Pm1340gt Belt Size

[Alan H.]

The belt on my new PM1340GT machine was labeled as a B25. It was almost impossible to get it on to the high speed side of the pulleys since it was far too small in length. I cut it in half and measured it at an outer length of 26.25". I believe that a B25 is actually supposed to be 28" so this one was mislabeled or just very poor quality.
I ordered a BX25 from McMaster and a new Gates Tri-Power showed up today.

The new belt slipped right on and easily fit on both speed ranges. However, on the outboard position as shown on the photo the side cover will now not fit. The motor pulley is hitting the bottom of the side cover when I try to put it on. I could trim the side cover to make clearance for it but wanted to find out more here if I could.

So what size belt have you 1340GT owners gone to when you replace the factory belt out?

 

[mksj]

You probably need two belt sizes for the Tri-Power, BX24 and BX25 if using the stock pulleys (or the BX25 might work for both). The stock belt is somewhere in between and was difficult from the get go, it also has to do with how it sits in the grove. My recommendation is to get something like a 2.9" motor pulley (3/4" shaft) to the larger drive pulley (low speed pulley ratio) and with the VFD set at 90Hz you should have something like 50-1600 RPM range with no belt changes. If you need to go faster, you can probably push the motor to 100Hz.

 

[Alan H.]

Mark, The BX25 would work well for both but for the cover. The adjusting/tensioning rod length is ok and you can tension it in either position. But the BX25 drops the pulley too low for the cover in the high speed position.

So perhaps I will try a BX24 before I go with the one motor drive pulley arrangement or trim the cover for clearance.

Of course the belt that came with the lathe was not usable and that was expected. This issue has been reported here on the forum before. In my case, once it was put on the low speed side you couldn't get it off. That was easily solved with some Klein large wire cutters.

 

[wrmiller]

Hey Alan,

I put a linked belt on mine while setting it up, and slotted the cover. Haven't thought about it since, until your question.

 

[Alan H.]

Bill, thanks - I too am thinking about slotting the cover. A 5" angle grinder with a flapper disc and 2 minutes would be all it takes!

I love link belts and have them on several of my woodworking machines, a drill press, and a 2 x72 KMG grinder. But I am sure you know they are directional and they don't like reverse.

 

[MonkMan]

I saw someone had referenced using a NAPA 5L280W as a replacement for the cheap belt shipped, with good results.

 

[mksj]

Different motor but same solution, used a die grinder on the cover. Even with the stock motor, I used the low speed pulley setup almost all the time and had a to end of around 1200 RPM at 90 Hz.

 

[Alan H.]

I saw someone had referenced using a NAPA 5L280W as a replacement for the cheap belt shipped, with good results.

Yes, I think that zmotorsports. I had taken note of the 28" length of the belt he used. So when I ordered my BX25 (which is 28" outside length as well) I was hoping that it would work.

5L and BX belts are supposed to be interchangeable except for the h.p. capacity. There are some slight dimensional differences in the cross section of 5L vs. BX belts. This would cause the 5L to sit only a slight bit lower in the pulleys. Cross sections are:

5L Belt = 5/8 (.625) Inches Width x 3/8 (.375) Height
B & BX Belts =21/32 (.65625) Inches Width x 13/32 (.40625) Height​

I am no belt expert for sure and maybe I am missing something.

Thanks for replies thus far.

 

[sanddan]

Bill, thanks - I too am thinking about slotting the cover. A 5" angle grinder with a flapper disc and 2 minutes would be all it takes!

I love link belts and have them on several of my woodworking machines, a drill press, and a 2 x72 KMG grinder. But I am sure you know they are directional and they don't like reverse.

Interesting...
I didn't know that, HaHaHa. I'll have to go out and check which way I have the belt running.

I installed the link belt when I was chasing vibrations, (didn't seem to make a difference), and didn't know they were directional. I like the idea of changing the motor pulley and going with single speed range. Mksj, where did you source the 2.9" sized pulley and is that 2.9" pitch dia or OA dia?

 

[Alan H.]

Yes, those tabs underneath need to "go with the flow".

I recently built a KMG belt grinder and used the Fenner Powertwist belt. Between some really nice pulleys and the belt, it runs unbelievably smooth. I do run the grinder in reverse from time to time for some slack belt grinding, but very slowly.

Fenner was quite firm on their position of not reversing the belt when I talked to them. Of course, there is always product liability issues at play. But when one looks at the layout of the belt it is conceivable that the tabs underneath could fold on you in reverse and cause a wreck.