Haas Mini Mill slightly out of square - adjusting?

Hi guys, I have a slight squareness error on my new Haas Mini Mill, identified by a ballbar test and confirmed with a square. The X is 40 microns per meter out of square with Y. I was thinking of loosening up the X mounting to the Y blocks and twisting the axis slightly to bump it into perfect alignment, but I'm unsure of whether this amount of error would require me to loosen the ballnut on Y to allow the adjustment, or how difficult this process is in general. Has anyone done this before and is it a PITA? Is this error even worth correcting? The tech said it was within spec, but ideally I'd like this error below 20 microns.

BTW, machine is fully levelled!

Thanks

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Originally Posted by MichaelKelly7104

Hi guys, I have a slight squareness error on my new Haas Mini Mill, identified by a ballbar test and confirmed with a square. The X is 40 microns per meter out of square with Y. I was thinking of loosening up the X mounting to the Y blocks and twisting the axis slightly to bump it into perfect alignment, but I'm unsure of whether this amount of error would require me to loosen the ballnut on Y to allow the adjustment, or how difficult this process is in general. Has anyone done this before and is it a PITA? Is this error even worth correcting? The tech said it was within spec, but ideally I'd like this error below 20 microns.

BTW, machine is fully levelled!

Thanks

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This would be in their test sheet and on them if this is out of spec, is this a new machine??

Who did the test??

You can't move the Linear Bearing Blocks, they are against a shoulder, and yes this would affect the Ball Nut alignment if you moved the linear Bearings

So that would be around .001" out of square over its X-axis travel, you would have to hand scrape this to get it any better

Hi Mac, it is a new machine, yes. The Haas tech did the test and said he was pretty happy with the result, though he will obviously be biased to some extent. I think it should only be around 16 microns out over 400MM, so around 6 tenths of a thou - is this reasonable?

Edit, I found this thread where the user realigned his machine on the blocks, is the mini mill different? https://www.cnczone.com/forums/haas-...xy-square.html

Just to clarify, I don't actually intend to move the bearing blocks themselves, but the X axis which sits on top of the Y axis blocks, hope this makes sense.

Thanks!

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Originally Posted by MichaelKelly7104

Hi Mac, it is a new machine, yes. The Haas tech did the test and said he was pretty happy with the result, though he will obviously be biased to some extent. I think it should only be around 16 microns out over 400MM, so around 6 tenths of a thou - is this reasonable?

Edit, I found this thread where the user realigned his machine on the blocks, is the mini mill different? https://www.cnczone.com/forums/haas-...xy-square.html

Just to clarify, I don't actually intend to move the bearing blocks themselves, but the X axis which sits on top of the Y axis blocks, hope this makes sense.

Thanks!

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The X axis sits on the Y axes saddle there is no easy way to move either axis, the thread you referenced I would take that as fluff and someone who is not a machinist, they had the Linear Rails replaced and most likely where never installed perfectly

Your Machine, the X axes sits on 4-Linear Bearing which are mounted on the top of the saddle and the Y axis Linear Bearings are mounted on the Bottom of the saddle all Linear Bearings are clamped against a machined register so to change any of this you would have to change how the Linear Bearing Block is clamped against the machined register, over that distance you would be looking at maybe 2 or 3 microns change, this would be a real challenge for someone that most likely does not have the equipment to do this job,, you would need AAA Granite Square at least 18" x 12" square to all faces to do the square test

Most regular machining centers don't get any better than .0005" in positioning and cut accuracy so 6 tenths into the mix are not going to change much, of course you can cut parts much more accurate than this it just depends how skilled the person using the machine is

Thanks for the info Mac. In other words, leave it and enjoy it?

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Originally Posted by MichaelKelly7104

Thanks for the info Mac. In other words, leave it and enjoy it?

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What the other post shows and how they were able to change it, your Mini-Mill saddle is (1) piece so you can't do what they were showing, yes enjoy it if it causes you to have a part problem then it would be something to look at then

Thanks for the info!

Question, I ran my very accurate level (0.02MM per 100CM) along the y axis and it appears there is a very slightly twist in the rails to the tune of 0.03MM per 100CM along the entire Y axis, is it worth adjusting the levelling feet to compensate? (if this will have any effect on the casting since it's a steel base machine) For reference it appears the front left foot is low. For the squareness, the X appears to be further forward on the right, and further back on the left. Would a lower left front foot cause this?

if it's off level then it could throw things off a bit .
If the machine was leveled correctly by the technician then it may be shifting the concrete if the floor isn't thick enough . Time and monitoring will tell . Overall they are light machines so it doesn't require an exceptional floor thickness , but I've dealt with some that were on thin concrete and leveling was a fairly regular occurrence on a couple mini's . Weather shifts will affect a bad floor greatly
If the floor proves to be an issue then steel plates under each foot helps

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Originally Posted by MichaelKelly7104

Thanks for the info!

Question, I ran my very accurate level (0.02MM per 100CM) along the y axis and it appears there is a very slightly twist in the rails to the tune of 0.03MM per 100CM along the entire Y axis, is it worth adjusting the levelling feet to compensate? (if this will have any effect on the casting since it's a steel base machine) For reference it appears the front left foot is low. For the squareness, the X appears to be further forward on the right, and further back on the left. Would a lower left front foot cause this?

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How are you checking the rails, are your way covers 0ff??

This does sound strange if the table had been leveled by the tech when he did the install this all should be good, is the Table still good this is normally what you check, for the Y axis to be twisted that would throw the table off as well

No, I mean with the level sitting on the table perpendicular to X travel, and running the table in Y direction, there is a very small amount of twist evidenced by the bubble shifting about 1 to 1 and a half divisions on a 0.02MM/M scale. Very slight, but there. Shall I increase the height of the foot where it appears to drop?

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Originally Posted by MichaelKelly7104

No, I mean with the level sitting on the table perpendicular to X travel, and running the table in Y direction, there is a very small amount of twist evidenced by the bubble shifting about 1 to 1 and a half divisions on a 0.02MM/M scale. Very slight, but there. Shall I increase the height of the foot where it appears to drop?

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This would have shown up in the Ball-Bar test, I would say your machine has moved or it was not level to start with, the machine needs to be leveled in all both directions

Did you reverse the level to see if it has the same reading

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Originally Posted by mactec54

This would have shown up in the Ball-Bar test, I would say your machine has moved or it was not level to start with, the machine needs to be leveled in all both directions

Did you reverse the level to see if it has the same reading

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It wasn't the actual measurement that I was interested in, more so the change across the travel. The machine was only levelled last week and hasn't been used for machining yet. I did however calibrate my level beforehand. Bear in mind this is a very sensitive level - 0.02MM per 100CM. On a more typical level it does show basically perfect measurements.

What would it have shown up as? Squareness error?

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Originally Posted by MichaelKelly7104

It wasn't the actual measurement that I was interested in, more so the change across the travel. The machine was only levelled last week and hasn't been used for machining yet. I did however calibrate my level beforehand. Bear in mind this is a very sensitive level - 0.02MM per 100CM. On a more typical level it does show basically perfect measurements.

What would it have shown up as? Squareness error?

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So, you have a machine level that is 1000mm / 1meter long?? .0001" per 12'' is a sensitive level and is what the Tech would have used

The circles would have been oblong if the machine was not level

Thanks for the info. Looking at the Renishaw QC-20 documentation an oblong circle also indicates a squareness error, which also suggests a levelling issue. The level is not 1 meter long, but the spec for its sensitivity is 0.02MM per meter per division, so about half the sensitivity per devision of the level you mention. I can definitely still see the error on my level. Would you tweak the foot slightly?

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Originally Posted by MichaelKelly7104

Thanks for the info. Looking at the Renishaw QC-20 documentation an oblong circle also indicates a squareness error, which also suggests a levelling issue. The level is not 1 meter long, but the spec for its sensitivity is 0.02MM per meter per division, so about half the sensitivity per devision of the level you mention. I can definitely still see the error on my level. Would you tweak the foot slightly?

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If you are not happy with how the tech set it up, you should call them back for a redo