Small saw. Proxxon or something else

Yes but unfortunately it's ferrous mild steel & stainless steel, that I need to cut!

@Nicholas Farr - Thank you so much for trying the experiment! In truth it's to tell from looking at them. To get clear my problem is that I can't use kitchen foil because it's non-magnetic. i.e. Its a magnetic contact that I'm needing to create and even the slightest air gap is to be avoided if humanly possible.

Magnetic Contact?

I presume that its not an electrical contact, but rather you want the ferrous sheet material to be in full contact with something magnetic over its whole area. Two things come to mind regarding this.

If the magnet is strong then the thin plate will conform to a flat magnetic surface even if it has a slight curl or bow. Also unless the steel plate is bonded to something rigid its not going to be easy to remove without damaging it, a knife even with a with a very sharp edge will be needed to lift a corner and then the very act of lifting the sheet may bend it.

Obviously whatever you are developing needs to stay confidential but if it eventually becomes a commercial product these steel plates will probably need some type of protective coating. Paint might be too thick for your humanly possible minimum gap requirement so electroplating is probably best.

Ian P

Oh dear! John, I was not for one minute suggesting that you use kitchen foil, it was the only thing I have in the house that has a thickness that is within your 0.02mm gap tolerance and I used it in the photo for comparison to give you the sense of size of any gap you may see between those three pieces of steel and the straight edge they are on, the three pieces are not on the kitchen foil.

Regards Nick.

P.S. if you click on the photo to see it in full size, you should be able to see the kitchen foil is in fact in front.

Edited By Nicholas Farr on 27/04/2021 22:29:07

The world is full of millions of small items made from sheet metal and pretty much none of them are cut with a grinding disc or saw blade in a production environment.

Traditionally a guillotine would be used to do something like you want, giving a straight cut edge. I don't know where you get your information on the rounded edge in the drawing you posted, but if the clearance between the guillo blades is zero that tiny radius on thin sheet will be undetectable by the naked eye, if that is what you mean by "optically flat". Ask your local sheet metal shop to cut some samples for you and try them out.

Otherwise, consider precision laser cutting. Something like this **LINK**

There are probably small benchtop machines available but you'll have to do your own research on that. If your budget does not stretch that far, consider contracting the job out to somebody like the linked company but local to where you live.

.

Another option to consider would be photo-etching

I have seen some remarkably good work done in Stainless Steel ... and once received a business-card in SS, with numerous cutouts and surface detailing.

MichaelG.

.

Edit: That particular U.K. company may be long gone ... but this looks promising:

https://tmnetch.com/stainless-steel-etching/?gclid=CjwKCAjwj6SEBhAOEiwAvFRuKNPsRPSO2UiHWe47CC-WgzkpnHCefTLrn82xEkx0xDz1W3qCK9XU3xoCzrQQAvD_BwE

Edited By Michael Gilligan on 28/04/2021 09:34:57

However Stuart, who this was addressed to, was wishing that he could find an equivalent to his FET for non-ferrous materials.

I thought that the KS 230 might be useful for one of my next projects and as, with various offers I could get one for the price of a tank of diesel, I decided I would see what one could do.

The supplied wood blade happily cut a couple of plywood offcuts as expected. I then fitted my well used 28020 blade and cut an offcut of 3mm aluminium. This loaded the motor a bit, but I don't know how worn the blade is. There is a warning label about feeding too fast.

Next up was a piece of 0.5mm galvanised steel, no problem, and finally some 0.1mm stainless steel shimstock. This was already not flat but the saw didn't seem to produce any further distortion. There is a small burr, but as I said I don't know the condition of the blade.

I have ordered some new 28020 blades (this supplier did not stock them) and will wait for them before any further trials.

Roger - thanks. I knew John wanted to cut steel but the discussion seemed to have widened. I repeat the plea for someone to build what i want - but so far my cries for someone to make my dreamed of chocolate bar; non-alcoholic drink...have gone on def ears.

Looks like you may have to make your own Stuart, something like this for the Sherline, similar concept to the one for the Myford

Jason,

I actually have a Sjherline lathe - an interesting project.

Stuart

I got the new blades and tried them to make a couple of pieces I needed. One was a 25mm square from 0.5mm steel as a shim to go under the toolpost on my FD150 and the other was an 8mm wide strip of 0.3mm phosphor bronze for part of the injection pump on my twin cylinder engine.

Both cut easily and were true to better than 0.1mm. There was a small burr but both remained flat. The videos are here:

https://youtu.be/aRkol-BX0Fg

https://youtu.be/zmNd55l1LcA