Grizzly 4003G Lathe Chatter Problem

Since I'm in an unfortunate lathe-limbo at the current point and time and find myself with an additional bit of knowledge, I figure I'll share it with the masses! Here's a short write-up of how to take the spindle out of a G4003G lathe. I wasn't planning on turning the project into a post, but since I find myself with a few pictures and a serious lack of lathe work to do...you get it...

So first and foremost, there is a cover on both ends of the spindle, these both need to be less attached to the machine than they are shipped as. The rear spindle cover comes right off with four screws, underneath the cover there should be two nuts for the spindle. Mine has one nut that is a funky split deal with two set screws. This comes off by loosening the set screws and with the persuasion of a hammer and chisel. The manual states that either this method can be used or ideally, use a spanner that is the appropriate size or build one. The front cover can not be completely removed at this time because it is sandwiched between the chuck mount and the machine.

IMG_5230.JPGIMG_5249.JPGIMG_5251.JPG

From here, we need to remove the cover of the gear box, drain the oil and stair in aww of the massive glitter show that is awaiting us at the bottom of our gearbox. It's worth noting that I followed all the steps when I first got my machine to flush all the metal shavings out of the gearbox, and yet they still remain in large numbers...

IMG_5257.JPG

There is also a snap ring that retains the three gears closest to the chuck of the machine. This needs to be removed from it's groove and shifted over.

At this point in time a hammer and a block of wood are required. Give the outside end of the spindle a sharp whack with the block and hammer combo to introduce a little bit end-play. Once you feel some endplay, continue giving the spindle some love. After an inch or so the back bearing should fall right out. Make sure put something between the spindle and bearing race if you plan to reuse those. A few more taps and the front bearing will be separated from it's race, once again protect your race if need be.

At this point the largest gear is the only thing holding you back. Keep tapping away and soon enough the large gear will slide freely. Your spindle is free!

IMG_5263.JPGIMG_5261.JPGIMG_5260.JPG

Sorry about the sideways pictures...

Make sure to note the order of gears and also be careful of the keyways in the spindle, they were loose in mine and were ready to fall out. It's also beneficial to note the orientation of the keyways.

This is a fantastic opportunity to completely clean out your gearbox of it's floor decorations.

My bearing races were warn quite unevenly and had a few fairly deep scratches in them. The shavings had their way with them apparently. My bearings were also warn slightly and had a few scratches in them. Nothing that screamed "super chatter" though...

IMG_5266.JPGIMG_5262.JPGIMG_5267.JPGIMG_5269.JPG

Here are the details of one of the bearings, I didn't take a photo of the other apparently...

IMG_5271.JPG

To get the bearing off the spindle a press was used, I was able to lay the bearing cover on my press blocks and press strait down to get it off. All went well without a hiccup.

I also took the races off because If I was replacing the one thing, might as well cover everything. These are simply tapped out via a punch and hammer. Just walk the punch around the perimeter and it comes out fairly easy. I was surprised by how horrible the finish and material was under the races...

IMG_5273.JPGIMG_5272.JPG

From here, a brand new set of bearing and races was purchased. Timkens were my nearest choice so I went with those. Interestingly enough, one was made in Poland and the other in Italy. Quite the different location from the US, which is where I was told they were made by the bearing professional. Details in the picture...

IMG_5284.JPGIMG_5283.JPG

I threw the races in the freezer for a few hours and they popped right into their appropriate holes without fuss. The larger bering needed to be pressed onto the spindle so I used the old race as support and on it went. From here is the hardest part for me. The spindle is reinserted into the gearbox and the gears are place on, the largest gear is a very tight fit so it needed to be persuaded all the way on by a small brass hammer. Little by little it went on.

This was probably the most time-consuming also because it's in such a hard to reach area. But after awhile its on. Then get everything in place, REAPPLY THE SNAP RING, and put the outer bearing in place, followed by the bearing nut. Then adjust the preload, seal everything up and enjoy your fantastic new bearings accompanied by your spectacular new finish!

IMG_5294.JPG

Wait, What? Crap!! Well if you look closely you can see that my finish is still poo and it sounds of a faint screaming child...
Anywho, the procedure is the same whether it fixes your problem or not! Let me know if I left anything important out, I can always post more details or additional photos.

Enjoy!





IMG_5230.JPG IMG_5249.JPG IMG_5251.JPG IMG_5257.JPG IMG_5260.JPG IMG_5261.JPG IMG_5262.JPG IMG_5263.JPG IMG_5266.JPG IMG_5267.JPG IMG_5269.JPG IMG_5271.JPG IMG_5272.JPG IMG_5273.JPG IMG_5274.JPG IMG_5283.JPG IMG_5284.JPG IMG_5260.JPG IMG_5294.JPG
 
Thanks James, I was hoping it was easier than that but educational. Is that electrical cord clamp on a clump of loose wires instead of the outer cord jacket?
 
:whiteflag: <---- perhaps I'll post a full write up with pictures of the process if anyone is interested.

Also...Anyone interested in a used Grizzly 4003G Lathe? :lmao:


I would like to see that,thx !
 
When you did the new bearings did you do a runin. Run with no load for a couple of hours the let cool and retightin the bearings. I always do that for spindle bearings.
 
I hope this doesn't come across the wrong way but, by any chance did you have a head crash or change a gear while the unit was spinning fast or under load? Less likely but worth asking, did you ever stomp on the brake pedal while turning a heavy piece of stock? Have you ever had a lockup of the side gears? These or similar events could lead to a bent spindle or some other shaft in the system. Any shaft that's riding on two bearings needs to be drop-dead straight. When spun by hand, does anything feel unusual -perhaps a tightness followed by a smoother feeling during one complete revolution of the spindle? How do the teeth look on all the gears; did you inspect them very closely? Does any gear appear to have skewed teeth? Does any gear appear to have an uncentered hole? When run without a chuck installed, does the machine show (or have audible sound) of any kind of cyclic vibration or rhythm?

Also, as far as the split collar to lock the spindle... that's actually a good mechanism -better than a collar with a set screw that digs into the threads. It's also more precise (and a little more expensive) than a double-nut collar -which is harder to adjust the preload.

Ray
 
Ray I believe he said its never been damaged. I think KD is on the right track, immediately after the bearing replacement the chatter went away, then after light use it returned. Like KD I'm wondering if he did a run in then reset the preload again because if it loosened up a bit again it makes sense that the chatter would return. Agree with you the split nut looks like an upgrade over a couple spanner nuts.
 
Thanks James, I was hoping it was easier than that but educational. Is that electrical cord clamp on a clump of loose wires instead of the outer cord jacket?


Hehe, About that.... :whistle:

I promise when I originally wired it that it was supposed to be temporary!

Last year when I went to go help my Dad rewire some of his rental homes I walked into the room and he immediately yelled, "Shhh! Shhh! don't move!" Then he pointed at an extension cord that had been stripped and each wire independently jammed into an outlet. "I ran out of plugs." He claimed..."It's only 120 anyways"!

While I usually try to abide by all regulations and common sense when it comes to wiring, sometimes I fail...then post it on a forum and feel a little bit silly!
 
Ray I believe he said its never been damaged. I think KD is on the right track, immediately after the bearing replacement the chatter went away, then after light use it returned. Like KD I'm wondering if he did a run in then reset the preload again because if it loosened up a bit again it makes sense that the chatter would return. Agree with you the split nut looks like an upgrade over a couple spanner nuts.


I may have mistyped, But after the bearing replacement nothing changed. I believe that I wrote that it made my machine run a little quieter, but the chatter still remains.

I ran the machine for 20 minutes at it's highest speed with the preload set. Then went back an hour or so later to retighten. I immediately noticed some addition resistance when spinning the chuck, which told me I was at too much preload. I did some turning at this setting and the chatter remained.

All this leads me to believe that I might be able to completely negate the spindle, bearings, and preload from the equation. Maybe...

Anyway heres where I find myself now...

image.jpeg

This is 316 SS, while it is a hard material, I used to get very smooth and almost mirror finish results with my current setup. This was a carbide insert tool at 600 rpms running .0044 in/rev. I would expect the lines in the material at a higher feed rate, but if you get up close and personal to the photo, you can also see small chatter marks...those I don't expect at any speed with a proper setup. There is also a quite squealing on the material. Oddly enough, my finish is even worse in aluminum.

Hey coolidge, want to take the 9-hour round trip and come fix my lathe for me? :))

image.jpeg
 
Do you have any viberation in the lathe? Have you moved the lathe location or added enything. Any new equipment with large power transfomer running. If nothing has changed use the live center cranked pritty tight. If you still have chatter then it is in the too down squealing is usley tool set above center or dull. aAlso try 200 to 300 rpm 600 might be to fast for 316.
 
Back
Top