5 replies to this topic

[MatsNorway]

I need a caliper like this one.

Do you guys know about a online shop that has it for the private market? Or even if it has a common name?

Edited by MatsNorway, 12 July 2015 - 13:47.

[saudoso]

You're looking for adjustable jaw or offset calipers:

 

http://www.amazon.co...ble jaw caliper

 

 

http://www.msi-vikin...aw_p_17525.html

 

http://www.msi-vikin...ange_p_688.html

Edited by saudoso, 12 July 2015 - 21:56.

[bigleagueslider]

Your picture shows a digital offset centerline caliper. You can order a new one from any online retailer that sells Mitutoyo products (p/n 573-105-10 or 573-106-10). Or you can occasionally find them on ebay.

 

If you don't want to spend the money for a specialized caliper, you can get the same centerline-to-centerline measurement with two suitably sized gage pins and a conventional caliper (or two gage pins, a surface plate and height gage) and a bit of arithmetic.

[Greg Locock]

Unless there is some hidden feature there then speaking as an ex toolroom metrologist that instrument is a triumph of precision over accuracy. How on earth do you ensure that the 'vernier' is parallel to the baseplate? 

[MatsNorway]

Kinda but kinda not Saudoso. Im more keen on the rounded tips than the offset arm. Greg,  i have a large one at work and it has a scale on the one with height difference. Wich i guess allows you to set it up according to a height difference measurement that you did prior.

 

I think it is a neat tool that is very nice to have in some situations. Perhaps not super accurate. But still wildly better than what i can do with some caliper when i am out and away from a workshop, it is also faster.

 

Also with the rounded tips you can basically feel if it sits right i believe. If it needs to be accurate i ask about getting it to the workshop for measuring on a measuring table. Or if not possible.. I make the necessary tool just for that one job.

Edit: also it needs to be at least 200mm+ in length. preferably 300 just to be sure.

Edited by MatsNorway, 13 July 2015 - 16:39.

[bigleagueslider]

For finding the center-to-center distance of two holes 200-300mm apart in your part, your best bet is to start by clamping the part base to a 90deg angle fixture. Then place an appropriate size gage pin in each hole. Then use another 90deg angle fixture to align the part vertically by making contact with the sides of both pins.  Then use a height gage and dial indicator to measure the vertical offset at the tangent of each pin. Once you have all of these values, it only takes a bit of trigonometry to determine the exact center-to-center distance between the holes.