Measurement tools

[jonathan01]

Here is my set of mics.

I don't know if it is supposed to be like this, but the 0"-1" mic when it is closed all the way, there is a little gap between to two rods that you can see though. I would have to quess the space is between 0.005" and 0.010".

 

[jonathan01]

Yesterday, I bought a digital caliper at ENCO using the 15% discount with free shipping:

Mitutoyo Manufacturer Part Number: 500-752-10 Electronic Calipers.
I got it for $131.75 with the discount and free shipping. Total with tax was $143.44.


:tiphat: Nelson

I might just buy this same caliper too. I am looking for a discount code now for them.

 

[metalmaster]

those look like some nice mics, but there should not be a gap between the faces of the 1 inch mic
if you close it all of the way does the barrel of the mic go past zero?
if it does you should be able to turn the inner barrel with a spanner wrench to reset the zero
hope that made sense and have fun when you get the new lathe.

mike

 

[Tony Wells]

Central tools are decent. You'll often find them in automotive machine shops, and catalogs. I had a bore gage made by them but I found it awkward to set and use. It was designed for engine block work.

The gap in your 0-1 is not a good sign. But then, it might not be scrap either. The very end of the thimble should have a screw that will release the ratchet, if it has that, and then the barrel will be mounted on a taper on the spindle. The details vary, but it would be worth exploring, since it is not usable as it is. Remove the barrel from the taper and try to close the mic again. There should be no gap when gently closed. Use a piece of paper to confirm the closure, and that is even on the entire surface. If the gap cannot be closed with the barrel removed, scrap it. If it can, then with the mic closed, gently replace the barrel with the zero as close as possible to the index line. Do not replace the ratchet and screw at this time. Open and close the mic a few times until you are satisfied with the zero alignment and the closure. Open it a few turns and then replace the ratchet with no pressure on the spindle/anvil faces. After tightening the screw, then close the mic using the ratchet and set the zero with the hopefully included wrench.

The "ruler" in machine shop parlance is a "scale" or just a "rule". Handy for all sorts of things.....stirring coffee, slicing cake in the office, etc.....and a famous machinist test that some of you may know about: The distance between the eyebrows of a trainee will determine whether they will make it through the training program. I know a couple of ME's that failed the test.

 

[jonathan01]

those look like some nice mics, but there should not be a gap between the faces of the 1 inch mic
if you close it all of the way does the barrel of the mic go past zero?
if it does you should be able to turn the inner barrel with a spanner wrench to reset the zero
hope that made sense and have fun when you get the new lathe.

mike

It gets hard to turn, almost like it hit the bottom of the threads. It has a cap on the top that I can unscrew, and it has a allen screw screwed into the side of the caliper. Would I use a spanner it the head of the allen? I am thinking that I just have to lossen the allen screw, and turn the inner barrel to reset zero, but have not tried that yet.

After looking at the gap again, it is probably on 0.003" 0.005".

 

[jonathan01]

Here is my indicator and mic with the top off. The indicator and base are made in china. They a MSC encomey sticker on the case, with made in china stickers on the base and indicator.

I am going to see what i can do to fix the gap.

 

[jonathan01]

I got it to close the gap, I took it apart more and got it.

I turn the small rod and it closed easy. What is the small straight knurled nut thing for on the inside of the caliper.

 

[metalmaster]

that will snug up the threads, you can adjust for wear if they get a little sloppy.


mike

 

[Hawkeye]

I picked up the identical set (blue foam and all) at a pawn shop last year, except that the 0-1" had been replaced by a Starrett No. 436. I haven't used it much, but I did a calibration on them, so they're ready when needed.

I wouldn't worry too much right now about measuring down to the nearest angstrom. Total precision only counts when your equipment and experience allow you to get that close. If and when you're ready for closer than 0.001, there are plenty of mic's available with vernier scales to get you down to 0.0001.

 

[Tom Griffin]

Tom,

Ok, I can agree with micrometers for diameters, but for lengths I would think either a dial caliper or the ruler like you said. What about for critical lengths? The Central box says Cranston, Rhode Island, but it is possible that they are still a import and are just sold the Rhode Island.

I have thread pitch gauges that came with my tap and die set. I also have a rethreading set, so I could run them onto my threads to test them, would this wrong to test threads this way or what?

I know that I need to get some HSS tool bits, didn't know what % cobalt to go for though. I also need to get center drills and such. I will also look into the clamp type knurl. I do need to look into colletes. They don't come with the lathe. I will probably see how much I spend on other tooling to see if I can get collets now or not. I know it comes with 1 live center for sure, but it may have two, it does have one tailstock drill chuck, it comes with a face plate, but I don't think it comes with a lathe dog. I need to get all the parting, turning, boring bars, etc. I only have a few cheap misc drills over 1/2", none with a taper. The spindle taper is a MT5, and the tailstock is a MT3. The tool post is a wedge type QCTP, with 5 holder.

Jonathan

For critical lengths on the lathe like steps in a part, you just rely on the dial indicator on your carriage stop. Use an indicator with at least 1" of travel, zero it on the end of your part and use it to measure your moves. If you want to use the caliper to check the overall length of a part, take it out of the lathe for measurement.

If you want to cut threads on your lathe, you'll need a thread gauge to set the tool. It's one of those arrow shaped things with the 60º v cuts in the side to align the tool. Using dies to check the diameter of the thread is not acceptable. To do a good job you need something to measure the pitch diameter. Thread wires only cost a few bucks and with work well without having to spend a bunch of cash for a thread micrometer.

Lathe dogs are also quite expensive because you need so many sizes. But you can get adjustable ones that cover a larger range to save money.

Tom