Bought a few gages

You did real good for $15, but don't use them for calibration. Tolerance is far too wide to be effective for that purpose. They'll be real handy for working on machines, or even inspection of manufactured products.

Harold

Seriously, I suspect the caliper was right on. The blocks are in such condition that .0010 is likely in error on most edges. You measured .0005 on each edge or .00025 on each surface. The micrometer has two surfaces. I bet is on a dirty block.

Block should be so clean that when placed on one another and twisted, they bond together without a fluid or bond - metal to metal.

Ceramic to ceramic does the same...

Looks like the set is ok for general use, don't expect high specs.

Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

Ignoramus20599 wrote:

Martin, thank you. How would you clean these blocks?

i

Ok - first I'll give some tips and then information and then a number to buy a manual if wanted.

1. When stacking blocks together, they should be clean and handled with gloves ("rubber"). The hand has oil and acids that etch the blocks.

2 Say we have clean blocks and wish to stack up a stack: Place two perpendicular to each other like you want to stack but rotated. Press at the union point and then rotate while pressing. The blocks should 'wring' together. Wringing gage blocks of steel, ceramic and optical parallels possible in one stack in this fashion.

Cleaning:

When they are new they are covered with preservatives to prevent the mirror surfaces contacting air and moisture. Before use, this must be removed but applied if not used for extended time. e.g. clean those that you use, keep the rest in a good buffer material.

The cleaning process is very simple - Takes several seconds per block. (Not yours). A can of denatured alcohol would be the best for normal materials. Place a sheet of clean wiping paper on glass - Crew 2 Kimberley Clark or the like (not fuzzy...). Pour some Alcohol on it and while holding the block, press down and drag across the paper and Alcohol.

Now for the black art and alchemy... professionals close eyes : Since your blocks are (quoting this manual) 'neglected or misused' and would normally be replaced - and rusty ones not in the box at all...

Get some very fine diamond dust and using the paper and Alcohol again with it - and the same wiping action - clean and cut the rust off. It might take spot treatment better - using a pencil eraser (ink) and spot grind. Use this method on the dimension surfaces. The other ones are not as critical. Eyes open again -

And that is about it for the basic thoughts.

The manual I have is from the class Mitutoyo teaches - I got an offer and was unable to attend (I was in Semiconductor PCB design and fab process step testing - to first devices (some say Silicon, but it was SiGe!). I bought the book. SO can you!

EDU102-10 3 ring binder 200 pages and 14 chapters "Metrology Handbook" USD $87.50 + tax several years ago... I believe Patti Akram at (630) 978 6471 might be able to help you.

1 day was $395 and 2 day was $550. Lunch included.

And if Patti is upset or can't do this anymore or recalled the offerers... let us all know - so we don't send more back to her! Take the class - it is very good. Different types...

Martin

Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

Ignoramus20599 wrote:

would normally

Simichrome is not as nearly as agressive as the diamond paste and works well if the blocks aren't too beat up. I cleaned up my shop blocks with Simichrome applied to a piece of copier paper held on a surface plate. Auto polishing compound would probably also work OK. But as Martin says, don't let anyone see you doing this.

Ned Simmons

perpendicular to each other

rotate while pressing.

and optical parallels

and its fascinting to note..that when two gage blocks are wrong together..its not unknown for the stack height to be less than the sum of the two blocks themselves....

Gunner

"Deep in her heart, every moslem woman yearns to show us her t*ts" John Griffin

manual if wanted.

("rubber").

Do you actually use your shop blocks with rubber gloves? I've never actually seen that done. Perhaps useful for people with rusty fingerprints I guess.

would normally

this method

Gak. The Mitutoyo manual actually recommends grinding gage blocks with diamond dust?

For cleaning just before wringing, I just rub the block's useful faces on a sheet of clean paper, whatever's handy. The surface should be pretty flat, like on a book or binder, surface plate, ground surface, etc. They wring together really well after that, even abused shop blocks.

Regards,

Robin

perpendicular to each other

then rotate while pressing.

ceramic and optical parallels

Not if the blocks are within proper range of thickness and flatness. The usual result is to gain a few millionths because the blocks aren't dead clean, but will still wring, albeit poorly. If the surfaces are good enough to wring, there's no reason for them to go together at a loss of size. That would defeat the purpose of the blocks. Remember, there are blocks out there with +/- .000002" tolerance, and likely even closer. I'm way behind in this game these days.

Blocks are known to change size----larger or smaller. To minimize the changes, they are subjected to a series of deep cold cycles, which helps stabilize the material. I don't know that they can ever be considered dead stable, at least not steel blocks.

One of the blocks in my A+ Webber set was discovered to have changed almost .000050" from the original certification when I had the blocks re-calibrated and certified. That's one of the reasons blocks should be re-calibrated on a regular schedule if certified work is in house. If a block is damaged, it usually won't wring-----so that's a dead giveaway that the stack would be oversized if it was held by the rods.

Harold

Exactly.

He should wring some other blocks in the set together to make stacks of the same height, then compare them with a tenths indicator on a surface plate. If the blocks are indeed worn out, this should make it obvious.

Correctly, repeatably and reliably measuring beyond .001" is really not as trivial as a lot of people think. Many things come into play like small nicks/burrs, dirt/dust, flatness/warpage, parallelism, temperature, etc. You have to cover all your bases. If the blocks actually seem to be out, make sure you can prove it in at least two different ways. There are many many sources of error at this level of precision.

The picture lists a tolerance of half a tenth. I can't imagine anyone here is actively doing work which would exceed this standard (save for actually worn blocks, which we are unsure of now).

Regards,

Robin

actually..the phenomenon is well documented with the finest sorts of gage blocks.

and no one can to this day..understand why

"Deep in her heart, every moslem woman yearns to show us her t*ts" John Griffin

I am going to read up on this stuff a little and experiment by comparing various combinations. I do like your idea of having at least something that is currently calibrated.

i

Right!

The manual shows 5 blocks stacked and the total error sums up!

Each block and each space between as there is a space still...

Best to use the fewest number of blocks. Lower errors.

Get several boxes - keep track of A & B so you can track problems if there are any. Multiple boxes allow division of a space by 2 or 3 ending up of the same value.

Guess what - surface height machines can measure the totals... One never knows until one tries. Sometimes a Gnats hair gets in the way and you are off.

Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

Gunner wrote:

perpendicular to each other

rotate while pressing.

and optical parallels

Gawk back - NO it didn't. That was the black art and alchemy. His blocks were rusty. So they looked - maybe grease. Blocks don't have to be used to micron levels - some people cut metal with a chisel. This was a nice note to a friend in a way (two) to clean up the spots or sides if out of care.

Iggy isn't working at NASA or JPL with his sets - but measurements are nice within bounds.

Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

Rob>

manual if wanted.

("rubber").

would normally

this method

My blocks are not rusty. I washed a couple of them and they looked quite nice. When I get time, perhaps next week, I will wash all of them and will try to compare them systematically.

i

According to woodworker88 :

For most purposes, that would do nicely with a sine bar or a sine plate. +/-0.000050" on a 5" bar would make a maximum angular error of 0.000573 degrees, or 0 degrees, 0 minutes and 2.06 seconds. I would say that that is close enough for most purposes. :-) I think that this is the sort of thing that "shop grade" blocks were made for.

Even with the (rather rare) 2.5" sine bar that would still be a pretty small error -- down in the low seconds.

Enjoy, DoN.

Its spooky when they sum down.

perpendicular to each other

rotate while pressing.

ceramic and optical parallels

Sorry. The way you wrote it could have been interpreted that way.

It's unlikely that you could remove even .0001" with the technique you recommended without a serious lapse in good judgement.. However, blocks that are ground to a flatness of less than .0001" do not necessarily wring - as I understand, that's a bit of a black art. The diamond paste will likely decrease the flatness of the block face, perhaps even enough to prevent wringing. That was my concern. Starrett sells gauge block stones for truing abused blocks. Not really cheap, but something to consider...

Regards,

Robin

I agree with Robin. The slightest abuse of the face of a block and they tend to cease wringing, or wring very poorly, with little to no holding power. Flatness alone does not explain the attraction of blocks. Surface finish plays a huge role. Raised damage, such as a scratch, is easily removed with one of the stones (hard Arkansas) that is supplied by Webber (Starrett). With care, a block can be restored to usefulness without altering its ability to wring, or materially effecting its size. I'd hesitate to use anything else.

I've been around Jo blocks for almost 50 years, and, aside from Gunner's comments, I've never heard anything about blocks losing thickness upon assembly, although I have personally experienced growth. He mentioned that it is commonly known that they can assemble with a sum of less than the total of all the blocks in a given stack. I'd love to read any documentation where that has occurred, or any kind of report that might lend credence to the concept.

Gunner? Any sites you'd care to offer?

Harold