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Posted: Thu May 08, 2014 9:28 pm
by db5
JPG40504 wrote:Hope you have better luck with that than I am having with the Mark VII.:(
Had no problem with this and still have the drilled hardwood. Do you want it? I can send a picture and you decide. Took a bit of thought before I undertook the task but it worked quite well.

Posted: Thu May 08, 2014 10:07 pm
by JPG
db5 wrote:Had no problem with this and still have the drilled hardwood. Do you want it? I can send a picture and you decide. Took a bit of thought before I undertook the task but it worked quite well.
Subject jump. Speed dial calibration.

I have been tail chasing since I discovered a Mark x motor belt would not fit the MVII. An over abundance of funky stuff that had to be found out and worked around.

Fortunately I have the idler shaft and sheaves from you know who. Tomorrow I try with those parts. That aluminum cam is not the same as my CNC machined one which I assume is dimensionally = to the oem plastic one. I think(hope?) the speeds will be correct with those parts and the 'accurate' cam. Then I decide what to do to use the funky parts for now.

I have decided 29 1/2" is the correct belt length. The idler/motor shaft spacing is 2" wider than a Mark x. When I am satisfied I have things right, I will post all this to the MVII headstock reassembly thread.

In the mean time I be still struggling. Talk about part/adjustments interacting!(or at least appearing that way)

Posted: Thu May 08, 2014 10:26 pm
by db5
JPG40504 wrote:
I have decided 29 1/2" is the correct belt length. The idler/motor shaft spacing is 2" wider than a Mark x. When I am satisfied I have things right, I will post all this to the MVII headstock reassembly thread.
Looked at my notes and the length you have is what I had from measuring the original. The width I didn't measure. I'm s Psych remember. Close counts just like government work;;) unless one is dealing with wanting to get things right. I never could find the right belt although ACE Hardware had one that I thought might work.

I'll be interested in your results. I may even buy another Mk. VII because the one I had was really great.

Posted: Thu May 08, 2014 11:47 pm
by JPG
[quote="db5"]Looked at my notes and the length you have is what I had from measuring the original. The width I didn't measure. I'm s Psych remember. Close counts just like government work]

One thing I have learned from this vicious cycle I have been riding(I have tried 6 different belt lengths) is that a small physical change begets a large speed range change.

Belt same width as a Mark x(the sheaves are essentially the same). The ones I have been trying are slightly narrower, but are wider than 1/2".

The most important thing I have learned is that the belt MUST be correct in it's travel in/out of the idler pulley or speed range will be impossible to attain. The belt length then merely sets the actual speeds by virtue of it's length also traveling out/in of the motor pulley correctly.

Thanks for the verification re 29 1/2" belt length. I have only found one source, but I think the 1/2" sizes are also being phased out like every one else!:(

Posted: Fri May 09, 2014 6:52 am
by BuckeyeDennis
JPG40504 wrote:One thing I have learned from this vicious cycle I have been riding(I have tried 6 different belt lengths) is that a small physical change begets a large speed range change.

Belt same width as a Mark x(the sheaves are essentially the same). The ones I have been trying are slightly narrower, but are wider than 1/2".

The most important thing I have learned is that the belt MUST be correct in it's travel in/out of the idler pulley or speed range will be impossible to attain. The belt length then merely sets the actual speeds by virtue of it's length also traveling out/in of the motor pulley correctly.

Thanks for the verification re 29 1/2" belt length. I have only found one source, but I think the 1/2" sizes are also being phased out like every one else!:(
It occurred to me that you might get lucky and find that 29.5" corresponds to a standard metric dimension. Sure enough, 750mm is 29.53". I'm not sure if the other dimensions are right on the belts here, but they look close.

Posted: Fri May 09, 2014 9:22 am
by JPG
BuckeyeDennis wrote:It occurred to me that you might get lucky and find that 29.5" corresponds to a standard metric dimension. Sure enough, 750mm is 29.53". I'm not sure if the other dimensions are right on the belts here, but they look close.
The '4L' sizes are more interesting!:):):):):):)

Posted: Fri May 09, 2014 9:33 am
by JPG
BuckeyeDennis wrote:It occurred to me that you might get lucky and find that 29.5" corresponds to a standard metric dimension. Sure enough, 750mm is 29.53". I'm not sure if the other dimensions are right on the belts here, but they look close.
The '4L' sizes are more interesting!:):):):):):)