# Possible Cylinder Square from scrap



## Redmech (Jan 27, 2018)

Up until today I only had one small import surface gage I purchased new from Grizzly. Not a very large base or much mass. I scored 4 different surface games off of eBay with plans of using one as a squareness comparator. I threw my Shars .0005 test  indicator and started checking out some large Caterpillar dozer wrist pins that I’d like to use as a squareness standard for my small home machine shop. The larger wrist pins come out of a 3508B V-8 out of a D11R, and the smaller wrist pins came out of D348 V-12 D10 “A” models.
Larger ones are 2.755” dia x 5.25” tall and the D348 wrist pins are 2.000” dia x 4.295”

Both the larger ones at a height of 5” check about .002” out of square.

Here are my options I see,

Mark the square where the halfway/.001” mark is and call that square,

Try sanding down the base on the side that is too tall that causes it to lean away from the test setup,

Not sure how this would come out, try chucking it up in my South Bend Heavy 10, make sure it’s in the Lathe square/zero runout and try facing the end.

I don’t have any sort of powered precision grinding equipment.

They are all very round, I’ve checked all over to make sure they aren’t out of round or have any slight tapers or anything like that.

I’m open to ideas or thoughts of my little project.

Should I use the V portion of my surface gage to put the cylinder square in? Or should I build a slight convex steel “bumper” to attach to the front of my squareness comparator tester.


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## Redmech (Jan 27, 2018)

My surface plate is an inexpensive 9”x12” surface plate from Woodcraft a few years ago. Not 100% sure of its flatness. 

Another project is to throw my surface gage and tenths indicator and map out the plate and see if there are any hills or valleys.


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## Asm109 (Jan 27, 2018)

Yes you can mount a piece of abrasive on the granite plate and sand the bottom to bring the squareness in. Locate the high side and rub with higher pressure on that side of the bar. Check frequently, you only need to remove a few tenths.
You are also correct that 1/2 way between max tipping towards the indicator and max tipping away is perfect square.  Mark that location anyways, its not everyday you can have something with 0 error.


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## 4GSR (Jan 27, 2018)

If you ever lay hands on a Brown & Sharpe cylindrical square, it's designed to be out of square by about 0.002-0.005".  It has a set of marks around the OD of the cylinder indication which place is exactly 90 degrees square, and others at various increments to tell you how much out of square you were.  Looks like your almost there.


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## Wreck™Wreck (Jan 27, 2018)

You will need a surface plate to inspect your surface plate so start there. After you have inspected the first two you will need another to inspect the first two again at which point you will have three, you will require a fourth because you are uncertain about the accuracy of the first three.

After reaching 100 surface plates you will be able to arrive at an average error ranging between 1 and 100, at this point I would suggest buying another surface plate and inspecting the first 100 for  deviations which you are sure to find.

When you achieve 0 error let me know as soon as possible, I have been searching for this for the last 18 billion years or so.
Thanx


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## Silverbullet (Jan 27, 2018)

I gave up those super accurate ideas years ago , doing work on government contracts building the missiles tubes and wings , mounts . Tomahawk mounts had to be super accurate down to the finish itself. They really only carry it to its launch site. So really was that needed no. Did it pay yes . There only so many things that need super tight tolerances. If it's past a half tho you really need the best equipment possible. Along with grinders , jig bores , lapping machines. Way to much for a hobbies but if it's your desire of perfection God bless and enjoy. If they were my pins I'd mark them like 4gsr said and have the reference .


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## Redmech (Jan 27, 2018)

Asm109 said:


> Yes you can mount a piece of abrasive on the granite plate and sand the bottom to bring the squareness in. Locate the high side and rub with higher pressure on that side of the bar. Check frequently, you only need to remove a few tenths.
> You are also correct that 1/2 way between max tipping towards the indicator and max tipping away is perfect square.  Mark that location anyways, its not everyday you can have something with 0 error.



Great comment.  A couple few tenths is all I need to remove. I hadn't thought how much I'd have to remove, but measuring 5" up, not much would be needed to square it up. Thanks!!



4gsr said:


> If you ever lay hands on a Brown & Sharpe cylindrical square, it's designed to be out of square by about 0.002-0.005".  It has a set of marks around the OD of the cylinder indication which place is exactly 90 degrees square, and others at various increments to tell you how much out of square you were.  Looks like your almost there.



I had no idea some were made purposely out of square. 



Wreck™Wreck said:


> You will need a surface plate to inspect your surface plate so start there. After you have inspected the first two you will need another to inspect the first two again at which point you will have three, you will require a fourth because you are uncertain about the accuracy of the first three.
> 
> After reaching 100 surface plates you will be able to arrive at an average error ranging between 1 and 100, at this point I would suggest buying another surface plate and inspecting the first 100 for  deviations which you are sure to find.
> 
> ...



I enjoy chasing accuracy that I really don't need. I only have a few CDO's (OCD, I have to arrange them alphabetically).   Even though I don't need to measure in the single digit millionths, it's a fun mental exercise to try as be as accurate as I can with the tools I have. Currently I only have one surface plate, but I can see myself buying a better American made one just to satisfy myself. I earn a fair living, I don't drink, do drugs, I'm a good husband and father, so I buy tools and enjoy working with my hands.


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## Redmech (Jan 27, 2018)

One other thought I just had on my convex bumper, I have to have It to compare my comparator with something that would be anything different than my exact diameter cylinder square. If Ibump my comparator up to a flat sided object, it would not read accurately compared to my round cylinder set into the V of the base. I'll have to get a plan together and build it to mount to my squareness comparator base.


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## Bob Korves (Jan 27, 2018)

Redmech said:


> Up until today I only had one small import surface gage I purchased new from Grizzly. Not a very large base or much mass. I scored 4 different surface games off of eBay with plans of using one as a squareness comparator. I threw my Shars .0005 test  indicator and started checking out some large Caterpillar dozer wrist pins that I’d like to use as a squareness standard for my small home machine shop. The larger wrist pins come out of a 3508B V-8 out of a D11R, and the smaller wrist pins came out of D348 V-12 D10 “A” models.
> Larger ones are 2.755” dia x 5.25” tall and the D348 wrist pins are 2.000” dia x 4.295”
> 
> Both the larger ones at a height of 5” check about .002” out of square.
> ...


I also use a large diesel wrist pin for my cylindrical square.  I was in the heavy truck and equipment parts business and got a new one free out of a defective piston and liner kit.  The cylindrical surfaces when new are ground incredibly accurately, because they need to be or they would not last under the constant pounding they get in the engine.  The grinding is high end work, done on high speed, spit em out machinery.  Amazing.  They fit pistons like gage pins fit precision ground holes, only better.  The end flats are not as accurate, because they do not need to be accurate for what they do.  I was lucky and one end of my pin sits flat without rocking at all on the surface plate.  If it rocks, give up until you can get the end ground flat on a surface plate in a rigid fixture holding it vertical.  Lapping them is a really fussy job.  You have to use perfect technique or the ends will become spherical from leaning on the upper portion of the pin while pushing the pin down onto the lapping plate.  You must push the pin quite low down on the side (right at the lapping plate) with a horizontally held V forked push stick while pushing exactly straight down in the middle of the top of the pin.  Otherwise the pin rocks and chatters and it will not be flat, but instead worthless.  The pin only needs to be lapped until you can see flat portions 120 degrees from each other, then stop.  It will work fine just like that.  There will be high areas not in contact with the surface plate, and that is OK, but grime, grit, etc., must not be allowed to collect there.  Carefully keep the bottom face clean without abrading the surface at all.  Now the calibration.  Find an accurate angle block.  I have a granite angle block and a cast iron one I have scraped in while marking it up against a granite master block.  Put the cylinder up against the block with strong light parallel to the block from behind the cylinder, and look for gaps where the light leaks through. The granite block works best for this because of the texture of the scraped angle block.  Carefully turn the cylinder and note what you see.  Carefully mark the two places where there is no light leakage, and recheck until you are satisfied you can find the same best location repeatably.  I also mark where the most out of square points are, and make sure I am finding them 90 degrees from the spots that fit best and 180 degrees from each other, and that the wedges of light showing at the spots with the most lean appear equal in angle as judged by the leaking light.  My angle block is certified accurate, but the "poor mans wrist pin cylinder square" is much easier to use for qualifying parts and tooling as being square.


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