1127 belts

[ttabbal]

So, I wanted to switch to high speed and remembered something that was a bit off. The belt came installed in high speed, however, there was no tensioner setup for it. The manual talks about loosening the motor mount, but there don't appear to be any slots etc.. Getting it off was kind of a pain. I would have had to completely remove the motor and twist it to release the tension.

Low range with the 2 belts works fine. There is a tensioner in the machine, but the belts are too short to use it for high range. I'm thinking of taking the belt to a auto parts store and getting one a few inches longer. Just wondered if someone else has seen something like this and what they did.

 

[Jeff.64]

I measured all three belts and they had an average width of 0.384” (9.7mm = 0.382”) and an average height of 0.238” (6mm = 0.236”). I spent a ton of time trying to find information on the Mountianrope M-33, M-27.5 and M-25 belts. I could not find a cross reference. SPZ series belts are 9.7mm (0.382”) wide and 8mm (0.315”) in height. Gates HI-POWER Z section belts are 10mm (0.394”) wide and 6mm (0.236”) in height. I received a PM-1127 a few weeks ago and have the same problem you're having. The M-33 belt was very tight. The belt tensioner idler was not in contact with the M-33 belt. Like you I had to remove the motor to change the belt. I did not want to try rolling the belt off with a screw driver and cause damage to the aluminum pulleys. I think a longer belt will be required. I have not yet determined the length. I intend on making accurate measurements of the vee angle on each pulley and determine if the SPZ series or if the Gates HI-POWER Z section belts will work. The belt tensioner idler on my machine is turned very rough and in my opinion would result in premature belt wear. I plan on making a replacement or cleaning up the original belt tensioner.
Go to page 12 of the attached pdf (page 11 of the manual) and you will see that an M-34 belt is used for high speed. The Warco WM-290V lathe looks to be very close in design to the PM-1127.

 

[ttabbal]

Thanks for the detailed info! I find this very strange, but fixable.

 

[tweinke]

Does Matt have any ideas on this issue? I would think he would have some thoughts or should know of the issue so it can be corrected.

 

[pacifica]

On my PM1340gt the belt and pulleys were substandard. I replaced the sheaves with martins, and the belt with a cogged gates belt; gates belt fits properly in the martin sheaves, no shredding, smoother running. I could've got the sheaves balanced but it didn't seem necessary. Motor movement is difficult.

Before I replaced sheaves and belt I was experiencing about .0003 runout on shaft---but over .004" on the sheave.Probably the most cost effective upgrade you can do. Heavy duty stand will make a big difference, Superior chuck can make a big difference. And leveling. Your choice and budget as to how much you want to do.

 

[ttabbal]

Does Matt have any ideas on this issue? I would think he would have some thoughts or should know of the issue so it can be corrected.

I remembered it on a weekend, so I thought I'd see if the community had run into it. I'll contact Matt as well, but I figured he'd be enjoying his weekend. I hoped someone might point out the adjustment point I missed or something.

 

[Deuce]

Did anyone ever solve this and find some better quality belts and/or a better size to make changes easier between HI and LOW speed? It looks like there was a design change in the 1127vf-lb at some point with new models having only 2 pulleys and the older ones (like mine) having a 3rd pulley. Changing the belts is enough of a hassle to go from HI to LOW, that I never do it. Longer belts would make it easier, or changing over to a 2 pulley system.

 

[ttabbal]

I leave it in low most of the time. I did end up taking the belt to a local store and they found a few that fit well enough. I don't think I found a good one to use with the tensioner in high range though. I dislike changing it enough that I modified the VFD settings, allowing me to speed up the motor a little more. Nice for aluminum.

 

[pacifica]

On my 1340 gt I experienced vibration from 650 to 800 rpm, I tried to measure it by putting a dial indicator against the front side. While running at 720 rpm I got a .003 " movement, at 1000 rpm there was no movement at all.
I replaced the sheaves with Martins, and took off about .005 on all the surfaces(face and grooves on the sheaves),I balanced using something like this:

.
Be sure to put a small chamfer on the inside edge of the pulley(sheave).
With the appropriate gates belt any shredding and noise is eliminated.
While running at 720 rpm I now get about .0005 " indicator movement, which is virtually undetectable.

 

[Deuce]

To wrap this up for anyone else, here is what I did to address the belt change trouble on the newer PM1127VF-LB lathes. I spoke with PM and they didnt have any suggestions other than a larger belt or the linked belts. The problem is that the next size larger belts wouldnt work with the limited travel that the tensioner has (I tried lots of combinations).

I ended up replacing all the belts with XPZ style. The factory belts were "M" size which is also apparently the same as "3L" size (as one original belt showed both). XPZ belts are a little deeper and notched so they bend easier.
I tried lots of sizes and decided the best fitting ones were XPZ612, XPZ710, & XPZ850.
I also made a larger tensioner mount so that it would have more adjustment as the stock one didnt have much before hitting the spindle sheave (new one is 10mm longer from the tensioner idler threaded hole (M10) to the pivot bolt clearance hole.

Belt changes are finally down to around a minute or 2 now. I only have to loosen the tensioner bolt, take off the low speed belt, mount high speed belt and tighten tensioner back up. To run low speed, I loosen the tensioner and unmount the high speed belt and move it out of the way (I keep it tucked around the motor area) without fully removing it (otherwise you would need to loosen the intermediate pulley and remove that belt in order to get the high speed belt out).