# Grizzly G4003G - Installed rubber motor mounts, fixed motor alignment, pulley, wiring issue



## coolidge (Apr 17, 2014)

I made some more improvements to my G4003G lathe by fixing some quality issues and installed some thick rubber washers to dampen vibration from the motor. Lets start with the quality issues...

Notice how far the pulley sticks out on the shaft, pretty lame.




Here's another pic, unacceptable imo PLUS the pulley was bored so poorly it wobbled a like it was made of jello. Luckily the replacement pulley arrived from Grizzly today 2 weeks earlier than expected! Replacement pulley was straight and true.




Here's why the pulley was sticking out so far on the shaft, the factory drilled the mounting holes too far to the left so the only way they could align the motor pulley to the spindle pulley was to hang it out off the end of the motor shaft (facepalm) Also note how they snaked the two cables through this mount e.g. between the motor and the motor mount, I re-routed one of these above and the other to the left of the motor, this allowed me to bolt the motor onto this motor mount while on the work bench WAY easier.




Here I have re-drilled and tapped the motor mount holes 5/16-18 relocating the holes about .400 inches towards the headstock. I also picked up some large 1/8 inch thick rubber washers at my local hardware store to dampen any vibration from the motor, I added smaller 5/16 rubber washers between the mounting bolts and motor, I used some grade 8 bolts I hand on hand. I have read where a few guys have isolated the motor from the lathe with rubber and this improved finish, meh I figured it couldn't hurt while I had everything apart. Also for the three large bolts that bolt this mount to the lathe, the CHINA washers were not so great, one was already bent inwards into the slot from the factory. I picked up some grade 8 thick washers to replace them.




This was the next quality issue, I had to unwire the motor to remove it, see the red wire lower left its missing a washer. I wondered why this wire was loose during disassembly, I found out later without the washer the screw bottoms out in the hole leaving the wire loose. I added a washer to fix this.




Here I'm using my digital angle gauge to align the motor parallel to the spindle pulley shaft, this tool makes it easy. I used a wood block and some wood shims to hold up/position the left side of the motor while I set the belt tension and tightened the right bolt. I also aligned the pulleys vertically.




Certainly closer than I could have eyeballed it. Notice how much farther onto the motor shaft the pulley is now, its nearly flush with the end of the shaft.




Buttoned everything up and celebrated with a cold beverage.


----------



## darkzero (Apr 17, 2014)

Good job. Curious about the rubber washers you used for the motor. Have you tested it & seen an improvement on finish?


----------



## coolidge (Apr 17, 2014)

Darkzero I have not tested it yet, finish so far has been 'okay' not exactly mirror like. Most of the reports I read where guys isolated the motor was due to poor finish when threading and in testing threading on my machine the finish was in fact not very good, but I was using the brazed on 60 degree bits during those tests I have an indexible threading tool now which I have yet to test. I'll get around to testing this over the weekend.


----------



## Dog (Apr 17, 2014)

I have been through this with this model lathe. The problem with using rubber to isolate the motor is it will compress and not do much except make your belt adjustment not hold. I ended up using this http://www.mcmaster.com/#standard-vibration-damping-pads/=rkru19 These pads are used for setting machinery on and don't compress much. I also had to install new bearings and balance the motor. That finally got the finish to acceptable but what a pain in the butt. Good luck. 
[h=3]High-Capacity Oil-Resistant Nitrile Vibration-Damping Pads[/h]


5940K51

High-Capacity Nitrile Vibration-Damping Pad, Oil-Resistant, 12" x 12" x 1/2" Thick, 1500 PSI Cap


----------



## coolidge (Apr 17, 2014)

Dog these are dense heavy rubber washers they did not compress much, others I found were too soft though.


----------



## AlanR (Apr 17, 2014)

To really use rubber washers for vibration damping you need them on both sides of the motor mount. I have some specially made mounts and bolts, there's a upper rubber washer and a lower. They have a stepped, reduced diameter that fits into the motor mount so there's no metal to metal contact at all.

These were originally used for sewing machines, we had a bunch of them.

I'll try to post a picture later on.


----------



## AlanR (Apr 17, 2014)

Here's a picture.




Nothing to stop you from using two short ones except for the length of the bolt.

In this picture I believe I have the rubber mounts reversed. The bolt (a fancy carriage bolt) goes through the table top and the motor hangs below. I used them with the long rubber part below the motor mount, I figured the weight of the motor needs the most cushioning, they're pretty soft. I used nylock nuts.


----------



## drs23 (Apr 17, 2014)

Well this is perfect timing. The motor on my G4003G died Monday. After jumping through the hoops Grizzly Tech Support put me through to determine it was actually a bad motor like I had been telling them for two days they're shipping a warranty replacement.

coolidge,

I found my motor pulley out about that far as well with the key sticking out an inch or so past the face of the pulley. Also found the setscrew completely missing. That must be the screw I found floating around when I uncrated it originally and couldn't find where it went.

Have you reassembled your motor/lathe yet? If so, can you tell any difference or enough difference that it made your mod effort rewarding?

I also noticed you installed NAPA belts in lieu of the factory installed Gates. What was the reasoning behind this. I ask because I was considering going back with adjustable link belts. I used some on an Atlas I used to have and it make a noticeable difference.

AlanR,

Where did you score your specialty thru-damper bolt. That sounds very intersting. Are they still available? If so, where? I've got the rubber washers that Dog mentioned on the way from M/C as of now.

Thanks for posting guys. Great timing!

Dale


----------



## AlanR (Apr 17, 2014)

drs23 said:


> Well this is perfect timing. The motor on my G4003G died Monday. After jumping through the hoops Grizzly Tech Support put me through to determine it was actually a bad motor like I had been telling them for two days they're shipping a warranty replacement.
> 
> AlanR,
> 
> ...


I'm in an old sewing plant and there's tons of stuff kicking around. I have no idea where they came from but I'd bet a sewing machine parts supplier would know.

You might find the rubber pieces at mcmaster.com You can make your own metal parts.


----------



## coolidge (Apr 17, 2014)

AlanR said:


> Here's a picture.
> 
> View attachment 74666
> 
> ...



Alan this is what I have done, the large rubber washer on one side and not known in the pics is a smaller rubber washer under the bolt head and washer. My machine seems to run smooth the motor seems balanced so I didn't feel the need to go with thicker dampeners that could dampen a shaky motor. Mostly I was looking to insulate from the motor to avoid any high frequency vibrations or harmonics. I think replacing the motor pulley will do more than these washers since that was the component out of whack.

- - - Updated - - -



drs23 said:


> Well this is perfect timing. The motor on my G4003G died Monday. After jumping through the hoops Grizzly Tech Support put me through to determine it was actually a bad motor like I had been telling them for two days they're shipping a warranty replacement.
> 
> coolidge,
> 
> ...



Reassembled it last night but not tested, I'll fire it up this even and report back. I took the time to align the pulleys both parallel and vertically I think that's important. Sounds like your motor was mounted just like mine, half assed. On a scale of 1 to 10 this was a 2.5 in terms of irritation, odd as it sounds I almost enjoy taking this CHINA stuff apart and improving it. I tossed the China belts on a shelf mostly because I was taking this apart and spending the time to align everything well I figured just go with some good quality made in USA belts. Hopefully I won't have to mess with this again for years. Napa had these in stock by the way, its a common size. They have a variable cog size design, wide, medium, narrow I guess to cut down on vibration. A link belt would probably be better even these are stiff, they have broke in some but still have a bit of set in them.


----------



## visenfile (Apr 18, 2014)

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.


----------



## drs23 (Apr 18, 2014)

visenfile said:


> 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.



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?


----------



## JimDawson (Apr 18, 2014)

drs23 said:


> 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.




You might take a look here:  http://www.mcmaster.com/#vibration-isolators/=rlare3


----------



## darkzero (Apr 18, 2014)

coolidge said:


> Darkzero I have not tested it yet, finish so far has been 'okay' not exactly mirror like. Most of the reports I read where guys isolated the motor was due to poor finish when threading and in testing threading on my machine the finish was in fact not very good, but I was using the brazed on 60 degree bits during those tests I have an indexible threading tool now which I have yet to test. I'll get around to testing this over the weekend.



Thanks, I don't have that issue but I am still curious & will follow this thread.




drs23 said:


> 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?



I don't have a G4003G but on my PM1236 I am using 1/2"/4L Fenner belts.


----------



## AlanR (Apr 18, 2014)

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.


----------



## AlanR (Apr 18, 2014)

JimDawson said:


> You might take a look here:  http://www.mcmaster.com/#vibration-isolators/=rlare3



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.


----------



## coolidge (Apr 18, 2014)

AlanR said:


> 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*.



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.


----------



## visenfile (Apr 19, 2014)

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.


----------



## TX COWDOC (Jan 3, 2021)

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?


----------



## TX COWDOC (Jan 5, 2021)

darkzero said:


> Thanks, I don't have that issue but I am still curious & will follow this thread.
> 
> 
> 
> ...


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?


----------

