It occurs to this noob that a true isolator would be good for this application is you would trust it. By this I mean the kind with no thru-fastener. These are used on auto window regulator motors and electronics, among other things. I have 3 on a an oil cooler adapted to a V Intek lawnmower (plenty of vibration), but the threaded fasteners are around 1/4-20. These isolators can be purchased new or from some surplus stores. I always miss the surplus ones as they are snapped up. Just an idea. You guys are making me leery (again) of the Chinese stuff.
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Grizzly G4003G - Installed rubber motor mounts, fixed motor alignment, pulley, wiring issue
- Thread starter coolidge
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I'm not sure but it sounds like you're talking about well nuts. If that's the case, there's no way they would hold up in this application. As you mentioned, 1/4-20 which is the biggest I've ever seen them in is not nearly robust enough to secure the weight of this motor and keep tension on the belt.
I'm intrigued by AlanR's solution but haven't had any luck in sourcing them yet. I'll continue to look today. My motor just came in this A.M. and I've got to just hang it on there like it was and get a couple of jobs out and rehang it when my rubber washers get here. Maybe I'll be able to locate said isolated through fasteners by then as well as my link belt.
On the subject of the adjustable link type belts which size would you guys go with? The Gates belts that are there measure 7/16" wide and the best I can measure the cogged "V" is 5/16" deep. I've found the belts to be 3/8", 1/2", 5/8". Has anyone else used this mod if so what size belts did you use?
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Thanks, I don't have that issue but I am still curious & will follow this thread.
I don't have a G4003G but on my PM1236 I am using 1/2"/4L Fenner belts.
The trick with any belt is to not make it too tight. I used the rubber mounts on an old Craftsman joiner, the original design was terrible so the machine vibrated like crazy.
I made a mount which hangs the motor, adjustable with a hand wheel. I used a much smaller Gates cogged belt than the original and even with that I found there was a narrow sweet spot at which the belt does not oscillate, definitely not too tight but also not too loose. I'm spinning the 3 knife cutter head at 5,500 RPM, the motor is 3,600 RPM, the motor balance is not great. The entire mount is supported by the bolts and bushings I pictured, I found a box of them when I went looking for something like that.
I used link belts on my mill drill and found the same thing but the sweet spots are much broader.
An idler pulley (or a roller like the serpentine belt tensioner on cars) on the slack side would be a good idea if possible, it's always the slack side that's a problem. If the lathe was mine I'd come up with a solution which has the motor mount horizontal rather than vertical, much easier to deal with and the rubber has a better chance of working.
You just have to watch the belts, it's easy to see.
I made a mount which hangs the motor, adjustable with a hand wheel. I used a much smaller Gates cogged belt than the original and even with that I found there was a narrow sweet spot at which the belt does not oscillate, definitely not too tight but also not too loose. I'm spinning the 3 knife cutter head at 5,500 RPM, the motor is 3,600 RPM, the motor balance is not great. The entire mount is supported by the bolts and bushings I pictured, I found a box of them when I went looking for something like that.
I used link belts on my mill drill and found the same thing but the sweet spots are much broader.
An idler pulley (or a roller like the serpentine belt tensioner on cars) on the slack side would be a good idea if possible, it's always the slack side that's a problem. If the lathe was mine I'd come up with a solution which has the motor mount horizontal rather than vertical, much easier to deal with and the rubber has a better chance of working.
You just have to watch the belts, it's easy to see.
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There ya go, perfect and not expensive - Versa-Mount Vibration-Damping Mounts
Notice that they specify compression and shear loads, that's why I'd mount the motor horizontally, put the mounts into compression.
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I get you, when I weld up my new lathe stand I think I will remove the motor from the lathe altogether and design an isolated motor mount on the stand.
AlanR's McMaster brochure shows the style I was referring to. They call it a sandwich , but most of industry calls 'em isolators. I do believe they come greater than 1/4-20 and most operate in shear. Kind of like some older auto motor mounts. A rubber biscuit between two fasteners.
Bumping this thread because I theorize that the vibration I am getting in my machine is impacting my threading, turning and facing. I will rule out whether this is a tooling issue (carbide vs. hss) this week. Where should the rubber washers go? Between the motor and the mount or the mount and the headstock? Any updates from the OP on this issue?
I'm trouble shooting some issues and am going to make some changes to my belts. I'm bumping this post looking for any more insights in the 6 years since this post. Still using the Fenner linked belts?