DRO questions

[RJSakowski]

I am just asking. How much does one use the z-axis scale? I am contemplating if I must get a 3-axis or 2-axis DRO.

I rely on my z axis DRO for my round column mill. There is enough backlash in the old beast to create uncertainty and with the fine feed dial at .085"/rev., counting turns and doing the math to calculate travel is too much, not to mention calculation errors. The DRO eliminates all that.

 

[Winegrower]

On a Bridgeport, the Z-Axis dial is large, easy to read, and stable. I have not found a need for DRO there. I added a quill DRO, but I use it rarely...mainly when drilling to a critical depth or countersinking.

 

[RJSakowski]

One advantage of a z axis DRO is the ability to zero tool offsets off the part the subdatum positions. Below is an example of manual machining using an RT for a 4th axis and the DRO for positioning. It involved 20 tool changes and would have been virtually impossible without the DRO.

Step	Operation	Face	Tool	Rotary Table	DRO Display	Coordinates, inches
				degrees	Function	X	Y	Z
	Notes: The following operations are executed on the rotary table in vertical position with the central axis aligned with the mill X axis. The rotary table should be adjusted so that it is square to the mill table to within 0.0005" over 5" travel, using shims if necessary. The 4" 3-jaw chuck is used as the workpiece clamping device. The flexible electrical contact datum point is assigned ABSolute 0,0,0 coordinates and located so that the X and Z coordinates will coincide with those of the workpiece (~8.65" above mill table and 4.75" from rotary table bed). The mill head should be set so there is 1.75 inches of clearance between the top of the head and the column retainer. Operating speed should be set at 1325 rpm. All tools excluding the 1/2" and 7/32" end mills and taps should be chucked in the Tru Center chuck adjusted for < 0.0002" runout.
1​	cut blank		bandsaw	NA	NA
2​	weld blank to stub		soldering iron	NA	NA
3​	level piece		rotary table	90/270	NA
4​	face side of piece		1/2" end mill	NA	NA	As Req.	Variable	N/A
5​	set DRO				ABS	0.4600	N/A	N/A
6​	1st face	top	1/2" end mill	180	ABS	0.0000	Variable	As Req.
7​	set DRO				INC	0.0000	N/A	0.0000
8​	1st face	bottom	1/2" end mill	0	INC	0.0000	Variable	0.0000
9​	measure top-bottom (XXXX)		micrometer
10​	set DRO to -1/2 (XXXX)				INC	0.0000	N/A	-.5(XXXX)
11​	find top face, set DRO Y		1/2" edge finder	90	INC	0.0000	0.0000	As Req.
12​	find bottom face, set center find on DRO Y axis	1/2" edge finder	90	INC	0.0000	.5(YYYY)	As Req.
13​	set absolute coordinates at Z axis datum		sharpened scribe		ABS	0.0000	0.0000	0.0000
14​	find top face, set DRO Z		sharpened scribe, 50X microscope	180	INC	0.1900	0.0000	-.5(XXXX)
15​	find bottom face, check DRO Z		sharpened scribe, 50X microscope	0	INC	0.1900	0.0000	-.5(XXXX)
16​	set DRO X,Y,Z				SDM 199	0.0000	0.0000	-.5(XXXX)
17​	set backup SDM coordinates				SDM 198	0.0000	0.0000	-.5(XXXX)
18​	set 2nd backup SDM coordinates				SDM 100	0.0000	0.0000	-.5(XXXX)
19​	zero tool Z axis		1/2" end mill		ABS	0.0000	0.0000	0.0000
20​	final face	top	1/2" end mill	180	SDM 199	0.0000	Variable	-0.4500
21​	final face	bottom	1/2" end mill	0	SDM 199	0.0000	Variable	-0.4500
22​	face	SMA	1/2" end mill	270	SDM 199	0.0000	Variable	-0.4490
23​	face	insert	1/2" end mill	90	SDM 199	0.0000	Variable	-0.1928
24​	zero tool Z axis		0000 center drill		ABS	0.0000	0.0000	0.0000
25​	drill insert pilot	insert	0000 center drill	90	SDM 199	0.0000	0.0000	-0.0500
26​	drill bypass pilot	bottom	0000 center drill	0	SDM 199	0.0000	0.0000	-0.1600
27​	zero tool Z axis		0.1875 center drill		ABS	0.0000	0.0000	0.0000
28​	drill sample port pilot	top	0.1875 center drill	180	SDM 199	0.0000	0.0000	-0.1800
29​	drill SMA coupler pilot	SMA	0.1875 center drill	270	SDM 199	0.0000	0.0000	-0.0500
30​	zero tool Z axis		3.35mm carbide drill		ABS	0.0000	0.0000	0.0000
31​	drill bypass capillary bushing hole	bottom	3.35mm carbide drill	0	SDM 199	0.0000	0.0000	-0.2373
32​	zero tool Z axis		1.55mm drill		ABS	0.0000	0.0000	0.0000
33​	drill bypass capillary hole	bottom	1.55mm drill	0	SDM 199	0.0000	0.0000	-0.0550
34​	zero tool Z axis		0.042" carbide pc drill		ABS	0.0000	0.0000	0.0000
35​	drill clearance hole for 0.008" drill	bottom	0.042" carbide pc drill	0	SDM 199	0.0000	0.0000	-0.0250
36​	zero tool Z axis		0.020" carbide pc drill		ABS	0.0000	0.0000	0.0000
37​	drill large bypass passage	bottom	0.020" carbide pc drill	0	SDM 199	0.0000	0.0000	-0.0100
38​	zero tool Z axis		0.039" carbide pc drill		ABS	0.0000	0.0000	0.0000
39​	drill secondary pilot	top	0.039" carbide pc drill	180	SDM 199	0.0000	0.0000	-0.0500
40​	zero tool Z axis		7o taper tool		ABS	0.0000	0.0000	0.0000
41​	bore lower sample port	top	7o taper tool	180	SDM 199	0.0000	0.0000	-0.0600
42​	zero tool Z axis		dual taper cone tool		ABS	0.0000	0.0000	0.0000
43​	bore upper sample port	top	dual taper cone tool	180	SDM 199	0.0000	0.0000	-0.0500
44​	zero tool Z axis		0.008 micro drill		ABS	0.0000	0.0000	0.0000
45​	drill final passage	top	0.008 micro drill	180	SDM 199	0.0000	0.0000	0.0030
46​	drill final passage	bottom	0.008 micro drill	0	SDM 199	0.0000	0.0000	0.0030
47​	zero tool Z axis		120o c/sink		ABS	0.0000	0.0000	0.0000
48​	cut 120o bevel	SMA	120o c/sink	270	SDM 199	0.0000	0.0000	-0.0090
49​	cut 120o bevel	insert	120o c/sink	90	SDM 199	0.0000	0.0000	-0.0090
50​	zero tool Z axis		0.008 micro drill		ABS	0.0000	0.0000	0.0000
51​	drill optical passage	SMA	0.008 micro drill	270	SDM 199	0.0000	0.0000	0.0160
52​	zero tool Z axis		0000 center drill		ABS	0.0000	0.0000	0.0000
53​	drill locating pin #1 pilot	insert	0000 center drill	90	SDM 199	0.1200	0.3100	-0.1256
54​	drill locating pin #2 pilot	insert	0000 center drill	90	SDM 199	-0.1200	-0.3100	-0.1256
55​	drill #2-56 fastener #1 pilot	insert	0000 center drill	90	SDM 199	-0.1000	-0.1950	-0.1070
56​	drill #2-56 fastener #2 pilot	insert	0000 center drill	90	SDM 199	-0.1000	0.1950	-0.1070
57​	drill #2-56 fastener #3 pilot	insert	0000 center drill	90	SDM 199	0.1000	0.1950	-0.1070
58​	drill #2-56 fastener #4 pilot	insert	0000 center drill	90	SDM 199	0.1000	-0.1950	-0.1070
59​	zero tool Z axis		#51 drill		ABS	0.0000	0.0000	0.0000
60​	drill #2-56 fastener #1 hole	insert	#51 drill	90	SDM 199	-0.1000	-0.1950	0.1820
61​	drill #2-56 fastener #2 hole	insert	#51 drill	90	SDM 199	-0.1000	0.1950	0.1820
62​	drill #2-56 fastener #3 hole	insert	#51 drill	90	SDM 199	0.1000	0.1950	0.1820
63​	drill #2-56 fastener #4 hole	insert	#51 drill	90	SDM 199	0.1000	-0.1950	0.1820
64​	zero tool Z axis		1.55mm drill		ABS	0.0000	0.0000	0.0000
65​	drill locating pin hole #1	insert	1.55mm drill	90	SDM 199	0.1200	0.3100	0.0572
66​	drill locating pin hole #2	insert	1.55mm drill	90	SDM 199	-0.1200	-0.3100	0.0572
67​	zero tool Z axis		7/32 end mill		ABS	0.0000	0.0000	0.0000
68​	c/bore SMA connector hole	SMA	7/32 end mill	270	SDM 199	0.0000	0.0000	-0.1690
69​	tap #2-56 hole #1	insert	#2-56 tap	90	SDM 199	-0.1000	-0.1950	N/A
70​	tap #2-56 hole #2	insert	#2-56 tap	90	SDM 199	-0.1000	0.1950	N/A
71​	tap #2-56 hole #3	insert	#2-56 tap	90	SDM 199	0.1000	0.1950	N/A
72​	tap #2-56 hole #4	insert	#2-56 tap	90	SDM 199	0.1000	-0.1950	N/A
73​	tap SMA connector hole	SMA	1/4-36 plug tap	270	SDM 199	0.0000	0.0000	N/A
74​	tap SMA connector hole	SMA	1/4-36 bottoming tap	270	SDM 199	0.0000	0.0000	N/A
75​	zero tool Z axis		1/2" end mill		ABS	0.0000	0.0000	0.0000
76​	cut weld	SMA	1/2" end mill	270	SDM 199	As Req.	Variable	-0.4700
77​	cut weld	bottom	1/2" end mill	0	SDM 199	As Req.	Variable	-0.4700
78​	cut weld	insert	1/2" end mill	90	SDM 199	As Req.	Variable	-0.1950
79​	cut weld	top	1/2" end mill	180	SDM 199	As Req.	Variable	-0.4700
	Notes: the final operations are performed on the mill table using a conventional mill vise. The vise should be adjusted so that it is square and parallel to the mill table to within 0.0005" over 3" travel, using shims if necessary. The flexible electrical contact datum point is assigned ABSolute 0,0,0 coordinates and located so that the Y and Z coordinates will aproximately coincide with those of the workpiece. A buildup block should be used to bring the bottom workpiece support to 0.32 to 0.33" from the top of the vise jaws. This block can be milled in place to ensure parallel conditions for the workpiece.
Step	Operation	Face	Tool	Rotary Table	DRO Display	Coordinates, inches
				degrees	Function	X	Y	Z
1​	find top face, set DRO Y		1/2" edge finder		INC	0.0000	0.0000	As Req.
2​	set absolute coordinates at X, Y axis datum		1/2" edge finder		ABS	0.0000	0.0000	0.0000
3​	set absolute coordinates at Z axis datum		2mm pin		ABS	0.0000	0.0000	0.0000
4​	find buildup block floor, set DRO Z		2mm pin, feeler gauge	SDM 001	NA	NA	0.0000
5​	find buildup block far surface, set DRO Y				SDM 001	NA	0.0000	As Req.
6​	zero tool Z axis		1/2" end mill		ABS	0.2000	0.0000	0.0000
7​	clamp workpiece in vise, milled side down
8​	first face	back	1/2" end mill		SDM 199	As Req.	Variable	-0.5800
9​	second face	back	1/2" end mill		SDM 199	As Req.	Variable	-0.5200
10​	third face	back	1/2" end mill		SDM 199	As Req.	Variable	-0.4600
11​	fourth face	back	1/2" end mill		SDM 199	As Req.	Variable	-0.4000
12​	fifth face	back	1/2" end mill		SDM 199	As Req.	Variable	-0.3600
13​	final face	back	1/2" end mill		SDM 199	As Req.	Variable	-0.3571
14​	reverse workpiece in vise with sample port to fixed jaw
15​	final face	front	1/2" end mill		SDM 199	As Req.	Variable	-0.3543
16​	drill mounting hole #1 through	front	120o c/sink		SDM 199	0.1990	0.1500	through
17​	drill mounting hole #2 through	front	120o c/sink		SDM 199	0.1990	0.7500	through

 

[MrWhoopee]

I got this one for my lathe

157.18US $ 42% OFF|Lathe Dro 2 Axis Digital Readout Display With 2pcs 50-1000mm Linear Glass Scale Encoder Measuring Ruler Milling Machines - Level Measuring Instruments - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

It's decently made and has been trouble free, quite satisfied.

I see the one you're looking at is even cheaper, that's a spectacular price.

79.3US $ 35% OFF|2 Axis Digital Readout Dro Display Linear Scale - Level Measuring Instruments - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

I like the colors too.

On a mill, the scale width is not a real big issue. You might lose a little travel, but not enough to worry about (unless it's a mini).

I put an ARO (analog readout) on the quill of my mill. Only 1 in. range, but infinitely adjustable.

 

[RJSakowski]

I see the one you're looking at is even cheaper, that's a spectacular price.

79.3US $ 35% OFF|2 Axis Digital Readout Dro Display Linear Scale - Level Measuring Instruments - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

[/QUOTE]
This doesn't appear to include the scales.

 

[MrWhoopee]

I see the one you're looking at is even cheaper, that's a spectacular price.

79.3US $ 35% OFF|2 Axis Digital Readout Dro Display Linear Scale - Level Measuring Instruments - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

This doesn't appear to include the scales.
[/QUOTE]

Ah, yes, I was mislead by the picture. I now feel better about my purchase, though it is substantially cheaper now than when I bought it.

 

[Suzuki4evr]

What type of mill will the DRO be going on?

For my mill, it has a separate (factory) Digital Scale on the Quill. In most cases it's all I need. But the occasions when I've needed to raise or lower the head because quill travel was too short, I was glad I had a Z axis on my DRO. Also on my Medium sized bench mill, I find keeping the quill choked up gives me better accuracy when taking deeper cuts, so in those cases I again use the Z axis DRO and lower head over extending the quill.

It is a knee mill

 

[Suzuki4evr]

I see the one you're looking at is even cheaper, that's a spectacular price.

79.3US $ 35% OFF|2 Axis Digital Readout Dro Display Linear Scale - Level Measuring Instruments - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

This doesn't appear to include the View attachment 304467scales.
[/QUOTE]
The one I am looking at is on eBay with 2 scales for $167.20 I think

 

[Suzuki4evr]

I got this one for my lathe

View attachment 304465

157.18US $ 42% OFF|Lathe Dro 2 Axis Digital Readout Display With 2pcs 50-1000mm Linear Glass Scale Encoder Measuring Ruler Milling Machines - Level Measuring Instruments - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

It's decently made and has been trouble free, quite satisfied.

I see the one you're looking at is even cheaper, that's a spectacular price.

79.3US $ 35% OFF|2 Axis Digital Readout Dro Display Linear Scale - Level Measuring Instruments - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

I like the colors too.

On a mill, the scale width is not a real big issue. You might lose a little travel, but not enough to worry about (unless it's a mini).

I put an ARO (analog readout) on the quill of my mill. Only 1 in. range, but infinitely adjustable.
View attachment 304466

Your DRO looks nice,but shipping to SA is very expensive, almost half the price of the DRO.

 

[Suzuki4evr]

I have had a three axis glass scale DRO on my mill for fifteen years and have yet to have it malfunction. IMO, the secret is providing a suitable scale guard. The x and y scale guards are mounted so that any oil, coolant, or chips would have to reverse direction to reach the scale seals. The z axis is more vulnerable but still no problems.

Do you have some pics of your setup?