KDXRIDER.NET

A micrometer is a tool everyone should own and I don't so I'm going to get one. Is there any drawback to the digital ones over the old fashioned analog ones?

I was considering this one. It looks like a good price, good range, inside, outside and depth measurements. Does anyone see any drawbacks?

heu...which one???

Digital is more accurate.... get one at Harbor Freight for like $20

That said... I have a dial...

Oops, this one:

http://cgi.ebay.com/ebaymotors/6-ELECTR ... 0205041634

Depends on how much $ you want to spend. I had a dial caliper at the machine shop that i worked at years ago. Parts had to be withen the 100,000's. It was a $100. The one you showed should work fine.

Here's a honey...


http://www.harborfreight.com/cpi/ctaf/d ... mber=93293

Awesome deal but I tend to shy away from HF stuff. By the time I factor in shipping I'll still pay $13. Either way I'll pick up a 6" one so that I can measure my cylinder and piston when I clean my KIPS.

Your ebay link shows a set of digital calipers but you are talking about micrometers? Two different things. You really can't use a set of calipers to accurately measure something like a cylinder bore. You'll get maybe within a couple of thousands of actual size with a decent set of calipers but when your tolerance is only .003-.005" or so you need something more accurate. Plus, with calipers you can only measure the very edges of the bore when you really need to be taking measurements at several different spots from the top to bottom to check for things like taper and concentricity.

Here's a set of cheap Chinese 0-3" micrometers that are good to .0001". Will work just fine for your purposes and be infinitely more accurate than those calipers:

http://www.use-enco.com/CGI/INSRIT?PMAK ... PG=INLMK32

Here's some telescoping gages that you can use in combination with the micrometers to measure bores (like the cylinder, wrist pin bore and such):

http://www.use-enco.com/CGI/INSRIT?PMAK ... TPG=INLMK3

This is some really cheap stuff but it'll still give MUCH better results than a $20 set of calipers and last much longer as well. Anyways, not trying to be an ass...just trying to help.

Thanks for the info. Will those measure inner diameter or is that what the telescoping gauges are for? Do they sell calipers that are accurate enough? I'm a little new to the whole top end rebuild since this is my first two stroke and I just want to make sure I have what I need once I get into it.

If you use the telescoping type and they are spring loaded, make sure they don't spring out harshly and 'dent' your cylinder wall.

And this happens VERY easily, I am reliably told.....

I won't jump too far into this thread, I am engineer for Mitutoyo, if anyone has general measurement gear questions feel free to PM me:)

Curious. On the HF ad, it's stated:

Accuracy: +/- 0.001'' (0.2 mm), Resolution: 0.01''



How do you have an accuracy that is better than your resolution? Like...how do you measure an ounce when all youse gots is a quart jar..and all you can do it fill it/empty it?

I'm thinking of a 525 interlaced NTSC TV screen with a beam that's 1/2" wide.........

Heck..that would look worse than my 40yr old Zenith rear projection TV...........




....maybe........

Another curiosity (Strider..maybe you could put in some real basic measuring FAQ type stuff if you have the time?):

How to you measure (example) a cylinder with telescoping gauges as noted above when the tool diameter is so fat?

Isn't a bore guage what's needed for that?

Being the unscrupulous scrounge I am...I'm content with using feelers to estimate piston/cylinder clearance. If I got the idea I was close to .003", I'd probably get it checked by a scrupulous un-scrunged machinist.

IS there such a thing?

Jeopardy,

I have the caliper in the link. I have actually seen the exact caliper labeled under different brands. I bought mine at one of those traveling tool shows. They will measure inside, outside and depth. They work great for just generally measuring stuff. When I am cobbling something together it is great to take the caliper to the hardware store to find that last little widget. I use to haul all the parts and pieces into the hardware store for a test fit.

I will see if I can dig up a metrology FAQ, Mitutoyo has a nice book that is a good intro.

CC, that do you mean by "tool diameter is so fat"?

Bore gages, telescoping gages and gage pins all measure different bore dimensions. Telescoping gages measure the LMC (least material condition) which is the worse case diameter if the cylinder is oval, but can miss odd number "lobing" of the cylinder.

Bore gages (3-point gages) measure the minimum diameter of the three points of contact, they can miss ovalness, but usually can pick up odd lobing.

Gage pins/cylinders are pretty useful in smaller sizes, not really practical for large bore measurements, they measure MMC (most material condition) which is the largest cylinder that can be fit into the hole.

There are lots of high end machines (CMMs and roundtest machines) that can totally characterize a given shape, but most people/small shops don't have access to the good stuff. It is pretty cool to see the actual shape of a cylinder, you can tell what kind of harmonics the lathe that made it has.

I don't claim to be an expert in metrology, I work in early stage R&D and don't get to use all the products on a daily basis. I use my calipers as a do it all too much because I am lazy, when I should be using the proper tool and setup. Calipers work well for a lot of tasks.

Re: 'CC, that do you mean by "tool diameter is so fat"?'

From the pics..the 'pins' that extend to the inside of whatever is being measured look to be fairly thick..large in diameter. Crude...but you're going to have a tough time measuring anything 'inside' if the edge/tool looks like this:

(|--|)

The '(' being the shape of what's being measured, the '|' being the diameter/thickness of the pin of the tool.


Maybe what I'm looking at isn't the measuring 'end' of the tool?

The ends are radius'd based on the diameter range the are designed to measure, so you get point contact on each end, so the radius of the gage is always smaller than the radius you are measuring.

You can kind of see the radius here:
http://www.harborfreight.com/cpi/photos ... /05649.gif

Mine are radiused, as per the pic. I was able to get QUITE consistent measurements

Re: 'You can kind of see...'

You are exactly right. I can see...kinda.........

Asked and answered. Thanks!!



BTW...'ya ever notice how many times questions that are asked are NOT answered..at all? I hear it ALL the time..drives me nuts. 'What time are you leaving?' 'Well.....we got to bed pretty late last night...'

'So...what time are you leaving!!??'