Scales for Mil DRO

[kvt85]

Ok   Finally looking to put a DRO on the MIL,   Knee mill,
What I have figured the travel out but should I get them
I.e   The table has just at 24 inches of travel.   SO figured prob get ones that could handle 25,   that gives me a little wiggle room on each end.   
Or should I allow more than that.    This will be the first time I have put Scales on a mill.

Advice would be welcome. 

Ken

[4GSR]

Don't cut yourself too short.  Most all of the scales out there are offered in metric lengths.  So you may have to purchase one that is 650mm of travel.  May even have to go up to a 700mm scale. 
If you can afford it, go with one of the packages that offer 3-axis of measurements.  They are dirt cheap now days.

[Carpenter84]

I'm with Ken - eBay or Amazon. There's lots of 3 axis units (or 2 if that's what you'd prefer, or 4 even) that are very affordable. I did a 4 axis, digital screen unit on my big mill for under $500 (to Canada).

Things to consider tho.
Try to stay as close as possible to the max travel on the mill. Consider the full length of the scale and brackets. You may have to decide to get a scale with a slightly shorter working length and put limit stops on the axis travel to make sure the full length of scale and mounting brackets will actually fit where you want to install.
I have cut the glass scale down to fit but it's not a job for the faint of heart (it's not a simple task).

[4GSR]

The cross-travel scale you definitely don't want to get too long.  May have to do what Shawn said, go with one a little short and limit your travel with a positive stop to keep from damaging the scale.  From what I remember your mill has the short knee on it which doesn't have a whole lot of cross travel.

[kvt85]

Thanks All for the suggestions,   
Here is what I had done   My table has just over 23 inches of travel so figured 24 inches of travel on a 42 inch table,
y axis has just over 12 so figured 13 inches,   and has almost 20 inches of room for mounting. on the knee
z knee has just over 13 inches of travel, so figured 14 inches,  and have plenty of room to mount the scale on on that area.   

Then figured 3 axis system,  and then later put on a quill dro for depth.   Or would it be better to put the z on the quill, and leave it off of the knee.

Ken

[Carpenter84]

I have two mills, one has 2 axis dro, other has 4. The 2 axis has a quill calliper style readout with nothing on the knee. This is the much less used mill that gets used for roughing and unimportant drilling. Each time the knee moves I have to touch off and rezero the readout.

The other mill has a 4 axis dro with scales on the knee and quill. I have the dro set to combine the knee and quill read out. This way I can touch off or set a datum and no matter if I move the knee or quill, I can always refer back to my datum or return to zero. But this machine is my main mill used for production. It also has 40 taper tool holders with set tools. My depth repeatability is sub 5 thou with this arrangement.

The 4 axis was twice as expensive as the 2 axis.

My suggestion would be based on how you’re used to operating the mill. If you set the quill and only ever move the knee during important operations, then go 3 axis and eventually get a quill read out if desired. The quill caliper does fit much nicer than the big thick dro scale and guard. That takes some customization.
That said, I operated with the one mill for a couple years with nothing on the knee, just quill and got by fine. Just more time consuming.

Good luck.

[Carpenter84]

If anyone interested, this is what I use on the quill on the Induma mill.

https://www.ebay.ca/itm/254671964550

My ONLY complaint is the LCD is a tad small for me and because I’m so tall I have to shrink down a bit to avoid the glare/shadow on the screen. I suspect this is not a common issue…

I tried looking for the readout I had on my old column mill which had a larger screen but I couldn’t find it. But I remember that readout having a rather slow response - laggy.

[4GSR]

I mounted the z-axis on the knee and bought a stand a long unit similar to what Shawn did for the quill.

I don't use the z-axis much on the knee, although it has been nice when you do need it.

[will.mcray]

Check these guys out. 

https://www.tpactools.com/

I have their four axis on my mill and have had no issues. 

Will


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[4GSR]

Check these guys out. 

https://www.tpactools.com/

I have their four axis on my mill and have had no issues. 

Will

Their 3-axis unit is exactly like the one I put on my mill a year ago.  Didn't pay quite that much for it, but things have gone up in the past year.


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