Grizzly 4003G Lathe Chatter Problem

[Jamespvill]

When he first adjusted the preload on the stock bearing he said the chatter wen't away for a couple of days.At this point I would pull the spindle and set it up on V blocks or better yet make up a quick bench center and check it for runout at the taper if on V blocks or center if on bench centers. If the spindle is with in a few tenths than bearings would be the suspect. The number on the timpkin bearings come up as for power transmission and wheel bearings when I googled the numpers. A standerd class bearing.

In hindsight, I may have gotten over-excited at the time and overlooked some less-than-perfect finish at the time. It's probably best if we pretend that tightening the preload the first time did nothing... :whistle:

Anyways, I'm taking Sunday off to rest my tired noggin...I'll restart my trouble-shooting come monday. Enjoy your Sunday everyone!

 

[Jamespvill]

So today was fairly busy and I didn't get to tinker with my lathe until this evening. I decided to strip her down naked and inspect anything and everything. First I took some readings on my spindle though. On the outside end I have right about a half-thou of runout, same exact results on the chuck end. I didn't take any readings in between, but will soon.

Taking the carriage off was was a bit of a task, but nothing out of the realm of possibility.


I assumed that because the bed is ground to precise dimensions and finish I would assume that anything else sliding on it would share the same properties. Maybe this is the wrong thought process, because when I flipped the carriage over to inspect the finish I was very surprised...


It appears as though they took the "out of sight, out of mind" approach to this particular process. In short, I was not a very happy chappy when I saw this. I know what a properly piece of scraped metal is supposed to look like, this looks like a horribly cast hunk of metal that was ground the least amount humanly possible and then had a hammer taken to it in a fit of lathe-making rage. Perhaps I have no idea what Im talking about, but It appears as though this is not good for precision machine-work.

Out of curiosity I decided to cover everything with dykem to see where it was actually contacting. I put it back together, ran it up and down the bed a few dozen times and then pulled it off....


Im not sure If I should be PO'd about these results or not...But I am. While this isn't something that could have changed in the last few weeks to cause a deterioration in machine work finish, I still believe it's a problem. I took some 1000 grit sand paper wrapped around my buddies small precision ground block and went up and down the surfaces a few time to knock down the high spots a bit. I put everything back together and cut some aluminum, the surface finish was better. But still not back to it's original glory.

Im to the point where I feel like putting the dang thing up for sale, informing the buyer of it's shortcoming and buying something else...Maybe just hanging up metal for for good!

Not really of course! I love metal work, But I currently hate my lathe and may put it up for sale soon if it doesn't decide to stop being so pissy!

Anywho....on a less negative note; I made a bunch of aluminum chips working on a tool to cut down .223 brass, that was relaxing and made me happy. )

 

[coolidge]

I don't know James, a half assed attempt at way scraping? The idea behind way scraping is to create valleys for oil and reduce friction e.g. reduce surface contact points but that would have to be like the worst example of way scraping I ever saw. Honestly I would be sending a photo of that to Grizzly and require them to explain it. I'm tempted to pull my carriage off now and have a look.

 

[Ray C]

The truth is, that's the style of "scraping" you'll find on virtually all Chinese machines. When I had my unit apart last year, I checked mine with dykem too and if I had to guess would say it was giving 40-50% contact. And to be specific, one side was probably 40% and the other 50. In any event, that style of "scraping" is in-use on about 10,000 of these lathes per year -and has been for the past 15-20 years or so... The style is crude -but it works. If it was totally ineffective, these machines would have gone extinct a long time ago.

Things improve as you go up in price range of course and if you want better scraping, better look to a Taiwanese machine costing 25% more...


Ray

 

[Ray C]

I spoke with Matt about this and he thinks we've just about covered everything but, there are two more things to check. He had two difficult situations and it turned-out to be something very unusual...

He had one machine that had a bad motor. It seemed to run fine but under any load it had a vibration. I'm guessing one of the brushes or commutator was bad. -Replaced the motor, problem went away.

Another machine had a tiny piece of swarf stuck in the flat spot of one gear tooth. It wasn't much more than a grain of sand but was embedded in the tooth. It caused a vibration that showed-up in the cut. He picked it out, filed it clean -problem solved.

As for carriage scraping... The rear way path almost (figuratively speaking) doesn't matter. I bears almost no force under cutting pressure -matter of fact, most force is lifted off the rear way. Front ways always wear-out first because they bear the brunt of the forces. Every old worn-out lathe I've seen (many, many of them) the front way is worn badly and the rear looks almost brand new.

Ray

 

[chuckorlando]

I would not be mad about the scraping. Truth is a great hand scrap job would run half the cost of that machine. At least out sourced. I would say it's par for the coarse on all the less expensive machines. New or used US or China. There is only so much that you can get for a dollar.

It is a good opportunity to learn a skill. Least thats my goal.

 

[Dog]

I posted on a similar situation I went through with this model lathe a while back which manifested itself in the finish of the threads especially. Here is a copy of my post which may be of interest to you...

"I had a G4003 lathe and (for the money) it had a lot going for it. We should probably accept that at that price point perfection is going to be hard to come by. That being said there were serious (to me anyway) issues that need to be addressed. I too do gunsmith work from time to time and the most maddening thing was thread cutting. Vibrations would be transferred from the motor (which is mounted to the bed) into the work piece. I could get a pretty nice surface finish while cutting stock, but where it really had a problem was threading. The surface of threads looked faceted! (really bad) What eventually solved the problem was a combination of things. I had the motor rebuilt and balanced which helped some then isolated the motor on anti vibration pads. That finally got the threading to acceptable. If you do a search on this lathe threading is a common problem that guys struggle with. There were other things that needed to be sorted out but, unlike the threading issue, would generally come under the heading of sorting out a new lathe. In the end I sold the Griz. It just left a bad taste in my mouth after all I went through with it and I got a good deal on another lathe that I have been happy with. So, as with anything it depends on what your expectations are. You can’t expect perfection for the price Griz gets for these lathes. Expect the G4003 to be a “kit” with work needed in some areas and you will probably be alright. By the way, it’s not just Griz that has these types of issues with their Chinese lathes. A recent search on line about Jet lathes was a real eye opener for me."

 

[Jamespvill]

I'll try these last few suggestions this evening, I've got a dozen or so parts that I need to crank out on my mill then anodize.

I didn't think that my machine was the only one with this beautiful scraping, but it's just another thing that added to this whole adventure. Good point about all of the other machines having the exact same result workmanship, Ray.

I was always under the impression that the 4003g was made in Taiwan?

This lathe was absolutely fantastic for the last 1.5 year, and I was very satisfied with it, so any of my anger with it as of late may not be fully justified. Unfortunately these last two weeks have really left a damper in my party.

In the big picture of things, I suppose $3,100 is pretty darn cheap for a "man-lathe" maybe I'll upgrade to the $5,000 club.

Anywho....I'll post an update later in the day.

 

[coolidge]

James if you sell the Grizzly I recommend you get a Mori NL2000Y, then I could farm out some work to you. :ideas:

[video=youtube;zhkv-YjNdbw]http://www.youtube.com/watch?v=zhkv-YjNdbw&feature=player_embedded[/video]

 

[Jamespvill]

James if you sell the Grizzly I recommend you get a Mori NL2000Y, then I could farm out some work to you. :ideas:

[video=youtube;zhkv-YjNdbw]http://www.youtube.com/watch?v=zhkv-YjNdbw&feature=player_embedded[/video]

Now, now, I said I might be upgrading to the 5 grand club, not the 40 grand club! Although I can't deny the want to buy that.... I know matt over at Precision Mathews carries a CNC lathe for right around 16g. Maybe one day when I have the cash or a business plan with the ability to net all that cash back in a fairly short amount of time! Oh, but we can dream....