I'm not sure why you're making it so complicated. Even easier using QCAD where you can just type out the "equation" as fractions of an inch when you enter a dimension so to use your example this will work in QCAD type 1' 2 1/2" * 7/12An inch in 7mm (fine scale or S7 ) is 0.5833 mm and you can do the feet and inches sums in your head so for example 1’2-and a half” is 14-and-a-half is 29 halves so type 29 * .5833 / 2 and so on.
Again it's simply what you are use to, I see that and think it's 1/64 less than 24/64, 24 is divisible by 8 so if you had to mark out 23/64" it is quite simply 1/64 less than 3/8" and my ruler has a graduation line for that, whereas the metric rule doesn't have a graduation mark for 9.128 mm. It's just very useful to be able to switch from one to the other as the situation dictates.Can’t be doing with fractional inches, 23/64” anyone?
Yes, can do similar in SW, though I’ve not tried typing feet and inches.As I said each to their own
I'm not sure why you're making it so complicated. Even easier using QCAD where you can just type out the "equation" as fractions of an inch when you enter a dimension so to use your example this will work in QCAD type 1' 2 1/2" * 7/12
Again it's simply what you are use to, I see that and think it's 1/64 less than 24/64, 24 is divisible by 8 so if you had to mark out 23/64" it is quite simply 1/64 less than 3/8" and my ruler has a graduation line for that, whereas the metric rule doesn't have a graduation mark for 9.128 mm. It's just very useful to be able to switch from one to the other as the situation dictates.
Thanks for showing us how you fitted the DROs to the mill Rob. I have the same/similar mill and have been thinking of doing something similar. The local Seig importer (ausee.com.au) sell DRO parts which look good to me so will probably use them. I tend to use the fine control for the final Z axis adjustment and your fitting doesn’t seem measure the fine control Z axis movement. Would it be possible to mount the reading head to the motor housing or somewhere else to measure both the main and fine Z axis adjustments? Or have I not understood your mounting?This seems to be the only shot that I have of the X axis scale in place with it's chip cover.
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Then I mounted the display - you will note that the bottom Z Axis display is reading al zeros this is because at this point I was still awaiting the longer replacement scale.
There are quite a few options for mounting the display you can angle the bracket out from the side of the mill if you have somewhere to mount it. I chose to fix it to the bench alongside.
Then it was onto fitting the Z axis scale. This was reasonably straightforward in that I was able to fasten the scale itself directly to the rear of the column. I confess that I did initially get it slightly too low which reduced the amount that I could raise the head of the mill. Meaning that I had to redrill one of the holes higher up to get maximum height.
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I was also able to finally use some of the brackets and mounting plates that came with the scales again fitting to the yoke which raises the head was reasonably straightforward.
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What did find was that I had to turn some spacers from aluminium bar to get the alignment between the read head and the yoke so that it ran up and down smoothly without rubbing on the chip cover.
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In conclusion, I am really happy with the DRO and now feel confident to do something similar on my lathe at some point. I do agree with Nick Baines comment that having that level of accuracy does tend to get you a little hung up on hitting 0.005 of a millimetre...