Poor mans lathe DRO's

[C-Bag]

My only problem is my apron lock is right where the two DRO's come together. I'm sure there is some work around but your details help a bunch, thanks.

[Paul Jones]

bob409,

The photos showing the setup details are very helpful and shows us what we have to machine to our specs. Also, thanks to Woodgeezr regarding the difference between the SR44 and LR44 batteries. I buy the 10 pack of Energizer 357/303 Zero Mercury Batteries using Amazon Prime for about $1.10 per battery.

Thank you,

Paul

[Manitoba Man]

Hi Bobs-Greetings from Canada

I have an Atlas lathe and a homemade mill/lathe both crying out for your DRO setup. Thanks. I like how you combined the x and y calipers on one bolt.


Bob

[barsyl4041@netzero.net]

Thanks Woodgeezer: Like you, I tried the SR44 batterys and found them lots better. I also found that sometimes the LR44 batterys were not dead, but had an oxide layer build up from setting around. a little cleaning with a pencil eraser on both sides of the battery and inside contacts fixed the problem. BLF

[Christophe Mineau]

but when it gives me erratic readings while I am using it due to a low battery or something else I usually fold it before thinking

Hi Franck, I'm sure you will be happy with that :
https://www.woodgears.ca/caliper/index.html

I have three digital calipers, the first keeps reliable, but like CBags, eats batteries like nothing. Why don't they feature an auto off on these calipers ?
The two others, very cheap, although a very similar build, started to give erratic measures, and random resets.

I ended making a research on the Internet and found that article from Mathias (the Great).
It is incredibly working !
And now, my best caliper is one of these cheap calipers, fixed like so.

Since I started having erratic measures, I purchased a dial caliper, which is, for the same precision, far more repeatable, but with this one, I very often make millimeters mistake. So, now, when turning something precise, I tend to use the digital one when approaching less than 1 mm to the target, and the final mm, I measure it with the dial caliper.

Christophe

[WyoGreen]

On another forum a long time ago I found a thread about the SR/LR batteries. Additionally, they said the calipers never really shut off, just the displays turn off. They went on with a comparison of the current drain of different brands of calipers. The Chinese made calipers had the biggest current drain, while the Mitutoyos had the lowest current drain.

Steve

[Frank S]

Thanks Christophe But then I wouldn't have the fun of watching my wife cringe at the sight of me destroying expensive useless things
When I need precision I break out my micrometer sets My biggest problem is not having a 3CR (Clean Climate Controlled Room) Of coarse I no longer have the luxury of languishing in the $100,000.00 a year expense account either

[Toolmaker51]

Quite good indeed. That quick attachment is critical in my estimation. There are certainly times when tools are at risk, regardless the expense. Additionally, 6'' works in envelope tolerances want to be held close. A 12'' would introduce error [doubled] if not flat and parallel to the ways. All DRO kits have hardware to adjust precise alignment with a moving machine element; carriage, table, or quill.
My lathe is equipped with 70's era electronic operating like a Trav-A-Dial. Both use a wheel of precise circumference to infer travel. Accurate within .002 over entire 54'' of travel, but face of way needs cleanliness to function accurately. The vertical axis of wheel requires 100% alignment in both planes to perform. The compound is equipped differently.
On fleabuy, found a 1950's era patent model of a vernier scale and division plate. Scale is mounted, the divisions are movable anywhere along length of scale. So not exactly 'Zeroed' in common manner but 2.000 or any reading is easily returned to. A little trig allows for PRECISE size control at any angle. Observing approach to desired measurement and cutting action almost simultaneously is better than counting flashing digits.
In keeping with observation different geological areas have preferential compound angles. 30* (even 29.5*) moves one half division of that dial. At 90*, you'll get 1:1 control of facing, snap ring grooves, counterbores etc. In the US, with carriage readers fairly common, 29.5*-30* is ready for fine diameter control and threading. With close diameters, I like a .0005, .0001, once a .00005 test indicator on the crosslide. For production, using QC toolpost and holders, only a two-axis DRO would be suitable. Long travel indicator stems on lathes is asking for trouble.
Fluctuation in calipers; digit [most visible], dial and vernier [least visible] have at least one more error inducer. All calipers have lathe-like 'ways'. Width of the beam face controls one direction by depth of the channel in the carriage. Few have an adjustment correction there. Along the edge, two miniature set screws compensate a gib. Many fool around with those to achieve smooth movement. WRONG! Using elevated sense of touch, correct adjustment is parallel jaws; then smooth travel. O/O/P results in different readings at every point between the jaws. Best method outside calibration lab is a bearing ball, offering minimal contact, no deformation, and no surface to 'fake' the jaws into parallelism. A drop of enamel, nail polish or linseed oil on screwhead seals the setting, yet removable. No Loctite!

[C-Bag]

On another forum a long time ago I found a thread about the SR/LR batteries. Additionally, they said the calipers never really shut off, just the displays turn off. They went on with a comparison of the current drain of different brands of calipers. The Chinese made calipers had the biggest current drain, while the Mitutoyos had the lowest current drain.

Steve

Isn't that interesting. So the screen only turns off so it doesn't lose its memory? Now why does the igaging lo buck made in China battery last literally forever and my 6" calipers die in hours? There is some wildly fluctuating manufacturing spec's there. Even as bad as the 6" is, I don't think I could smash it like Frank. I'm just weak I guess.

[Toolmaker51]

All DRO's have two sets of accuracy tolerance. Repeatability and Resolution. Repeat is ability to interpret return to the same previous or predetermined setting. Resolution is how fine an increment can be read. They are interdependent and individual at the same time. Most place Repeat a higher importance. To them Resolution would mean if drawing tolerances appear met. However...
Where calibration is actually maintained, resolution ranks high. Typically a 4:1 ratio is used. The instrument must have resolution 4x finer than tolerance range, meaning +/- .002. [.004 total] demands accuracy of .001. And +/- .001 = .0005. And +/- .0001 = .00005. And +.0001/ -.0000 = .000025.
Size control is what it's all about. Then cleanliness, temperature, and humidity need restrictions. Yep, accuracy's expensive.