hello again,
So I got around to disassembling the headstock, project is nearing completion. Before I reassemble I need to replace the 10A-7 front baffle (oops, I even knew to not do this, and forgot about that woodruff key...) and while I am waiting for parts, I might as well replace the belt. The one that is on there is OK, but I figure a new one makes sense while the headstock is apart. I'm sure there is a post on here somewhere with those details, so please forgive me for asking where I find a replacement belt, (Atlas Press Co. S7-126 on the belt)? Thanks and Merry Christmas!

-Vulcan-


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## wa5cab (Dec 19, 2015)

Vulcan,

First, if the Woodruff key punched a fairly clean notch in the dust cover, it won't really hurt anything to pound if back flat and reuse it.  However, if you have already bought the new part, I would use it.  And in any case, you need to use a new Woodruff key.

The spindle belt on the early 12" Craftsman lathes is a 4L310.  You can buy one from any local or on-line supply house that still carries US made belts.  If they list two options, buy the more expensive one.


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## ZZYL-Vulcan (Dec 19, 2015)

OK thanks Rob (do you go by Rob?). Why the new woodruff key? I will admit it got a scratch or two in the removal process, but it still fits snugly in the keyway and isn't too mangled...


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## wa5cab (Dec 20, 2015)

Nyet Rob & Nyet Bob.  

First, Woodruff keys are dirt cheap.  So no reason NOT to replace a 70 year old one.  Second, if it's been used as a broach, it probably suffered a little deformation of one end, especially in the area that has to fit through the slot in the bull gear.  When you put the whole thing back together, one of the last things that you have to do is to adjust the running clearance between the bull gear and the spindle pulley, which you do by moving the bull gear before tightening its set screw.  So it must slide freely.


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## Mondo (Dec 20, 2015)

I have taken burrs off Woodruff keys that had to be removed with pliers or pried out of their seats on a shaft.  Lay a fine file or piece of fine sandpaper on the bench and rub the rough surfaces of the Woodruff key on the file or paper until smooth, then re-install.  Sure, Woodruff keys are cheap.  But my process sure beats the time and gasoline consumed driving to the hardware store.   The only times I buy new a Woodruff key are when they are so mangled that smoothing as described above is not practical or the key is loose and wobbly in it's seat.  ... Or if I have lost one in the shop swarf.

Spiral_Chips


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## wa5cab (Dec 21, 2015)

Any time that you have to sand, grind or file on the sides of a key, you usually end up making it a little thinner.  This increases the key tilt which decreases the surface area of the sides of the key seat or slot that is in contact with the key.  This increases the wear rate on the sides of seat or slot.


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