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Which type/brand of razor blades stay sharp longest? (cutting card/greyboard)

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John Smith 4727/04/2021 13:17:25
257 forum posts
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Hello

Which type/brand of rasor blades stay sharpe longest?

Background
I am cutting cardboard and greyboard. Currently I am using Swan-Morton 10A non-sterile Surgical Blades.


But I am getting through a lot of razor blades and it's extremely frustrating when I make a hash out of something just because my blades have become bluntened. Also the old blades need to be safely disposed of etc ==> slows me up!

Surely if blades can cut steel continuously for (er hours?) they must exist to cut cardboard for few minutes! What are the best blades?

J

JasonB27/04/2021 13:25:42
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Having been involved in the Graphic design and Art business for a number of years the weapon of choice was always a 10A Scalpel, most trade customers would by them by the box.

What surface are you cutting on?

Edited By JasonB on 27/04/2021 13:26:22

Circlip27/04/2021 13:27:10
1354 forum posts

If you mean razor blades, Blue Gillette carbon steel ones. If scalpel blades, Swan Morton carbon steel blades, NOT Stainless. Carbons can be re honed easily.

Regards Ian.

SillyOldDuffer27/04/2021 13:56:19
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Agree with Jason. Truth is razor sharp edges are delicate and don't stay sharp for long. Many ordinary materials like paper and cardboard are distinctly abrasive. I've never found better than Swann-Morton.

I use more Stanley-knife blades than scalpel sized, but same problem. For many purposes it's important to change blade frequently. In between scalpel and carpet-knife size, I use the type of knife where a sharp strip is notched so the end can be renewed by snapping the worn section off. They aren't suitable for everything.

Stainless blades don't resharpen easily, at least not back to 'as new' condition in my clumsy paws. They're disposable, buy in bulk and dispose carefully.

Carbon-steel blades can be resharpened but it's a fair amount of fuss. My microtome has a Carbon steel blade that has to resharpened often to keep it tip-top, it's a time-waster. A carbon-steel cut-throat razor is also handy for microscopy: it takes even longer to keep in good condition, partly because I don't have a suitable strop.

Easier to accept blades don't last and change them at the first sign of trouble.

Dave

Douglas Johnston27/04/2021 14:07:20
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760 forum posts
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I would have thought a light treatment with a very fine diamond hone would get the edge/point back to good sharpness.

Doug

Zan27/04/2021 14:09:21
282 forum posts
19 photos

Use a diamond hone to resharpen

They last for ever. I did this at school teaching A level graphic design. Saved me hundreds of blades a year. Even better  is at home where an Arkansas whet stone or leather workers type of lap ( leather strip charged with 4000 grit) to polish. Had one blade in for years

Ps do you use a self healing cutting mat?

edit...typo

 

 

Edited By Zan on 27/04/2021 14:10:05

Edited By Zan on 27/04/2021 14:10:53

Dave Halford27/04/2021 14:19:44
1757 forum posts
19 photos

A workmate used a small polishing mop in an electric drill to resharpen scalpel blades

norman valentine27/04/2021 14:54:12
280 forum posts
40 photos

If you just strop them on a piece of card you will get a little more life out of them.

I assume you are using a proper cutting mat?

Edited By norman valentine on 27/04/2021 14:55:14

V8Eng27/04/2021 16:13:30
1634 forum posts
32 photos

I prefer a rotary cutter, less chance of self inflicted injury and the blades seem to last well.

Of course that all depends on whether or not it can work in your particular application (I am not familiar with greyboard).

Edited By V8Eng on 27/04/2021 16:22:33

John Smith 4727/04/2021 17:44:48
257 forum posts
11 photos

I don't know about 'proper' but I am using a cheap "Self Healing Cutting Mat A3" that I got from HobbyCraft

https://www.hobbycraft.co.uk/self-healing-cutting-mat-a3/572007-1000?_br_psugg_q=cutting+mats

Interesting idea to sharpen the surgical blades... but either way I am disappointed to learn that there don't seem to be any harder material available. Can't one buy them made out of anything more durable?
e.g. Boron Nitride, Tungsten Carbide, Cermet... or even micro-diamonds for G*d's sakes

OK a bit of further googling has revealed
"Carbide Stanley Blades"


e.g. https://www.axminstertools.com/stanley-carbide-knife-blades-pack-of-10-136403

Have any of you tried them?


@Zan - But if I'm going to stop and sharpen them what would I need to buy? What exactly do you mean by a "very fine diamond hone"? How do you use them - is it time consuming? How long do they last?

@V8Eng - What exactly do you mean by "a rotary cutter"? What do they cost/where do you get them from (in UK)?


Michael Gilligan27/04/2021 17:56:56
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18992 forum posts
945 photos

I do have one micro-surgical scalpel with a ruby blade

... but I doubt if I could find another at an affordable price.

... and I wouldn’t waste it on cardboard.

MichaelG.

.

P.S. __ when you discover what a Rotary Cutter is :

Olfa blades are by far the best we have ever used.

These people provide excellent service: https://olfacutters.co.uk/

Edited By Michael Gilligan on 27/04/2021 17:59:15

old mart27/04/2021 18:05:53
3349 forum posts
208 photos

I would prefer the Stanley type over the scalpel, they are safer to use on cardboard. Less likely to suddenly fracture and fire off a sharp projectile.

I buy Irwin bimettalic blades if I can.

V8Eng27/04/2021 18:19:57
1634 forum posts
32 photos

Rotary cutters.

RS

CPC

I have used the RS one very successfully on patterned wallpaper and fairly thick cardboard.

The CPC one has a smaller wheel.

Other suppliers such as stationary outlets probably stock them as well.

 

Edited By V8Eng on 27/04/2021 18:21:56

Rod Renshaw27/04/2021 18:47:40
336 forum posts
2 photos

I can understand the OP's frustration - why can a tool last for ages when cutting steel but not when cutting card, which is so much softer?

The difference is in the cutting edge which needs to be much thinner, ie have a smaller included angle, so that it will cut a soft material cleanly rather than just push it aside or tear it. A lathe tool might have an edge with an included angle of 80 - 90 degrees, so there is plenty of metal around and behind the edge to provide support.

A knife or scalpal blade might have an included angle more like 12 -15 degrees, so the actual edge, the only bit that actually cuts, is very thin indeed and gets little support from the bulk of the tool. The Japanese say that a sword edge is sharpened until it is "invisible", that is, until it is so thin it no longer relects light. I am not sure if this can be literally true but it does give the idea of a thin edge.

Also, after any use the edge will start to wear, and the effect will be more serious in the thin blade because there is so little material in the actual edge and it is soon worn away. With a metal cutting tool a little wear may not be so noticeable, the motor provides power and the steel being cut resists tearing until the situation gets worse.

Woodworkers have this effect too. A chisel is normally sharpened with an included angle of 25-30 degrees. But a worker in oak or an exotic hardwood may need to use 35 degrees. Those working in the softer woods can use as little as 17 degrees for a handheld chisel used with care (and not with a mallet), and may need to use this extreme angle to get clean cuts.

It seems pardoxical, but the softer the material being cut the sharper the edge needed. As has been said above card is abrasive and will wear knife edges quite quickly compared with, for example, knife edges used on meat or many vegetables.

Rod

Grindstone Cowboy27/04/2021 18:54:24
714 forum posts
58 photos

Slightly off-topic, but I was cutting some industrial flooring vinyl the other day which had tiny particles of grit embedded in the top surface to make it non-slip. Could do about two or three feet of cut with a fresh Stanly knife blade before having to re-sharpen it. The professionals must have a better way?

Rob

Bill Phinn27/04/2021 19:42:14
576 forum posts
86 photos

Yes, Swann Morton 10A for card and paper.

I don't use much greyboard these days, but do use the much denser [and archival] millboard.

Since I can't realistically cut either type of board by hand, I use the Victorian boardcutter in the photo for doing so.

Its blade cuts with a shearing action, so thankfully it has a very different profile from the crazily sharp edge a guillotine blade has to have.

img_0535.jpg

John Smith 4727/04/2021 20:16:32
257 forum posts
11 photos

Ah I've seen "rotary cutters" but never really understood them! What are the pros & cons of rotary cutters?

Background
I am trying to cut extremely strong greyboard. I have Logan mount board cutter (model: 350-1 Compact Elite) and I am struggling to cut accurate straight lines.



It comes with one of these things "Straight Cutter Elite" that hooks onto the cutting edge,

But it fails to cut straight edges, even with a nice new blade installed. (I may be doing something incorrectly but It seems to veer off by about 1 to 1.5 mm!) So I have had to resort to multiple passes using scalpel blade but the scalpel blade is rather thing and bendable - so that isn't as good as it might be. With patience it's broadly fine but it also seems to become blunt with just a handful of cuts. (And yes, I am being careful to not hit the face of the blade against the cutting edge, before anyone asks!)

If rotary cutters work well, then I wonder why Logan Graphics don't seem to supply them?


John Smith 4727/04/2021 20:23:06
257 forum posts
11 photos

@Bill Phinn - out of interest when you cut thin strips of board, does the Victorian Board Cutter (/guillotine?) put a curl into the board that has been cut off to do they recover and lie completely flat after having?

Also where do you get your "mill board" from?

JasonB27/04/2021 20:31:22
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I must have cut 1000s of mounts with a Logan cutter and never had problems, similar design to yours but all metal and fixed not pivoting blade. Most customers with problems did not put enough pressure onto the guide rail and the force of the cutter being pulled through the board then drags it away from the fence.

Bill Phinn27/04/2021 23:03:29
576 forum posts
86 photos
Posted by John Smith 47 on 27/04/2021 20:23:06:

@Bill Phinn - out of interest when you cut thin strips of board, does the Victorian Board Cutter (/guillotine?) put a curl into the board that has been cut off to do they recover and lie completely flat after having?

Also where do you get your "mill board" from?

I don't often need to cut narrow/thin strips, but if I do then yes, I would expect a certain amount of curling of the strip, even if the grain direction of the board is parallel, as it ordinarily should be, with the long edge of the piece being cut; if the grain direction is at 90 degrees to the cut, the curling will be much more pronounced.

The curling can, however, be reversed quite effectively if the strip is very lightly damped and placed under a weight between pressing boards until it's completely dry.

One of the best features of the boardcutter, apart from the fact that it will cut through the full width of a 3mm sheet of millboard in one pass, is the foot operated clamp, which guarantees the board will not move while the considerable cutting force of the blade is doing its work.

I buy my millboard [branded Gemini] from John Purcell Paper.

Besides the boardcutter, I also have a fairly old Avery P640 rotary trimmer, which is very useful for paper and card as long as you don't try to cut through too much material at once. If you do, you will not only get a rough finish, but the material will tend to want to move during the cut.

If I was buying one of these kinds of table-top rotary cutters again, I'd probably opt for one of the Rotatrim Professional series of rotary cutters, which I've tried and which seem to be more robust than my Avery.

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