Cincinnati precision measuring attachments - how to install the dial indicators?

I have a 1-B Toolmaster that was factory equipped with the optional precision measuring attachments for all three axes. Before DROs were common, these attachments were a more accurate method of measuring travel than the micrometer wheels on each leadscrew. Sort of like a jig borer.



Unfortunately, someone along the way removed the X-axis longitudinal components on the front of the table (I'm looking to buy the assembly, if anyone has one for sale), but the Y- and Z-axis parts are all still place. The dial indicators and the barrel micrometers and standards are long gone, of course, so I'm working on identifying and sourcing replacements. Cincinnati's parts catalog refers to them only by their Cincinnati part numbers, and the descriptions are generic, e.g. "Dial - indicator".

The barrel mikes and standards are easy enough to replace, but I'm having a hard time figuring out which dial indicators to use, and more importantly, how to install them. They are housed in cast iron "cups", and the inside diameter of the "cups" suggest AGD 2 indicators, probably something like a Starrett 25-111 (0.0001" increments, +/- reading from zero, 0.025" total travel).

The problem is that no AGD 2 size indicator body (at least that I can find) can be slipped into the cast "cup". The diameter of the body isn't the problem, it's that with the length of the stem, it can't be tilted enough to slide into the "cup". Starrett's customer service suggested that I enlarge the stem opening, but obviously these had indicators in them when they were new, so I'm reluctant to break out the carbide die grinder. Nor can I find an indicator with a removable stem, which would allow the indicator to be reassembled once the body is in the "cup".

Anyone know the secret to these things? Did Cincinnati have a special dial indicator with a short stem made just for these precision measuring attachments? I know that Bridgeports had a similar system, and the photos I've seen of the "cups" on those machines are just as baffling.

Here's what the cup for the Z-axis travel on my Toolmaster looks like (the third photo is the backside):

P&W used a separate spring loaded piece - and called it the "dial Indicator rod" - it fit in a bushing housed in the "cup"

I.E. some detail to transfer motion from end measure (or barrel mic) to tip on indicator

John, thanks for the reply. Cincinnati used a similar setup, but for simplicity I omitted it from the photos above. Here is the page from the Cincy factory parts catalog that shows the complete precision measuring assemblies for the Y- and Z-axis precision measuring assemblies (all of the photos I post here are from the Z-axis vertical assembly). And below that is a photo of the "cup" again, but this time with the internal plunger, spring, and Woodruff key keeper (items 59, 58, and 57 respectively in the parts diagram).





These parts all seem to work fine (the plunger moves more than the required travel in the bore), and even without them assembled into the "cup", I can't get the dial indicator into the "cup". Here's a screen cap from a video that shows the problem. The stem of the indicator is binding in the hole that connects the bowl to the counterbore where the spring and plunger are located before the body of the indicator can drop into the bowl.



I'm probably missing something really easy and obvious...

I'm probably missing something really easy and obvious

Click to expand...

Indicator is back wards and cannot have the "mounting shank" installed

However CMMco installed said indicator without such a "mounting shank" installed is something that will have to be figured out

Appears from "cup" details is was stud mounted with a centralized stud on the back and a fastener entering from bottom of "cup"

See part #54 above for a hint

While there, do note Part #56 has no "mounting shank" installed - and no doubt has the proper BACK on the indicator to suit the "cup's" design

Yes, the original indicator must have used a stubby threaded post back to mount to the cup. The stock post back from Starrett is too long, but could easily be modded to the correct length.

The parts catalog illustration suggests that the original indicator had a very short stem and spindle to slide into the bore, or as you suggested maybe the stem was removable.

Look at Federal indicators.They supplied a lot special oem indicators for machinery.

ratbldr427 said:

Look at Federal indicators.They supplied a lot special oem indicators for machinery.

Click to expand...

Thanks for that tip. I haven't been looking at old Federal indicators, but will do so.