I was happy to hear Padre discuss digital calipers again in a (somewhat) recent episode as I 've...

[G+_Rob Allen]

I was happy to hear Padre discuss digital calipers again in a (somewhat) recent episode as I've been meaning to make a post about the subject for over a year. The knock-off calipers are indeed cheap, but a look at the relevant value might sway some viewers towards something better.

 

You can get a cheap caliper for about $15 from Amazon (shipping depends on Prime) and $10 from eBay (free shipping). However, bump the price up to $25 and you can get an iGaging EZ Calc that's built to higher standards. A search around Google or YouTube will show that the iGaging calipers compare favorably even with $120 Mitutoyos.

 

My only concern here is whether the generic manufactures will start labeling their units as "iGaging", but I haven't heard reports of that yet. The following seller has been around a long time and ships genuine units to the best of my knowledge.

 

silver frame:

http://ebay.to/2zjS3ii

 

black frame:

http://ebay.to/2y0xBQo

 

Some generic calipers have been measured to draw 5 times more power than better brands, even with their power turned off! That's why they go through batteries like crazy. The iGaging units, on the other hand, have proper power management and they use a larger CR2032 battery rather than the LR44 that the generic models use.

 

-RobAllen

 

P.S. Both LR44 and CR2032 coin-cell batteries are available from eBay in bulk packs of 10 for $2-$4. I only use sellers with high volumes and 99.5% or higher feedback for these batteries, as I want to receive fresh units. So far, so good.

http://ebay.to/2y0xBQo

[G+_Shooter_FPV (Shooter_FP]

+Rob Allen I've never used calipers, but might grab one to maybe start designing. The one question I've always had... when you measure something, do you squeeze the calipers tight on the object you're measuring, or is it just a light touch? May sound like a silly question, but I'm a caliper rookie.... :)

[G+_Jay Schinkel]

Is he a seller on eBay ?? This sounds like a commercial.

[G+_Jay Schinkel]

Ken Jancef? ... Most calipers that I've seen have a small wheel to open and close and that wheel will slip when you've come in contact with your material so that it reads correctly !! I'm sure that it could be overtightened to read incorrectly if you tried hard enough !!

[G+_Paul Hutchinson]

Ken Jancef If you squeeze hard enough all calipers (micrometers too) will give a wrong reading either by the subject or caliper deforming. This is a major reason why non-contact optical measurements rule the roost when it comes to high accuracy dimensional measurements.

 

However it is not difficult to get the feel for how much force you should use on a given material to overcome surface grime while not distorting the measurement. As Jay Schinkel points out the limited slip wheel helps a lot but is not fool proof. For soft materials use a light touch, hardened stainless steel use a firm touch. It's easy to achieve a feel across all material types that consistently gets you +/-0.002" accuracy, not difficult to achieve +/-0.001 and with practice you can achieve +/-0.0005". These errors are in addition to the usual +/-0.001" absolute accuracy of a good measuring caliper. As with most worthwhile things in life, practice makes perfect. Repeat measurements on different material types over and over again until you get the consistency you desire.

 

Another factor to consider when buying a measuring caliper is how long will it remain accurate. Expensive ones from the long established companies (Starrett, Mitutoyo, Fowler) will maintain their accuracy for decades. Budget units may go out of calibration in five years or less. I recently checked a 25 year old Fowler vernier caliper at work and it is still is accurate to +/-0.001".

[G+_Shooter_FPV (Shooter_FP]

Paul Hutchinson Jay Schinkel Thanks for the info. The robotics teacher at the school I work at uses calipers, but not sure what brand. I was thinking of getting a set, I may want to start designing, or at least modifying, parts to 3D print. It's good to know the in's and out's before i dive in...

[G+_Rob Allen]

Jay Schinkel No, I'm not an eBay seller. I just pointed to a seller that has sold a lot of these calipers with good feedback because I didn't want to point anyone to a bad source. I've been planning to buy a set for myself for a long time, but I literally need the $25 for food and clothing. I encourage everyone to check articles, feedback, and youtube videos as you will find that cheap calipers are typically worthless.

 

Padre and Brian once had pairs of the cheapies and found out how bad they were at eating batteries, but I don't know what brand Padre uses now.

 

Sorry that I cannot reply sooner to comments or questions, but I don't have regular Internet access. Thanks for your comments.