Jeweling metals, need info

[owen moore]

The photo you included in your post appears to be a rifle bolt. Brownells gunsmith supply has a jeweling fixture for similar parts that allows the part to be accurately indexed for rotary and linear spacing. I believe they even sell the Cratex abrasives and grit compounds. You may also want to check Midway USA as well. On your flat panel project you will want to figure out a way to index the part at the desired spacing. A milling machine would be handy.
Years ago, I used a simple pencil with a type writer eraser and a drill press for small parts. Good luck with your project!

[drum365]

Just a few quick comments... (I have never done this technique, but have researched it some for a future project I have in mind)

AFAIK, a more common name for this technique is "engine turning" - try googling that. There's lots of info out there. It was very popular on aircraft and auto dashboards "back in the day." You might also have more luck using that term in searching YouTube, etc.

mklotz' suggestion of using a piece of leather glued to a dowel is, I believe, the traditional way of doing this.

Good luck, and I hope you post pictures when you're finished!

[rendoman]

Thanks for the advices that you all gave me!
This rubber rods seems "easy" to use, I just sent a mail to Cratex in order to know if shipment is possible. I'm also searching something similar in Europe, till now nothing found, as usual . Tomorrow I will search better!

[petertha]

I bought this set & use it quite often for metal finishing. Very inexpensive compared to Cratex. I'm wondering if the largest cylindrical shape could just be used directly, meaning chucked in a drill press or mill & impart the swirl. I'll try & see if it works & take a picture for you. If you want lager diameters of course you would have to make a mandrel like you were thinking.
https://www.richontools.com/index.ph...79f0bff49eec1c

This is a cam plate for my model radial engine made from A2 tool steel. After grinding a slight radius on the lobe corners, I used the green wheels (in link) to blend the surfaces. It leaves a semi shiny matt finish. Thereafter I use polish with a felt wheel. Both were done with a Dremel tool.


Also you can get diamond lapping paste very inexpensively from Ebay or Aliexpress. Lapping compound can be aluminum oxide or other abrasives but in your application you don't really have to worry about diamond embedding. They also come in petroleum or water based if that's important. I find the petroleum comes off quit eeasily with alcohol or similar solvent.
https://www.ebay.ca/itm/8pcs-5-Gram-...wAAOSw241Yl89n

[Jack55]

I once did this technique to a Cessna 152 firewall. I screwed it to a table and cut slots in a board that spanned it. The slots were spaced slightly less than half the diameter of the abrasive pad I was using. I then screwed a fence onto the work table to slide the slotted board down as I went. Again, each row spaced down slightly less than half the diameter. The 1/4" shaft of the abrasive pad fit into the slots of the board and I just used a cordless drill and the slots kept the pad in position. Each alternating row I had to move the indexing board down and space it right so all of the circles are staggered. Not a speedy process but it turned out well. I experimented with a compass on paper to get the spacing right. I used one of those screw on abrasive pads for the firewall, about 2" diameter if I remember correctly, but I've also used a scotch bright pad glued onto an elevator bolt with good results.

[petertha]

Here's the green 'rubberized abrasive wheel' results in mild steel spun in a drill press. These are not Cratex, they are offshore brand & I just ran it without dressing the end which is probably why inconsistent rings. Results are so-so. I think the grit is too fine for the look you are after. Somehow I think something like sandpaper on the end of a hard dowel material might be the most controlled way of obtaining whatever degree of micro-scratches in your particular material. If its too faint then coarsen up the paper & visa-versa. I've done this with a Dremel before just free handing over an array of felt pen dots (because the surface was slightly curved). Lapping compound would probably work too, but me thinks rather messy. Good luck & show us what you ultimately decided.

[Toolmaker51]

rendoman, ALL the suggestions made are correct. The tool variations occur in diameter, hardness, and speed of the pad; and on project side in size, contours/ shape and material. Aluminum needs less pressure, grit size, and duration than stainless steel, for example. Valve lapping compound offers a wide range of grit size in convenient packages that likely are sold world wide.
A panel for your electronics will be a far larger 'spot' than a rifle bolt, based on proportions. I'd tend to sit down with sketch of the panel and start drawing a fish scale pattern to gauge an attractive size. Milling machine isn't critical, they are slow to index and not always desirable RPM. You can use the mills table though; a rail to guide that panel and marks to regulate the spacing. Having the quill stop will make the pattern look it's best.
Leather on a dowel is going to work well, long lasting, and delivering a consistent pattern. You should be able to make equal spares to finish the work.
https://www.google.com/search?q=engi...nt=firefox-b-1

Supposed origin of engine turning was to retain lube in sliding surfaces of firearms, high grade time pieces, and lock works. Not too different than scraped machine tool slides. It was associated with quality, evidence of additional man-hours in products. That degraded somewhat applied as decoration instead of a functional process.

[rendoman]

Thank you all!

I asked MSC Industrial Supply Company for a small quantity of rods , as Cratex said, unluckily they said the minimum order size is $200 USD, with high priced shipping.
For a couple of small rods that you can send in the envelope with normal mail, it's not worth the expense.
I will search soon for lapping compound! Finger crossed

[petertha]

Sometimes you can find inventory or used on Ebay & similar. These look a bit worn, but if you wanted a less expensive way to try vs. new.
https://www.ebay.ca/itm/Cratex-abras...wAAOSw8Mda6gKy

This is a jeweler supply place in Canada that handles Cratex brand. I'm sure there must be European dealers of similar products.
Cratex Cones

Personally, I think for Cratex you are paying for the quality & consistency of the finer grit wheels. But from what little experimenting I was doing, I think you are going to need coarser grit to make those striations. Without knowing your material or application hard to know, but I'd estimate between 120-220 grit. I'm not sure what that corresponds to in Cratex coarse/fine etc. but the link provided in post #17 looks helpful.

Why don't you make a simple mockup from a wooden dowel or metal rod & glue some common sandpaper or emory paper on the end? You may find its a perfectly good tool, or failig that, at least you will have a better idea of what kind of lapping compound to buy because its not exactly inexpensive either.

[Toolmaker51]

Petertha made a good suggestion about sandpaper. What we call 'wet or dry' also known as silicon carbide [black abrasive on a plastic-like sheet]adhered to a dowel should work nicely. Use water to float away the stuff that will ruin the pattern. If you know a leather worker......his contact cement will work.
You can catch him with a fast motorcycle, when he isn't busy with electronic projects. Rumor has it, he's nearly always wearing leather.
Lapping compound according to Google.com [US] gets you these results.
https://www.google.com/search?q=lapp...nt=firefox-b-1