Cardboard cutter

N

Nico Cappelli

Joined
Apr 20, 2019
Messages
27
Hi guys!

In The place were i work we have to cut a huge amount of cardboard (fridge and refrigerator boxes) so i have made 2 D2 fixed blade box cutters.

utility knives are the Best Way to do this job, but i like to understand how much steels and geometry matters. These 62/63 Hrc d2 box cutters stay reasonably Sharp longer than regular(2weeks Vs 1), but edge tend to chip when meets clips... Unfortunatly sometimes happens.

So i want adjust geometry(d2 cutters geometry in pictures), steel (choosing from d6/m2/cpm-10v in annealed conditons because i have some scrap of these) and hardness, and make 2 new cutters.

I can give some additional information sayng this blades need to cut fast and bevel becomes very Hot (over water boilng Point), and the sharpening metod is only a fews steps on 600 Grit diamond disk.
Thanks
IMG-20190822-211442.jpg
[/url][/IMG]
IMG-20190822-211442.jpg
IMG-20190822-211442.jpg
 
10V would give an improvement in both toughness and edge retention. You could match or exceed edge retention along with a much bigger boost in toughness by using Vanadis 4 Extra, 4V, or PM CruWear.
 
Stacy E. Apelt - Bladesmith said:
I would take the edge down to .010" (.254mm) before sharpening.
Click to expand...
Ok i will do this! But you think the edge chipping resistance don't decrease?

Larrin said:
10V would give an improvement in both toughness and edge retention. You could match or exceed edge retention along with a much bigger boost in toughness by using Vanadis 4 Extra, 4V, or PM CruWear.
Click to expand...
I can use 10v...but i need to HT it properly. what is the optimal hardness for this work?
 
With an edge thickness of .010" ( .254mm) the edge wll still be very strong. Even half that will be OK unless you will be cutting into staples or wood.

I would make the blades RC60.

How do you plan on doing the HT? Do you have liquid nitrogen available?
 
Stacy E. Apelt - Bladesmith said:
With an edge thickness of .010" ( .254mm) the edge wll still be very strong. Even half that will be OK unless you will be cutting into staples or wood.

I would make the blades RC60.

How do you plan on doing the HT? Do you have liquid nitrogen available?
Click to expand...

Thanks for the reply. obviously I listen to your advice and once decided steel and hardness I will plan the heat treatment. I can have access to liquid nitrogen if necessary. I also have a small self-built freezer cell with freezer compressors, capable of reaching - 80 ° (-112F). But I always rely on the advice I find in the datasheet, crucible in the case of cpm-10v steel, it does not refer to the need for a sub cooling down. I believe because the high tempering temperatures already reduce residual austenite to a minimum. Correct me if I'm wrong
 
Cryo isn't used in industrial use because they don't care about RA. In knives we want the lowest RA possible. Cryo lowers that and created hard eta carbides.

You are correct, the high-V steels often use the upper tempering range.

Austenitize at 2050F, cool to room temp, place in LN for 6 hours, temper twice at 1000-1025F and you will be at Rc60-61. The cryo will increase edge life.
 
Stacy E. Apelt - Bladesmith said:
Cryo isn't used in industrial use because they don't care about RA. In knives we want the lowest RA possible. Cryo lowers that and created hard eta carbides.

You are correct, the high-V steels often use the upper tempering range.

Austenitize at 2050F, cool to room temp, place in LN for 6 hours, temper twice at 1000-1025F and you will be at Rc60-61. The cryo will increase edge life.
Click to expand...
Ok Perfect i can do this ht! You think is better protecting blade also during tempring? Oil quench or plate quench?.... Have scrap only for do one box cutter in 10v.... For The other one, i choose d6 or m2? Or another in d2 with adjusted geometry and hardness?
 
Oil quench. If you have quench plates, put the blade in them after the oil.

If tempering at 1000F, it isn't necessary to protect the blade.
 
Last edited:
CPM10V is my daily carry and I use the crap out of it. For me it’s a really hard steel to beat. Yeah it’s not as tough as other steels but I honestly sharpen it about twice a year. I use it for cutting cardboard for packaging and all kinds of other stuff. It’s a great steel. But I went with spiderco folder in 10v. But honestly if I was cutting boxes all day long I would just get a box knife and a ton of blades. Easy and fast to swap out. Also less work liability problems if so thing happens.
 
JTknives said:
But honestly if I was cutting boxes all day long I would just get a box knife and a ton of blades. Easy and fast to swap out. Also less work liability problems if so thing happens.
Click to expand...
Yes, this is the first thing i said! But if i can create a blade that stay reasonably Sharp for a month or more isnt bad!
 
A blade edge will wear depending on the steel it is made from, HT and geometry, and what it is cutting. It isn't reasonable to expect it to last greatly longer than a commercial knife just because it is a handmade knife.
 
Stacy E. Apelt - Bladesmith said:
A blade edge will wear depending on the steel it is made from, HT and geometry, and what it is cutting. It isn't reasonable to expect it to last greatly longer than a commercial knife just because it is a handmade knife.
Click to expand...
Yes of course. Standard utiliy blade are made of carbon Steel(1080/sk5) hardened to 55/58hrc(approx because My traditional durometer have some issue with low thickness) i tryed also ceramic blades but with very bad results.
 
IMG-20190831-WA0038.jpg

heat treat done! After quench hardness was 64/65 Hrc but after cryo, incrise to 67/68! really impressive

By the Way, after 2 temper at 1000F 540°c now it is 61/62.... I can Keep this hardness or better do a third temper at a bit higher temperature to reduce to 60?


XXXmqtmx
 
Not an answer to your question, but I just noticed you are from Forli. My grandparents are from Sassoferrato (just north of Fabriano).
Buona giornata!
 
I would be a little worried with the accuracy of you hardness tester. Those numbers are a bit high for just about any alloy. If I had to guess I would say your sitting around 5hrc lower then what your tester is showing. Even in the best situations with testers and standard test blocks your going to be sitting around +-1rc. We use tighter tolerance calibration blocks that are +-.5rc but thy are quite pricy. We just had to buy another one as we had completely used up the last one. We surface ground it down to a fresh surface but in all honesty it’s now at best a ballpark test block. It seams to measure the same as it did but nothing we would calibrate with.

You can get higher accuracy in hardness testing but generally requires a different tester and a much more strict surface condition. I think the industry’s standard is a tukon microhardness tester. It uses a 4 sided pointed diamond. You then use a microscope and measure the dimensions of the impression. This is way overkill for knives and would take way to long. Plus in all honesty you will not notice much if any difference between say a 60 and 61rc blade. But you sure as hell will if a blade is 55rc and your thinking it’s 60rc. So I circle back around to saying you should take a look at your tester and calibrate it have it calibrated.
 
Nico Cappelli said:
Yes of course. Standard utiliy blade are made of carbon Steel(1080/sk5) hardened to 55/58hrc(approx because My traditional durometer have some issue with low thickness) i tryed also ceramic blades but with very bad results.
Click to expand...
Let us see the final knife you come up with would be really cool,hey Stacey /Larrin thanks for your responses.I recently have seen some utility blades with carbide(Home depot) ,I would think these would last pretty long also but the 10v idea much more interessting
 
Hardness is not everything when it comes to edge holding. People have tried to make tungsten carbide blades and does not work out so well. It’s so brittle that you can’t really put an appropriate edge bevel and angle and n it. Think of the ceramic kitchen knives, yeah thy are great till there not then thy suck way more.
 
Once upon a time I had a cardboard deluge to deal with after a move.

I started out with a utility/razor knife.

THAT FRICKING SUCT!

Then I tried a longer knife which worked a lot better but still required considerable PHYSICAL efforts.

My wife happened upon me in the midst of my unceasing labors, took one look, walked off and came back with a cheap, beat to crap woodsaw (crosscut as if that factoid is important) from my discard box in the workshop. I've been using it ever since and it goes thru cardboard like a cat goes thru fancy feast. I've never cut myself with that saw nor has it been maintained in any way. Been going for years.

Just sayin......

Corey
 
61-62 Rc is a good target for 10V.

67-68 Rc as-quenched after cryo is not crazy for 10V. I've seen 69 Rc.
 
Last edited:
You must log in or register to reply here.
Back
Top