On Tuesday, November 15, 2016 at 3:29:49 PM UTC+1, Larry Jaques wrote:
On Tue, 15 Nov 2016 01:10:57 -0800 (PST), robobass
wrote:

On Saturday, November 12, 2016 at 11:25:44 PM UTC+1, wrote:
On Sat, 12 Nov 2016 13:23:22 -0800 (PST), robobass
wrote:

On Thursday, October 13, 2016 at 1:59:47 AM UTC+2, wrote:
On Wed, 12 Oct 2016 12:34:02 -0700 (PDT), SteamboatEd Haas
wrote:

Hey gang I'm making some parts out of delrin; they've got fins on 'em and when they're cut to length the fuzz is everywhere! I'm thinking of using my brass tumbler with walnut shells unless someone's got a better idea. Here's a link to the problem: https://www.flickr.com/photos/steamb...7673545442262/
Walnut shells might work. If they don't then tumbling with abrasive
media and water will. I have deburred acetal plastics, both Delrin and
Acetron, in one of my vibratory tumblers. I used trianglar and
cylindrical abrasive shapes. The only problem is that the plastic will
get a matt finish. For your eventual use I don't think that will
really be a problem. Even walnut shells, if they can remove the burrs,
will give you a matt finish. You can tumble the parts after deburring
with polish but it takes a very long time, in my experience, to polish
acetal plastics in a vibratory tumbler. You might want to try an
abrasive filled nylon brush first to remove the majority of the burrs
first. I have had good luck doing this. It is easy to melt the plastic
if a light touch isn't used though. Even brass wire brushes tend to be
too aggressive.
Eric

Eric, can you point me to a source for fine abrasive filled nylon brushes? I spend a lot of time cleaning 5/16-24 brass threads. I use .2mm bristle brass brush wheels and tripoli. It works, but I'm on the lookout for something better.
Does MSC sell to your part of the world? They sell Weiler brand nylon
wheel brushes that have a filament diameter that is nominally .018 but
can be as small as .010. I have used these brushes and the ends can
wear to a point which is what you need to get into the root of a 24
TPI thread. Weiler does make good brushes and with that name may be
made much closer to you than me here north of Seattle. Have you
considered fine steel brushes? They cut fast and can be too aggressive
on soft metals like annealed brass. But a light and quick touch could
result in a roughing op. that leaves the surface perfect for a fast
tripoli treatment. You could try a jewellry supply company for the
brush but they tend to carry ones that are too small. I have had the
occasion more than once to polish small brass threaded parts and found
that E5 emery on the right buff will cut fast, get to the root of the
thread, and leave a finish that is usually already good enough and if
not then either tripoli are rouge can be used. For REALLY nice color
on brass I like Fabuluster. But that's probably more work than you
need to do if you are stopping at the Tripoli stage. BTW, did any of
the sprayer suggestions here pan out?
Eric

Eric,
I did try a .010 nylon bristle brush from McMaster but it didn't do anything. Here is a photo of what I'm doing:
http://i389.photobucket.com/albums/o...psxgwuln1x.jpg
Now I am applying something called Stop Ox II with an airbrush, which minimizes waste quite effectively.

Cool!

P.S: I'm sending that link to the Neutrino Bass Cable to a musician
friend. He's a rhythm guitarist but sits in on regular bass guitar on
occasion. I think he'll get even more of a kick out of it, as he's
retired from the NRL in D.C. Y'know, I'll bet those sound even better
than those Oxygen Free Copper cables everyone is (was?) selling. g


Upper right is the typical result after a vinegar pickle in a ultrasound bath. Lower right is when something went wrong and I had to torch the part for way too long. Upper left is after using a .008 brass brush with tripoli, and lower left is after finishing with a cloth wheel and fine compound.

That's a lot of process work, but brass sure is pretty when it's
finely polished like that. I think it's my favorite metal. Your
finished product is beautiful. Is that a high-shore rubber sleeve? Or
maybe thick PVC?


I was happiest when running a drill press mounted 3" wheel at 2350rpm, but I simply can't get those wheels anymore. The suppliers will insist that they are brass, but they are all plated steel these days. I have a 10" brass wheel that I run on the lathe at 1100rpm, which is maybe too fast.

Y'think? That's 51.6% faster than your ideal. Why didn't you slow
down the lathe? Or did that speed work best with the density of the
larger diameter brush?


I get good fast cleaning, but a bit too much scratching, and I can't just drop it in the ultrasound bath to clean it. Overall I'm in pretty good shape, but I'd still like to find a bristle wheel for the fine polishing stage. McMaster has Tampico brushes which look good, but I wonder how long they will last, as they aren't exactly cheap.

It seems like almost all brush prices have skyrocketed lately. I tend
to use bronze brushes (toothbrush size) for cleaning gunk out of
threads. They tend to hold up considerably longer than brass. The
cheapies bend half their bristles on the first pass, and the good ones
have tripled in price over the last decade.

I have no experience with tampico wheel brushes, so I don't have
anything to offer there.

I was wondering how you hold those parts while cleaning. I hate
getting my fingers in the way of the high-speed bristles for some
reason, so I think I'd run weld the ends of a strip of sheetmetal to
opposite flats of a 3/8-24 nut, run it through the bandsaw to halve
it, clean up the cut threads, and run a piece of hose over the handle
to hold the halves together. I could 'clamp' it on the brazed end to
clean up the free end, then rotate it through the revolutions to get
all the threads cleaned. I first thought of using a long standoff, but
that wouldn't hold it for the free end threads.

Just thought I'd share that.

--
If government were a product,
selling it would be illegal.
--P.J. O'Rourke

Larry,
I hope your friend wants a cable, cause sales have been dismal. I have no idea why.

I do realize that I'm running the big brush way faster when looking at surface speed. I do need to experiment with this further. The brush should outlast many dozens of small brushes. I found it surplus.

I don't have an issue with holding the parts. I spend so much of my day holding these things to the various abrasive wheels that it is second nature. When I do on rare occasion touch knuckles with the man, I just step back and remind myself that I need to keep focus. That said, if you looked at my hands, your first guess at my profession would not be concert pianist. Ironic, since for most of my life I was an orchestral double bassist.