Micrometer and telescoping gauge

[AEAdam]

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.

Could swear I saw a Mitutoyo spec sheet calling micro inches microns. I have absolutely heard folks at work calling micro inches microns. Machinists have TONS of names they get flat out wrong.

Scale for ruler is notorious. A rule or ruler is an absolute direct reading instrument. Scales read relative to specified length or distance ratio.

Woodworkers don’t know their terminology either. Wood planes aren’t planers, and tenons aren’t tendons. Some people just don’t give a **** about what something is called or how it’s spelled.

 

[PCustoms]

Could swear I saw a Mitutoyo spec sheet calling micro inches microns. I have absolutely heard folks at work calling micro inches microns. Machinists have TONS of names they get flat out wrong.

Drives me a little nutty when I get people at work that start talking about thousands of an inch when the prints we deal with are all in metric, and have been for years.

 

[Shadowdog500]

A micron is the same as a micro meter (μm) which is one millionth of a meter and one thousandth of a millimeter.

 

[PCustoms]

A micron is the same as a micro meter (μm) which is one millionth of a meter and one thousands of a millimeter.

Stop that

 

[Shadowdog500]

Tear the engine down before deciding what tools you need.

I’ve bought several Telescopic Cylinder Bore Gauge sets from HF to a better set on Amazon and don’t put much faith in them. You may need to buy a set from Starrett that costs around $325 and you still have to get a feel for them before getting accurate measurments.

I picked up a home shop/hobbyist grade micrometer set for $180, along with a $30 micrometer stand, and a dial bore gauge set ($139)on Amazon from Anytime Tool. They probably wouldn’t last daily use in a pro shop but they seem to be fine for the occasional use in a home/hobby shop. The dial bore gauge is easy to use and gives accurate measurements once you figure it out and learn how to set it up.

They sell what I have as a combination set on Amazon for From anytime tools for $279. Look up “Micrometer Set and Dial Bore Gauge 0.7"-6"/0.0005" Deep Engine Hole Cylinder Measurement Gage”

 

[Shadowdog500]

Stop that

What’s the deal with not saying thousands? Is thousandth better? Fixed it for you!

 

[whateg01]

What’s the deal with not saying thousands? Is thousandth better?

I can't tell if you really don't know the difference between thousand and thousandth.

 

[Shadowdog500]

I can't tell if you really don't know the difference between thousand and thousandth.

The first has a K and the second has an m. LOL! Or 10^3 and 1/10^3

 

[AEAdam]

Now THIS is the annoyingly pedantic GJ I know and love. Thank you for restoring the rightful order to the empire.

And for the record it’s “thou” which rhymes with “towel”, or “mills”, not “thousands” or “thousandths”.

 

[Firebrick43]

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.

Doesn't matter if its applicable or not to this specific application. One is not accurately going to check any bore to 0.001" with a set of calipers and if its pointed out, maybe they will learn that.

 

[jayemm]

Drives me a little nutty when I get people at work that start talking about thousands of an inch when the prints we deal with are all in metric, and have been for years.

I'm pretty familiar with the metric system and have inspected many machined parts that were mostly dimensioned in inches. But I then (and still do) find it easier to visualize measurements less than 1 mm by mentally converting it to thousandths.

 

[jayemm]

Stop that

Or to hopefully make it easier, know that 25 microns equals 1/1000 inch. See how little them microns really are.

 

[Shadowdog500]

I'm pretty familiar with the metric system and have inspected many machined parts that were mostly dimensioned in inches. But I then (and still do) find it easier to visualize measurements less than 1 mm by mentally converting it to thousandths.

The dials on my lathe and mill are in imperial
I’m not working in metric, first thing I do is convert everything to imperial.

I’m afraid to say the units on my dials in this thread.LOL!.
Maybe I’ll start calling them “milli-inches” or “mil” for short.

 

[jayemm]

The dials on my lathe and mill are in imperial
I’m not working in metric, first thing I do is convert everything to imperial.

I’m afraid to say the units on my dials in this thread.LOL!.
Maybe I’ll start calling them “milli-inches” or “mil” for short.

Or you could call them kilo-micro inches (10^3 X 10^-6 = 10^-3= 1/1000) ---- "kilomikes" for short.

 

[alfadan]

I can't tell if you really don't know the difference between thousand and thousandth.

Could say 'mil' just to confuse matters!

 

[Tostal]

Or to hopefully make it easier, know that 25 microns equals 1/1000 inch. See how little them microns really are.

Them microns are actually even littler, 'cos there's 25.4 of them in 1/1000 inch.

 

[Tostal]

Could say 'mil' just to confuse matters!

Afaik, a 'mil' is what is removed by a Machinist using a milling machine.
Whereas, a 'smidgeon' is removed by a 'normal' person using a file or a grinder

 

[Tostal]

Some readings on my cheap digital caliper :-

As manufacturer said, accurate to +/- 0.001 inch. (which is good enough for what I use it for )

 

[PCustoms]

Some readings on my cheap digital caliper :-

Ok?

Do a full gage R&R.

Still not the appropriate tool to measure bore ID.

 

[jayemm]

Them microns are actually even littler, 'cos there's 25.4 of them in 1/1000 inch.

True. I rounded off because it's close enough for me if I want to mentally convert microns to tenths of thousandths.

 

[Tostal]

True. I rounded off because it's close enough for me if I want to mentally convert microns to tenths of thousandths.

I do the same, decimals are just too hard to do in your head

 

[PCustoms]

I do the same, decimals are just too hard to do in your head

Metric makes it easy!

 

[Tostal]

-------------------------------"Skin flint" old man.-----------------------------------------(I have know idea what the bore size is------------

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

I was trying to save the OP some money by suggesting a cheap digital caliper might be sufficient for this one-off job.

The (original, unworn) bore size could be measured with an engineer's rule to the nearest mm. Any oversize on cyl. bore (not sure if applicable to engine in question) would be disclosed by the aforementioned cheap digital caliper, as could the diameter at the bottom of the piston skirt to check piston to cyl. clearance. OP says he's not going to rebore the cylinder, so why buy tools to measure the extent of wear, just do a 'nail-test'.

 

[PCustoms]

I was trying to save the OP some money by suggesting a cheap digital caliper might be sufficient for this one-off job.

The (original, unworn) bore size could be measured with an engineer's rule to the nearest mm. Any oversize on cyl. bore (not sure if applicable to engine in question) would be disclosed by the aforementioned cheap digital caliper, as could the diameter at the bottom of the piston skirt to check piston to cyl. clearance. OP says he's not going to rebore the cylinder, so why buy tools to measure the extent of wear, just do a 'nail-test'.

A $1000 mitutoyo isn't going to measure the bore any better then a harbor freight caliper, as it's simply the incorrect tool.

 

[theoldwizard1]

Well, I got it apart and my initial guess at the root problem (rod/crank failure) was wrong. Deep scores/groves in cylinder bore and on the piston. Won't be needing any measuring tools !

Salvaged a few parts off of the engine (carburetor and magneto/coil) and more parts off of the mower deck (transmission, controls, cables, etc). Some scrapper is going make a few bucks because the deck is cast aluminum !

 

[Tostal]

Edited:- as Op is scrapping the mower.

 

[RoninB4]

Well, I got it apart and my initial guess at the root problem (rod/crank failure) was wrong. Deep scores/groves in cylinder bore and on the piston. Won't be needing any measuring tools !

Salvaged a few parts off of the engine (carburetor and magneto/coil) and more parts off of the mower deck (transmission, controls, cables, etc). Some scrapper is going make a few bucks because the deck is cast aluminum !

-At least you didn't spend money for instruments not needed or waste time preparing for a bore/hone job. Better luck next time.

 

[AEAdam]

-At least you didn't spend money for instruments not needed or waste time preparing for a bore/hone job. Better luck next time.

Wait. Is that a good thing or a bad thing? Haven't we all bought tools for jobs that we never got around to? What about that anvil I bought when I wanted to take up blacksmithing? I love my anvil.

 

[Packard V8]

Deep scores/groves in cylinder bore and on the piston. Won't be needing any measuring tools !

I had a B&S marine sump pump overheat and fail like that far away from any replacement. All I had was some sandpaper. The cylinder bore was too small to get my hand in, so I whittled a 2x4 to diameter and wrapped the sandpaper around it, oscillating it between my palms. That took the sharp edges and high spots out of the bore; nothing can be done about the grooves. Polishing the piston with sandpaper again, just to remove high spots; don't worry about the grooves. The rings should have been replaced, but that wasn't possible, so they were just cleaned and went back in. Rinsed all the parts in diesel fuel, put oil and gas in it. It started, smoked a bit, but ran well enough to do the job as a sump pump until we could get back to port. Just check the oil level regularly.

jack vines

 

[Shadowdog500]

Afaik, a 'mil' is what is removed by a Machinist using a milling machine.
Whereas, a 'smidgeon' is removed by a 'normal' person using a file or a grinder

Mil does mean 0.001”, and was a common word for machinists in the US. It became confusing when people started using metric in the US and it isn’t used that much anymore.

 

[Wrench97]

If you are not having it bored, cut the ridge out of the top with a ridge reamer, hone the bore, get a new set of rings set the end gap in the bore with a feeler gauge, and run it. Why measure something you are not going to change?