Atlas MF motor belt

[intrepid]

Trying to locate the correct motor drive belt for a Atlas MF. The manual calls for a L3-125. This is a 1/2" x 34" belt. The old broken belt measures 3/8" x 31". The pulley groves on the machine and motor measure only 3/8" wide. The counter shaft 2 step pulley appears to be the factory correct with marking M6-427. The hole shaft is 5/8" with a 1/2" bushing. The spindle belt is a 1/2" belt. Several other topics elsewhere all state the motor drive belt to be 1/2". Did Atlas use different width drive belts over the years? Seems the 3/8" belt may be a little light for this application but no way will a 1/2" belt fit these pulleys.

 

[34_40]

It could be like mine,just a mish mash of parts and I can't really go by what "the book" says. Mine was a 4 pulley setup originally, but a prior owner swapped it to 2 sheeve pulleys. So when trying to swap speeds the belt is to wide to clear the mounting, there is no room between the pulley and the mount.

 

[Soggy618]

The M6-427 is one of the countershaft pulleys for the 618 lathe; this takes a 3/8" 3L belt.
I'd follow your instincts and use a belt that fits.

BTW, the P/L for the lathe shows the belt as L9-125, which derives from an older 9" lathe model.

 

[BGHansen]

I swapped a Harbor Freight segmented belt on my MFB. Saves you from pulling the spindle and seems to work fine.

Bruce

 

[intrepid]

I swapped a Harbor Freight segmented belt on my MFB. Saves you from pulling the spindle and seems to work fine.

Bruce

Yes Bruce, that is my plan for the spindle belt when needed. For now I am just trying to figure out and understand the motor drive belt. As Soggy618 suggested I will follow my instincts and go with the 3/8" belt. Just hoping the small width belt can handle torque and power supplied by the motor.

 

[JPMacG]

I use a 4L350 belt for the motor-to-countershaft of my MFC. I think 4L means it is 1/2" wide. By the way, I found that a ribbed belt runs smoother than a standard belt around the smallest groove of the the motor pulley. No need for a link belt here (unless you just want to use one). The countershaft is easily removed for belt replacement - unlike removing the spindle.

 

[intrepid]

Just wondering JPMacG what is the number on your counter shaft pulley drive? Is a also a two step pulley?

 

[JPMacG]

Yes, it is a 2-step pulley. The Atlas part number on the pulley casting is M1-80B.

 

[intrepid]

Yes, it is a 2-step pulley. The Atlas part number on the pulley casting is M1-80B.

Thanks, Its starting to make some since now. It appears Atlas did use different size pulleys and belts on the various models. Mine is a MF and from what I have been able to determine now it does have the correct 3/8" wide pulleys and belt. Other models like the MFC they used the 1/2" motor drive pulleys and pulleys. I suppose there are other differences between the models but at this time it is no big deal. Now once I get mine in operation, like I mentioned before, I am hoping the 3/8" belt can handle the power and torque supplied from the motor. If not, I now know how to upgrade. Thanks all.

 

[wa5cab]

The Alas mills all have two belts that some of the replies apparently confused. The two belts are the motor to countershaft belt, commonly called the motor belt, and the countershaft to spindle belt, commonly called the spindle belt. All 12 mill models used a 3/8" wide motor belt. The three base models had 4-step cone pulleys and used a 3/8" wide belt. The three A-models had 3-step cone pulleys and a 3/8" wide spindle belt. The three B-models and the three C-models had two-step cone pulleys and used a 1/2" wide spindle belt. There is no need for a 1/2" motor belt. My 3996 12" lathe has a 3/4 HP motor and a 3/8" motor belt. It was bought new in 1981. I changed the motor belt about 5 years ago, more because I had the replacement belt on the shelf than for any other reason.