Fractional Calipers - Good Idea, Terrible Product

MontanaAardvark

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A while ago, I saw the calipers that display in decimal inches, metric, and fractions on sale at Rockler's and bought one. They're on the top in this picture.

Calipers.JPG
As you can see, they're labeled General, a long established tool importer and seller. You can also see the main feature for these: they read out in fractions of an inch, down to 1/64. 1/64 is a bit critical for most woodworking, but they work just fine in the metal shop. Except for the fact that they're made of a plastic or glass-filled plastic and are therefore not as hard (in the scratch or dent resistant sense) as steel calipers would be. They also read out in decimal inches or decimal millimeters at the touch of a button.

Yeah, I have fraction-to-decimal charts around, and yeah, I have memorized lots of fractions in decimal format, but it's really convenient for things that aren't close to a multiple of 1/8, or a few others that are lodged in my brain. Plus, it's nice to measure something and know that if I measure .143, which isn't something I know by memory, it's "close enough" to 9/64. They're handy.

Unfortunately, they also act weird sometimes. They reset too often and that includes resetting zero or mode.

Enter the calipers on the bottom. Little Machine Shop carries these; they're stainless, and just look a lot better. LMS listed them as a weekly special about a year ago, and I grabbed this one. Plus, I had been hoping the weird resetting was some sort of electrical interference problem and that more metal on the back of the electronics might help.

Suffice it to say that was as good as burning the money. They reset constantly. I'll very carefully open them to measure something, just to find that as I'm getting close to the dimensions, it resets, goes to zero in mm mode. Fresh batteries don't help. Sometimes it seems like any pressure on the plastic body makes them reset. I just tilted my pair to look at them and the display is flashing 0.00mm 2 or 3 times a second.

I don't know, maybe there are good products out there, but I stopped leaving these in the shop and just keep them here by my computer where I can almost use them as ruler. The most casual use. But I doubt there are good ones. My guess is there is one maker of the the chips for these over in China.com and they're all the same.

If you know of good ones, I'm all ears. Otherwise, just a friendly warning to my fellow HMF members. Don't buy these unless you have infinite patience.
 
You might try bending the battery contacts slightly. The holders for those button cells are crap and the weak plastic case lets them move just a little. Lose contact with the battery and it's game over. I have some decimal calipers from HF that this helped with.

It might help to shim the top of the battery to the lid with something non conducting. Plastic, paper, etc.. Pushing them down a little bit helps a lot in some cases.
 
I've fixed 2 cheap calipers that were doing the same thing as you describe (resetting, etc.). There is a tiny wire (human hair sized) that is soldered to the circuit board. The other end is free - not hooked anywhere. As near as I can tell the loose end of the wire is meant to be trapped between the plastic cover and the metal frame of the sliding part (lets call this a ground).
When I carefully got the wire trapped in place both calipers started working OK. (I've also tried fixing other calipers with similar problems with no luck!)
 
I bought a small pair of digital calipers on sale from H Freight. They really felt cheap in the hand, but they were easier to get into tight spots than my dial or verniers. Decided to keep ‘em because they were so cheap. Every time I went to use them, the batteries had died. They were “auto off” supposedly. I do keep a large stash of the little pill-like batteries around, but who wants to put batteries in their calipers every couple of weeks. I thought that I would like the metric-inch and fraction capability, but it’s just as easy to convert them in my head or use look up at the wall at one of my conversion posters. I guess I am just old school, give me a decent vernier or dial caliper any day. HF did take it back after more than 2 months.
 
I bought a small pair of digital calipers on sale from H Freight. They really felt cheap in the hand, but they were easier to get into tight spots than my dial or verniers. Decided to keep ‘em because they were so cheap. Every time I went to use them, the batteries had died. They were “auto off” supposedly. I do keep a large stash of the little pill-like batteries around, but who wants to put batteries in their calipers every couple of weeks. I thought that I would like the metric-inch and fraction capability, but it’s just as easy to convert them in my head or use look up at the wall at one of my conversion posters. I guess I am just old school, give me a decent vernier or dial caliper any day. HF did take it back after more than 2 months.

Older digital calipers that retained position when turned "off" still draw current. Some of the later HF calipers actually do shut off (almost) when the power button is pushed. They do not retain the position though. Here is a quote from the thread http://www.hobby-machinist.com/threads/batteries.64094/#post-530959,
"I have one pair with a black scale cover that came from an auto supply store, perhaps fifteen years ago. It draws 13 microamps, on or off. I also have a 12" pair with black scale cover, purchased from HF and it also draws 13 microamps on or off. A third pair labeled PT draws 7 microamps on or off.
However, the two latest pair are from HF and draw 13 microamps on but only 1.4 microamps off."

Also, the doallar store batteries just don't have the capacity that the name brand batteries have. In researching the batteries, I found that the Everready EPX76 had the highest capacity and should last well over a year. Second was the Eveready 357 which should also last over a year. The most cost effective solution was the 357 as the EPX76 Cost about three times as much where I buy my batteries.
 
I have had a number of calipers now that would suddenly jump by multiples of .200". I suspect that this is an internal defect rather than poor battery connection. A bad battery connection would most likely reset the display to zero. On mine, when I have a bad connection, they default to mm as well.
 
A while ago, I saw the calipers that display in decimal inches, metric, and fractions on sale at Rockler's and bought one. They're on the top in this picture.


As you can see, they're labeled General, a long established tool importer and seller. You can also see the main feature for these: they read out in fractions of an inch, down to 1/64. 1/64 is a bit critical for most woodworking, but they work just fine in the metal shop. Except for the fact that they're made of a plastic or glass-filled plastic and are therefore not as hard (in the scratch or dent resistant sense) as steel calipers would be. They also read out in decimal inches or decimal millimeters at the touch of a button.
I have an Igaging set, they read to 1/128, they are absolute readers, they are a good quality. When I need accuracy, I take out a mic.
 
I have that General caliper , worked good still dose but the lens got cracked, have since bought another brand that works good too. Never had a reset problem with them
 
The battery dieing is annoying. I have to remove the battery when they aren't in use to prevent having to replace them constantly. Mine are older HF calipers. If newer units don't do that, I'll have to think about getting some as it's really annoying.
 
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