[4]

Kryptonite Bushings

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

epanzella

Active User
Registered
Joined
Apr 8, 2013
Messages
1,035
A friend of mine needed to get four bushings turned down in a hurry as a huge job paving an airport was held up waiting for the work to be done. The bushings were 9 inches long, 6 1/2 inches in diameter and had a 3 inch bore. The busing are used to mount a paving hammer on a 50,000 pound excavator. One excavator broke so they had to move the hammer to another machine and they were too wide by 3/8". I don't know what the hell they were made of but any faster than 200 rpm and .025 DOC and my carbide cutters were spewing flames like the 4th of July! HSS cutters would last about 5 seconds! It took me 9 hours to do the four of them. Anybody have a clue what those kinds of bushings are made of?
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
3,694
Unobtainium. Seriously, 'tho, just about any alloy steel can be heat treated to that level. Ceramic tools will triumph over such hard stuff.
 

rwm

Active User
H-M Supporter - Gold Member ($25)
Joined
Mar 25, 2013
Messages
1,758
Kryptonium. The fissionable isotope of Kryptonite.
R
 

darkzero

Global Moderator
Staff member
H-M Supporter - Gold Member ($25)
Joined
Nov 27, 2012
Messages
3,929
I don't use mine often but these come in handy. Of course you can simply just use any file to get an idea of how hard something is & don't really need this set.


18750_700x700.jpg
 

epanzella

Active User
Registered
Joined
Apr 8, 2013
Messages
1,035
I did a file test before accepting the job. It did score but seemed it took more effort than normal. Not having a lot of experience machining hard stuff I thought it was just my imagination but I guesss it wasn't.
 

rgray

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 26, 2012
Messages
1,199
Sounds like it was a job for a grinder.
 

Flyinfool

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Apr 29, 2019
Messages
262
Where I work we use a steel material called ETD 150. This is a prehardened grade with additives to make it machinable. We use it to make gears that do not require any heat treatment or other secondary processes yet wear almost forever at 7,000 rpm.
I took some drops home for my stock.
When I went to use it to make something, it literally vaporized the edge off of HSS tools. The HSS barely even left a scratch. The only way I found to cut it on the lathe was to use carbide tools and a fairly aggressive cut. No sneaking up on a dimension. Dig in and go right for size.

Your bushings might be something similar.
 

markba633csi

Platinum
Registered
Joined
Apr 30, 2015
Messages
4,210
ETD 150 stands for "elevated temperature drawn"
It's a chrome moly steel with a fair percentage of silicon in it, no wonder it's hard to cut
 

epanzella

Active User
Registered
Joined
Apr 8, 2013
Messages
1,035
Yeah those bushing were the nastiest stuff I ever machined. Because .375" had to be removed I tried at first to use a cutoff tool and just leave a facing cut. As I only have HSS cutoff tooling it dulled before it even made a groove. Even my normal insert tooling was having trouble because the inserts weren't thick enough and the tips were breaking. Finally I used a huge weded carbide cutter that I had to machine to fit my BXA holder. The carbide was about 3/16 thick and it lasted for the whole job but I had to sharpen it 2 or 3 times per bushing.
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
3,694
Where I work we use a steel material called ETD 150. This is a prehardened grade with additives to make it machinable. We use it to make gears that do not require any heat treatment or other secondary processes yet wear almost forever at 7,000 rpm.
I took some drops home for my stock.
When I went to use it to make something, it literally vaporized the edge off of HSS tools. The HSS barely even left a scratch. The only way I found to cut it on the lathe was to use carbide tools and a fairly aggressive cut. No sneaking up on a dimension. Dig in and go right for size.

Your bushings might be something similar.
I have used ETD150 for high stress parts, the "150" stands for the tensile strength, not a lot higher than 4140 HT, which I have machined a lot of, in my opinion, neither is particularly difficult to machine, but yes, skim cuts are not recommended. It is made by LaSalle Steel, also maker of "Stressproof".
 

Holescreek

Active User
Registered
Joined
Nov 10, 2013
Messages
804
I ran into a similar situation when I was turning the ends on Rockford ball screws for my CNC mill. Carbide wasn't working so I switched to CBN/PCBN (plated cubic boron nitride) inserts. IT got through the hard stuff fairly easily and I cold save the carbide for finishing the slightly softer core material.
 
[5] [7]
Top