[smokediver576]

Hey Folks,

Interesting Saturday night question for you. I'm trying to machine a steel part on a brush cutter head (super heavy duty weed wacker). I know that it's some sort of hardened steel (standard file will barely make a scratch in it) but not sure what values to put into HSM Works for material type. I'll be using a Lakeshore Carbide - carbide / 5 flute - 1/4" EM. Anyone got an idea on F&S that's not going to kill my brand new EM?

I'm thinking an investment in the hardness hand files is in my future.

Thanks,
Awall

[lens42]

You might consider annealing it before machining and then reharden it.


Sent from my iPhone using Tapatalk

[chuckorlando]

Any answer anyone could give you is a guess. I'll guess it's hardened 4140.

[GLCarlson]

Any answer anyone could give you is a guess. I'll guess it's hardened 4140.

Yep.

Another possibility is one of the specialty boron steels like 15B37H. These are used widely in farm implements (plows, planters, harrows, etc). Straight from the mill, they machine fine- great finish even with M2 HSS, if one gets the feeds & speeds right. Once hardened, tougher'n woodpecker lips.

Annealing and rehardening is a good approach, but without knowing what you have, getting the conditions right is unlikely - and some materials need very specific temps & times to reach optimal condition. You could wind up with a part that looks OK but won't handle the stress of operation at speed.

This is one of those situations where I'd buy a replacement rather than risk an accident.

[MetalShavings]

I recently had a similar situation although it was the metal on a certain surplus military rifle that I was looking to duplicate. I inquired in all the places I could think of that one would think you could find the answer but, for the most part most of the folks who took the time to reply were just guessing.

The metal of my rifle part never seemed to rust so I ruled out hardened 4140 steel. I had intended to make my part out of 4140 and just harden it but I had a gut feeling that wasn't the correct type of metal. Some one mention that it might be made of the same metal that hand-tools are made of; like ratchets and wrenches and such. It could very well have been the case but I had no access to that type of metal and besides, I think that hand tools are cast or forged; which appears to be the way this rifle part was made.

I just wanted to know what type of metal and hardness it was so that I could choose a metal that was close enough to that so as to give me a safe long wearing part. Since it wasn't a "Load-Bearing" part (for lack of a better description) I chose to duplicate the part in question with 304 stainless steel. It worked out perfectly for me.

Before I finished my project I had scoured the internet in search of the same type of info you're looking for. I even tried tracking down the manufacturer to ask their customer service for those specs. The rifle in question was a WWII era rifle so I didn't have much luck there but, that's not to say that you can't acquire the information you're looking for by asking the manufacturer; that's if you haven't already done so.

MetalShavings

[pickled]

Unless it's a real high end part it won't be made from anything too crazy. I ran into some s7 tool steel a few weeks ago in a chipper blade and it was a riot to work with...tougher than snot! Figure that if you treat this mystery material like 0-1 or S7 at 220-225 BHN you won't be "surprised" when you hit a hard spot. The next safest setting would be to run it like 304L as MetalShavings did.

[pickled]

Yeah and be sure to pick up a set of files too. They come in handy for stuff like this and you can usually find them on sale at Grizzly.

[kstrauss]

I don't see hardness files on the Grizzly website. Do you have a part number?

[pickled]

I bought a second set from them just last year I believe. This is the exact same set I have that's listed on this Ebay (NOT MY LISTING!).
Grizzly T10277 Rockwell Hardness HRC Tester File Set Knives Axes | eBay

[kstrauss]

Thanks! Unfortunately it appears to be a discontinued item on the Grizzly website. The files from Tsubosan are on eBay for almost the same price.

[pickled]

It is hard to go wrong with a real Tsubosan file. They are typically well made by people that also know how to use them. The Grizzly files are fine and I verified my 65, 60 and 50 files against appropriate standards so they are as accurate as I needed them to be to tell whether or not I'm dealing with something that bites back :-). The good old ball bearing drop and rebound test works pretty well too as long as you have a part/stock geometry that is conducive to that type of testing. Anything is better for your tooling than using a poorly calibrated eyeball 9000 system to guestimate what is in your hands....

[smokediver576]

Well, this is the path I took. I think I slowed it down 50% due to testing it in aluminum first and being a little bit scared of how fast it was going. I still need to work on learning more on feeds and speeds v/s wild ass guessing.

In HSM Advisor I used H13 Tool Steel (45-50RC). LakeShoreCarbide - cabide - 5 flute - 1/4" end mill

RPM: 3,400
SFM: 222
Cut Feed: 20 IPM
DOC: .03
Climb milling - 2D Adaptive out of Fusion360

Results were very good but still not sure if I had the F/S set right. When I go back into HSM Advisor I get a different recipe than I had the other night. I think I messed something up.

Modification to adapter allows you to use a standard 7 1/4" skill saw blade (bulk blade pack = $2 each on Amazon). Yes, I know this may cause some to freak out and start flaming me for the dangers of using carbide tips. However, this is for use in remote areas with crews using protective gear. We've been using this method for about 5 years with no issues. Tooth flicks off - no big deal. We rarely run the saws at full RPM anyway. Pictures below.

[pickled]

Makes sense to me. I've had carbide teeth fly off from blades on my table saw while cutting laminates and it stings a bit, but I assume the risk while keeping my mouth closed and wearing eye protection. To be honest the typical OEM brush cutter blades are made SOOOO cheaply these days using extremely poor material choices that dull quickly. It's as if there was no optimization performed to balance toughness with edge holding. They just stamp them to a price point and move on. Glad that you were able to knock it out. Doug P.

[smokediver576]

Makes sense to me. I've had carbide teeth fly off from blades on my table saw while cutting laminates and it stings a bit, but I assume the risk while keeping my mouth closed and wearing eye protection. To be honest the typical OEM brush cutter blades are made SOOOO cheaply these days using extremely poor material choices that dull quickly. It's as if there was no optimization performed to balance toughness with edge holding. They just stamp them to a price point and move on. Glad that you were able to knock it out. Doug P.

Yep, and at $40 to $50 buck a blade it's pretty expensive!