Advanced Knife Machining WIP, Pointy Fighter

I was excited to see your FS thread after following this WIP closely. They're fantastic! Thanks for sharing with us.
 
I just bought one of these and reading this WIP was a pleasure. I can't wait to get one of these in my hands!

A more obscure question (maybe even a bit off topic): how do you clean the inside of the mill with all the shavings and how often do you clean it?
 
aznpos531 said:
I just bought one of these and reading this WIP was a pleasure. I can't wait to get one of these in my hands!

A more obscure question (maybe even a bit off topic): how do you clean the inside of the mill with all the shavings and how often do you clean it?
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typically, when its full, or when you need to run another material.

Many machining centers will have a chip conveyor, otherwise, usually a metal dustpan.
 
I replied in a PM, but if anyone else is interested...

The big mill has pans that can be rolled out and scooped. I run scales in production for other makers and process hundreds of pounds of handle materials at a time. Most of these chips are very fine and I have modified the machine so these fines can flow directly through the pans and into the sump, otherwise it corks up and overflows onto the shop floor. There is a divider in the sump between the dirty side and the clean side (where the sump pump lives). I use a large centrifugal pump that is rated to pump solids and flow all that crap through filter bags that catch everything over 200 microns. I decant the coolant out of this mud, dry the mud and dispose of it. I also periodically filter the sump down to 10 microns, particularly if I've been running G10 or grinding in the machine.

The coolant you choose is critical because this much "food" in your sump can go funky pretty fast. And you don't want something that will attack plastics or create issues with epoxy bonds down the road. BTW, this means no anti foam, which can be a problem with high pressure filtering. I use Master Chemical Corp Trim MicroSol 585XT, the new formulation that doesn't foam so bad. It washes off the parts clean and doesn't grow funk with all the cellulose and textiles I feed it.

When running scales I'll dump the pans a couple times a day. Other types of work can take over a week to fill the pans.

The little mill doesn't have pans. It was actually designed for two small chip conveyers out the back but I don't have that option. The ends of the enclosure open up and you can shovel chips very easily. Last week we were running an aluminum job where we'd have to stop in the middle of the day to shovel chips, over 50 pounds at a time. Other jobs it can run days or even weeks without filling up.

You don't know misery until you've been up to your shoulder in greasy rotty sump livers with lots of titanium and tool steel needle sharp fines embedded in your skin and a herniated disk in your back and mysterious slime in your hair. Sumps and wet chips are the bane of my existence and are probably half of what's wrong with my back. So I've tried to optimize my operation with pumps and skimmers and filters and high quality fluids to minimize manual sump mucking.
 
Super cool all the way through Nathan!!! :thumbup: :cool:

I also like your snazzy grinding attire... ;) An old hobo would be embarrassed to be as dirty as I am when I'm grinding. :D
 
I too would be interested in a shorter blade version of this knife.

Also, very curious to know if it is it possible to achieve the same results with stainless steel? Or is it simply too hard?
 
Buffalohump said:
I too would be interested in a shorter blade version of this knife.

Also, very curious to know if it is it possible to achieve the same results with stainless steel? Or is it simply too hard?
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I may do a 6" version of this in the future, but that isn't my next project.

I'm working on a shorter knife in a similar vein now. It is in the same family, but is thinner and is designed primarily as a cutting tool rather than a stabbing weapon.

I thought about using stainless for the next project because a lot of end users are people in uniform and, not necessarily being knife knuts like us, a lot of them prefer stainless for ease of care. I considered Elmax for the next project, but ultimately I chose CPM 3V, which came in yesterday. I'd have used this same A2 again except edge retention is a primary goal on the thinner cutter and was not the main focus on the fighter. In my opinion properly treated A2 gives up nothing to 3V in gross durability.

The fighter in this WIP is astonishingly durable, which was the goal. I haven't described my testing of this blade here because I felt it would be taken as hype, but I should do a video some time because the people I've demonstrated it to have been very surprised at what it will tolerate and not only not break, but also continue to cut. I don't think you can do that as well with any stainless because too much of the composition is composed of an element that isn't contributing to the strength of the matrix. Perhaps I'm missing something there, but years of testing and evaluating the hot stainless steels of the day as they've come out has led me to that conclusion. They're fine for most knives but they are a compromise.
 
Thanks for the detailed response. I like tool steels in large working blades (choppers) for sure, but for anything that is going to be carried a fair bit, close to the skin, I would say that stainless has a LOT of advantages. I also live in a humid climate so for me, stainless is preferable in most instances.

Of course, tool steel can also be coated to help prevent rust. This is a trade-off though, as I vastly prefer the look of steel in the raw. It is also very practical for refurbishing. Whichever way you decide to go, I will be watching with considerable interest, but from my POV a 4 - 6 incher in Elmax would be totally awesome! However, 3V is definitely something I would be interested in too, not having anything in that steel presently.

Forgot to say: thanks for the fantastic WIP, it totally blew my mind... :thumbup:

Nathan the Machinist said:
I may do a 6" version of this in the future, but that isn't my next project.

I'm working on a shorter knife in a similar vein now. It is in the same family, but is thinner and is designed primarily as a cutting tool rather than a stabbing weapon.

I thought about using stainless for the next project because a lot of end users are people in uniform and, not necessarily being knife knuts like us, a lot of them prefer stainless for ease of care. I considered Elmax for the next project, but ultimately I chose CPM 3V, which came in yesterday. I'd have used this same A2 again except edge retention is a primary goal on the thinner cutter and was not the main focus on the fighter. In my opinion properly treated A2 gives up nothing to 3V in gross durability.

The fighter in this WIP is astonishingly durable, which was the goal. I haven't described my testing of this blade here because I felt it would be taken as hype, but I should do a video some time because the people I've demonstrated it to have been very surprised at what it will tolerate and not only not break, but also continue to cut. I don't think you can do that as well with any stainless because too much of the composition is composed of an element that isn't contributing to the strength of the matrix. Perhaps I'm missing something there, but years of testing and evaluating the hot stainless steels of the day as they've come out has led me to that conclusion. They're fine for most knives but they are a compromise.
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Nathan,

I know this is an old thread, but never-the-less, very informative information...

I see that you used Aluminum for your fixture. What is the advantage over a steel plate fixture? How long would you estimate an Aluminum fixture with taped screws for hold downs will last?

Very interested in your feedback.

Dennis
 
Dennis Paish said:
Nathan,

I know this is an old thread, but never-the-less, very informative information...

I see that you used Aluminum for your fixture. What is the advantage over a steel plate fixture? How long would you estimate an Aluminum fixture with taped screws for hold downs will last?

Very interested in your feedback.

Dennis
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Dennis,

When I started out I used to use steel for fixtures, but not so much anymore. The primary advantage to steel is it doesn't dent or wear out as quickly as aluminum, but unless you're making thousands of something the difference isn't that significant. I have used aluminum fixtures in production for years without problem. The yield strength of 6061 T6 isn't that much lower than mild steel. ~ 40-45,000 PSI vs 50-60,000 PSI

Aluminum can be made into a fixture very quickly. In fact, many fixtures are made of offhand drops and are one time use fixtures. It's frequently faster to make it new than find the old fixture and zero it out.

The threads are roll form tapped which work hardens the aluminum and leaves a smooth hard durable thread that doesn't gall or wear out a quickly as you might think.
 
Nathan.
When grinding the bevels and blade edge in the vise edge up, how do you ensure your blade accuracy and repeatability from one blade to the next?

Is one vice used for side A and the other for side B?

You don't have any plans moving next door soon, do you?

Thanks,

Dennis
 
Nathan the Machinist said:
Dennis,

When I started out I used to use steel for fixtures, but not so much anymore. The primary advantage to steel is it doesn't dent or wear out as quickly as aluminum, but unless you're making thousands of something the difference isn't that significant. I have used aluminum fixtures in production for years without problem. The yield strength of 6061 T6 isn't that much lower than mild steel. ~ 40-45,000 PSI vs 50-60,000 PSI

Aluminum can be made into a fixture very quickly. In fact, many fixtures are made of offhand drops and are one time use fixtures. It's frequently faster to make it new than find the old fixture and zero it out.

The threads are roll form tapped which work hardens the aluminum and leaves a smooth hard durable thread that doesn't gall or wear out a quickly as you might think.
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I also wanted to add, aluminum fixtures can give you a bit of forgiveness if you're a bit sloppy clearing chips between cycles... Obviously better to just blow it out well, but if you miss something it will just crush into the aluminum instead of damaging the part.

On the flipside if you goof bad and leave something big, it can deform badly enough to bork your zero and your part.

I know you know this already, just thought I'd mention for academic reasons.
 
Dennis - I wish to thank you for bringing up this old thread. I'd missed it before, and it's GREAT!!!! Nathan - THANK YOU!!!! for a good informative WIP. I "play around" with CNC stuff, and my mill is truly a "mini" mill compare to your "mini" mill of 6,000 lb!!

Ken H>
 
Dennis Paish said:
Nathan.
When grinding the bevels and blade edge in the vise edge up, how do you ensure your blade accuracy and repeatability from one blade to the next?

Is one vice used for side A and the other for side B?

You don't have any plans moving next door soon, do you?

Thanks,

Dennis
Click to expand...


The machine has encoders on the lead screws so it knows where it is. The motion is accurate to .0002" and repeats to .0001" (or at least it did when new, during the paleolithic era). The vises are swept in square with dial test indicators and Kurt vises are pretty well made and designed to repeat. We take that a step further here in the shop by using a torque wrench to close the vise so it's exactly the same each time. There are works stops that control the position of the work in the vise. So, all told, the location of everything is accurately measured and repeats well from part to part. This is pretty basic and how it's done in most machine shops.


Now, all of that said, I actually do it a little differently now. In my ongoing quest for a better as-machined finish I've started angling the vises on the table so there is a similar amount of Y axis motion compared to the X to reduce artifacts from very small movements.

I've made some refinements to my process. If anyone is interested I'll put some pictures together.
 
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