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View Full Version : Suggestions for making stainless alloy stock thinner?



Tait
10-29-2010, 08:43 AM
I am working to make some knives out of a high-chromium alloy stainless called AEB-L.

It is readily orderable as thin as 0.106 inches; however, it reads out as about 0.112. For a my current design, the thickest I'll need is only 0.080 or so, and probably no more than 1.4" wide.

I have tried to search on the subject, but it is not obvious how to make thin out thicker stock. I don't have a surface grinder, nor do I have a lot of space for one. I can grind it down on a belt sander with a flat plate, and it's a test of skill and patience.

I also have a Wiess mill-drill (pic here) (http://www.weiss.com.cn/products/wmd30v.php).

Would a fly cutter or a face mill be reasonably accurate and useful for taking (annealed) steel from 0.112 down to .080? Which would be better?

Are there other good options?

Tait

p.s. If this has been discussed previously, a tip on how to search better, or perhaps a link would be much appreciated.

rkepler
10-29-2010, 09:52 AM
The knifemakers that I know usually use a 2" belt grinder mounted to a surface grinder table. Most use a magnetic chuck, if the material is non-magnetic they just surround the part with thinner magnetic stock. If you don't have many you might get somewhat close with a surface grinder using a wider-than-normal grinding wheel.

lazlo
10-29-2010, 10:20 AM
Would a fly cutter or a face mill be reasonably accurate and useful for taking (annealed) steel from 0.112 down to .080?

How would you hold it? Mounting thin stock on a mill table is tough.

AEB-L is very close to 440-B. Good corrosion resistance, decent, but not great, edge retention. If you're trying minimize grinding time, I'd look for 440-C (which has more carbon) flat-ground stock in the correct thickness.

http://www.diehlsteel.com/flatground.aspx

Tait
10-29-2010, 11:30 AM
Lazlo wrote:
AEB-L is very close to 440-B. Good corrosion resistance, decent, but not great, edge retention.

Lazlo,

Thank you for the thoughts. I had similar thoughts.

I have played with 440C and didn't like it much; I found even it it to have limited ability to maintain a very sharp edge, and did not like the gumminess when grinding it. AEB-L is the next one on the list (hopefully will be a little less gummy). I've never used AEB-L personally. Here's why I'm trying it:

In researching (e.g. googling) AEB-L, I ran across Devin Thomas's FAQ about AEB-L here (http://www.irculture.com/dtknives/faq.cfm), which states that, in practice, AEB-L IS NOT a lot like 440B. The argument that it is similar is based on carbon content; however, AEB-L has less chromium than 440B which supposedly leaves more carbon content for carbide formation. Also, AEB-L reportedly has carbides in range of 1 micron, while the pictures I have seen of 440C show carbides of much bigger than 30 microns, which in theory adversely affect holding of a very sharp edge.

I called and discussed 440C versus AEB-L with Mr. Thomas directly (very nice guy by the way - and his knives are beautiful). I also verified the information from him with a knifemaker who is a university trained metallurgist, and they both confirmed the above information.

So, that's why I'm trying AEB-L.

Tait
10-29-2010, 11:37 AM
Lazlo wrote
How would you hold it? Mounting thin stock on a mill table is tough.

I'm not sure.

Here are two ideas, neither of which seem especially clever or easy:

One possibility would be to cut the stock maybe 2 inches longer than needed for the part, drill holes in the end and bolt the whole thing to a piece of aluminum, mill the middle portion to desired thickness, then cut off the (still thick) ends.

I have heard of others super-gluing the stock to a block which is mounted to the vice or table. The strength of this to resist breaking free could be improved with a very shallow trough milled into the block (just wider than the piece) to keep the piece from turning.

I'm sure there are other more clever ideas out there.

Tait
10-29-2010, 12:08 PM
The knifemakers that I know usually use a 2" belt grinder mounted to a surface grinder table. Most use a magnetic chuck, if the material is non-magnetic they just surround the part with thinner magnetic stock. If you don't have many you might get somewhat close with a surface grinder using a wider-than-normal grinding wheel.

I'd love to rig up a surface grinder setup to my existing 2" belt grinder - and there are some great pictures out there, (first hit on Indian George Surface Grinder (http://www.google.com/images?q=indian+george+surface+grinder) for example).

I have a total of 14 linear feet for my entire workshop, which already includes a 2x72 surface grinder, a mill/drill, a kiln, an arbor press, a hardness tester, a vise, and a granite block for flat hand-sanding. So, with toolbox, I have maybe 10 square feet for remaining tool AND work space. To make the space work, I'm making some compromises like drilling with the mill/drill rather than dedicating space for a drill press. If I get a bandsaw, it will probably be a portable with stand just to save space.

I just priced sending them out for grinding. Rough quote was $100 to $150. Not interested.

So, unfortunately, I don't really have space for a separate belt sander for thickness grinding.

I guess I'll look into trying to rig up something for my existing sander...

Evan
10-29-2010, 12:46 PM
This sounds like a project that first leads to another project. In this case a project that both solves the problem and fits your available space very well. What you need is a Jeweller's Mill.

It is something that would complement knife making very well, especially since you have a kiln that can be used to anneal stock.

Here is one at a reasonable price.

http://www.jewelerstoystore.com/Econo_Rolling_Mill_p/r64.htm

How to use, in brief:

http://www.essortment.com/hobbies/howandwhento_said.htm

Tait
10-29-2010, 01:18 PM
I hope you are joking!

I was looking at a much bigger rolling mill a few months ago and the guy almost had a heart attack when I asked whether it would work for steel - NO, NO, NO - it's only for soft metals like annealed gold or silver. Even brass could damage the rollers. So I dismissed these as a possibility...

Evan
10-29-2010, 01:33 PM
Depends on the rollers. That cheap one may not be sufficient but the more expensive ones are. However, they climb in price very dramatically. It is all about the rollers though and they aren't hard to make. With a kiln you can heat treat and case harden so you are set up to make rollers that will take the pressure. All you need is a short length of O6 tool steel in the right diameter. It machines like aluminum with a beautiful finish and is used to make punches and dies. The machinability rating is 120% of O1 and will make rolls that will flatten anything that is annealed.

Tait
10-29-2010, 01:39 PM
Got it. Thanks!

That sounds like a great solution - and less wasteful of steel than grinding it off. I will look into how to make it work.

Maybe I should just build a small forge and hammer it to approximate thickness.

Tait

lazlo
10-29-2010, 03:44 PM
I called and discussed 440C versus AEB-L with Mr. Thomas directly (very nice guy by the way - and his knives are beautiful). I also verified the information from him with a knifemaker who is a university trained metallurgist, and they both confirmed the above information.

Are you talking about John Verhoeven and Roman Landes? They wrote an academic paper about knife sharpening experiments that raved about AEB-L. Roman's son Larrin posts about it on all the knife forums like he's the Uddeholm marketing director :)

But other than Devon, I don't think I've ever seen a custom blade in AEB-L -- you mostly see it in Damascus. I noticed that AlphaKnife supply carries it.

The "Like 440B" comment come from the late, great Bob Engnanth:

http://www.worldknives.com/info/types-of-steel-20.html


AEBL seems to be about 440B. Extremely easy to grind, in fact, I think I may have set a world record with it a few years back, over a hundred blades from bar stock to 220 grit within eight hours. Heat treat like 440C. Edge holding is best when heat treating includes a freeze cycle. Very easy to polish and buff. Very nice choice for miniatures, kitchen knives, etc. AEBL has several quirky habits in grinding that make it difficult to use on thicker or larger knives. Makes nice kitchen knives. "Hoss" uses this in his beautiful stainless Damascus and reports that it holds up very well.

Let us know how it turns out!


Maybe I should just build a small forge and hammer it to approximate thickness.

You're going to have a hard time keeping it flat if you're trying to reduce it by 30 thou by forging, especially if you don't have a power hammer. You might ask a local machine shop if they'd grind it for you on a surface grinder.

Tait
10-29-2010, 05:01 PM
Thanks for the reply.

Yes, I was talking with Roman! (Not hard to guess, I suspect...). Unlike anyone else I know, he's actually tried using AEB-L, and tells me that it gets critically sharp.

I do know the Engnanth quote - that's a great article, which I've read many times. (Incidentally, I've seen some stuff ground by him. They're so well done it's almost discouraging). Since I am planning to make a few paring knives, and do intend on a freeze cycle, I think I'm within his recommended parameters.

Since the bid for machine grinding was like $100-150 for four pieces, for now, I think I'll probably just put a 60 grit belt on the grinder and manually grind them down. Shouldn't take too long.

I'll probable have to think through this again when I start working on folders (my goal in knifemaking...).

Thanks again - I really appreciate the input, (even when it's stuff I think I understand already, it's nice to get confirmation that I'm on track).

Tait

beanbag
10-29-2010, 05:12 PM
Even though I haven't done it myself, I imagine facing could work if you held down the sheet flat with some kind of temporary glue. I think some possibilities are superglue, loctite, and various metals that you can melt on and off. Don't try using double stick tape, as that's too flexy. You might need to sand to improve adhesion, and be forewarned that machining could induce stresses.