Making or sourcing ~20mm metal circles? (not legal tender or holey)

[Whales]

I'm trying to make a special battery adapter for a particular product my work has a lot of.  Having access to ~20mm metal circles/rounds of some description that I can solder to would make my life a lot easier.  Preferably something I can make myself or source from within Australia (or otherwise avoid the 1-3months of China shipping I'm seeing at the moment).

Ideas so far:

• Coins: would be almost perfect (depending on solderability of alloy), sadly defacing coin of the realm is illegal.
• Coin blanks: I've only seen slow overseas suppliers OR precious metal ones from within Aus
• Washers: hole in the middle causes me problems with my battery contacts, unless the hole is really small (<4mm)
• Hole saws: again creates a hole in the middle.
• Custom PCBs: I feel like this might be technological overkill

Any clever techniques or methods that I could make some out of flat metal sheet?  Or any known supplies of pre-made ones?  Any thoughts or advice appreciated, I'm going in circles.

[sleemanj]

Thin nickel sheet might be suitable to punch with a circular craft punch die available at your local crafty type store.

[Monkeh]

A hole saw should work without a pilot in a press.

You could also part off from round stock on a lathe or even just a band saw.

[Whales]

Thin nickel sheet might be suitable to punch with a circular craft punch die available at your local crafty type store.

Ooh, I didn't realise you could easily get punches this big.  Looks like there are a few places in Australia, thankyou.

A hole saw should work without a pilot in a press.

I'll give this a go.  I'll get a new (cheap) holesaw, my sets are all too large.

You could also part off from round stock on a lathe or even just a band saw.

*jealous glare*

I do have brass round stock of the right size and a band saw, but it's a tiny 140mm blade-length unit that blunts easily and wanders whilst cutting.

[DrG]

For sourcing, there are lots of suppliers along the jewelry / tag / token / hobby markets. Here are a few to give you some search options.

https://www.aliexpress.com/item/32716955260.html?spm=a2g0o.productlist.0.0.2f952084QZxOYi&algo_pvid=0e4feabd-a56f-480d-a110-05c09ae5210c&algo_expid=0e4feabd-a56f-480d-a110-05c09ae5210c-21&btsid=0ab6fa8115981585640436065eee76&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

https://www.etsy.com/listing/605668731/10-deburred-choose-your-metal-12?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=metal+stamping+blank&ref=sr_gallery-1-9

https://www.dhgate.com/product/58mm-aluminum-stamping-blanks-2-28-inch-diameter/401215302.html?skuid=383440067284910080#s1-24-1b;srp|3229652801

[Kasper]

I'm guessing you already looked here but its not in your list so...

https://www.digikey.ca/en/products/filter/battery-holders-clips-contacts

[Domagoj T]

Specifying thickness, material and quantity could help us with suggestions.
It really is a different story if you need 200 or 200 000.
Anyway, when I needed some thin, but large plastic washers with small hole, I used a lathe to put a hundred or so roughly cut pieces on a mandrel and turned them all at the same time. They had to have a small hole in the middle, though (but in my case that was needed anyway). If you can live with a 5 mm hole, the process should be possible for you as well.
If not, or you don't have access to a lathe, and need fairly small quantities look into having it laser or waterjet cut.
Laser is fairly cheap, but some shops may refuse to cut copper alloys. That was the case when I had to have some things cut from bronze sheet (something about reflections damaging the laser).
I ended up waterjet cutting. There is basically no restriction on material there, but it is a bit more expensive.

If you need large quantities, punching will be much cheaper, after the initial setup fee.

[voltsandjolts]

All of this sounds like a real kludge.

[nali]

Putting "20mm brass disc" into Fleabay brings up a bunch of hits - they're used by engravers & for dog tags that sort of thing.

[Whales]

Thankyou for all of the suggestions.

eBay and Alix: economical shipping from overseas means 1-3 months of shipping at the moment, I'm not willing to wait.
digikey: I'll take a look and see if they have any huge ones. EDIT: sadly look to be all square, not round.  NB broken link, possibly due to silly geo-region redirects?
lathe: *seething jealousy overflowing further*

quantity: circa 50
thickness: around 1mm.  Thinner than a coin (<2mm) and stabler than foil (>0.3mm)

I've modified a 22mm hole-saw to remove the center-drill and so far it appears to be a promising option when paired with my drill press.  I've made some neat 18mm circles out of FR2 but I will have to see how it performs on some thin metal sheet stock.

[Whales]

All of this sounds like a real kludge.

A circle is a circle, no matter if bought from someone else or cut yourself  

[Domagoj T]

If the hole saw works for you, great.
As for the lathe, get one. It's an amazing tool to have. Even small desktop ones are very usable. I bought mine three years ago and it's the best money spent, used almost on daily basis.

[tszaboo]

Just make a drawing for it, send it to a local shop.It is really easy, if you did it once. We literally have one every second corner in an industrial park, and they do these kind of things all the time. They can laser cut this in an hour.

[mathsquid]

A lathe would be nice, but for cutting 20mm round stock, you could use a small or mini chop saw.

[voltsandjolts]

All of this sounds like a real kludge.

A circle is a circle, no matter if bought from someone else or cut yourself

Sure, but I was refering to the root problem - a plethora of batteries, holders and packs already exist so you don't have to kludge a battery pack together with washers.
But what you are trying to adapt is a secret, so who am I to 'judge your kludge' 

[Doctorandus_P]

You can make some kind of jig and clamp a piece of material between  2 ball bearings, and then use a bench grinder.

This tends to work best if the axis of the bench grinder is around 80 degrees from the rotation axis of your jig, so it "grinds a lot" and "rotates your jig a bit.

For 50 it might be a good idea to make some kind of pendulum of spring loaded jig that pushes the part with the right force into the grinding wheel until it stops at an endstop. And make 2 pieces of the ball bearing part of the jig, so you can mount a piece of material in one jig, while the other is grinding.

[themadhippy]

off the wall idea,knock outs from metal electrical back boxes

 

[Brumby]

A hole saw should work without a pilot in a press.

My first thought also.

Have done this with plywood.  Cutting metal shouldn't be a problem, just go slow and steady.  Digging the blank out from the teeth will be fun, though.

[Monkeh]

off the wall idea,knock outs from metal electrical back boxes

16 per box for a 2-gang 25mm, for 50p.. Why didn't I think of that?

Not sure the aussies use equivalent boxes though.

[Nusa]

defacing coin of the realm is illegal.

Given that you only need 50 of them, what about coins of other realms? The 5 cent euro coin comes to mind as likely to be available at money exchange places, but there are probably many candidates (Canadian and US nickels are the same size).

[vk6zgo]

defacing coin of the realm is illegal.

Given that you only need 50 of them, what about coins of other realms? The 5 cent euro coin comes to mind as likely to be available at money exchange places, but there are probably many candidates (Canadian and US nickels are the same size).

Or pre-decimal Oz pennies?
Nobody seems to care about defacing them.
I know some stuff from that era is now valuable, but pennies were around in huge quantities.

Another point, are they used in-house, or are you selling the devices?
If the former, is it that important that the spacer be a full disc?

A square with the corners cut off may do the job OK, although it probably wouldn't  look good enough if you have to sell them.

[BrianHG]

How about a source for tokens used in arcades.

[themadhippy]

Not sure the aussies use equivalent boxes though.

clipsal  are aussies and they do a few metal boxes,for example  part no SB471

[Raj]

Do what they did-
https://hackaday.com/2014/02/08/behold-lil-screwy-a-homebrew-100-ton-press/

[kaevee]

I have about 100 Nos of Aluminum circles of 25mm dia / 0.8mm thick. Will they do?

If you need any other metal/alloy, they can be manufactured.