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 ARCHIVED TOPIC: Bevelling/rounding the top of a brass tone ring


Please note this is an archived topic, so it is locked and unable to be replied to. You may, however, start a new topic and refer to this topic with a link: http://www.banjohangout.org/archive/350695

Hawgfiddle65 - Posted - 01/30/2019:  04:42:16


Hi all

A recent post on a goldtone tone ring got me thinking . I have a ring roller and have rolled brass rings out of round section brass bar. How would you go about bevelling or rounding over the top edge of a rectangular section brass ring that would be set in a rebate in a rim?

Would you start with profiled brass pre rolling or do you profile the brass once rolled?

In the absence of any fancy metal work lathe , I have a longworth bowl chuck which I suppose I could adapt with spacers to hold a rolled ring with the top surface proud and use some sort of file/abrasive to profile the top edge. Might get a bit hot!

Any ideas. How do the pros do it.

Jim

JIm

OldPappy - Posted - 01/30/2019:  04:56:54


I polish and profile mine on the same lathe I use for rims. The hoop has to be flat to get a consistent result, but I simply use a file, then sandpaper until I get it how I want it. You do have to move the sanding block or file, and do it in in short increments to avoid getting hot.

Ken LeVan - Posted - 01/30/2019:  05:59:07


What Andy says.  I round off the head bearing edge of all tone rings using a disk sander, a spindle sander, and sandpaper and files.



One thing I would say is that you have to make a radius template to make sure you are rounding it evenly and accurately.

rudy - Posted - 01/30/2019:  06:07:31


I've used carbide bearing guided router bits to produce 1/8" or 3/16" round over edges on brass many times.  It's quite easy and no big deal.  It is necessary to take lighter cuts and reduce your router speed and material feed rate.  As an example, for a 3/16" radius roundover it's quick and easy to make 3 passes, raising the bit 1/16" for each pass until you achieve your final 3/16" depth (when using a table-mounted router).



The companies that produce commercial router bits have specialty carbide bits for non-ferrous metal which have a slightly different relief angle, but standard bits work fine.



Personal protective equipment and the standard safety precautions are mandatory, no different than if you're using wood.



I've also sanded the edge profile, but that takes more time and care with maintaining the correct shape.



For tone rings I switched to using round brass rod a long time ago, both for ease of use, cost, reduced labor in bending and shaping, and because there's such a minimal amount of difference in the produced tone.

Zachary Hoyt - Posted - 01/30/2019:  06:19:21


I've recently begun doing it, and so far I've used the router table as Rudy describes. I use a 1/8" roundover bit for what I'm doing and have done it with one pass, but a very slow feed rate. With wood I am concerned about feeding too slowly and getting burn marks on the wood, but I don't think that is an issue with brass. It does make me a bit nervous because my fingers are so close to the table surface, I prefer applications where they're higher up and out of the plane of the router bit, but with care it's safe enough, I guess. The other thing I noticed is that the brass chips fly much further than wood, so a lot more vacuuming is required after routing to clean up the mess.
Zach

Hawgfiddle65 - Posted - 01/30/2019:  06:24:28


Hi all

Thats great.

Never even considered using a round over bit!

Jim

m ellis allen - Posted - 02/01/2019:  14:22:43


I made a quick jig that I use in conjunction with a drum sander in my drill press. It puts the ring at an angle and stablized. I just have to slowly rotate the ring around.

Dan Drabek - Posted - 02/01/2019:  14:38:11


I don't have a lathe, but I would guess the process would take about 15 minutes using a single cut 10" mill file and a vise.
Take long strokes along the circumference. After roughing it out with the file, it could be polished with a soft sandpaper block.
Finishing on a buffing wheel would be optional.

DD

Helix - Posted - 02/01/2019:  14:45:49


I had to learn this the hard way.

All of you are correct in your own paths. And as it should be.

Until I had a customer who is a real machinist who was rather shocked that I didn't know this as an adaptive sub-genius like all of us including the good person who posted.

Real machinists use a simple hand held tool that is available, I can't remember now, just look it up in the right place.

Where there is a wheel, there is an avenue. Some are monorail minds. All good rails need a wheel.

Really funny to me now, hell, I had a fire for about 1 second until the router died a sickening death, like "HEeeeeeelllpppppp.... I sucked brass chips up into a perfectly good router. A big one, not upside down, not sanding pieces difficult to get out of one's eye!!!

Just watch yourselves, someone might get hurt, I didn't , Old Pappy is very valuable to me. The rest of you can rip what you sew.

I love you all, not everything you do.

Watu wa Tai. Jambo Rafiki.

If you don't I'll ask the Watu wa Tembo. Get busy and build some coolest stuff known to this century. It's OUR job.

Helix - Posted - 02/01/2019:  14:47:31


At least try a cabinet scraper first.




Helix - Posted - 02/01/2019:  14:53:37


If you recall Mr. Drabek, I got ridiculed for using a modified Longworth chuck to center MY rims. Knock it off.


Dan Drabek - Posted - 02/01/2019:  15:14:38


Until they try, many craftsmen don't realize how accurate the hand and eye can be when shaping things like wood or metal. Using a smoothing plane and felt sanding block, I can shape the back of a resonator into a curve that looks like it was machined. It's really not that difficult.

The most accurate hand work I have ever done was to grind an 8" astronomical telescope mirror into a perfect paraboloid with a focal length of 42" and a surface accuracy of two millionths of an inch. This was achieved by doing nothing more than rubbing two glass discs together with a sprinkle of carbide grinding powder between the discs. After grinding, I went on to polish the discs with an equally simple technique. No power tools or specialty hand tools needed. Here's a photo I took through the scope I made with that mirror. 



The point is, don't sell yourself short in the level of accuracy possible with simple hand tools. Look at some of the incredible jade carvings from ancient China. Or the artistry of 13th century Japanese swords. It's possible to take your work to places you never thought possible, until you try. 



DD



Helix - Posted - 02/01/2019:  15:46:17


Yes, except the accuracy needed here is not given to just mammal geniuses.



 

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