Recommendation on Calipers

[Odd_Ball]

Stone the burr off the tip where there is no light and I bet the jaws close up properly.
You should be able to find the damage with your fingernail.

Ok, so I used a white ceramic stone and very slowly have eliminated most of the burr. The needle is now just a hair above zero at full close and there is almost no light shining through the closed jaws. In fact the light is only shining through in two areas, and even then just barely as I have to hold at just the right angle to get barely any light coming through. Like there is a slightly worn out area in the middle of the jaws and another one near the tip past where the wide flat area of the jaw face turns into the thin blade.

It seems to me that now I need to slow down and focus on technique. First on eliminating any remaining burr, and second on getting the faces completely flat and square with each other as well.

Do you have any advice here? Is it better to put the calipers in a vice and pull the stone, or other way around? I also tried closing the caliper jaws along their entire length on the stone and moving the stone back and forth for a time. This seems like a promising way to flatten both sides square to each other, but I'm wondering what you all might think.

Btw, I am using a 6" x 1/2" x 1/2" white ceramic stone from Brownells, but I also have the brown ceramic stone and up to 2500 grit sandpaper on hand.

Overview of progress:
I should also mention that in playing around with the feeler gages, I am still finding about 0.4 thousandths of extra interference (even though at full close the needle shows only a hair above zero on the dial). In otherwords, I need to open the calipers to +0.002" in order to be able to insert & move the 1.6 thou gage between the jaws. Previously I had to open the calipers +0.0035" in order to insert/move the 1.6 thou gage between the jaws.

[ar15barrels]

Ok, so I used a white ceramic stone and very slowly have eliminated most of the burr. The needle is now just a hair above zero at full close and there is almost no light shining through the closed jaws. In fact the light is only shining through in two areas, and even then just barely as I have to hold at just the right angle to get barely any light coming through. Like there is a slightly worn out area in the middle of the jaws and another one near the tip past where the wide flat area of the jaw face turns into the thin blade.

It seems to me that now I need to slow down and focus on technique. First on eliminating any remaining burr, and second on getting the faces completely flat and square with each other as well.

Do you have any advice here? Is it better to put the calipers in a vice and pull the stone, or other way around? I also tried closing the caliper jaws along their entire length on the stone and moving the stone back and forth for a time. This seems like a promising way to flatten both sides square to each other, but I'm wondering what you all might think.

Btw, I am using a 6" x 1/2" x 1/2" white ceramic stone from Brownells, but I also have the brown ceramic stone and up to 2500 grit sandpaper on hand.

Overview of progress:
I should also mention that in playing around with the feeler gages, I am still finding about 0.4 thousandths of extra interference (even though at full close the needle shows only a hair above zero on the dial). In otherwords, I need to open the calipers to +0.002" in order to be able to insert & move the 1.6 thou gage between the jaws. Previously I had to open the calipers +0.0035" in order to insert/move the 1.6 thou gage between the jaws.

I would strip the caliper apart so the moving jaw is off the beam.
I would fix the stone and work the jaw on the stone.
Keeping in mind that calipers are not normally trusted below 0.001", I would not make much fuss about the 0.0004" you are seeing now or a couple tenths variation across a jaw face.
Just know that that when the jaws are all the way together and no light is visible that you are good.
Don't measure in areas of the jaw that show light.

[Odd_Ball]

I would strip the caliper apart so the moving jaw is off the beam.
I would fix the stone and work the jaw on the stone.
Keeping in mind that calipers are not normally trusted below 0.001", I would not make much fuss about the 0.0004" you are seeing now or a couple tenths variation across a jaw face.
Just know that that when the jaws are all the way together and no light is visible that you are good.
Don't measure in areas of the jaw that show light.

Thank you for all the feedback and advice on this, Randall. Mainly I'd like to eliminate the light shining though the closed jaws, and I think I am 90% there already. At a minimum I need to expand the non light area a little more to have a bigger workable area.

I agree that as a practical matter they are completely useable right now for reloading purposes, which was the original point of this thread. Like you and others have noted, calipers are not really for 0.001" accuracy, so being off by 0.4 thousandths is not really significant, in this context at least.

Thanks again, and Merry Christmas!

[Odd_Ball]

Polishing a Turd

What do you recommend for Calipers? I've been using my digital Harbor Freight special for a while and was thinking about an upgrade.

Fwiw, I dug out my HF digital calipers and essentially gave them a 25 cent trigger job using a needle file set and some flitz using a qtip and cleaning patch. They now open and close smoothly and feel like entirely different calipers. Different enough that I am actually starting to use them again.

Disassembled and ran a flat needle file up and down the little channel on the rear of the beam and took down alot of peaks and rough spots. Cleaned up the outside edges of the beam with the file where there were rough spots. Unscrewed the digital display/electronic part from the movement and used the flat needle file to clean up the large flat areas, and the triangle and square needle files to get into smaller corners and the surfaces the beam rides along. It all felt like sandpaper and needed to be filed down and polished. The thin narrow bar that rides in the channel of the beam also had to be straightened and adjusted so that it could move without interference.

Something to consider while you look for a good deal on a replacement, or even to have these as a back up.

[Odd_Ball]

Any lubricant attracts dirt. No lubricant should be used on measuring tools.
Except for thimble threads on micrometers, which is almost nothing to speak of.

Thanks for pointing that out. I wasn't using the mineral oil to lubricate anything, I was only following up after cleaning with mineral spirits to get an oil film back on after being degreased. I used compressed air and shop towels to dry off everything and remove basically all oil applied.

Calipers are not micrometers. Calipers are a rough measurement compared to micrometers.
.001 isn't worth debating concerning accuracy of calipers.

So the tips are a bit tighter than the mid and base? Not a bad way to be out of parallel. Loose gibs would be the opposite. Some have been known to lap the jaws.

Most reloading measurements will be with the mid or toward the base of the jaws. Just know that any measurement at the tips is relative and not discreet.

Make sure they're clean. One good way is to close them on a piece of paper and slide the paper out.

I'm definitely not worried about the accuracy at this point. All three calipers I have now (the Lyman, the HF digital and these used Mitutoyos) produce the same measurements of things. Both the HF digital and the Mitu's have a little light shining through the jaws but it doesn't seem to change the measurement produced.

The only thing left to do with the Mitu's is take out that last 0.4 thousandths of interference on the jaws so they will properly zero when fully closed. I've brought it down from 2 thousandths already so I might as well go a little more.

[LuckyGuy]

Wellllll

What do you recommend for Calipers? I've been using my digital Harbor Freight special for a while and was thinking about an upgrade.

Dial or Digital. I like Digital.

[ar15barrels]

A matter of personal preference on the feel. But I prefer Brown & Sharpe.

I love my Swiss made dial test indicators but never even though to seek out swiss made calipers since the Mitutoyo's served me so well.

I popped over to eBay and found these:

http://www.ebay.com/itm/174133456054

For $30 shipped, I will give them a try.

They came in yesterday.
These are really nice calipers.
They are tighter than Mitutoyo which makes them feel smoother.
Starrett's and Chinese are looser which makes them feel cheaper.

[67Cuda]

They came in yesterday.
These are really nice calipers.
They are tighter than Mitutoyo which makes them feel smoother.
Starrett's and Chinese are looser which makes them feel cheaper.

Another convert, nice.

[JagerDog]

They came in yesterday.
These are really nice calipers.
They are tighter than Mitutoyo which makes them feel smoother.
Starrett's and Chinese are looser which makes them feel cheaper.

Some prefer B&S. Good tools. Personally, I like a thumbroll which TMK they don't offer.

[ar15barrels]

Personally, I like a thumbroll which TMK they don't offer.

Doh, I didn’t even think about the thumbroll giving so much mechanical advantage.
Now I need to compare them all based on actual force to move the moving jaw instead of the perceived force at the thumb required to move the moving jaw.
Mitutoyos might be just as tight, but easier to move due to the thumbroll.
I’ll likely stick with mitutoyos because they are all over the shop already.

[BrassCase]

My Mitutoy 505 arrived today from my E-bay purchase. $38.00 plus shipping. Came with the case, worn sleeve and instructions. Not a scratch on them or the crystal.

Be patient with E-Bay as these and other good brands come up all the time. I got these early Christmas morning so bidding was light.

[JagerDog]

Just a quick note. It's good practice to store your calipers with at least a few though opening between the jaws. Helps prevent corrosion at the measuring surfaces. Depending on the environment and frequency of use, it can help maintain your tools.

[BrassCase]

Just a quick note. It's good practice to store your calipers with at least a few thousandths though opening between the jaws. Helps prevent corrosion at the measuring surfaces. Depending on the environment and frequency of use, it can help maintain your tools.

Fixed it for you.

[67Cuda]

Just a quick note. It's good practice to store your calipers with at least a few though opening between the jaws. Helps prevent corrosion at the measuring surfaces. Depending on the environment and frequency of use, it can help maintain your tools.

It's always a good idea to not have the measuring surfaces closed while stored, but, in my experience, that has never happened to me.
Corrosion is a sign of inferior materials used to produce the item.

[JagerDog]

It's always a good idea to not have the measuring surfaces closed while stored, but, in my experience, that has never happened to me.
Corrosion is a sign of inferior materials used to produce the item.

I always have to scoff at "never had a problem" as an argument for most anything.

I suspect you're in a dry climate and not around much in the way of corrosives. Even the most corrosion resistant steel still can corrode. Calipers, needing to be "hard" aren't the most corrosion resistant steel.

I merely mentioned a "best practice".