finding right digital caliper

[timebombprod]

been gathering al the tools for a valve adjustment and i have the feeler gauge and mostly everything else, i been looking at digital calipers. heres the problem, im pretty sure the clearance of my gs is .001-.003mm and the smallest measurement ive been able to find on a digital caliper is .01mm, how expensive is one that measures correctly for this clearance? i have the correct feeler gauges.

[phydeauxmutt]

You don't use the calipers to measure the clearance, you use the feelers.

The calipers are to verify the thickness of the shim, once you get it out.

The ones available at Harbor Freight are good enough.

[timebombprod]

my feeler gauge measures to .002mm is that good

[timebombprod]

holy *@%^$*@%^$*@%^$*@%^$ now i understand what im doing lol it all makes sense

[alke46]

Make sure you know what you are measuring. Correct clearances in the gap is stated as 0.03---0.08mm, not 0.001--0.003mm
One must know the difference between metric and inch measurements.

FWIW, 0.001--0.003" is equivalent to 0.03--0.08mm

[timebombprod]

Make sure you know what you are measuring. Correct clearances in the gap is stated as 0.03---0.08mm, not 0.001--0.003mm
One must know the difference between metric and inch measurements.

FWIW, 0.001--0.003" is equivalent to 0.03--0.08mm

thanks man

[Datsa Noydb]

You may have figured it out by now, but just in case you haven't, ...

you need to be VERY careful when mentioning valve clearances.
In inch measurements, they are (roughly) 0.001" to 0.003".
In metric measurements, they are 0.03 to 0.08 mm.

Note that both of them have a "3", but one is maximum clearance, the other is minimum.

Also note the different number of zeros to the right of the decimal point.

Just for reference, the maximum clearance of 0.08mm (0.003") is the thickness of a piece of paper.
The minimum clearance of 0.03mm (0.001") is one third of that, roughly the thickness of tissue paper.
You are throwing around 0.002mm, which is one-tenth of that.

You have to be VERY careful which system (inch vs. metric) you are using and how many zeros you put in there.

[bwringer]

Yep, unit confusion is very, very common. Stick with one or the other, and seek out metric feeler gauges if at all possible. Metric is better, I think, because you have more steps available in the feeler gauges. However, you can certainly do a good job either way.

Another common error with the extremely thin feelers in this range is that two or more stick together with the oil surface tension very easily. This seems to happen to me every time at some point, so I'm always alert for it.

The digital calipers from HF will definitely do the trick for figuring out shim sizes on the unknown shims, especially if you first measure a few known shims to get the proper feel for the error and pressure to use. The calipers rarely read bang-on, but with a little experimentation, you'll find, for example, that 2.70 shims measure 2.72, so you can be pretty confident that your unknown shim measuring 2.67 is a 2.65. However, it's at the edge of the device's precision. I've found HF's digital micrometer is the bee's knees for this stuff, it's more precise, and it's still very modestly priced.

With both of these, it's best to remove the battery between uses. The electronics never quite shut off completely on these less expensive tools, so the battery will drain in a few months if you leave it in.

Or spend ten to 20 times the amount for Mitutoyo or Starrett...

[Grimly]

Or spend ten to 20 times the amount for Mitutoyo or Starrett...

Or learn how to use a traditional micrometer and pick up a Kennedy 0-25mm #335-001 for ~$10 to $25, which is actually a Mitutoyo with a Kennedy badge on it. I got that and a Moore&Wright one for a tenner a few months ago.

A bucketload of these lovely old precision tools are available because of the boomers dying off and everyone changing over to digital anyway.

[bwringer]

Or learn how to use a traditional micrometer and pick up a Kennedy 0-25mm #335-001 for ~$10 to $25, which is actually a Mitutoyo with a Kennedy badge on it. I got that and a Moore&Wright one for a tenner a few months ago.

A bucketload of these lovely old precision tools are available because of the boomers dying off and everyone changing over to digital anyway.

True, but metric micrometers are rarer than unicorn poo on this side of the pond.

There are some nice old instruments around, but they all read in inches over here. Sure, the conversion is not difficult, but it's an added step and a chance to make a mistake.