Micrometer and telescoping gauge

[theoldwizard1]

So I have a dead (locked up) B&S Quantum 5.5 HP that I am think about rebuilding it, just for fun. I have a decent set of calipers, but I know I really need a micrometer and a telescoping gauge to measure the bore and piston (fingers crossed, I am guessing it is the the rod and crank).

"Skin flint" old man. Recommend a brand and size (I have know idea what the bore size is) of micrometer and telescoping gauge that won't hurt my wallet too much.

 

[Steve_P]

2-6" dial bore gauge, something like this

Amazon.com

And a .0001" graduation generic Chinese micrometer in whatever size ranges you need.

If it's seized, then the connecting rod may be seized to the crankshaft and the crank will need to be ground .010 under and a new undersized rod.

If it's a 5.5 HP engine, it's not worth fixing.

 

[Tostal]

To check a cylinder bore size, I use a cheap digital caliper (mine came from a Lidl store @ c. $11.00) - its accuracy is +/- 0.001 @ <4").

(Obviously if boring and then honing a cylinder, then more accurate measuring equipment would be needed.)

 

[Packard V8]

If it's seized, then the connecting rod may be seized to the crankshaft and the crank will need to be ground .010 under and a new undersized rod.

If it's a 5.5 HP engine, it's not worth fixing.

For true, piston seized in the bore is one thing, rod seized on the crankshaft is another and crankshaft seized in the block is worst of all.

Since it's a piece of junk as it sits, you can't hurt it.

Freeing a stuck piston, honing the bore and new rings is easy/obvious.

Just to see if I could, I freed up an aluminum rod seized on the iron crank, polished the worst of the ridges off the crank rod journal, nipped a thou off both the rod and the cap mating surfaces, carefully made it back round with an adjustable reamer, blued and scraped it to the spec clearance verified by Plastigage and it was still running last I heard. These are not precision instruments.

Even Honda, with a reputation for quality, has some tolerance. I paid $5 for a seized Honda mower; a quick check showed there was no oil in it. Turned it on its side, pulled on the blade and it freed up. I filled the cylinder and crankcase with diesel and turned it over several times by hand, drained the diesel, filled the crankcase with oil, cleaned the spark plug, sharpened the blade, filled the gas tank. It fired right up, no noise, sold it for $100 and it was still cutting grass last I heard.

jack vines

 

[PCustoms]

To check a cylinder bore size, I use a cheap digital caliper (mine came from a Lidl store @ c. $11.00) - its accuracy is +/- 0.001 @ <4").

(Obviously if boring and then honing a cylinder, then more accurate measuring equipment would be needed.)

You're not checking a bore to +/- 0.001" with that, sorry.

 

[paulsomlo]

Remove the cylinder head and get a rough idea of the bore. Then, go to ebay and buy a used snap gage and micrometer.

 

[theoldwizard1]

If it's seized, then the connecting rod may be seized to the crankshaft and the crank will need to be ground .010 under and a new undersized rod.

These DO NOT EXIST !

If it's a 5.5 HP engine, it's not worth fixing.

Probably not ! This is mostly for "fun". The Chinese Honda clones are so cheap, but installing one on this mower would be a challenge because the carburetor is on the opposite side.

 

[theoldwizard1]

Remove the cylinder head and get a rough idea of the bore. Then, go to ebay and buy a used snap gage and micrometer.

Any brand besides Mitutoyo or Starrett ?

 

[Firebrick43]

You're not checking a bore to +/- 0.001" with that, sorry.

Some people will believe anything the manufactures claim!

 

[308guru]

Any brand besides Mitutoyo or Starrett ?

Brown & Sharpe is a contender as well.

 

[Firebrick43]

Any brand besides Mitutoyo or Starrett ?

When I had apprentice we would sit down and form a tool plan. I always helped them where I could to save money and always suggested B&S, Mituoyo, or Starret micrometers but most of the time they opted at my suggestion for the 30 dollar Shars telescoping gauges.

And while not a visually nice as my B&S, they worked the same.

Telescoping gauges are pretty hard for most to get a good feel and accurate measurement anyways.

 

[The Cobbler]

think about rebuilding it, just for fun.

for fun, I would not bother too much with clearances .
first off see why it's seized . if it's scored , it's not worth fixing. if the crank is scored , or broken , it's not worth fixing .
seriously the parts will probably cost more than a new engine, or at least a good running one would be cheaper

Depending on what you find wrong, see if you can free it up , hone the cylinder , clean it up etc. put it back together & see if you can get it to run.
Mustie1 on you tube does this sort of thing a lot , just to try to get it to run.
don't put much ( or any) money in to it .
Use it as your learning experience .

 

[paulsomlo]

Any brand besides Mitutoyo or Starrett ?

Fowler

 

[RTM]

Any brand besides Mitutoyo or Starrett ?

Brown & Sharpe is a contender as well.

Fowler

If you are feeling like an import, I think Moore & Wright is a nice touch, if you can't find one.

Vintage Lufkin was good also.

 

[AEAdam]

So I have a dead (locked up) B&S Quantum 5.5 HP that I am think about rebuilding it, just for fun. I have a decent set of calipers, but I know I really need a micrometer and a telescoping gauge to measure the bore and piston (fingers crossed, I am guessing it is the the rod and crank).

"Skin flint" old man. Recommend a brand and size (I have know idea what the bore size is) of micrometer and telescoping gauge that won't hurt my wallet too much.

I think you can't go wrong with a 2-3" and a 3-4" mic. Cars often have pistons over 4". Starrett 436 is a classic, easy to read, basic thou mic, more than good enough for this task. Expect to pay around $25+shipping for one on eBay. You might get lucky and get 2 for that price. Brown & Sharpe, and Lufkin are also recommendable.

Using a telescoping gauge is good practice, as you have find out of round conditions. These are available very cheap on eBay, even Starrett in the size range you need. I see them for less than $10+shipping. I would avoid the new Chinese models. The ends are sometimes funny (square, they should be domed slightly). Why bother with new Chinese stuff when you can buy really good quality old USA stuff that's actually nice to use. Even a little corrosion won't hurt them, can easily be cleaned. I wouldn't (don't) look down my nose at older Japanese precision tools.

 

[RoninB4]

Telescoping gauges are pretty hard for most to get a good feel and accurate measurement anyways.

-I've had a set of telescoping gauges for several decades, have used them about a dozen times, and never really trusted the readings. I bought inside mics, then bore gauges for closer work when I couldn't get a consistent reading from the telescoping gauges. Some folks claim they can get a repeatable reading to +/- .0005 (.001 total) with theirs. Either they're optimistic or I just never developed the touch with mine but I don't trust a reading from a telescoping gauge if the tolerance is +/- .001. Telescoping gauges are also not the same as a snap gauge.

As to the issue from the OP- I'd do what some others have suggested and try to free up the motor with methods they've suggested. If it's more than a quick/simple swipe with a hone then it's a bigger job. Do you even have the machinery to bore a cylinder? What is the limit you can overbore to with available parts?

For measuring instrument suggestions I'd have to ask what the piston to wall clearance (per side) is supposed to be. Nothing wrong with buying budget minded tooling provided it can yield reliable numbers that can be trusted. Accuracy and precision are not interchangeable have two different meanings. I'll use a tape measure, a ruler, a caliper, a micrometer, or a dial indicator depending upon what my tolerance is. Putting the motor back into service may just be for fun but it's even more fun when it didn't cost you anything but some time. I once had a motorcycle that hadn't turned a revolution in 10 years. I put some Marvel Mystery oil in the cylinders, dropped in gear, and dragged it around the driveway until the pistons unglued themselves from the cylinder walls. I rode that bike (1982 CB 900F) for another two years until I got the ZRX. Just a suggestion.

 

[Firebrick43]

-I've had a set of telescoping gauges for several decades, have used them about a dozen times, and never really trusted the readings. I bought inside mics, then bore gauges for closer work when I couldn't get a consistent reading from the telescoping gauges. Some folks claim they can get a repeatable reading to +/- .0005 (.001 total) with theirs. Either they're optimistic or I just never developed the touch with mine but I don't trust a reading from a telescoping gauge if the tolerance is +/- .001.

I would agree with the optimistic part. One slow evening I was having dinner with some of my tool room buddies and the "accuracy" of telescoping gauges was called into question. I went and retrieved some of the dial bore master setting rings and covered the certified dimension on it with blue tape. Two of the four were the best toolmakers I have ever met and .001" was pretty much what they could measure to. They all had variations as much as .0008" from measurement to measurement.

Telescoping gauges are also not the same as a snap gauge.

Yea, I don't know where the snap gauge came into the conversation, they are not really useful in measuring bores.

 

[theoldwizard1]

As to the issue from the OP- I'd do what some others have suggested and try to free up the motor with methods they've suggested. If it's more than a quick/simple swipe with a hone then it's a bigger job. Do you even have the machinery to bore a cylinder? What is the limit you can overbore to with available parts?

I still suspect rod and crank. The engine locked up after a brief (5 minutes) cool down. I am NOT going to pay to have the cylinder bored.

 

[AEAdam]

I would agree with the optimistic part. One slow evening I was having dinner with some of my tool room buddies and the "accuracy" of telescoping gauges was called into question. I went and retrieved some of the dial bore master setting rings and covered the certified dimension on it with blue tape. Two of the four were the best toolmakers I have ever met and .001" was pretty much what they could measure to. They all had variations as much as .0008" from measurement to measurement.

Yea, I don't know where the snap gauge came into the conversation, they are not really useful in measuring bores.

Some machinists call telescoping gauges (telescoping) “snap” gauges, because they are spring loaded. (I know you know this but for everyone else), you precompress the gauge, put it in the bore then release the clamp and the gauge snaps to fit the bore.

Then we usually probe around, up and down, in line with the piston arm and perpendicular to it. You can easily find the max and min diameter spots. Then you remove the gage and mix it to get the bore diameter.

I think it’s typical for cylinders to become egg shaped. They don’t typically wear cylindrically.

 

[PCustoms]

This is a snap gage

 

[Firebrick43]

Some machinists call telescoping gauges (telescoping) “snap” gauges, because they are spring loaded. (I know you know this but for everyone else), you precompress the gauge, put it in the bore then release the clamp and the gauge snaps to fit the bore.

Then we usually probe around, up and down, in line with the piston arm and perpendicular to it. You can easily find the max and min diameter spots. Then you remove the gage and mix it to get the bore diameter.

I think it’s typical for cylinders to become egg shaped. They don’t typically wear cylindrically.

Do they use thier C clamp thingies to measure their “snap” gauges?

 

[RoninB4]

Yea, I don't know where the snap gauge came into the conversation,

-Not trying to ridicule another member, just clearing up terminology/misconception for those playing along at home.

Then, go to ebay and buy a used snap gage and micrometer.

-Just trying to help you Paul with something familiar to me.

 

[RoninB4]

They all had variations as much as .0008" from measurement to measurement.

-I could get the correct reading of a known diameter in 3-4 tries but when it's not known which reading should I have believed? Inside mics and bore gauges were my solution to a "feel for procedure" that my clumsy fingers never attained. An inside mic I can obtain .0005 pretty easily.

 

[RoninB4]

I still suspect rod and crank. The engine locked up after a brief (5 minutes) cool down.

-There's one way to find out

I am NOT going to pay to have the cylinder bored.

-Nor would I, it may be a simple/easy job after all. One way to find out...

 

[signcrafter]

How about you tear the engine down to see what you are dealing with. For fun

 

[alfadan]

Just for the sake of conversation, I understand that telescope gauges DO wear, so they end up with flat spots on the ends. Maybe imperceptible without magnification, but can still cause errors. Cheap sets (like mine lol) that are soft and used sets can throw you off.

 

[AEAdam]

This is a snap gage

If you put "Snap gage" or "Snap Gauge" into an ebay search, you will get Telescoping gauges. I didn't bring up the term. Just offering factual information that people misidentify T-gages as "Snap gages".

A machinist I watch on youtube and really appreciate calls Mitutoyo "middatoya" If you search "mitutoya" on ebay, you will find tons of tools that literate people can't find. Over the years I've found plenty of deals for "Starett" or "Starret" tools. The name is Starrett.

By the way: This is a ruler. Scales are different. Starrett has never called this tool a scale because it isnt' one. Try telling ANY machinist the thing he carries in his short pocket ISN'T a 6" scale.

I don't care about the names. Just trying to help a brother get a good deal.

 

[hop up]

Inside mic and youncan find used ones cheap the telescoping gauges are good but as said quality is key for a decent measurement as imports are what they are

 

[hop up]

A few makers

 

[theoldwizard1]

So ...

What is the difference between a Mitutoyo 103-138 and a 103-178 beside mm vs inches ?

Does anyone make a 0-2" (0-50mm) micrometer ?

 

[paulsomlo]

-Not trying to ridicule another member, just clearing up terminology/misconception for those playing along at home.


-Just trying to help you Paul with something familiar to me.

Yeah, I don't know where I picked up that terminology - could have been here on GJ, or maybe even on PracticalMachinist.

 

[alfadan]

Does anyone make a 0-2" (0-50mm) micrometer ?

I don't think so. 1 to 2 is what you're gonna find (.0025 to .005 decameter)

 

[RoninB4]

I don't think so. 1 to 2 is what you're gonna find (.0025 to .005 decameter)

-Yep, there are mics that can cover more than a single range, even up to 0-12", with interchangeable rods but they're on the bulky/clumsy side to use as the size increases. I have a set and have rarely used them for just that reason. They're also sort of a PITA to reset with the standards every time you change the rods/range. Once set they're not supposed to need adjustment again but they often will due to debris/dirt on the mating surfaces throwing the "zero" off by .0005 or more.

 

[RoninB4]

Yeah, I don't know where I picked up that terminology - could have been here on GJ, or maybe even on PracticalMachinist.

-That's ok, I've probably got several terms I use incorrectly too that I've picked up from somewhere.

 

[AEAdam]

Come on GJ. You are letting this member down. He’s rebuilding a shot lawn mower engine. Naturally he needs the digital Mitutoyo bore-matic

If he’s buying micrometers, what mic stand should he get? You know, the heat from your hand changes the reading of the mic.

Or screw it and just get a surface plate, a height gauge with a test indicator on it? Black granite or Crystal pink? Discuss.

 

[AEAdam]

-Yep, there are mics that can cover more than a single range, even up to 0-12", with interchangeable rods but they're on the bulky/clumsy side to use as the size increases. I have a set and have rarely used them for just that reason. They're also sort of a PITA to reset with the standards every time you change the rods/range. Once set they're not supposed to need adjustment again but they often will due to debris/dirt on the mating surfaces throwing the "zero" off by .0005 or more.

Right. Pretty sure @paulsomlo calls them “snap mics”.

Seriously, my money is your cylinders will fall between 2-3”. And I’ve read a BUNCH of threads that say the cheapest Chinese mics are actually fine, as are the cheap digitals. The digitals are nice just for unit conversions. That’s pretty darned convenient. Also dead easy to read.

Check out SHARS.COM

 

[whateg01]

Some people will believe anything the manufactures claim!

For this application, it doesn't even matter. A tape measure would be good enough to make it run again if it is any shape to run. It would be different if it was a racing kart engine, but it's just a mower.

 

[whateg01]

If you put "Snap gage" or "Snap Gauge" into an ebay search, you will get Telescoping gauges. I didn't bring up the term. Just offering factual information that people misidentify T-gages as "Snap gages".

I see people calling calipers micrometers too. Or calipers that are calibers. Doesn't make them that. At least not until m-w says it's so.

 

[paulsomlo]

For this application, it doesn't even matter. A tape measure would be good enough to make it run again if it is any shape to run. It would be different if it was a racing kart engine, but it's just a mower.

I would look for a Starrett or Mitutoyo tape measure, though.

 

[RTM]

I would look for a Starrett or Mitutoyo tape measure, though.

My Starrett has a cheap feeling plastic case. I haul it out to make people think I know what I'm doing, when I prefer so many others.

But many are like Is that a Stanley knock off?