Re: Chinese digital caliper - first report
- From: Larry Jaques <ljaques@xxxxxxxxxxxxxxxxx>
- Date: Wed, 24 Feb 2010 11:00:24 -0800
On Wed, 24 Feb 2010 09:05:40 -0500, the infamous Joseph Gwinn
<joegwinn@xxxxxxxxxxx> scrawled the following:
I just got a $30 Harbor Freight (item 47257) six inch digital caliper, from the
noodle factory, partly as an experiment, and ultimately to give to my 9 year old
nephew.
It is functional, albeit more crudely made and less accurate than a Mitutoyo
(which costs four times as much). The random error of the 47257 seems to be
about 0.002", largely due to head looseness. I tightened the head gib, and the
error dropped to about 0.001", which is what HF claims. I don't know how well
the gib adjustment will hold - the two adjustment screws seemed a bit loose.
The clamp thumbscrew (that locks the head to the bar) was bent, so I
straightened it with an adjustable wrench. No idea how it was bent, as this
takes some force. The caliper came in a plastic case, and shipping damage was
not apparent.
The head slid reluctantly on the bar. This appeared to be due to a coating of
blackish grease, which easily wiped off. But still there was too much drag and
slip-stick. It turns out that the bar was precision ground but not polished,
leaving grind marks perpendicular to the bar, so the grind marks were slowly
filing away at the gib, which is brass. Not good, so I polished the grind marks
by hand with crocus cloth. This helped immensely. I suppose that crocus cloth
wrapped around a metal sanding block would do an even better flat polishing job.
After cleaning all the nasty grease away, I lubricated the caliper with pure
lanolin (used for instance to lubricate brass musical instruments). Pretty
smooth now.
You realize that a few days or weeks of use would have made it much
smoother, too, don't you? (Not near -as- smooth, but smoother.)
The manual says that the caliper requires a SR44 (silver oxide) battery, but it
came with two alkaline cells. Another corner cut.
I will use this caliper for a while in the shop and see how it goes.
With all that time invested in the thing, that $30 HF caliper is more
costly than the eqivalent Starrett. Ironic, ain't it? <snort>
Nice job, BTW.
--
"Politics is the art of looking for trouble, finding it whether it
exists or not, diagnosing it incorrectly, and applying the wrong
remedy." -- Ernest Benn
.
- References:
- Chinese digital caliper - first report
- From: Joseph Gwinn
- Chinese digital caliper - first report
- Prev by Date: Re: Obama turns confidence clock back to 1983
- Next by Date: Re: Nam Vet Epic Beard Man vs. Tyronne: AC Transit Bus Fight
- Previous by thread: Re: Chinese digital caliper - first report
- Next by thread: Re: Chinese digital caliper - first report
- Index(es):
Relevant Pages
|
