any advice for a 3 axis DRO for my mill?

[mike-sid]

I think my mill needs a DRO and a vice.  I need some advice on buying a DRO.  I have no idea of good brands and features I need.  I'm also thinking I  will use this DRO on my next mill when I upgrade to a Bridgeport type mill. I figure I can use the head unit but might need new scales.  Any and all advice welcome.

[mike-sid]

My mill's table is about 6.5"×25"

   

[EdK]

I have a DRO on my lathe from this place.

http://www.dropros.com/

I've been very happy with it so far. The two times I've needed a question answered they were very quick to respond and you get to talk to people that actually know something about what they sell if you need to call them. Once I upgrade my mill to a larger one, I'll be purchasing a DRO from them to install on the mill. Their DROs are a little more costly so if you're looking for the cheapest possible then check them off of your list.

Ed

[mike-sid]

Ed, those look good. Now I'm starting to think. ....do I need a 3 axis? Or will 2 be good enough?

[EdK]

(02-22-2015, 03:42 PM)mike-sid Wrote: Ed,  those look good.  Now I'm starting to think. ....do I need a 3 axis?  Or will 2 be good enough?

If you plan on eventually getting a knee mill, then I'd go with a 3-axis. X, Y and knee. For the spindle you can get one of those scales that has the built-in readout. That's what I plan on doing. But, it's easy to spend your money for you so you have to decide if a 3-axis is worth it for your situation.

Ed

[f350ca]

I have a two axis on the mill. There is no backlash to compensate for on the knee, unless gravity fails. Couldn't be without x and y now but have never felt i needed one on the knee.

[EdK]

(02-22-2015, 06:24 PM)f350ca Wrote: I have a two axis on the mill. There is no backlash to compensate for on the knee, unless gravity fails. Couldn't be without x and y now but have never felt i needed one on the knee.

Good point on the lack of backlash compensation needed on the knee.

Ed

[mike-sid]

Ed, my mill is a knee mill.  I just took some measurements.  The table is 25"x 6 3/4".   My  X axis travel is 13 3/4", my Y axis travel is 5 1/2" and my Z travel is 10 1/4".    The base of my mill is a Hardnige TM and the head is a Bridgeport J head.

[Highpower]

(02-22-2015, 06:24 PM)f350ca Wrote: I have a two axis on the mill. There is no backlash to compensate for on the knee, unless gravity fails. Couldn't be without x and y now but have never felt i needed one on the knee.

(02-22-2015, 06:51 PM)EdK Wrote:

(02-22-2015, 06:24 PM)f350ca Wrote: I have a two axis on the mill. There is no backlash to compensate for on the knee, unless gravity fails. Couldn't be without x and y now but have never felt i needed one on the knee.

Good point on the lack of backlash compensation needed on the knee.  

Ed

Ummm.... stupid question time. 

What difference does it make between the table and the knee if you have backlash in either lead screw?
If you have backlash in the X or Y and the table doesn't move - neither does the readout on the DRO, as the read head is attached to the table/saddle - not the lead screw. Backlash shows up on the dials - not the DRO. Isn't that one of the biggest benefits of using a DRO? 
What would make the knee any different?

Granted, I have my Z scale attached to my quill (which also has a slight amount of backlash in the rack/pinion) but changes in depth of cut are always spot on. If it jumps a couple of thou too far when moving the quill it shows up on the readout and I re-adjust accordingly.



My DRO also has the capability of combining two Z-scales. I could add another scale to the knee on my mill and the DRO will keep track of the tool position relative to both the quill and the knee. Pretty cool but way beyond my needs.

[Dr Stan]

I bought a 3 axis Sinpo off EBay for my Fray #7 mill and have been quite happy with it.  As you can see on the mill it has the traditional X and Y axis with a third one which can be parallel or set at an angle to the X axis.




I also have a Shooting Star on my Logan lathe.  Good product, but I was not impressed with their customer service.

BTW, this pic was taken before I mounted the DRO on the mill.