# G4003g Owners, Would Like To Compare Backlash



## HitFactor (Jan 15, 2016)

I setup my G4003G a few weeks ago. This was an upgrade from a G0602 I bought last spring. I have to say I'm really impressed. I thought the G0602 was pretty good, but the G4003G is even better.

I have everything cleaned and adjusted. Installed a DRO PROS EL700 3 axis on it. BTW, super support from these guys.

Here are my questions.

There is .018 backlash on the carriage handwheel. It's all inside the apron. How much backlash do other G4003G show?

If this isn't normal, can you point me at where the problem might be?

I took out the main bolts in hopes of getting a look inside the apron gearbox. Well it wasn't that simple so I buttoned it back up. Does anyone know the steps to get in there? An overview is OK, I'm trying to figure out how much time I need to set aside.


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## Chipper5783 (Jan 15, 2016)

I have two lathes, an 11" and a 15".  Both are respectable machines.  Both have 0.03" backlash on the carriage hand wheel - I don't see it as a problem.  Unless you can get it to zero, then you'll have to manage backlash - same as the cross and compound screws - managing backlash is part of machining.

The 11" lathe (a Smart & Brown 1024) had a lot more - about 0.1" when I got the machine.  I ended up taking the entire apron apart to address several issues.  This machine has quite a complicated apron, I learned a lot.  The carriage traverse is a pinion engaging a rack.  The bushing supporting the pinion was worn, as was the pinion shaft - I made replacements for both components. I think I got a good result.

The backlash on your machine is much less than mine.  I'd say use the machine as is.  It is probably fine.


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## Bob Korves (Jan 15, 2016)

It does not matter whether you have .018" or .002" of backlash, you still have to deal with it.  Yes, it is better to have it less, but not better by much.  I do not use the handwheel dial much on my Kent USA (Chinese!) KLS-1340A lathe.  The graduations and distance per revolution are pretty ugly to keep track of.  I use a magnetic back indicator stuck to the ways instead to keep track of travel.  When the backlash might interfere with a rigid cut, I lock the carriage.  End of problems.  My lathe, which is like new, has .020" backlash in the carriage handwheel.  I do not believe there is any simple way to reduce the backlash there.  Just deal with it by always moving in the same direction to your mark and making sure the backlash is out in that direction.  Works for me and for lots of other machinists.  Backlash is just a fact of life...


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## Hex173t (Jan 15, 2016)

I have the G4003G lathe and my carriage backlash is ~.027".  No worries.


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## coolidge (Jan 15, 2016)

My G4003G has .018 backlash, its meaningless since I have an EL400 DRO installed and feed against the backlash. The carriage dial scale of .010 per graduation makes it more meaningless as does the course 'thread' of the feed mechanism e.g. its not exactly designed for precision feeding on Z. With the DRO I can turn to +- .0003 on Z.

Now my headstock is leaking oil onto the motor that is annoying. I also have the dreaded motor harmonic pattern showing up on turning and facing cuts like some other G4003G owners have reported. I ordered a made in the USA 2hp Baldor motor to replace it today, should be in Tuesday.


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## abrace (Jan 15, 2016)

coolidge said:


> Now my headstock is leaking oil onto the motor that is annoying. I also have the dreaded motor harmonic pattern showing up on turning and facing cuts like some other G4003G owners have reported. I ordered a made in the USA 2hp Baldor motor to replace it today, should be in Tuesday.



Would love to see some pics of the motor and your impressions of it after it is in.

I haven't even uncreated my G4003G yet but I am dreading the motor already.

Baldor makes a great motor


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## coolidge (Jan 15, 2016)

Abrace sure I'll posts some pics. I used to live near Hampton, NH small world. God I could rip into some lobster or seafood chowdah right now (stomach grumbles)


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## abrace (Jan 15, 2016)

Should have some decent seafood in Washington, I hope.

Hard to beat lobster though...no doubt. I live near Manchester, probably 35-40 minutes from Hampton.

Small world.


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## mksj (Jan 16, 2016)

The stock Chinese motors on these lathes sound to be real dogs. Coolidge surprised  you didn't go  with a 3 phase metric motor, they seem to work well and less than a single phase. 
http://www.hobby-machinist.com/threads/g4003g-going-3-ph-vfd.34549/


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## coolidge (Jan 16, 2016)

I would have gone with a 3 phase plus a full VFD conversion but I'll be selling the G4003G when I find a 1440 Logan 6565. It could be a couple years that Logan is a rare bird, the G4003G will meet my needs in the meantime. I'm sure the new owner will appreciate the Baldor motor upgrade.


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## tomh (Jan 16, 2016)

Bob pretty much summed it up!
Don't worry about the backlash, most all the lathes I've run had / has backlash in the carriage and the only places I've seen read discussion about it is on the net.  Most people never pay any attention to it, they just use a indicator or a DRO and move on.  The MTT class teaches the students to use a  uses a magnet back dial indictor when using the carriage.   I have the 4003g and  I am satisfied with it and  haven't had any problems that the others seem have had.
Either I'm lucky or I just don't pay ant attention to the little things .
Good luck and have fun  with the lathe.


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## HitFactor (Jan 16, 2016)

Thanks for all the replies.

This gives me more time to make chips without wondering if I should be taking things apart looking for something.

I have not notice any motor harmonics yet. Today I'll be cutting brass, I imagine it's going to show if I have a problem.


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## tomh (Jan 16, 2016)

If you don't look go for problems and you wont find them
If you find a problem go looking for a solution. Don't automatically blame the lathe. 
Most problems with finishes are from types of  metal /  feed / speed / tool  position or from the tool bit   geometry  ( not always but most of the time )


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## coolidge (Jan 16, 2016)

Lets have a look at the harmonic problem shall we...this first pic is at the finest feed, slowest speed 70 rpm with the thick rubber motor isolation washers removed. Wow that's ugly, its about half this bad with the rubber washers installed.



This is with the rubber washers installed, 3rd finest feed, 220 rpm.



This is at 800 rpm, finest feed and its still showing up.



Note the spiral pattern even when facing.



In testing this issue I ran at half a dozen different spindle speeds, three different feeds, light to heavy cuts, the spiraling is more severe to less severe but there on every combination. Yes I chucked up some aluminum also, same result.


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## JR49 (Jan 16, 2016)

coolidge said:


> Lets have a look at the harmonic problem shall we


Coolidge, and all, Don't have a lot of info about this, but I distinctly remember reading (don't know where, but it's been about 2 years) about someone who had the exact same harmonic problem with his Grizzly.  In fact your pics are what reminded me, they look similar.  All he did was to put pieces of 1 1/2" thick wood planks between the feet and concrete floor, and it cured the problem.  The reason I remember it so well is because that's why, when I built the feet for my Logan, I designed the 6"X 6" metal feet to also have 1 1/2" thick Redwood squares under them.  Don't know if its helping my lathe or not, but I figured, at that time, with NO machining experience at all, It certainly wouldn't hurt.  Quick side note to Coolidge,  your casters are great--Pics coming soon !  Hope this helps,  JR49


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## coolidge (Jan 16, 2016)

JR49 said:


> Coolidge, and all, Don't have a lot of info about this, but I distinctly remember reading (don't know where, but it's been about 2 years) about someone who had the exact same harmonic problem with his Grizzly.  In fact your pics are what reminded me, they look similar.  All he did was to put pieces of 1 1/2" thick wood planks between the feet and concrete floor, and it cured the problem.  The reason I remember it so well is because that's why, when I built the feet for my Logan, I designed the 6"X 6" metal feet to also have 1 1/2" thick Redwood squares under them.  Don't know if its helping my lathe or not, but I figured, at that time, with NO machining experience at all, It certainly wouldn't hurt.  Quick side note to Coolidge,  your casters are great--Pics coming soon !  Hope this helps,  JR49



This problem began when I had my lathe on 1 inch thick rubber leveling feet, in fact at one point I removed them and sat the lathe on the concrete to see if that would help, no improvement. Apologies to the author of this thread we are getting way off topic so I'll wrap up with this.

*Summary Findings:* The issue did not exist when my lathe was new, it appeared after about 15 hours of use which in my case spanned about 18 months as I was very busy with other things and only used the lathe occasionally during this time period. It has gradually become worse with another 10 hours of use. I have tried quite a number of tests and fixes, adjusting the gibs, resetting the preload on the spindle bearings, different speeds, feeds, depths of cuts, materials, etc. The only constant in this is the motor and the drive shaft the motor connects to. I had been thinking it was a bearing issue on the drive shaft, others on the forum felt the same. But recently I came across what appears to be a definitive test performed by someone else who owns this lathe and posted pics of very similar harmonic patterns, on both OD turning and facing. This guy disconnected his motor, left it off and spun the spindle with a big drill, the harmonic pattern vanished. To confirm he left the motor disconnected, but turned it on, again ran the spindle with a big drill and the harmonic pattern returned. So it seems to be traveling from the motor into the lathe casting. Another guy installed some industrial rubber spacers between his motor and the lathe, where there is no metal to metal contact between the two, he reported this did not completely eliminate the harmonic pattern, but it was like a 95% improvement. Anyway I'm going to try a new Baldor motor as my next step at fixing this.


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## Bob Korves (Jan 16, 2016)

coolidge said:


> This problem began when I had my lathe on 1 inch thick rubber leveling feet, in fact at one point I removed them and sat the lathe on the concrete to see if that would help, no improvement. Apologies to the author of this thread we are getting way off topic so I'll wrap up with this.
> 
> *Summary Findings:* The issue did not exist when my lathe was new, it appeared after about 15 hours of use which in my case spanned about 18 months as I was very busy with other things and only used the lathe occasionally during this time period. It has gradually become worse with another 10 hours of use. I have tried quite a number of tests and fixes, adjusting the gibs, resetting the preload on the spindle bearings, different speeds, feeds, depths of cuts, materials, etc. The only constant in this is the motor and the drive shaft the motor connects to. I had been thinking it was a bearing issue on the drive shaft, others on the forum felt the same. But recently I came across what appears to be a definitive test performed by someone else who owns this lathe and posted pics of very similar harmonic patterns, on both OD turning and facing. This guy disconnected his motor, left it off and spun the spindle with a big drill, the harmonic pattern vanished. To confirm he left the motor disconnected, but turned it on, again ran the spindle with a big drill and the harmonic pattern returned. So it seems to be traveling from the motor into the lathe casting. Another guy installed some industrial rubber spacers between his motor and the lathe, where there is no metal to metal contact between the two, he reported this did not completely eliminate the harmonic pattern, but it was like a 95% improvement. Anyway I'm going to try a new Baldor motor as my next step at fixing this.


Coolidge, check the drive belts for smooth running or having "oscillations."  Do they track smoothly and without flapping around?  The "fix" you posted also would have bypassed a belt problem, and an issue due to belt problems would likely come on gradually, a motor not so much...


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## coolidge (Jan 17, 2016)

Been there done that Bob, replaced the factory belts with Napa made in USA variable spaced cog belts, replaced those with made in Europe link belts. Ran it with only 1 belt vs 2. Speaking of which, for sale a bunch of G4003G belts hardly used lol.


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## Ianagos (Jan 18, 2016)

I had a very similar problem on the grizzly 9x20 lathe I had I never did figure that it was the motor. Hmm I sold it and bought another harbor freight version which was about 30 times better. May have been the motor. But I remember I changed bearings belts and messed with the lead screw but nothing ever cured it. These Chinese machines just don't have the mass to dampen it out. I do love the rumble that I hear when my pacemaker starts up.

Btw the carriage wheel on my packer has atleast .1 of backlash I've never cared to measure you should have no problem with that small amount of backlash.


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