LMS Hi Torque Lathe Belt Question(s)

TReischl

TReischl

Registered
Registered
Joined
Jan 8, 2020
Messages
8
I am really pleased with the lathe in general. I bought the "deluxe" version a month or so ago. One issue is that the carriage wheel handle just clips the cross slide crank when the moon and stars are in a certain alignment. I can live with that. The DRO on the cross slide can interfere with rotating the compound. Hasn't been a major issue yet.

Where I do need some information is the drive belt. It looks like a 5mm pitch belt, but it isn't. Close as I can determine it is about 4.7 to 4.75mm pitch. That is a very strange size that I have not been able to locate anywhere. I did buy a 5mm pitch X 100 tooth belt in case I was measuring incorrectly. No go. Are there any other sources for these belts other than LMS and MM?

LMS is out of them as I write this. Chris was kind enough to recommend that I contact Micro Mark. I ordered two. Now I am not badmouthing Micro Mark because they had what I needed. But $46 for two belts (including shipping)? Normal, standard belts of this size are about $7 apiece and I can get them from my local Grainger with no shipping. It is not LMS's or Micro Marks fault someone designed a machine with odd belts. The belt is marked 1.5 X 100 and I cannot find anything even close on the web.

These are definitely wear items. And yes, I totally screwed up and wrecked the one that came with the lathe. I am thinking of replacing both the pulleys so a standard belt can be used. That could get tricky depending on the center distance between them.

The good news is that I totally enjoy using the lathe, even with the quirks mentioned above. Since I got it I have been tooling it up. Die holders, carriage stop and lock, tool post lock handle and even an ER-32 collet chuck. All made on the lathe except for the collet nut. I also have a MM hi torque mini mill which is a good machine. Added a simple reversing switch to it for $11 and that makes tapping really easy.
 
There's been a lot of discussion on the 7x12MiniLathe forum on groups.io regarding replacement belts for these machines. Apparently the OEM belt is not readily available, maybe because the mfr wanted to capture some additional income. Pretty low, but many do that sort of thing.

There are ways to reduce the cost of replacing the belt, but you have to modify the machine by replacing the pulleys along with the belt. Apparently you will need to bore the pulley out to fit, and also cut a keyway. Both can be done on your lathe. Some cost and time up front, but the replacement belts will cost a lot less. More info can be found in that forum's files section. Look for "Minilathe Timing Belt Survey.pdf".

Searching ebay might find belts that are drop-in replacements for a lower price. BTW if it's a screwy pitch in mm's maybe it's an imperial pitch. 4.75mm is pretty close to 3/16 inch. Everything else on the lathe is metric but.....it...could...work....(or maybe not) :)
 
So, if I read you correctly, did you get the LMS 7350? Perhaps I misunderstand the belts, but I thought they were typically good for over 2 years if alignment and tension are good. I understand with the vibration and settling of shipment, this can sometimes change that ideal alignment. It goes without saying that the most accurate measurement of the cog spacing would be done on the gears, and not the belt itself, which stretches.

And yes, you can cut/Shape a keyway on the mini-lathe. For me it was labor intensive as each pass was only about 2 thousandths of an inch.
 

Attachments

  • 4 Shaping 4mm keyway in spindle spacer.jpg
    4 Shaping 4mm keyway in spindle spacer.jpg
    333.6 KB · Views: 142
Last edited:
Yes, it is the LMS 7350. I am not sure where you got the idea that the belts have a typical life of 2 years. As I mentioned in the original post the damage was caused by operator error. Jammed the lathe, the circuitry tried to increase power to compensate and that began the degradation of the belt.

The most accurate way I have found to determine belt pitch is to measure over 10 or 20 teeth, then divide. This type of belt does not stretch very much, they are fiber reinforced. Some are even steel reinforced.

I am familiar with lathe operations like keyway slotting, though in my case I would use the mini mill rather than the lathe, much faster and easier.
 
Slotting an Outer Diameter keyway on a mill is a snap. Slotting an inner diameter keyway on a mill is more problematic. This is why most people rely upon using a shaper/broacher for cutting keyways inside of pulleys/gears. BTW, they keyway on the spindle is 4mm. If you do have a method of using a mill to cut a keyway inside of a small diameter pully, it would be educational for me to see it.

I bought the same lathe, and really like it as well. From the factory, how much taper does it have over a foot? I got super lucky, and the factory taper was only 4 tenths of 1/1000th of an inch.
 
addertooth said:
Slotting an Outer Diameter keyway on a mill is a snap. Slotting an inner diameter keyway on a mill is more problematic. This is why most people rely upon using a shaper/broacher for cutting keyways inside of pulleys/gears. BTW, they keyway on the spindle is 4mm. If you do have a method of using a mill to cut a keyway inside of a small diameter pully, it would be educational for me to see it.

I bought the same lathe, and really like it as well. From the factory, how much taper does it have over a foot? I got super lucky, and the factory taper was only 4 tenths of 1/1000th of an inch.
Click to expand...

Nothing problematic about slotting an inner diameter on a mill. Pretty much the same routine as on a lathe. Set up part, lock spindle, insert cutter and stroke away. What is better about doing it on the mill is there is no endless cranking of handwheels back and forth. There are quite a few vids of doing it on YouTube. IIRC, Click Spring does it a few times on one of his builds. Maybe the clock. . . .

I am thinking that LMS has the folks at the factory spend a little more time setting these machines up. Mine is about the same as yours as far as taper goes.
 
TReischl said:
Nothing problematic about slotting an inner diameter on a mill. Pretty much the same routine as on a lathe. Set up part, lock spindle, insert cutter and stroke away. What is better about doing it on the mill is there is no endless cranking of handwheels back and forth. There are quite a few vids of doing it on YouTube. IIRC, Click Spring does it a few times on one of his builds. Maybe the clock. . . .
Click to expand...

Makes complete sense... I had mis-interpreted your statement as somehow using the mill in some other function than a shaper.
 
addertooth said:
Makes complete sense... I had misinterpreted your statement as somehow using the mill in some other function than a shaper.
Click to expand...

Yup, sometimes my fingers get ahead of my brain and I do not come out as clear as I would like.

One of the things I do on the mill now and then is put in a "deadman" instead of a keyway. Not sure if "deadman" is a correct term, it is what tool makers I worked with called it but that could have been just a local term. If I need to press something into another part and it absolutely positively must not turn I will just drill and ream between the two on the circumference and insert a pin. I have also drilled and tapped for a set screw. Sort of like a round key. . . .seems quick and dirty to me. . . . but it does work.
 
Yes, I was imagining you were going to mill a "half round" in the pulley, and then rounding the top of the key to match.
 
You must log in or register to reply here.
Back
Top