Bearing Race ID Help Please......

[JoeLee]

That would be calibrated thin foam?

Sounds like you have added several variables.

Do what I, eKretz, and Doozer said. Just a few thou deflection on the indicator and there is no issue.

Keeping the indicator centered.... LOL.... that's the issue, and then don't get any grit under that bearing race, etc, etc. Indicate the table directly and you KNOW!

I don't believe that there is any foam that is flat enough to use for this purpose. It changes with temp and humidity. Glass is no where near perfect, even good quality glass.

All around a bad idea to stack such materials for precise measurings.

JL......................

[JoeLee]

Idea being that the machine table probably has many imperfections from years of use (and occasional abuse) in addition to the T-slots which cause the indicator to bounce around a bit when tramming the head. Inserting the smooth surface of this bearing race helps to save on unnecessary indicator wear. When spot checking a machine that has a good table surface it's quick and easy to set the indicator to only deflect a few thousandths, so the needle won't bounce too much. It's when the head is way out of tram, or the table is pretty banged up, that the introduction of the smooth surface might be needed. On my worn out old machine I've stoned down the high spots caused by previous owner's activities, but there are sufficient number of divots that I use a pair of 1"x2"x12" parallels to give me a smooth indicating surface.

Your correct. My table isn't as bad as some but it has a few nicks here and there. Even the scraping will cause my tenths dial to flutter. Dropping off into a T slot and then back up on the table causes my dial to never return to where it was on the other side of the slot. It's best to keep it loaded throughout the entire sweep and to have a smooth surface so the dial doesn't flutter. That bearing race is perfect.

JL..................

[754]

Try this it helps.
use DTI in Indicol or other holder that allows needle to sweep approx 6 inch circle.
now my table is frosted so in between those marks, I can see if there is wear or damage. .. make a sharpie mark in 4 locations you deem good.
now you want indicator needle tilted to about 15 to 25 degrees to table. Now use indicator travelling in a direction where the needle is trailing.
now it rides over the tee slots or holes easily .
Once used to it , gets easier... get it to 1/2 thou... it's a thou over a foot.. good for 97 percent of work.

[old mart]

Thats exactly what I have done with bearings from a helicopter output shaft. Brand new and somewhat pricey, about 10 times the commercial cost. I have a drawer full of inner and outer races from 1" to 12" diameter. Perks from museum stock.

[Doozer]

..... Dropping off into a T slot and then back up on the table causes my dial to never return to where it was on the other side of the slot....
JL..................

Problem with the indicator
or flex in the linkage arm.
Seriously, I had an Alina
indicator that was flakey
like that. Sent it to MR
Tool Repair, fixed it for $20.
Check out what you have.
Skipping over the slot
should absolutely never
be a problem. For real.

-Doozer

[mickeyf]

I put an indicator in the end of an arm mounted in a collet. The arm is about 9 inches long, so the swing from one side of the table to the other is about 18 inches. Adjusting the table itself with that to as close as I can get it is surely as good as adjusting to a more precise surface that is less than half that distance, yes? And yes, the T slots can easily be dealt with.

[JoeLee]

I put an indicator in the end of an arm mounted in a collet. The arm is about 9 inches long, so the swing from one side of the table to the other is about 18 inches. Adjusting the table itself with that to as close as I can get it is surely as good as adjusting to a more precise surface that is less than half that distance, yes? And yes, the T slots can easily be dealt with.

You mean like this ???? Been doing it this way for years.






JL........................

[JoeLee]

Problem with the indicator
or flex in the linkage arm.
Seriously, I had an Alina
indicator that was flakey
like that. Sent it to MR
Tool Repair, fixed it for $20.
Check out what you have.
Skipping over the slot
should absolutely never
be a problem. For real.

-Doozer

I don't use my Starrett flex post for tramming. I try to keep it as rigid as possible.

JL...............

[754]

All I can say is your method with 1/2 the arm stick out would work well with needle turned 90 degrees ,and running only one direction.
but.. and this matters. .. it takes a few times... for it to get comfortable and fast...
turning the indicator will help huge unless you are using the ring..

[JoeLee]

All I can say is your method with 1/2 the arm stick out would work well with needle turned 90 degrees ,and running only one direction.
but.. and this matters. .. it takes a few times... for it to get comfortable and fast...
turning the indicator will help huge unless you are using the ring..

Well, with the block under the needle the needle never slides on anything, I slide the block around under the needle so it doesn't make any difference which way it sits. It's just a pain. The ring would make it a lot easier.

That 1/2" bar does have a little flex to it, maybe it's more the 1/2" shank going into the collet.
I've always wanted to make a new bar, preferably something that is arched, like one of those camel back things. I also would go to a larger dia. shank. like 3/4"

JL...............

[sarge41]

What 754 mentioned is a good tip that I forgot, the one about turning the indicator 90 degrees and running one direction. I can see using a plate such as the bearing race when "roughing it in", but then I go to the indicator on the table itself. That way, there is no surprises.
Sarge41

[J Tiers]

........................ Dropping off into a T slot and then back up on the table causes my dial to never return to where it was on the other side of the slot. It's best to keep it loaded throughout the entire sweep and to have a smooth surface so the dial doesn't flutter. That bearing race is perfect.

JL..................

Going into a slot and BACK to same point? Or going into a slop and up the other side of it?

[JoeLee]

What 754 mentioned is a good tip that I forgot, the one about turning the indicator 90 degrees and running one direction. I can see using a plate such as the bearing race when "roughing it in", but then I go to the indicator on the table itself. That way, there is no surprises.
Sarge41

Yes, it is a good tip. If I'm moving my indicator along something back and forth I always try to have the needle in line with the travel and not 90 deg. to it.


But in my instance with the block under it the indicator never really moves on the block. I keep it under the needle as I sweep the table.

JL..................

[JoeLee]

Going into a slot and BACK to same point? Or going into a slop and up the other side of it?

Either way. But were talking a tenth or so.

JL.................

[Doozer]

So you are chasing a tenth of repeatability and you think a bearing race in between is going to get you that tenth ?
Take a toke and pass it over to me. You must buy the good stuff. LOL

-D