Let the Laughing Begin

On Tue, 5 Sep 2017 07:04:03 -0700 (PDT), wrote:

On Monday, September 4, 2017 at 9:25:51 PM UTC-7, Jeff Liebermann wrote:
On Mon, 4 Sep 2017 14:01:39 -0700 (PDT), wrote:

The professional is the one that's accurate and the cheaper one that was both showing the wrong pressure and probably letting pressure bleed off through the cheaper filler nozzle.

Here's my bicycle pump tester:
http://802.11junk.com/jeffl/pics/bicycles/misc/slides/Bicycle%20pump%20pressure%20gauge.html
I scribbled a little about how it's used in a previous postings:
https://groups.google.com/d/msg/rec.bicycles.tech/YsqvNggfDDM/CoySfXtGAQAJ
https://groups.google.com/d/msg/rec.bicycles.tech/YsqvNggfDDM/XeXJLe5kAQAJ

For a leakdown test, I attach a small pressure vessel to one port, and
pump up the pressure with a bicycle pump attached to the other port.
Then, I watch the pump gauge to see if it remains stable. If the test
gauge leaks, I paint the plumbing with bubble mix looking for the
source of the air leaks. If the gauge itself is suspect, I take it
apart and check the mechanism for leaks.

Well, that certainly seems a better method than getting a good pump to begin with.

Quantity is my substitute for quality. When I tested my collection of
floor and frame pumps, I found a few defective pumps and a few
inaccurate gauges. I don't recall the numbers, but one gauge read 8
lbs low for a 60 lb tire pressure. Cleaning the crud out of the
mechanism most fixed that. I don't think I own anything that might
resemble a "good pump".

This was from 3 years ago:
http://802.11junk.com/jeffl/pics/bicycles/misc/slides/bicycle-pumps.html
I now have about twice as many frame pumps. I also have 4 working
floor pumps, 2 sick floor pumps, 1 worthless foot pump, and maybe a
dozen assorted pencil, analog, and digital gauges. The various cheap
automotive type digital gauges seem to be the most consistent and
accurate, but also have mechanical problem, such as fitting only
Schrader valves or a leaky fit. Maybe, some day I'll buy a "good
pump" and recycle all the junk pumps. A proper dead weight pressure
gauge tester/calibrator is not in my budget (although I could probably
build one).

Incidentally, when I go for rides these daze, I generally throw the
bicycle into my Subaru and drive to where I want to ride. Before
leaving, I usually top off my leaky tires with some air from a cheap
12V automotive air tire pump. The one I have has an automatic shutoff
when it reaches a set pressure. I just set the dial, start the air
compressor, and I'm ready to ride when it's done. The problem is that
it's horribly inaccurate. The dial settings and built in pressure
gauge don't agree and are rather inaccurate. However, they are fairly
consistent, so I just calibrated the readings and scribbled a
calibration chart. After that, frame and floor pumps seem so
uncivilized.

At one time, I proposed a portable bicycle tire inflator consisting of
something like the automotive automatic shutoff compressor that I'm
using, with an added LiIon rechargeable battery. Or maybe powered
instead by a model airplane gasoline engine. I think I can make it
small enough to be fairly flat and pocket size. A little marketing
research indicated that nobody I asked would pay money for such a
thing but might consider building one from a kit. Very strange but I
decided that it was too risky and let the idea die a natural death.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558