# X axis on a G0704



## Gman45acp (Sep 19, 2014)

I am setting up a used G0704 and while squaring the vise to the table  along the X axis with a indicator touching the back of the vise I am getting .0015 movement on the Y axis as the vises moves along the indicator.   Any idea what might cause this

gman45acp


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## chuckorlando (Sep 19, 2014)

Might try adjusting the gib.


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## JimDawson (Sep 19, 2014)

Either the vice is not square with the table, the Y gib is loose, or there is a lot of backlash in the Y leadscrew.

Try locking the Y axis when you are indicating the vice.  If that stops the movement then it time to take a look at the Y axis.  If not, then the vice is out of square with the table travel.  If you are relying on keys attached to the base of the vice for precise alignment, just remove them and then dial the vice in.


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## wrmiller (Sep 19, 2014)

Gman45acp said:


> I am setting up a used G0704 and while squaring the vise to the table  along the X axis with a indicator touching the back of the vise I am getting .0015 movement on the Y axis as the vises moves along the indicator.   Any idea what might cause this
> 
> gman45acp



You say "with a indicator touching the back of the vise". Where are you indicating, exactly? Is it a milled/ground surface? Is it a continuously increasing or decreasing displacement on the indicator? 

Bill


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## tmarks11 (Sep 20, 2014)

Gman45acp said:


> I am setting up a used G0704 and while squaring the vise to the table  along the X axis with a indicator touching the back of the vise I am getting .0015 movement on the Y axis as the vises moves along the indicator.   Any idea what might cause this



We need a bit more clarification on the process you are following.

the correct way to zero a vise:
1. align the vise square to the table slots as close as you can, 
2. tighten down the right bolt, gently snug the left bolt
3. Starting with a DTI in a holder attached to the quill at the right side of the vise, with the DTI riding on the *inner face of the FIXED jaw of the vise
*4. Move the X axis so the DTI sweeps the vise to the left side of the vise
5. tap the vise gently with a plastic hammer until the error on the DTI reached zero. It is common to have 0.030" or more error in alignment at this point.
6. Repeat the process until you are within 0.002".

is that what you are doing?
The slots on the table don't actually have to be squarely aligned. You align the vise to the quill and the travel of the table, not the slots in the table.

You must be using the fixed jaw of the vise for alignment.



Gman45acp said:


> I am getting .0015 movement on the Y axis as the vises moves along the indicator




EDIT: i misread your post, thinking you were talking about 15 thousandths variation (0.015").

If you are talking about 1.5 thousandths of an inch (0.0015") than you are done. You can dial it in closer (I can get it to less than 0.001), but it is really kind of a waste of time. The mill will deflect at least that much during normal operation. If your operation requires you to be accurate within 0.001", than you are using the wrong machine (surface grinder will get you within 0.0002" without much effort)


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## chuckorlando (Sep 20, 2014)

I aint a big fan of locating keys on my vice. They are fine if they are on the money and a huge pain if they are not.


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## wrmiller (Sep 20, 2014)

chuckorlando said:


> I aint a big fan of locating keys on my vice. They are fine if they are on the money and a huge pain if they are not.



+1 here. I snug down one side, run the dial back and forth a few times and I'm done. Usually within a couple minutes or so.

Bill


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## Gman45acp (Sep 27, 2014)

Thanks for the replays.. I have the vice square with the quill.   As I run the di across the ground fixed jaw of the vice the di deflects + and - from one  half to three quartersof a thousands as I am turning the handle of the x axis.     Is that normally for a grizzly mill?

Thanks


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## wrmiller (Sep 27, 2014)

I have a repeatable .0005 bulge in the center of my fixed jaw on an import vise. I was getting all concerned and started thinking of how I'm going to fix it, when I stopped at thought about how small that is, regardless of how much deviation I see on a super accurate di. So I set my calipers to a half thou and tried to see the huge gap I was envisioning. I very quickly started laughing and promptly lost all concern about that 'huge' bulge in my fixed jaw. Seriously? I doubt the specs on my import vise are any better than what I'm seeing.

What make is your vise?


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## tmarks11 (Sep 27, 2014)

Gman45acp said:


> Thanks for the replays.. I have the vice square with the quill.   As I run the di across the ground fixed jaw of the vice the di deflects + and - from one  half to three quartersof a thousands as I am turning the handle of the x axis.     Is that normally for a grizzly mill?



So what you are saying is that if you dial in your vise, so both ends are at 0.0000" relative to each other with the DTI, you are seeing a bulge  (like miller said) in the middle of the vise as you run the DTI down it?  Or do you think the table is shifting during travel, making the DTI oscillate?

Either way, 0.00075" is way beyond the accuracy you should expect from the machine.  A good quality bridgeport, a much larger more capable mill, is generally only considered good for an accuracy of 0.002". Yes, I know you can get better (and I have), but it requires a care and feeding beyond what is reasonable.


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## Gman45acp (Sep 29, 2014)

I have the  di touching the fixed jaw on one side to the four inch vice jaw.    Every turn on the crank moves the x axis .100 and during every turn on the x axis there is no movement of the di for .060 and the on the last .040 of the turn the di moves +.00075 and then returns back to zero.   This happens on every turn of the crank.   Why would it run true for 2/3 of the travel then move off for the .040 and then return. I probably am expecting to much from the mill but would like to know why this happens

Any ideas


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## wrmiller (Sep 29, 2014)

Woa, that's not what I was describing on mine. I have no idea what that is other than maybe a bent lead screw?


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## tmarks11 (Sep 29, 2014)

You could start out by tightening the X-axis gib (look on page 41-42).  You have tapered gibs with an adjustment screws on both ends.

I also suspect that Bill is right, your lead screw is slightly warped, and it is causing the table to deflect in the y direction.  Tightening your gib may solve this problem, but for that slight amount of movement, it probably isn't worth it. 

To be blunt, you are expecting too much. You are talking about less than a thousandths error. Even a $15000 bridgeport is only going to give you accuracy to 0.002".  The machinists I trained with said trying to exceed that accuracy is a waste of time unless you really have a critical part (and that is where cylindrical and surface grinders come into play).

If I push on one end of the table on a bridgeport, I get 0.001-0.002" deflection.  Cutter deflection under load can cause a similar amount of error (ie. 0.0005".)


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## chuckorlando (Sep 29, 2014)

Have you tried adjusting the gib? Might have a bend in the screw.


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## Contract_Pilot (Sep 29, 2014)

Bent lead screw! I had mine replaced under warranty! Easy to check remove screw and roll on flat surface!


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