How to use a die?

[Danny M2ZParticipant @dannym2z]

Posted by Andrew Johnston on 18/03/2015 11:27:50:

One last snippet, Swann Morten surgical scalpel blades can be bought either in stainless steel or carbon steel. Presumably the choice is up to the preference of the individual surgeon. My last major operation didn't involve scalpels, so there would have been no point in asking the surgeon. And I'd already niggled him by asking too many technical questions about the equipment to be used which he couldn't answer!

Interestingly, the people who build really competitive indoor free-flight models (F1D) swear by carbon-steel blades for precisely cutting indoor grade balsa without crushing. I once imported a few dozen packets of 'Candidus' blades from the U.S. and had no trouble trading them at the (Oz) National Champs.

I was lucky enough to be given a brand new pre-WWII Swiss 'Allegro' razor blade sharpener. It's a very interesting tool that sharpens and hones a blade, flipping it over to do both sides. I can organise a photo if anybody is interested.

As a builder of indoor models myself, the difference between carbon-steel and stainless-steel razor blades is readily apparent when one attempts to snap a blade to a point.

My finest (sharpest) scalpels (used for eye surgery) are also made from carbon steel so maybe it all boils down to the refinement of the grain size. The surgeon who gave them to me is also now using ceramic blades and a laser for some jobs.

I suppose that it's 'horses for courses' but I reckon that carbon steel still has it's uses, even though quite specialised.

* Danny M *

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Danny M2Z on 25/03/2015 08:01:29:

I was lucky enough to be given a brand new pre-WWII Swiss 'Allegro' razor blade sharpener. It's a very interesting tool that sharpens and hones a blade, flipping it over to do both sides. I can organise a photo if anybody is interested.

.

Yes please, Danny

MichaelG.

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P.S. … To perhaps slightly confuse the Carbon vs Stainless debate; the best razor blades I know are Merkur [a subsidiary brand of Dovo, Solingen], and these are described as Platinum coated High Carbon Stainless Steel.

Edited By Michael Gilligan on 25/03/2015 08:28:36

[pgk pgkParticipant @pgkpgk17461]

I don;t think carbon steel takes a 'better' edge necessarily than other steels but it definatey holds that edge way better than the kitchen knife comparison with stainless steels used. I observe the same with modern cheap pocket knives or even a large Bowie knife I bought recently. Brand new that bowie knife could shave the hairs on my arm but just cutting a couple of bramble trails to free a sheep was enough for the edge to be dulled.

I can't recall any surgeon who used carbon steel scalpel blades since the availablity of stainless. rarely in any op is one doing enough cuttng to dull a blade and they're not going to be reused. If it did dull you'ld just bin and swap.

Scalpel blades are used in all sorts of crafts and the market is there for that too. The only other reason for wanting a sterile bade holding an edge for longer (if the carbon scalpels do?) might well be in plant research and propagation with woody stems and the like.

Indeed you can (or could) get scalpel blades in paper spaced ot foiled packs of 10+ compared to the single wraps of surgical stuff. In prehistory I;ve worked with shonky folk that would chuck a wrap of those in spirit to save a half-penny

My woodcarving chisels get honed to extremes and then hold a decent edge.. carbon steel again. And for the ultimate in sharp I once had a freezing microtome for cutting histopath sections from a CO2 frozen chunck of patient. The lab that resharpened them for me used to check the quality of the edge with high-power microscopy after lapping/honing the edge with fine paste on a rotating glass disc. they'd cut many thin slivers through frozen tissue before showing any signs of going dull – so thin were these few micron slivers that they could only be hadled with a very soft wet brush to manipulate them through to fixing them on slides.

[Danny M2ZParticipant @dannym2z]

Posted by Michael Gilligan on 25/03/2015 08:13:30:

Yes please, Danny

MichaelG.

Ok, as this is getting away from the subject matter I started a little thread of its own about my razor blade sharpener as it is a fascinating device.

* Danny M *

[Tom DaviesParticipant @tomdavies31655]

Final update: With the new die and technique I was able to thread stainless steel as well — in fact I just started the thread with the new die, and then used the old cheaper die to continue cutting it, so it looks as though the lack of expandability is the problem, rather than the sharpness of the cheaper die. Or perhaps the cheap die would cut from the beginning now that I am using a drill press for pressure and angle. Have to try that.

Tom

[pgk pgkParticipant @pgkpgk17461]

..just another nostalgic snipet into the debate:

Surgical scissors and needleholders are available with tungsten carbide slivers inserted for the cutting/holding edge and marketed with gold anodised handles. Undoubtledly they hold an edge way better than surgical stainless.. until staff drop them and kick them around the theatre. In practical terms way cheaper to buy cheapo pakistan made surgical stuff and sling it at any signs of wear beyond a simple slick-up with a stone.

Who remembers the travellig knife sharpeners with a wheel on the front of their bicycle – up on it's stand and peda away withe the stone wheel spinning between the handlebars as they sharpened?

( and apologies for hijacking the thread again)

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