# Tramming a bench top mill.. Y-Axis



## Pcmaker (Mar 29, 2019)

I have a Precision Matthews PM-25MV mill and I've been working on tramming the X axis. I got it to a few thou from end to end of the table. The problem will be the Y Axis.

I put an indicator on the table, and from front to back, it's off by about 6 thou. Pretty much the only way to tram it is to add shims, which I'll be using automotive feeler gauges. The plan is for me to loosen the 4 allen bolts and add .006 worth of feeler gauge in between the front of the Z axis column. 

Any useful tips to tramming the Y-Axis of a bench top mill?


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## Groundhog (Mar 30, 2019)

I also used feeler gauges to tram my Syil X4+. However I could get a tenth or so just from torquing the front/rear bolts a little differently. It didn't matter how much planning I did, it took more trial and error to get it right than anything else.


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## rwm (Mar 30, 2019)

How exactly did you measure this?
Robert


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## Pcmaker (Mar 30, 2019)

Im thinking once I get the X axis trammed, I want to tack 4 small welds so it doesn't move again, then I can focus on tramming the Y Axis. I'll never use the adjustable head and even if I did, I can just grind off the tacks.




rwm said:


> How exactly did you measure this?
> Robert



Spindle indicator, measured the back of the table and moved the table to the back, watching the indicator move 6 thou


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## rwm (Mar 30, 2019)

I don't think that proves you have a error in the square of your column. That is a different problem. 
Robert


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## RJSakowski (Mar 30, 2019)

Pcmaker said:


> Spindle indicator, measured the back of the table and moved the table to the back, watching the indicator move 6 thou


What you are actually measuring is a non-parallel condition between the y axis ways and the table top.  If you think about it, the indicator in spindle is stationary while the table moves under it.  The indicator could be mounted on any external surface to make the same reading.

 One cause for this type of measured difference is loose gibs.  As the center of gravity of the table shifts, it can cause the table to lift and tilt.


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## rwm (Mar 30, 2019)

To check the Y axis squareness with the Z, use a cylinder square or precision ground square. Mount the indicator on the spindle touching the square surface. Then operate the Z axis and note the reading over the travel. If the Z axis is square you can then move the spindle feed and check the spindle squareness as well.
HOWEVER, if your Y axis is not parallel to the table top as RJ mentioned all bets are off. Tighten the Y axis gib and recheck that.
You could use a 2 dial tramming indicator however that will measure the sum of the Z axis error and and spindle error. You could theoretically have (for example) a 5 deg error in the column and a matching 5 deg error in the spindle and that indicator would read 0.
Robert


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## Pcmaker (Mar 30, 2019)

If I'm not mistaken, then does this mean that my work piece will be square even if the Y axis isn't? I'll just not get a good finish?

I don't have a cylinder square, just a regular machinist square. I'll mount an indicator on the headstock and run the Z axis up and down the square to see if the needle moves. Unless I'm misreading your post.


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## RJSakowski (Mar 30, 2019)

I have the problem with table lift on my Tormach 770.  I discovered it when I mapped my table surface.  The gory details are in post #2 in this thread: https://www.hobby-machinist.com/threads/g0704-accuracy-question.60622/#post-499447

To get around issues like this when tramming a mill, I mount a piece of aluminum to the table and mill the face.  If this is done with the table in a fully supported position, in an balanced condition,  and with tightened gibs,  Table tilt shouldn't come into play.  The faced surface should be parallel with the ways.  Tramming can then be done in the usual fashion to this surface.

As far as mill alignment goes, it differs with the type of mill.  My mill drill has a spindle in a quill for vertical motion.   The Tormach has a fixed spindle in a head which moves on vertical ways.  The G0755 mil has both vertical ways and a movable quill.  Knee mills accomplish vertival motion with the knee and a movable quill.  Proper mill alignment requires proper sequencing of the various adjustments.


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## ttabbal (Mar 30, 2019)

I can't offer any advice squaring a bench top mill. However, I would advise against welding, even tacks. The heat is likely to cause some movement, and with a precision surface even a little bit matters.


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## RJSakowski (Mar 30, 2019)

Pcmaker said:


> I don't have a cylinder square, just a regular machinist square. I'll mount an indicator on the headstock and run the Z axis up and down the square to see if the needle moves. Unless I'm misreading your post.


The most accurate method of tramming a mill is to use an offset indicator in the spindle.  Regardless of any runout issues, the indicator is necessarily rotating around the spindle axis so the indicator tip traces a path in a plane perpendicular to the spindle axis.  Resolution is as good as the resolution of your indicator.  The issue of the non-parallel table does exist in this method and it also would exist using a cylindrical square.   

If you have a fixed spindle as the Tormach has, the spindle axis must be aligned parallel with the z axis ways AND the z axis ways must be perpendicular to the x and y axis ways.  As Robert said above, it is possible to align then so two offsets cancel and the tram is perfect. 

 My round column mill/drill, on the other hand, has a movable quill and for all intents and purposes the head is stationary. Tramming can only be accomplished by shimming the column.  If you have a mill where the head can be rotated in the x-z plane, You could tram in the x direction by adjusting the angle of rotation.  You could also do so  by shimming the column but it would be ridiculous to do so.  If your mill has nod capabilities, you can adjust y direction tram in the same way.


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## Groundhog (Mar 30, 2019)

PCmaker,
Welds (even tacks) will shrink as they cool and distort the accuracy of your tramming.

There is a product (at least there was awhile back) that is liquid/putty like and is forced into the gap between the column and the base after it is shimmed/adjusted to the desired position. It is said to dry very hard and without changing dimensions. It is (was?) made expressly for tramming mill columns and the like. I don't have a clue as to name, supplier or anything else though. Google I guess!


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## Pcmaker (Mar 30, 2019)

I'm trying to tram the X axis right now. So, I move the table all the way to the left zeroed the indicator, then moved all the way to the right. The difference is  .007 thou

I then tapped the head to where the indicator shows .0035

Is this the right way to do it? I just did it, then moved all the way to the left and it still seems like I still have that much of a difference. What am I doing wrong?


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## stupoty (Mar 30, 2019)

Pcmaker said:


> I'm trying to tram the X axis right now. So, I move the table all the way to the left zeroed the indicator, then moved all the way to the right. The difference is  .007 thou
> 
> I then tapped the head to where the indicator shows .0035
> 
> Is this the right way to do it? I just did it, then moved all the way to the left and it still seems like I still have that much of a difference. What am I doing wrong?




I might be miss understanding, but it sounds a little unconvetional.  I think ur reading flatness errors.

Normaly a dial indicator goes on a long stick mounted in a collet in the spindle and is swung around to cover a circle area that fits on your tabStu

Also as somone else mentioned, you might be seeing sag from gib looseness or possibly spring if u have anything bolted down in the t slots.

Stu


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## Groundhog (Mar 30, 2019)

this article might help https://www.cnccookbook.com/tramming-milling-machine-tool-indicator/


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## Pcmaker (Mar 30, 2019)

stupoty said:


> I might be miss understanding, but it sounds a little unconvetional.  I think ur reading flatness errors.
> 
> Normaly a dial indicator goes on a long stick mounted in a collet in the spindle and is swung around to cover a circle area that fits on your tabStu
> 
> ...



Yep, I made something like that. It swings through the spindle. I zeroed it on the left side, swung it to the right, and it's off by .007

If I tap the head, what should I aim the indicator to be? I always though it was half the difference from the left to the right.


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## Pcmaker (Mar 30, 2019)

Groundhog said:


> this article might help https://www.cnccookbook.com/tramming-milling-machine-tool-indicator/



The thing on the side is a good idea. Instead of tapping with a rubber hammer, you can just turn on the set screw to move the head of the mill.


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## kd4gij (Mar 30, 2019)

Pcmaker said:


> The thing on the side is a good idea. Instead of tapping with a rubber hammer, you can just turn on the set screw to move the head of the mill.




Yes I did that mod to my g0704 mill many years ago. Works great. One on each side. when I need to cock the head just loosen them up and swing them out of the way.


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## MSD0 (Mar 30, 2019)

Pcmaker said:


> Yep, I made something like that. It swings through the spindle. I zeroed it on the left side, swung it to the right, and it's off by .007
> 
> If I tap the head, what should I aim the indicator to be? I always though it was half the difference from the left to the right.


That’s correct. Keep splitting the difference until it’s as close as possible.


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## Pcmaker (Mar 30, 2019)

MSD0 said:


> That’s correct. Keep splitting the difference until it’s as close as possible.



I've been doing that. I get to half, then go back to the left, re-zero, then I go right, and it's still off. After doing it 3 times. 

I'm going to put in a set screw to push the head back and forth instead of me tapping with the hammer and see if that does it.


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## rwm (Mar 31, 2019)

You are doing it correctly by rotating an indicator in the spindle. That will work. Yes half the difference in readings.
Since your mill has a movable head on the Z as well as a spindle I was trying to make the theoretical point that a cylinder square could isolate these. That is probably overkill for your needs. I have seen some people use a large bearing race on the table and run the indicator on that to avoid the T slots. That seems like a great idea if you can find one in your travels.
RJ that is a clever solution to your off parallel table but seems like a real pain. How often does that problem occur on a quality machine like a Tormach? Did you consider getting the table ground flat?
Robert


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## ThinWoodsman (Mar 31, 2019)

Pcmaker said:


> I don't have a cylinder square, just a regular machinist square.


Easy enough to turn one out on the lathe:
http://homews.co.uk/page307.html


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## Pcmaker (Mar 31, 2019)

I got the X axis down to .003 and the Y axis down to to .004

I'm having problems after tramming the X axis. When I tighten down the nuts to lock down the head, the indicators move. I'm thinking of keeping the nuts tighter so the head doesn't move as much when I tighten the nuts. 

or should I compensate for the head movement when I'm tightening down the nuts. Or both of these. There's 3 nuts that lock down the head's X axis.


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## MSD0 (Apr 1, 2019)

Pcmaker said:


> I got the X axis down to .003 and the Y axis down to to .004
> 
> I'm having problems after tramming the X axis. When I tighten down the nuts to lock down the head, the indicators move. I'm thinking of keeping the nuts tighter so the head doesn't move as much when I tighten the nuts.
> 
> or should I compensate for the head movement when I'm tightening down the nuts. Or both of these. There's 3 nuts that lock down the head's X axis.


Are you tightening the nuts a little at a time (after checking with the indicator) or all at once?


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## Pcmaker (Apr 1, 2019)

MSD0 said:


> Are you tightening the nuts a little at a time (after checking with the indicator) or all at once?



Yep, little at a time, still moves. I think I had the nuts on too loose. I'll try again today.

I'm using one of these to tram the mill


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## astjp2 (Apr 1, 2019)

Can you post a few pics of your machine?  That seems to be off a lot still.  It almost sounds like the table is not of the same thickness.


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## yendor (Apr 1, 2019)

You should be tightening down the column nuts with a torque wrench otherwise you will find yourself chasing ghosts.

Tighten them in steps - IE:
Alternating corners at #15
Then add #10 and tightening all (4) again starting with a different corner.
Then add #10 again for a total of #35 and tightening all (4) again starting with a different corner.
Working around the bolt pattern will give you the best even torque on all (4) Bolts. - DON"T always start with the same bolt.

Once all the bolts have been torqued down - That is when you take your measurements.
Record the values and determine What (how thick) and Where you  might need to place shims.
You have to be sure you have LOCKED the Table Gibs down on BOTH X & Y Axis.
And LOCK the Spindle Vertical Travel when measuring.
The TABLE does NOT need to be and should NOT be moved to tram the HEAD to the Table.

If all the moveable parts are not locked down when you measure you are just chasing ghosts.
The TRAM is simply getting the Spindle set Vetical - Right Angles both side to side and front to back.

When making up the shims for a machine that is trammed via the column bolts you would be best off to make "U" shaped shims that go around the corner bolts.

I used cutup peices of a soda can.
To make the shims without having burrs on the edges I made 8 peices approx 1-1/2' square.
Sandwiched them between (2) peices of 1x3 clamped it down on my drill press and drilled a 7/16th hole thru them all at one time.
Then I used a pair of avation type metal snips to cut out the "U"
Lastly I sanded them lightly to remove any burrs from the snip cuts.


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## Pcmaker (Apr 2, 2019)

astjp2 said:


> Can you post a few pics of your machine?  That seems to be off a lot still.  It almost sounds like the table is not of the same thickness.


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