Hacking Iron (attention: Frank)

Bill Lantry

Member
Messages
2,663
Location
Inside the Beltway
Hey, everybody,

As most of you know, I have this lathe:

g0462.jpg


It's solidly built, and powerful. One bad thing: the low speed is 600. Actually, on mine, for some reason, the low had crept up to 720. So today, I was going to make a present for my son's 18th birthday, which involved loading a large chunk of wood. I wasn't overly enamored of the idea of spinning a huge unbalanced chunk at 720, so I thought I'd peek inside the reeves drive to see what the problem was.

First, for those of you who don't know how a reeves drive works (I didn't, until today), essentially, you've got two pulleys. One is fixed width. But the other changes width based on how you move an external lever. This changes the "gear" ratio... the belt is squeezed out towards the edge of the pulley as you raise the speed.

Anyway, it seems that, on mine, I had accidentally tried to change speeds with the motor off. The gear attached to the external lever had slipped one notch, hence the 720. So I took two screws out, and pulled out the lever. Then I backed the mechanism back down a notch, reinstalled, and was back to 600.

Cool. But not being one to leave well enough alone, I decided to play a little bit. There are three points of configuration: the lever itself, the way it attaches to the housing, and where the gear meets the actual reeves mechanism. Turns out the top reconfigured speed gets pretty close to 4000. Yikes! But that did tell me I could mess with the speed. So I "overclocked" it the other way (or should I say 'underclocked'? ;)

In any case, I now have a bottom speed of 540!! Don't think I can go much lower than that and still have much power. And what a difference it makes! Was able to rough a very large blank without the usual drama... well, at least with far less drama! Huge, huge difference. Frank, you gotta try it. Not sure if it'll hurt the belt or not, but even if it does, it's worth it.

Really, it's not just that I've reduced the biggest problem with my lathe. This is the first time I've ever hacked a woodworking machine. These are heady days! ;)

Thanks,

Bill
 
Underclocking a Reeves drive! Who'da thunk? :D I've noticed I can do something similar with my Sears lathe.

One point to mention...the sets of pullies (called sheaves) both move, or at least they do on my lathe. (You mentioned above that one set of wheels appeared to be a fixed width.)

One pair changes sizes as you turn the knob. As you discovered, a gearing mechanism makes the two sheaves move closer and farther apart. What you might not of noticed is the other set of sheaves also moves in and out as you change the speed. There is a VERY strong spring that tries to push the two halves together*. As you move one set of sheaves, the other set does the opposite. As you make one smaller, the other gets bigger, and vice versa. If you're not seeing both sets of sheaves change size simultaneously, then the spring-loaded one is likely stuck and not sliding as it should. When this happens, your belt will slip, especially at lower speeds. The problem is often barely noticeable when it first shows up, but it gets worse over time.

There are some tricks to taking the spring-loaded wheels apart. Improperly done, you can shoot metal at high speed through the wall of your shop. It's easy once you have the setup to take it apart. I've not done the Grizzly version, but you might get some ideas from this writeup done by Darrell Feltmate, showing how he cleans and lubes the Reeves drive in a lathe like mine.

Hope this helps -


* As a note, if you ever take the belt off your lathe while the spring is still installed (a broken belt, for example) and the two spring-loaded sheaves don't close completely together, do NOT get your fingers in between the two halves as you try to loosen them. The first time I had the belt off mine I didn't know there was a spring (like you, I thought it was fixed width). I was turning the spindle and just checking out how things move when WHAM! the two halves slammed together. (They had very suddenly become unstuck.) I was very glad my fingers were not in the middle, because I'm certain it would have broken bones.
 
As you lower the speed, you should be increasing the torque not reducing it? Since you gearing down the motor, you should be increasing the mechanical advantage therefore increasing torque.Unless of course this things works totally different than what I have seen.

Just an FYI for you Vaughn, some Reeves drives do have a fixed pulley. I know that is the case on some PM drill presses. My J-Line lathe is like yours and both pulleys shift but I don't think that is actually typical for most reeves drives.
 
Belt lenth will make a difference in the speed and power of a reeves system. Can't rember which but I think I went with a little little longer belt and it slowed down slightly but to long and it will slip. This happened will tring to find the right one.
Bob
 
Belt type

I happen to turn with the same Grizzly lathe. I replaced the belt with a premium belt from NAPA auto parts store, part # 3L24OW my lower speed is now around 520 rpms. Have not used the belt long enough to see how it will wear. Probably not much help but there it is.
 
Top