Using a rotary table as a replacement for a big lathe

[S. Heslop]

I'm planning on casting a thing like this at some point. Its about 10 inches in diameter total (the hoop is 8 inches). Not sure if it'll be brass or aluminium, but alu would probably be easier to cast.



It's way too big for my little 7x12 lathe, so I was wondering if it'd be safe and/or viable to fit it onto a 6 inch rotary table on an X2 sized mill to clean up the casting and maybe locate the holes (looking at the holes in that picture, the maker didnt seem to care about getting them too accurate).

It's all pipe dreams at the moment, but i'm just running through every step to see if it'd be at all possible before I take the plunge.


Oh, and the component is from a zither style banjo, slightly popular in England during the turn of the last century, famous for their poor construction and tinny sound.

[Pete.]

I would do it all by hand TBH. Hand-filing or even a cheap dynafile would make easy work of cleaning off casting flash, and might even look more natural for the part. If the parts come out very similar I'd carefully spot and drill the first one then up-turn it onto a sheet of steel and drill through it to make a drilling template, use the template to drill all the others on the drill press.

[Fergus OMore]

If it is a ukelele banjo, the body is usually wood. In any case(?) they are dirt cheap.

We have an ancient one with all sorts of mother of pearl adorning in, and a leather hide case and whatever-- and no one wants it.

Well, it would be interesting to learn more

[S. Heslop]

I would do it all by hand TBH. Hand-filing or even a cheap dynafile would make easy work of cleaning off casting flash, and might even look more natural for the part. If the parts come out very similar I'd carefully spot and drill the first one then up-turn it onto a sheet of steel and drill through it to make a drilling template, use the template to drill all the others on the drill press.

I'm mostly concerned about making the 8 inch part as accurately (and as accurately round) as possible, as i'm planning on making it to fit standard 8 inch banjo heads. From what i've been told it's semi-important to get a tight fit, but from experience I've found that the heads don't have alot of room for error. Mind there are so many stupid myths around the tone and setup of an instrument, and the rule of thumb seems to be that the more expensive a thing is the better it'll sound (i've even heard people argue that gold plated banjo fittings sound infinitely superior to non plated!).

But yeah in regards getting it round, buying a mill might be overkill. I might get away with bolting it to a sheet of MDF with a hole in the centre to use as an axis, along with a drill press and drum sander.

[S. Heslop]

If it is a ukelele banjo, the body is usually wood. In any case(?) they are dirt cheap.

We have an ancient one with all sorts of mother of pearl adorning in, and a leather hide case and whatever-- and no one wants it.

Well, it would be interesting to learn more

Nah it's not an existing thing. I've just been looking for an excuse to build a banjo from scratch for ages, but since I already own one it seemed perhaps silly to build one just like it.

http://savethebanjos.com/Cammeyer%20ZB.htm I found this online a while back (its where that photo is from) and honestly I just think it's a neat way of constructing a banjo, and probably not too hard to replicate.

But yeah my problem is that I always feel I need an excuse to do or buy something. Like this banjo also gives me the opportunity to get into casting, something i've wanted to do for years but always felt I needed more of a reason than 'just for the hell of it'. It's the same story in regards mills, like with Pete's suggestion I find alot of stuff i'd use a mill for I can get around with by using files and a drill press.