Jump to content
jdm

1 inch = 1 inch = 1 inch

Recommended Posts

With a conventional mechanical micrometer, like the ones shown, while the zero point with the anvil closed can be set up by the operator using the small 'C' spanners usually provided with the instrument,  the ultimate accuracy along it's operational measuring length is determined by the pitch accuracy of the lead screw in the barrel, there is usually means of tightening the nut to lead screw pressure with an adjustable collet arrangement on the nut. If you are attempting to work to tenths of a thousandths of an inch, ambient temperature will make a small difference to accuracy.

I have this fairly ancient 'Draper' 0-4" caliper mic. set that has the replaceable anvils and the set up test pieces, which specify length accuracy at 20 degrees C.

Draper micrometer.jpg

Edited by JohnD

Share this post


Link to post
Share on other sites

Just did some tests on my Roebuck digital caliper, using the Draper test pieces....

For each test I closed the caliper first and checked the 0.000" reading then opened it up and placed the test piece in and closed it till it was lightly clamping it...

1" Test.... spot on

 

2" Test....minus one thou

 

3" Test....minus 5 tenths of a thou

Ambient temperature 28C

Quite pleased with this :thumbsu:

 

 

Roebuck caliper 1 inch test.jpg

Roebuck caliper 2 inch test.jpg

Roebuck caliper 3 inch test.jpg

Edited by JohnD

Share this post


Link to post
Share on other sites

Great thread.  Reminds me of the "What's heavier?" thing.  Pound of feathers or gold. 

FWIW, I've always been partial to analog instruments.  It's probably personal, but I feel more in control, and know when it's zeroed. 

Share this post


Link to post
Share on other sites

I literally just watched this comparison video the other day between watching videos on casemaking.. I'd have liked to have seen a comparison done on both sets of jaws as internal measurement is often less nice than external. The cheap measuring tools are good enough for their purpose.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing

    No registered users viewing this page.

  • Topics

  • Posts

    • I thought some of you might like this. https://hackaday.com/2020/07/10/its-time-for-watch-clocks-to-make-a-comeback/
    • Thank you Thorsten, I have investigated further and Cousins in the UK have one that is by all accounts a good replacement, DJ0060B01. Also my measurement of the old o-ring in case it can help anyone, 0.6mm inner, 2.05mm outer, 0.9mm height. Sent from my Moto G (5) Plus using Tapatalk
    • Nothing special, after planing I finsihed it with a random orbital sander up to 1000 grit and then applied an oil based marine varnish. This is my general work bench in my workshop, it is used for pretty much everything other than hammering and sawing, although usually its covered in parts of what ever I have disassembled in my workshop. I love that picture of the tree gent over by the wind. When you get out to the farming areas we have trees bent over and gnarled like that by the wind, but nothing as dramatic as that tree. I have a few Jarrah trees growing in my back yard, but they are a slow growing tree and because of this they are not 'farm grown' all Jarrah comes either from land clearing or old growth forest and so is becoming harder to find quality jarrah for reasonable prices. My house was built in the early 1980s and its 90% made of Jarrah, all beams are Jarrah, the outer cladding is jarrah as are the skirting boards and kitchen cupboards. The salvage value of the wood in my house in a few more years will be more than the house is worth.
    • Stainless steel won't blue; I don't know of any watch hands being made of it either. If the supplier doesn't state or know the material check them with a magnet. Hands can be almost any material from gold to plastic but brass and steel are the most common.
    • Well done.  nothing ventured nothing gained  
×
×
  • Create New...