FIXED! Shock Mount Replacement for Type D and Type H 500-series plugins (was [TekScopes] Another interesting Tektronix web site)


Dave Wise
 

FIXED!

"DJI ZH3-3D Damping Rubber Set (Part 42)", less than $10 at ebay.
This is four bags of four different isolators, for an RC helicopter camera mount, one of DJI’s “Zenmuse” series.
The ridged ones are too soft.
The ball shaped ones (two bags, gray marked "A40" and white "30")
are, as far as I can tell, *perfect* drop-in replacements.

From my repair notes:

These are 348-0007-00.
348-0087-00 plus 361-0113-00 (used in 1A6 and 1A7) might work too.

One of the three replaced way back
when is now severely crazed. Bad batch of rubber?
I tried Julian Bunn's fan mount rejuvenation procedure
(see "Another interesting Tektronix web site" at Tekscopes
at groups.io). Soak in olive oil 1/2 hour, boil in water
5 minutes. No effect, must be a different rubber.

Original part 348-0007-00 is a hollow rubber ball approx
15mm dia across equator, with a 12mm OD flange at each end.
Rubber is about 1.5mm thick. Neck OD 9mm, neck to neck 11mm.
Clearance hole for #8 screw. Chassis holes are 5/16" (8mm).

Dave Wise

From: David Wise
Sent: Monday, June 21, 2021 5:12 PM
To: TekScopes@groups.io
Subject: RE: [TekScopes] Another interesting Tektronix web site

Maybe 275-1N or 7110-0.5 or 7110-1.0 .  The latter can be had for $8 each at https://www.shopbdproduct.com/product_p/7110-1.0.htm .

Dave Wise

From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of stevenhorii via groups.io
Sent: Monday, June 21, 2021 3:52 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Another interesting Tektronix web site

All on this thread,

There are Barry mounts which come in various sizes and damping abilities:

https://novibration.com/

Scroll down the pages of this distributor’s Web site until you get to “Ball
mount series” which sounds like what you are looking for.

I have no conflict of interest with this company. I have seen Barry mounts
used quite a bit in various pieces of equipment when isolation from
vibration is important.

Steve Horii



On Mon, Jun 21, 2021 at 14:34 Dave Wise <david_wise@phoenix.com> wrote:

Thank you, Daniel, for your research and ideas.

The natural shape is a hollow ball. It must have been molded.
The screw plays no role in normal use; it limits motion extremes to keep
the cushions from tearing or coming out of the mounting holes.

I replaced all the cushions in my D and H, maybe ten years ago, with
new-old-stock I bought from Stan Griffiths. (They all have the same orange
paint stripe.) Most are fine but one is a mosaic of cracks. I’ve read
that making rubber is not 100% science. I figure there was a bad batch.

A solid ball with a hole through the middle would be too stiff unless the
rubber was exceptionally soft.

Another TekScopes member created a photo album, "541 Flip-flop fan
mounts", in which he created fan mounts from the sole of an old sandal. It
seems to me that I could combine that with your tubing idea.

- Long screw or stud, nuts, washers
- Thick-wall latex or silicone tubing, with 5/16” outside diameter (slip
fit in the mounting hole) when the screw is in
- Three foam rubber disks with 5/16” hole

- Put screw through tubing
- Thread first disk onto it
- Slide into first mounting hole
- Thread second disk onto it
- Slide through second mounting hole
- Thread third disk onto it
- Add washer and nut just snug

The foam rubber disks cushion axial motion, the tubing cushions radial
motion, and the screw holds it all together.

I will look around for an old mouse pad. Cut into disks with scissors and
hole with a paper punch. This just might work!

Dave Wise

From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Daniel Koller via groups.io
Sent: Sunday, June 20, 2021 5:42 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Another interesting Tektronix web site

Hi all,
I took a look at my D. My shock mounts are not gray - they are black.
They are just so oxidized on the surface they look grey, but they darkened
up with rubbing.
They have the consistency of latex surgical tubing, which makes me
wonder if A) that is what they are made of, and B) maybe that is what they
can be made of. I think if allowed to expand fully, they would be closer
to "I" shaped - a tube with flanges on the ends, rather than "ball
shaped". They take on the ball shape because they are compressed in their
mounts. You might be able to approximate them with surgical tubing. I
don't know if latex can be formed like thermoplastics, but if so, you could
try heating a section of tubing and blowing into it to bulge it out.
Donno. But making a flange would be hard. That might have to be molded.
Regarding molding hollow things - maybe mold the solid part, then
freeze it and drill out the center in a drill press? Keep it frozen in the
mold until drilled. Might be able to cast it in RTV that way. But the
resulting part will still be stiffer, in my opinion, than the original,
just based on poking at the ones I have on the chassis.
Another possible option is to 3D print. I have been playing with a very
soft thermoplastic polyeurethane (TPU) in my 3D printer. One needs a
special extruder with very little clearance between the extruder gears and
the feed tube, OR a direct extruder that goes right into the print head, in
order to be able to "push" the plastic through. But it does work, and I
have successfully printed lens caps and gaskets. I have not yet tried
stand-offs and vibration mounts, but I do plan on printing a door bumper
for a car, which has some of the features of the D's mounts. In the end,
the consistency will be a bit stiffer than RTV I think. There is
"Ninjaflex" TPU available, which is even softer, but I have not tried it
yet.
Ok, and lookie here:
https://www.plasticballsupply.com/1-2-in-0-5-black-buna-rubber-resin-balls/?utm_campaign=shopping&utm_medium=cpc&utm_source=google&gclid=CjwKCAjwzruGBhBAEiwAUqMR8HA-hPxNS7QI8J9bTUim39oKHQD8fSUIEJESdlbOjltfInNCf-jM_xoCt7EQAvD_BwE
<
https://www.plasticballsupply.com/1-2-in-0-5-black-buna-rubber-resin-balls/?utm_campaign=shopping&utm_medium=cpc&utm_source=google&gclid=CjwKCAjwzruGBhBAEiwAUqMR8HA-hPxNS7QI8J9bTUim39oKHQD8fSUIEJESdlbOjltfInNCf-jM_xoCt7EQAvD_BwE
Rubber balls. You still need to put a hole through them. The
dermatologist can provide the answer. Just go have a mole removed and ask
them for the hole-punching razor tool they use to circumscribe the mole.
I saved one or two and they are about 3 and 5 mm in diameter or so, with
various sizes available. This is cheap if insurance pays for the
service. Otherwise, you can get biopsy punches on amazon.


https://www.amazon.com/Biopsy-Punch-Sterile-Stainless-Steel/dp/B07R25NHBR/ref=pb_allspark_dp_session_sims_pao_desktop_5/141-2449543-9055469?pd_rd_w=4kBMY&pf_rd_p=3ac2ce50-9d75-4bd3-868d-72b252a0623c&pf_rd_r=1B8PSTPQSFTG3WBK8GEW&pd_rd_r=59842b2f-725a-4e66-90d4-d34a3844db5d&pd_rd_wg=wZjGh&pd_rd_i=B07R25NHBR&psc=1
<
https://www.amazon.com/Biopsy-Punch-Sterile-Stainless-Steel/dp/B07R25NHBR/ref=pb_allspark_dp_session_sims_pao_desktop_5/141-2449543-9055469?pd_rd_w=4kBMY&pf_rd_p=3ac2ce50-9d75-4bd3-868d-72b252a0623c&pf_rd_r=1B8PSTPQSFTG3WBK8GEW&pd_rd_r=59842b2f-725a-4e66-90d4-d34a3844db5d&pd_rd_wg=wZjGh&pd_rd_i=B07R25NHBR&psc=1
I think careful use of one of those punches can put a neat hole through
a rubber ball, and rubber washers seem to be available in plenty of sizes
on the interwebs! Good luck.
I'd be curious to know how you replace these. My 503 has latex
isolation mounts in parts of the circuitry. I'm betting they are getting
pretty dried up.
Dan

On Sunday, June 20, 2021, 04:16:31 PM EDT, teamlarryohio <
larrys@teamlarry.com> wrote:

Been far too long, but the ones I used were the same type generally as the
fan mounts. Otoh, McMaster has a huge variety of hardware bits.
G'luck!
-ls-













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