Carbide Grades

[rake60]

A brazed tool bit or an index-able inset, the grade of carbide should
match the application.

Grade C2 is a hard carbide. It works very well when cutting cast
iron or any other non-ferrous metals. Use it on steel and it will most
likely chip the end off the tool.

Grade C6 is a softer but tougher carbide. It works very well on
steel, but lacks the abrasion resistance required for cutting cast iron or
the other non-ferrous metals. If you use a C6 on non-ferrous material
the cutting edge will wear away quickly.

Not to say you CAN'T use a C6 to cut cast iron. Of course you can!
But using the right grade for the material will make your tools or inserts
cut better and last longer.

General rule of thumb, Harder = Wear Resistance
Softer = Tougher

 

[Hilmar]

Rake,
how do you brace a carbide tool bitt and what do you use for bracing
Silver solder or what?
Hilmar

 

[Tin Falcon]

Hilmar :
I believe what Rick is talking about is comercialy produced bits. Most home guys do not braze on there own carbide tips. Yes it can be done and is within the capabilities of the hsm.
IMHO HHS is better for the home shop but that can be another thread. Brazing is similar to soldering but at a higher temp. brass is uses instead of solder . yes silver solder would also work.
Tin

 

[rake60]

I have tried brazing carbide to a holder myself. It didn't work very long.
Enco sells both import and USA made bits: Enco Tool Bits
They are very inexpensive and can be ground to just about any special
shape you need. Just keep them from getting too hot when grinding or
the heat will cause the brazing metal to melt, and the carbide loosens.

 

[Bogstandard]

The most used tool in my shop is called here in the UK a profile tool.
Seen here on ebay -
http://cgi.ebay.co.uk/12MM-LATHE-IN...Z012QQcategoryZ112399QQtcZphotoQQcmdZViewItem
In fact this shop is where I buy most of my gear from.
It gives great finishes on most metals because of the round profile. Also when an area wears, just rotate it to a new area on the tip. My last set of ten tips lasted about four years, and as I said it is used every day.

John

 

[rake60]

My turning tools were also bought from an eBay store.
They are standard triangle carbide inserts.

The whole set of tools was about $15
The replacement inserts, I prefer Kennametal TCMT 21.51, run about $4
each. I've made a lot of chips with those inexpensive little tools.
The experts will tell you they are cheap imports from India and nothing
but junk. Everyone is entitled to their opinion. My opinion is
THEY WORK JUST FINE!

Now I DO need to buy a proper parting tool. My hand ground HSS tool
works well, but every time I chip, or burn it up, I go into a

mode that just isn't healthy at my age. :?

 

[lugnut]

John, The tool you talk about (profile tool) sounds very interesting, but I can't find a thing about it here in the US or at least as far as I’ve looked. Would there be another term or name I might search for? I guess if I could find a round carbide insert, I could build the rest?????
Mel

 

[Bogstandard]

Mel,
I only know it as a profile tool. The only problem of making the holder as I see it is that the tip has tapered sides for support, so maybe a tapered D bit could get the right recess. I have seen an article very recently about someone making this type of tool just by using bits of silver steel with a hole in the middle for mounting the tip. He just turned a slight taper on the end of the rod and parted them off. An ideal situation because you can make the tip whatever diameter you want, great for all those nice rounded corners on turned bar.

Rick,
No probs with el cheapo tooling, we are not into high production areas in our hobby so go with what works. With reference to your parting problem, I use one that has a long replaceable blade that I just sharpen every now and then. I do most of my parting under power as I find that by doing it by hand causes polished spots when you slow down the infeed and breaks the tip off when when it grabs again. If I part off by hand I am very aggresive with it, fairly high speed and go for it, but I have the belts adjusted on my lathe so that they slip if it really digs in. Large diameter cast iron is one of the easiest, just go in as far as your tool allows you to and just drop the billet on the floor, or tap it with a sledge and it should break away cleanly. I can't use a hacksaw too well because of my bad right arm so I tend to part everything off in the lathe, even 1/8" rod.

John

 

[rake60]

I really shouldn't complain about my home made parting tool.
I ground it over two years ago and it's been used and abused ever since.

I ground it from a piece of 3/8" square cobalt HSS tool steel hoping it
would hold up well. It has! It will part a thin disk off a piece of 1" dia.
1018 cold roll steel easily, but I'd still like to try a carbide insert parting
tool such as the one I use every day at work. It's made by Iscar.

The blade can moved in for more rigidity for shallow grooves or extended
out for parting off larger diameter stock. Problem is $$$$$ :shock:

 

[Bogstandard]

Hi Rick,
Here are my two parting tools that I use all the time. For exact width grooving tools I do as you do and grind them up out of HSS.

The front one uses flat blades that you just 'touch up' when needed, just changed the blade in this one, the old one is underneath (new blade about $6 US) last one lasted about 3 years. In theory it should be able to part off about 6" diam. but the largest I have done is 4" in brass.
The 'big guns' one at the back is a replaceable tip version, but with a twist, you can regrind the front edge and move it forwards, they start off life about 1" long. Bought 5 tips about 5 years ago (same price as other blades above each), this is the third one. Nothing gets away from this one, it takes no prisoners.

On this pic it shows the cast iron I parted off yesterday, plus the 'dross' end which I cleaned up to show what it is like.
The big diam. billet at the back is what my friend got me for a flywheel, cleans up and machines well with HSS. I have no idea what material it is but it is very heavy.

John

 

[tattoomike68]

C2 is soft but tough carbide and will take a pounding interupted cut in abasive materials like cast iron skin.

Cutting cold roll steel C2 will crater and dull fast. use C6 on flame and plasma cut parts and any other tough steel parts. (4140)

Carbide likes feed, I never use it with less than .005" feed on the lathe. I like .010" to .012" feed rates on the lathe the best.