Carbon arm finish

[tubee]

Today i have beed busy with replacing the aluminium tone-arm tube from my diy arm into a 10/9 mm cross-woven carbon tube. I had to grind the tube to get it with a tight fit in the alu headshell.
I want to finish the carbon to get a beautiful look, and for additional dampening. What laquer shall i use, any comments? My thougts are to use high gloss acrylate spray.

http://img109.imageshack.us/my.php?image=armoq2.jpg

Thanks

[moray james]

If you want the finish to provide a nice look then hard wax would be an excellent choice (carnuba is the hardest wax) and a heat gun or hair drier will assist in getting a super smooth and shiny hi gloss finish. If however you want the finish to not only provide a hi sheen but also tune the tone of the arm then you might consider violin varnish (many types). High grade art supply orange shellac is probably the hardest natural resin that you can find but you can add in powdered gemstones to impart colour and hardness, I would think that with a composite tube made from carbon fiber (plasma treated PET mono filaments) which is held together with in most cases epoxy that hard coating with gemstone add mixtures like diamond and others would tend to brighten and highlight the more subdued sound of the epoxy in the CF tube. The bonding resin tends to be the predominant contributor to the sonic signature of most composites. I will be most interested to know what you decide to try and what you think of the results. Regards Moray James.

[tubee]

Thanks Maray for reply.

I think the hard shellack for violins would be great. I didn't know they added gemstone in it for extra hardness. Thanks for the info.
The used carbon tube is from germany, ordered in a shop for making kite's and so on. It had a sticky outer layer, but i had to polish that off with grain 1000 sandpaper to fit the tube. The carbon itself was harder, and dense woven with some bonding, not sure what.
I think my father had somewhere shellack. I see just it can be solluted in alcohol

[moray james]

resins such as shellac, air drying oils, PVA , polyurethane and many other organic resins can be crosslinked by adding borax (benzoic acid). See this link to a patent. ½›�ú²¿ÖÇ»ÛØ”®a¾Ö- Éú¼¼átËŽŒ£ÀûÙYÓ�¾W- ßB·f¿Æ¼¼¹É·ÝÓÐÏÞ¹«Ë¾ÔOÓ‹( 2003 ) Regards Moray James.

[moray james]

http://210.69.13.146/search/PatDetai...6675&DBName=US Look here

[sletol]

Your arm looks really great, I must congratulate you on that, first of all!
I think one should keep in mind that violin varnishes are choosen for the opposite of good dampening properties. (It is considered an advantage in a violin that as many vibrations as possible are excited for a long a time as possible). A carbon arm OTOH is stiff and light, and one has has to think in other directions, if one wants to improve it. Because it is stiff, mainly high frequency vibrations will become exited in it, therefore some rather soft, dampening stuff on its surface could possibly be an advantage. High quality tape, for example (Tesa)... Well, that was meant as an example only, not taking the looks into consideration!
Another possibility - and this is my favorite with low mass arms- is to instead add some mass, say, 2-3 grams of plasticine, to the cartridge body itself, to help keep the whole assembly immobile even when the stylus is working with strong bass signals, and also dampen somewhat high frequency vibrational energy at the origin.An ugly looking thing? Possible.
(I personallly always enjoy the look af a good techical solution...).

[moray james]

borax or sodium tetraborate decahydrate, chemical compound, Na2B4O7·10H2O Regards Moray James.

[tubee]

Thanks for compliment Sletol. And for answers Moray.

The arm has been in use for 18 years allready, and want to clean ball bearings & replenisch the oil after that long time. In meantime solve resonant problems of metal arm tube with carbon. The Akia DD drive base will be discarded, a belt drive is more steady in speed. Still thinking of a good solution for that. (find a Thorens?)

For the arm i like dampening & good looks if possible. Experimented with rubber sheets between cart and headshell, but this was not sufficient. I hope carbon will solve some problems. I am thinking to exchange the metal armbase in a Delrin-one too.

[bulgin]

Hi Tubee, Moray James @ All

Congratulations on your work on the arm! You guys are too clever!!!

My suggestion for varnishing would be a two-pack automotive clear sprayable varnish, which I have used often, spraying all kinds of things (also my Quad 405), using an airbrush and a small compressor.

Btw, I have just done the opposite with one of my Micro (I think MA-505) which had a straight graphite arm and removable offset headshell.

I've used two of these arms for many years and eventually connecting pins started getting loose or breaking and a severe headshell shortage resulted.

I decided to replace the graphite wand with a curved thinwall aluminium tube. After looking around for something to use, my eye fell on two landing sleds from a radiocontrolled helicopter.

I cleaned it up and started by running some basecoat/clearcoat auto paint varnish into it and let it dry for about two weeks.

In order to solve the headshell problem, I decided to go with the sme-type connector and over the last two weeks, finished the job. There were many fiddly bits to make and having a lathe and milling machine, I could put a very high finish on all parts, after which I anodised it 'natural'.

My first extended listening session was last night and I am very pleased with the result. The graphite wand was good but the new curved aluminium replacement seems to have more 'grip' on the music with sharper defined transients.

If anyone would care to see the mod, I have pics.

Regards all

bulgin

[tubee]

Nice to hear about your mod Bulgin, and yes i am interested in pictures