Micrometer choices????

[Rusty105]

Ok, the time as come to get some outside mics to assemble my engine, but what micrometers to get?

I have been searching all over e-bay for deals, and have found a few pieces, 0-1" micrometer .0001, some telescoping gages. But now I have 2 questions. I need a 2-3" and a 4-5" to check crankshaft bearings and piston to cylinder clearances.

1) do I get name brand gages, Starett, Mitutoyo, etc, in just those 2 sizes, or a 0-6" set of no-name imports with .0001 precision? For the few times I will use them will they be reliable??

2) Is a dial bore gage 100% necessary? Can I use the telescoping gages and measure with the micrometers? I know the Dial bore gage will save time, but I am in no rush.

Thanks

[CRE2004]

1.) I'd invest in the good ones. Buy the two you need now and add to your collection as you need them.
2.) A dial bore gauge will be much quicker and more accurate. You can get by with the telescoping snap gauge if you're just double checking things.

[Rusty105]

Thanks,

1) I will probably just get the ones I need for now, as far as quality, what brands are recommended?

2) Right now I am just checking bore dimensions, to be sure I have clearance. As far as bore gages go, I have seen a lot of .0005, but not many .0001 precision. In an all out big $$ motor I can see the need, but for a general high performance weekend warrior is it necessary?? The pistons I am using have a .0025-.0045 clearance requirement.

Thanks again

[CRE2004]

Starrett or Mitutoyo are both nice ones. I prefer ratchet stops on the ends and find it more accurate but I know of some "old timers" who insist their "feel" is just as accurate

Buy some standards for each mic as well.

If you've got .002" to play with on the PTW clearance, you should be fine with a snap gauge.

[Ed-vancedEngines]

Tis is probably above your budget to just ocassionally use but in my books there is nothing to beat the Brown & Sharp Slant Line with carbide faces and friction thimble with .0001 capabilities. That is what all of my Outside mices are. I also check then very frequently with a *Standard* to keep accuracy.

Next in my books are the Starret of whatever a person't choice would be.

Next would be the Mitutoyo. Mitutoyo began as an acceptable lower cost measuring tool years ago but by now is highly accepted by most machinists as being a very good tool. Not bad at all for the price.

I have been in shops that are using tools from Central, which I have never used. Fowler is also one that I see used but have limited experience with them. Maybe their mics may be ok. Don't know.

I did buy a Fowler Digital Bore Guage that was supposed to have .00005 accuracy which in my opinion is a joke, and after trying to use got put back in the box to never again be used. It is far tooo inconsistent. Maybe their actual Dial Bore might be better.

The Mitutoyo Dial Bore Guages are actually some pretty good pieces in my opinion.

One suggestion is to visit your local pawn shop and check what they have. At least you can see it and hold it in your hand. I do this myself too.

Using a Telescope Guage and fransfering the measurements to an Outside Mic is not supposed to be very accurate at all. This does really depend much more on the user's experience with precision measuring tools, and their feel of measuring. It can get real trickey and can yield some really bad measurements. BUt it can also be very close. It does depend on you and your abilities and experience.

The Machinists hand book which I have not read in years, will tell you that measuring ID with an ID mic is recognised as capability of .001 accuracy, and measuring with transfer measurement devices will decrease accuracy by .001 for each measurement transfer. So by thier words this would mean that for most users you could reasonably expect to be in a tolerance range of .002 when using Telescope Guages and transfering those measurements through OD mics.

I have held precision tools most of my life and can get very accurate to within .0002 by using telescope Guages and transfering to my mics. Do not expect this though. I have done this for off an on 45 years. I am good. Even though I feel that I am very good at using precision measuring instruments and guages, I check and double check and even triple check myself all the time. I never ever measure anything with any mic or other instrument and blindly accept my first readings as fact.

You can buy precision mics by size as you need them or you can buy a big set which will give you options by using one large frame with several different sized anvils to make it usable in many different sizes. When buyng any precision mics over 1 inch try to get a measuring standard with them and a spanner wrech to adjust them with. That way you can keep them accurate. When buying a 1 inch mich first wipe both anvil and thimble faces clean with your finger and measure by feel to a zero measurement so that the thimble and anvil are contacting the other and see how accurate they are reading. They should be reading zero and the marks should be lining up perfectly. IF the marks are a long ways apart that mic is already probably ruined by mis-use. If the marks are within .001 to even .002 of each other it is probably ok and just needs recallibration.

I would not buy used mics over the internet.

Dial or digial calipers also do come in handy very often. Mitutoyo, Brown & Sharp, Starret, Smiec, are all good brands. With a Digital Caliper watch for an uneven movement or inconsistent reading when buying them used. The O indication should always be at the top at 12:00 o'clock unless they have been damaged. By at the top, I ean hold it in your right hand with the ID part up and the OD part down. The Central, Fowler, Craftsman, and possibly others may be acceptable. Those sold by Harbor Freight aren't.

Dial indicators made with brands of Sunnen, Starret, Brown & Sharp, Mitutoyo, are all very good instruments. Acceptable and actually very good are Peacock, and Phase II. Don't know about other brands. Dial indicators should always have a smooth movement.

Plastiguage can still be used for checking of bearing clearances. IT is not as accurate and checking parts before assembly with mics dial bore guages or inside mics but it can be used and can be used acceptably by understanding the shortcomings and reading the thickest mashed plastiguage strip and not those that didn't mash. I have found on the average that plastiguage is within .0002 of actual measuinring with mics.

All of the previous written are the opinions and experience of only this one person. Hope it helps you some.

Ed

[CRE2004]

The one thing you need to keep in mind is that if the cylinders were honed with a torque plate on, measuring them will most likely give eroneous information anyway due to bore distortion.

[Rusty105]

Thank you Ed-vancedEngines for your recommendations, and things to watch out for, I have used presision measurement tools for a little while, but by no means 100% proficient.

CRE2004,
One of the things I am looking for is this distortion you mention. The block was supposed to be bored and honed with torque plates, that was a few years ago, on top of that I forgot what type of rings I told the shop to hone for (Moly or cast iron) Back then I just took the word of the shop that things were done right! I have since "grown up" and realized it is best to check things twice, and save myself 3X the headache.

[PeterGunn]

Ed,
I bought from Grainger the Westwood digital bore gauge which looks like the spittin' image of the Folwer. I found the same thing as you, not repeatable and very confusing to use. I'm sure this is the Chinese stuff marketed by many under house names as their cheapest line. I also tried snap gauges and got consistantly inconsistant readings, doing rods and mains I don't want to chance it.
I am looking at the Brown & Sharpe Intrimik bore gauge, I need the 2.0" to 2.4" for the rods and the mains, has anyone had any experience with these?? Repeatability??
What measuring instrument is everyone using for bores??
Thank You..............Pete.

[Ed-vancedEngines]

The Mitutoyo seems to be a very good Dial Bore Guage in the .0001 version.

I have never been proviledged to own a Brown & Sharp Dial Bore Guage but would be very comfortable with any instrument they make.

If you have never experienced the Joy of using the Brown & Sharp Friction Thimble mics with Slant Line Graduations, you are missing something. All of my Outside Mics are B&S Slantlines.

Ed

[stock z/28]

Hello,

In my opinion the Brown and Sharp - Standard- and Federal -Mahr- gages are hard to beat- Sunnen is very good as well, but seems way overprice to me.

I have a Mitutoyo .0001 reading dial bore gage that I bought new in 1976 and it still works fine.

On the mics I would suggest getting the .0001 reading with the ratchet stops, and I personaly wouldnt buy a mic with out the carbide faces.

Getting the standards is a must as well. I use some BS gage blocks for checks too.

One thing I have done that is kinda neet from for an automotive machine shop is to use the Sunnen rod gages (mine are AG-300s) to check the mics in a range that are in between the standard size.

As kind of an example I have precision rings that I use to set the gage- lets say 2.22470" then set the mics to 2.2247" and compare "0s". Over years I have been surprised by how many mics would check well at 2.00 and 3.00 but in the "middle" of the range, where I normally use them are off.

Hes really right about checking Pawn Shops-- jobs around here that required having your own personal gages are dropping fast, and there is not much of a market for used precision tools, to most individuals.

I as well would stay away from the digital bore gages. I like digital tools for some applications (especially the ability "0" at any spot) but I have not been impressed with bore gages.

While Im at it Does anyone have an Ag300 they would like to sell? A friend is looking.

Thanks

Jeff

[Cobra]

Swiss made Brown & Sharpe micrometers are the best, with USA Browne & Sharpe the best of the domestics. Starrett micrometers are not worth consideration. Avoid Sunnen dial bore gauges as older models used a troublesome Federal indicator and new ones use a modified Mitutoyo indicator. Sunnen does not offer small repair parts and gauges must be sent to them for repair. Sunnen is also big $$$$. Avoid all electronic gauges as there is no way to be sure readings are correct, and as models change often repairs become impossible. Standard Gage makes the best dial bore gauges currently available. Avoid buying vintage bore gauges on ebay as parts are no longer available for virtually all of these. Master setting rings should be acquired for bore sizes you work with. I have worked with, (100,000's of part checks), and repaired most brands of inspection gauges, so if you have a particular problem, just ask.

[Dave Koehler]

Rather than tout what I like and don't like I will add this. IF you are going the Ebay route you had better know what you are buying if it's used. The wiser move is only buy NEW and the name brands listed by others.

A good measuring tool that is respected and well cared for is an investment and are good for handing down to the next generation. Cheap stuff is well.....just that and the results show it.

If you buy new you will want to compare the price before bidding to what you can buy from the suppliers, like ENCO, MSC, etc. Ebay, being what it is, can be more expensive than calling up and getting it shipped to you in a day or two by the suppliers without all the hassle.

Dave Koehler
www.koehlerinjection.com

[Rusty105]

Starrett micrometers are not worth consideration.

Why do you feel this way? I knew they are not the cream of the crop, but are they really that bad?

[Cobra]

Rusty, Starrett mics are usable, just not comparable to a good Swiss B&S, and they are pricey. Many brands sell just because of their perceived quality. When purchasing inspection tools try to compare different brands and features. Intrimics and other three-point mics are good direct reading instruments. Dial bore gauges can only be considered comparators as they must be set to a standard and this gives another chance for inaccuracy. Gauges, setting standards, and the parts you are checking need to be the same temperature, and this temperature needs to meet engineering requirements.

[SchmidtMotorWorks]

Swiss made Brown & Sharpe micrometers are the best

Yep, Swiss measuring tools are the way to go but avoid the ones with gimmicks. If you have time to wait, you can find these on eBay.

Another good place to look is in shops that repair these instruments, sometimes the owners never pick them up.