hard milling follow up...

Smallshop

Smallshop

KNIFE MAKER
So I did eventually manage to hard mill a blade. Was not fun. Ruined the blade due to the bow it introduced....$60 in endmills....no more hard milling...lol.

I did what I call "pattern machined". I did this to lessen the finish grinding.By leaving "valleys" there is much less material that need to be removed to get to sharp. The real solution to my problem (back pain limiting my grinding) is just to leave less stock. I left the blades .100 thick at the edge....way too much stock. I am going to change my roughing before heat treat...leave less...hate life less. Lol.

Here's what I came up with. Cuts nice...kinda interesting. Machine time is ridiculous long but grind time is amazingly short....what do I want to wear out first...a Ted or a CNC mill....

I want to try a few of these in the future...with the nice gray air cooled flat finish in the valleys and a fine grind on the high spots for contrast. I liked the result. My business partner hated it...but after 26 yrs of marriage this is not a first for her to not like one of my experiments....(let me know what you think please.)

those are Claro walnut blanks the prototypes are sitting on....!d6.jpg
 
In a former life, I worked in a machine shop and myself and a friend did a few test runs in knife blades for kicks.
Eventually we found that we could rough in the bevel with a flat mill and then go back over it with a ball mill, first with a relatively large step over ( I think .010), then again with a smaller step over (like .001 or .0005). It took a while, and it wasn’t commercially viable due to the time it took, but the blades required very little in the way of grinding and finishing to look very nice.
 
Kev said:
it wasn’t commercially viable due to the time it took
Click to expand...
Ahhh....you know then. Lol.

That being said my machines are paid for so I do not have to make a rate that covers a pricey machine tool payment....but even maintenance of these is not cheap...Nor power usage, etc, etc.

There may be a path there (no machinist pun intended) between not making myself physically miserable...and not ruining a milling machine...lol. Surfacing in 3d is tough on ballscrews and slides...not finishing knives is tough on the checking account...

regardless...I have 16 blades to finish grind that have a bit too much material on them....nose to the grindstone literally...lol....or nose to the 36 grit...
 
I did a little web surfing on this topic because of this thread. Lots of talk about ball mills and 25-40% step over. Also interesting was no flood coolant. Misting was recommended.
 
tkroenlein said:
I did a little web surfing on this topic because of this thread. Lots of talk about ball mills and 25-40% step over. Also interesting was no flood coolant. Misting was recommended.
Click to expand...
I ran dry air. what's weird is the RPMs were way up there! I was running a 1/8 ball mill at 8500 rpm...and it didn't hiccup (didn't last long either...lol...3 $20 endmills to get 'er done). one of the recommendations was as high as 12000 RPMs....my mill tops out at 10K. guys said coolant gets interrupted and will ALWAYS break the endmills.

Once again...you absolutely cannot beat abrasives for efficiency of removing metal.
 
I do know a guy who cnc mills his entire knife, bevels included, then cleans everything up on the grinder. Saves him a bunch of time, once he has it programmed in, that is.
 
That actually looks really good!! As long as you could deal with he warp!

Snecx hard mills his blades on a small tormach... Folder blades no less. Dunno how he does it but may be worth a shot reaching out to him...

Here's an example
 
Smallshop said:
I ran dry air. what's weird is the RPMs were way up there! I was running a 1/8 ball mill at 8500 rpm...and it didn't hiccup (didn't last long either...lol...3 $20 endmills to get 'er done). one of the recommendations was as high as 12000 RPMs....my mill tops out at 10K. guys said coolant gets interrupted and will ALWAYS break the endmills.

Once again...you absolutely cannot beat abrasives for efficiency of removing metal.
Click to expand...

Ted, just curious.....and keep in mind, I am not even close to ANYTHING resembling even an amateur machinist.....but I've got a good buddy that was having the same issues you are describing with wearing out tooling and long machining times. He ran into a pro machinist and he told him to slow WAY down with his spindle speed....like as slow as your mill will run.

My friend tried it and showed me, in person, I saw with my own eyes. Slowing the mill down to the lowest ridiculously slow speed, he could peel a HUGE chip that would stay dead cold with no heat colors at all on the chip, no heat to the tooling and no mist or coolant needed. It ended up being faster because of the massive chips he could shave and he hardly wore out any tooling.

It goes against every recommendation in the machining manuals, but maybe worth a try? Experiment on some scrap?

Just a suggestion.
 
This guy! The first link is tooling, second is a video with milling showing speeds in the comments.
https://www.instagram.com/p/CKCMhybD8P3/?utm_source=ig_web_copy_link
www.instagram.com

Aaron Gough on Instagram: "I still find the hard milling process really amazing... To be able to cut 62.5HRC steel like this with pretty much no heat and barely even any noise is just amazing. The spindle belt and the air blast are both making far mo

948 likes, 56 comments - aaron.gough on October 19, 2020: "I still find the hard milling process really amazing... To be able to cut 62.5HRC steel like this with pretty much no heat and barely even any noise is just amazing. The spindle belt and the air blast are both making far more noise than...
www.instagram.com www.instagram.com
 
J. Doyle said:
Ted, just curious.....and keep in mind, I am not even close to ANYTHING resembling even an amateur machinist.....but I've got a good buddy that was having the same issues you are describing with wearing out tooling and long machining times. He ran into a pro machinist and he told him to slow WAY down with his spindle speed....like as slow as your mill will run.

My friend tried it and showed me, in person, I saw with my own eyes. Slowing the mill down to the lowest ridiculously slow speed, he could peel a HUGE chip that would stay dead cold with no heat colors at all on the chip, no heat to the tooling and no mist or coolant needed. It ended up being faster because of the massive chips he could shave and he hardly wore out any tooling.

It goes against every recommendation in the machining manuals, but maybe worth a try? Experiment on some scrap?

Just a suggestion.
Click to expand...
John...it is almost a given that most guys run too fast and feed too slow...I actually calc my feeds and speeds close to the recommendations by the endmill mfg. With some tweaking....

BUT....hard milling is counterintuitive...and heads the other way...high speed and lighter feeds....And I have no experience with it.This is the first hard milling experiment I've done. totally new to me. i was amazed at how good it worked....I learned enough to realize I should do all mill work before HT.

The equipment I own was how I've supported my family for 20 years doing contract machining. I didn't buy it to make knives (except the knife grinder...my favorite shop toy!) But since I have them and some health issues to boot...I'm going to be trying to do more and more on them....I just want to make the best blades i can.

That can be a sinkhole if not careful. Folks don't often realize design time in CAD, programming in CAM, tooling design and building there-of to make blades is labor intensive. Un-like sketching a shape on steel and gettin' her done.

You guys have helped (helping) me through a rough patch more than perhaps all of you realize. So I'm rethinking my processes to do more on the mill....and I have started designing a small folder (small Opinel style)...very challenging...and it's not as soul-less as I thought it would be...lol!

great group of people here...
 
You must log in or register to reply here.
Back
Top