by ex-Gooserider » 19 Jan 2021, 02:19
I agree, digital calipers are FAR easier to read, and these days are nearly as cheap as verniers... Vernier calipers (or micrometers, etc) are not easy to read w/o lots of practice... Digital calipers are far simpler and also have the advantage of being instantly switchable between inch and metric systems... Since Martin's chair is presumably EU / UK manufacture, it is probably metric, but it doesn't hurt to be able to rule out inch sizes... (Minor note, my Quickie manual chair parts book calls out an inch bearing for the caster wheels, but what is on the chair, and confirmed by calling Sunrise tech support is a metric bearing...)
While it is possible to spend hundreds of dollars on a high end (Starrett, Mitutoyo, etc) caliper, you can get cheap ones for around US$10 from places like Harbor Fright or eBay... They won't be QUITE as precise, and won't have things like resistance to coolants, USB logging, and general fanciness, but for anything we do on chairs the cheap ones are more than good enough....
I would avoid the plastic versions, as they don't hold up well, but the Chinese metal units are fine...
ex-Gooserider
T-5, ASIA-B
Jazzy 1100
Jazzy Select 6
Quickie Q-7
Invacare Mariner
Want to make / get a better chair, ideally one that stands.