Another shear tool

[olderdan]

Inspired by Tony Foales carbide shear tool version I had to make mine in a different way without the use of a milling machine. I had a ½ square braised carbide tool which I turned the shank down to a 3/8 dia to fit a square tool block from my cutter grinder which fits my tool holder, this does have the facility to vary the shear angle to suit different materials. Apart from the excellent finishes it produces it is very useful for work hardening steels which do not allow a small final cut to size, this tool will shave off a tiny finishing cut. These tools do have a limitation when working to a shoulder but raising the tool close to the bottom edge will do for most items.




Semi hard cast steel

[DIYSwede]

Thanks Olderdan for yet another (seemingly) simple, versatile tip!
"-Dang, why didn't I think of THAT!"

Changing the shear angle this easily will probably improve finish even more,
also being able to cut up to a right shoulder, should that need arise...
Sometimes feeding from the chuck can improve the finish even further.

I'm already off to the tool scrap bin, where a few oversize shank brazed carbide tools sits.
I'll just have to turn them down to fit!
Up until now I've been using a 4x4 mm HSS sitting in a DIY-ed lo profile V-block in the tool holder for a shear tool...

Cheers
Johan

[Ralphxyz]

Olderdan, do you have a link for the ½ square braised carbide tool ?

Ralph

[metric_taper]

Ralph, that looks like a C-8 type brazed carbide bit.

https://www.ebay.com/sch/i.html?_fro...l+C-8&_sacat=0

[flyfr8rs]

Olderdan, thanks for the great post. I've found shear tools great for certain jobs, but to date mine are all HSS. I'm not familiar with the type of clamp that you chucked up to hold the carbide bit in the lathe...it looks like it would be very handy for certain tasks (obviously like this one). Could you perhaps tell me what that is called, and even better where I can find them. THANKS!

John

[tonyfoale]

Alan,

I am glad to know that my post inspired at least one person. I love your ability to change the angle, but do you do that?

[olderdan]

John, it is a clamp type driving dog for between centres work, I had centred the blank in the 4 jaw both ends. It was given to me by a retiring turner it has no makers mark and have not seen another like it, it has left and right hand threads so stays central and balanced.

[olderdan]

Tony, I have not used it much as I have only just made it, The ability to change angle is just a byproduct of the way I had to make it.

[olderdan]

Ralph, that looks like a C-8 type brazed carbide bit.

https://www.ebay.com/sch/i.html?_fro...l+C-8&_sacat=0

Thats the one, I should have mentioned in my post that using a braised tool bit does require the ability to be able to sharpen it.

[DIYSwede]

Just sharing a few experiences from my uses:

Shear tools can just take one or two thou - use something else for roughing.
Let the piece cool after roughing if you aim for really tight tolerances.
(Use the compound at 3-ish degrees for controlled DOC into the tenths range)
Cutting edge has to be really sharp and can dull pretty fast, though geometry isn't critical.
(Some people reported meagre results when using inserts, where the cutting edge hasn't been ground & honed)
Really fine feed, cutting oil and only a few hundred rpms for super finish.
As the tool doesn't exert any high tool pressure, it cuts cool and deflection is minimal even for long stickouts.
(I use it for instance for checking if my lathe cuts tapers).
Excellent for finishing difficult materials: "Mystery metals", rebar, cold rolled, copper and even lead.

YMMV

Johan