Thread: Poor finish with my finishing tool.

Originally Posted by 19brendan81

Can you stick up a photo of such a tool Dave?

historically I havent used coolant much, except for boring, and if I do its out of a spray bottle. Now my new lathe has a pump and nozzle i'll probably start using it a bit more.

Here you go Brendan, this works good on mild steel for me.


Here it is taking 2mm deep cut


And this one a 0.05mm cut


The tool could do with a hone as I have used it a bit.

Dave

I forgot to add that I grind the 3 faces, then hone them with a oil stone and put the nose radius on with the oil stone not the grinder. A few rubs around the nose give you what you need.

Dave

Dave , That looks like a knife tool ... we are all going to try that from now on

Knife tool, not sure I have heard of that one. I just played with different grinds and this one seems to work the best on mild steel.
Although I don't recommend it, you will see I have miles of over hang on this bit of scrap, but the tool seem to slice the steel off and not want to grab into the work. I only had it that far out because I didn't want to chuck up the rusted area.
Those cuts where done at 200 rpm and the bar is about 35mm round (would have to check).

Dave

Edit,
I don't own any of these books you guys talk about, is there reference to a tool like this?

Originally Posted by Dave J

I don't own any of these books you guys talk about, is there reference to a tool like this?

Yes there certainly is ..in HH's books, he uses knife tools quite a lot . MIKE

Hi Mike,

I don't know what Harold Hall calls a Knife Tool? But... "That's not a knife!" ... (apologies to Mick Dundee)



Style AR – Right Hand for turning to square shoulder. Used for general machining operations such as turning, boring, and chamfering.
Style AL – Left Hand for turning to square shoulder. Used for general machining operations such as turning, boring, and chamfering.
Style BR – Right Hand 15º Lead Angle for turning when no square shoulder is needed. Used for general machining operations such as turning, boring, and chamfering.
Style BL – Left Hand 15º Lead Angle for facing when no square shoulder is needed. Used for general machining operations such as turning, boring, and chamfering.
Style C – Square Nose for chamfering. A perfect general purpose tool of great utility for chamfering, facing, and turning. Tool can also be used to make special form tools.
Style D – Pointed Nose - 80º Included Angle used for undercutting and O.D. and I.D. chamfering.
Style E – Threading Tool. Standard 60º included angle for universal threading, V-Grooving, chamfering, turning, boring, and facing.
Style ER – 60º Offset Threading Tool. Tip is offset from the shank. For threading and V-Grooving to a shoulder.
Style EL – 60º Offset Threading Tool. Tip is offset from the shank. For threading and V-Grooving to a shoulder.


This is a knife...



Hope that helps...



Regards
Ray

Thanks Ray, maybe in Mikes book it has a tool similar to mine that he has named a knife tool. That one you posted looks like what they call a shear tool.
This shape is my standard work horse as most of what I do is in mild steel. I usually sharpen that other end as a left hand so it's only a matter of turning the tool around.

If anyones having trouble grinding this tool I could do a step by step process to help out.

Dave

This is a scan from HH's book .he calls it a knife tool . Almost identical to DAVES. BTW HH doesn't use any back rake for his turning tools . As it says the rake is sideways , across , but not back MIKE

Hi Mike,
I don't put a flat on the end of mine, I just put a small radius with the oil stone.But other than that it's similar.

Dave

Edit
I notice he calls his a finishing tool, mine is used for both roughing and finishing and works well both ways.

Originally Posted by morrisman

This is a scan from HH's book .he calls it a knife tool . Almost identical to DAVES. BTW HH doesn't use any back rake for his turning tools . As it says the rake is sideways , across , but not back MIKE

That's one of the books I have. That tool is described as a finishing tool, in this case used to make the final finish on the cylindrical squares I'm going to do..... once I get this finishing tool down pat. I think with all the info here I should be right. In theory!

I do have to take into account the Simon retard factor though!

Simon

The tool I posted above is the same type I used to finish my cylinder squares. You need to pay attention to the honing to get a great finish, like I said earlier you are only shaving off hair like material on the final pass. For roughing you can use it strait off the grinder and it will a reasonably good finish, but always give it a bit of a hone.

Dave

Originally Posted by Steamwhisperer

Hi Simon
If you grind up a shear tool you can get a mirror finish with HSS

Phil

Hi Phil,

Nice one, I had a bit of a play with a shear tool, and works like a dream, weird shavings, beautiful finish

Regards
Ray

PS. Thanks Stuart for the bone.. I mean link... http://www.gadgetbuilder.com/VerticalShearBit.html

Originally Posted by RayG

PS. Thanks Stuart for the bone..

Looks like I might have to give it another try. In the vertical shear bits defence I did just try the one off the shaper, the angles might have been less than perfect and I know it was touchy on the shaper to set up.

Stuart

Wow, this thread has grown, performed a few tests today, but did not grind down the 1/2 inch bar, as these are worth a bit, have plenty of 5/16 HSS with no holder.

tested using my home made circular saw carbide tool, and the diamond tangential holder.
ignore the rough sections, kept it as is for an easier reference of the finishing cuts.
fig a/b show the finish.
section 1 is the carbide tool at 170 rpm and the feed about 20 percent off the slowest feed.
section 2 is hss run towards the tailstock, 70 rpm and the slowest feed
section 3 is hss run towards the chuck. 70 rpm and the slowest feed
section 4 is the carbide tool at 70 rpm and the slowest feed.
the depth of cut on all were 0.05mm.
noticed when cutting 0.05mm deep the cuts were not constant, was o.k at 0.1mm deep.

At 300 rpm and a feed rate 20% from the slowest setting, the carbide tool gives a better finish than the hss on the slowest speeds.

honed the hss with a new diamond sharpening stone with a shallow radius, and honed a round edge on the carbide tip.
fig-c/d show the carbide tool, and circular saw the tips came from.
The tool looks like crap, but works great, even works on broken rough cuts.

Dave, could you possibly post the angles of the tool, the finish looks great, what was the feed rate?
will definitely be grinding the 1/2 inch now.

Brendon, will try to copy Dave's tool first, if no success will take up the offer.