Need Help

[gunboatbay]

I need to fabricate 4 small brass disks as shown on the attachment (metric measurements). I don/t have any brass round stock to cut slices from. All I have is a piece of brass strip 14mm wide x 250mm long x 2mm thick. Anyone have a suggestion on how to accurately make these disks from the material I have on hand??

 

[peatoluser]

You could cut out some sqares, roughly file to shape, soft solder or glue them to the end of a previously faced bar, 10mm or 12mm, then turn OD

 

[kvom]

The only thing that comes to mind is:

1) cut off 4 14mm pieces (e.q., squares)
2) super-glue to a larger round piece of fixture, such as aluminum
3) mount fixture in a rotab and mill the circles
4) heat to remove the glue

repeat

or use lathe as previous poster.

 

[Noitoen]

Took the words out of my keyboard

 

[portlandron]

Being it's the right thickness go with the super glue.

Cut to ruff O.D. and make sure what ever you glue it to is flat and smooth or the super glue will not hold very good. Then use your lathe or mill to cut the O.D.

 

[gunboatbay]

Thank you all for the suggestions. I'll try the super-glue idea.

 

[shred]

I'd probably go the superglue route, but some other possibilities are-

-- If you can put a hole in the middle (repairing later if need be), friction-turning them would work nicely. I think there's a way to do that without center holes, but I can't recall it.
-- You could also trepan them on the lathe from rough stock held in a 4-jaw, but that gets tricky at the end.

 

[mgbrv8]

A trepanning tool could do it. or a simple hole cutter in a drill press

trepanning cutter
https://www.abbeon.com/store/images/photo1/abbeon/TREPANNING.jpg

Hole cutter
http://zenstoves.net/Supplies/CircleHoleCutter.jpg

 

[Ken I]

Like Shred suggested - friction turning - face a bar off in the chuck - place your rough square (octagon - whatever) and secure it with a pre-turned and centre-drilled button - you must use bearing type live centre.
Eyeball the alignment - apply a bit of force with the tailstock (you don't have to go nuts) - machine taking light cuts.

Done it plenty of times - ideal for rounding disks cut from sheet metal. When turning thin disks it helps if the support is the finished size - or bigger and finish onto the support bar. You can also stack up multiple disks but you don't want to exceed about 1/3 to 1/2 the diameter in total thickness.

Re other comments - its amazing how much superglue will stand but avoid too heavy interrupted cuts or generating a lot of heat.

Ken

 

[MachineTom]

Take an AL bar turn to 11MM, center drill end, then part off, face cutoff and piece in chuck, now sandwich the disk between the two AL pieces, turn or file to size. no glue, very quick.

 

[Blogwitch]

I made a load of small brass discs for collar marking for a dog kennels using this method without the centre hole. I just stuck the bits of metal together with double sided tape and skimmed the outside to size after they were trapped between chuck and tailstock.
I made a couple of dozen in about as many minutes.

http://www.homemodelenginemachinist.com/index.php?topic=1510.0

A little bit of heat from a blowtorch soon has them separated.


John