Grizzly G0602/G0752 Spindle replacement

Actually, yes I realize that probably anyone who read my post probably hasn't done this. That's why I mentioned that in my post. I wasn't trying to complain just stated a fact. And... I thought I could quote what Grizzly said so if anyone else was wondering about doing this there would be something for them to go to. I hope no one thinks I was complaining. Have a good day, Warren.
 
Hello Everyone, I finally received my test bar from India. I didnt have much time last night but I checked it out a bit. I noticed while checking it that i can pull on the spindle and the dial indicator seems to move about 2 thousands of an inch back and forth. Is this normal? I was thinking that wouldnt be good for accuracy... Do you think I need to tighten the pressure on the bearings I just replaced to get rid of any movement shown on the indicator? Otherwise it seems good even though it looks like I will need to adjust the headstock. Thanks for anyones time on this.
 
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Can you post a link for the MT4 test bar?
Thanks
 
> I noticed while checking it that i can pull on the spindle and the dial indicator seems to move about 2 thousands of an inch back and forth. Is this normal?

A few weeks ago I was examining the spindle on my King when changing chucks. I did indeed notice quite some play in it when I was attempting to jiggle it around my hands to test for play with the bearings, not too impress either.

However, keep in mind when in operation, the spindle only spins one way, (not back and forth like AC current), and has a constant load on one side only, not jiggled from all sides at once (lets ignore centripetal forces here). I think the effects are much more minimalized than one would think. At least this is my theory until some old-timer posts here and proves otherwise. Then I get to look like an idiot. :)
 
Yes, that could be to a certain extent... But, I was thinking what about when you put pressure on your piece of work with your tool as your cutting it, wouldn't that push it a bit making it be "out" more than it really should be and not always the same amount? Doesn't sound to accurate to me... but if this is how all, or most lathe spindles are.. so be it. I guess it can be worked with in that case.
 
Ok, if we really want to get technical here, your issue is even worse than stated. Reason being is there is a lot of flex going on, the cross slide itself has some give, even your toolbit itself has some flex (which often can impact your finish). In fact, even they ways themselves will flex and buckle during operation (you don't see it with your eyes).

The problem is rigidty, rigidity, rigidity. And is one of the reasons it is so dangerous to do a parting-off operation with a mini-lathe.

Each lathe has a different amount of flex when cutting, and even the same model will be out of tolerance to one another, simply due to difference in tightness of gib strips, length of toolbit, and other factors.

Here is the good news though, it doesn't matter too much once you've got the FIRST turning cut done. One thing all lathes have in common, is turning your dial 1/4'th of a mm for example, should advance the cut exactly that amount in comparison to the other cut previously. It doesn't matter how much give/flex there was previously. Each notch turn on the dial should be consistent in COMPARISON to the previous operation. This is because you are using the same machine and set-up.

Does this make more sense?
 
I noticed while checking it that i can pull on the spindle and the dial indicator seems to move about 2 thousands of an inch back and forth. Is this normal?
Are you talking about axial or radial motion? If axial, that seems to indicate a need for increased preload on the bearings, as the structure should be quite stiff in that direction.

Is there hysteresis in the motion? As in, does the resting position depend on the direction of the last-applied force? That would indicate a gap instead of just compliance, and would support a need for increasing preload.
 
Apprentice, thanks for the response, I do understand about the lathe needing to be very rigid , etc for perfectly accurate cuts. Thing is if the whole lathe did not flex at all ( I know they all do some :) ) then with the spindle moving side to side, or top to bottom you wouldnt get accurate cuts because it would move with the pressure of the tool against the work seems it would make a taper cut... furthermore it would move differently with different pressure. I can work with the material flexing when the tool is puttng pressure on it, that seems workable but seems if the spindle changes just by pulling or pushing a bit on it that would be hard to compensate for. Anyway, just trying to find out if all spindles do this or if trying to preload the bearings more might make it less of a movement of the spindle..

Jwmelvin, Thanks for your response also, it seems to move sideways back and forth and probably up and down too if you push or pull on the spindle a bit. Dont really have to push hard but it seems to be no more than 2 thousands of movement. Was thinking of trying more preload only I didnt want to put to much either. I will need to check and see if after pushing or pulling the spindle it stays there or moves back to the original position.

Maybe im worrying about something I shouldnt, guess I will experiment some. Thanks.
 
After setting up the headstock alignment, and tailstock I started doing some cutting with the lathe. I am noticing the lathe making a lot of noise when I am cutting the outer end of a 1 1/4 " rod furthest away from the chuck and it seems to be chopping the metal abit also. I am thinking it has to do with being able to move the spindle back and forth by that .002 or a bit more. If anyone has the time I was wondering if you might put a indicator on your spindle and see if it moves or how much it moves if you put some hand pressure on it back and forth, side to side (push towards the opposite side your on then pull towards you) and let mw know how much your spindle moves. I will probably see about tightening the load on the bearings to see if it helps but your input would help. I don't want to put to much preload on them if I can help it. Thanks in advance.
 
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