G4003G Lathe Help needed

Hello The thread that Steelhead refers to inserted anti vibration pad (cork sandwiched between rubber) this material is used between the motor and lathe, it works. Yes you can further reduce vibration with a 3 phase motor and VFD as stated earlier. I did this to a china lathe I have it did improve greatly, however it does not cut like the Southbend 13X40. So lesson as always cry first or second it is always our choice.
 
Question: in this lathe, is the pulley directly attached to the motor shaft?
 
This is coincidental, I am going through the same thing. I have this pattern showing up on my lathe (4003G). Mine is not near this bad, but I'd like to see it go away just the same.
I thought it was some type of phase issue from the motor through the gears. I thought that using better bearings might hide or dampen the effect. I started a thread over on 6mmbr. A fella there told me this was called "Shleshinger normal", says it's related to how many and what type bearings are used in the head stock.
I don't think I will make the major type mods to resolve. Just bearing replacements with a higher ABEC rating. Like you, I have my eye open for American iron. But for now, my machine works fine and since I learned of vipers venom my cuts look a lot better. I grind my own tooling and it doesn't take long to figure out an angle needs to be better. I use the Warner tooling that Bob Pastor promotes as a gage to match my grinds.
I have noticed that running a loose belt as suggested helps. I had a nasty vibration show up and as pointed out here, it was a set screw coming loose. Tightened it and that problem solved. I think with a little tinkering these machines can run real good.

Now, to learn more about ceramic bearings.
Jim
 
Simple $2 fix, similar to rubber motor mount alteration but much more extensive because it stabilizes all imbalance and oscillation anomolies from the motor, headstock, gearbox, pulleys, chucks, and spindle.

Due to the high top heavy design of these types of benchtop lathes, any imbalances and oscillations are greatly magnified but can be simply damped and eliminated by attaching a perpendicular support strap between headstock/bed area to an exterior structural support like the vertical 2x4 in the following photo;


M1870102.jpg
 
I think some did not read everything from the top, I do it as well. There is only one grade of bearing made in this size, it is not possible to buy a better grade (ABEC rating) of bearing in some sizes, like this one, according to Timken and NSK. The wavy cut in the picture is with the new bearings, as it turned out I did not have then tight enough and with a more correct pre-load I got the right hand portion of the example, much better. As Jerry pointed out, I don't know how to grind tools so this is some of my problem. I am going to bolt it to the wall as Don suggests, can't hurt.
 
Ian, I bought a heavy (just over 2000lbs) Jet GH-13x40W in 2005 and had issues similar to yours. I got the single-phase model, which uses a chicom 3hp motor. There were multiple problems with this machine, but when the 'local' (180+ miles away) JET dealer brought a mechanic out to deal with vibration, one of the first things he checked were the OEM 3 & 4-jaw chucks. Neither chuck seated correctly on the D1-4 spindle nose, and his comment was "These chucks aren't worth the powder it'd take to blow them up!" They took both chucks with them when they left, and UPS left two new BTC chucks at the back door two days later.

That helped, but less than a year after I'd purchased the lathe, the single phase motor crapped out. Jet didn't have a replacement motor in stock here in the states, so they credited me $300 towards the purchase of a motor of my choice. I decided to switch to a 3-phase, and use a VFD to run it. It took some changes to the machine's wiring, but I've never regretted that decision. Also installed new U.S.-made drive belts at this time.

The last thing (should've been the first thing) I changed was moving the lathe about a foot to the right - I'd set it up in my attached 3-car garage, which had the floor poured in three slabs. I'd had the headstock set up half on one slab, and half on the next. The mechanic had pointed this out to me a couple of years before I was forced to deal with the issue (bought a Haas TM-1 and had to move both lathes & knee mill to make room for it), but I was too stubborn/lazy to move it until then.

It runs pretty smooth now, and I can do decent work with it. But everytime I visit someone else's shop and find a fine old American lathe, I can't help feeling a good deal of envy....
 
I had a Lux Matter Taiwanese lathe that had the same patterns after turning. Chris Self finally chased it down to a motor that was out of balance. Had it balanced and everything was fine.
 
Another thing you should check is you tool angle to the job. If the tool cutting edge is at 90 degrees to the centreline of the lathe it will have the least cutting force pushing across the lathe and the most cutting force towards the chuck .
As you angle the cutting edge more going in the direction towards parallel with the centreline and the cutting point , pointing back to the tail stock you increase the cutting force acting across the lathe. Too much angle in this regard can bend the job and cause rough finish as the job is constantly trying to move away from the cutting edge because all the cutting force is directed that way. Somewhere between the two extremes is a good angle to cut at and the thinner the shaft diameter the more you need to move the cutting edge angle towards the 90 degree position.
 
I also have a 4003 lathe. i am not having any problems so far or at least I am not aware of any and I know you pretty much get what you pay for but want to upgrade before the problems start. I also know this has been discussed many many times before and really hate to ask but i am in the market now. I want a good dependable accurate lathe as everyone does. Any suggestions on alternatives.
 
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