yet another diamond tool

[tel]

Been thinking of one of these for a long time, Cedge's thread finally gave me the impetus to get started.

Pretty much a copy of Lew's design, as it looked a lot simpler to do.

One little 'refinement' - I made sure that the top of the tool coincided with the lathe centre height - just lay it upside down on a flat surface, push the tool bit down to ditto and nip up.

It works well, given that the tool bit is a roughly done freehand grind - I'm blown away by the quality of the facing.

 

[Lew Hartswick]

Yep. That looks just about the same. Now are you going to try the " Threading " version?
...lew...

 

[tel]

After I get a few more things out of the way - yes. Made a tool grinding jig for it this morning.

 

[Hilmar]

If You grind the same angle on a horizontal version it should work the same.
What am I missing????

Hilmar

 

[tel]

Ease of setting to height.

Ease of tool grinding - just a flat grind on a square tool bit.

Seems to cut better than any horizontal tool I've managed to grind, especially on facing.

Because we can ;D

 

[Hilmar]

Ease of setting to height.======= Debatable

Ease of tool grinding - just a flat grind on a square tool bit.============ Absolutely

Seems to cut better than any horizontal tool I've managed to grind,
especially on facing.=======with same angle the big question is == 'Why '==

Hilmar

 

[Bluechip]

Good Grief !! ..... I threw about 20 of those things away recently. : :

A forging in one piece with a 'swan neck' but just like yours in Pic 1 in plan view.

Shank was 5/8" square, which put the cutting edge about 3/16" above centre, so out thet went.

Got them about 3 years ago when I bought my Myford S7, they were among the 'accessories'.

Marked 'Sir Joseph Whitworth Elswick Works' in an elliptical design.

Thought they were some oddball device from ancient times, for an equally oddball purpose. Apparently not !!

We Live and Learn. I've also learnt I don't have the worlds most swarf infested Myford.

Thanks Tel

Bluechip

 

[IanN]

Hi,

Seems to cut better than any horizontal tool I've managed to grind,
especially on facing.=======with same angle the big question is == 'Why '==

Hilmar

The reason the tangential tool arrangement gives such a good finish (all other things being equal) is down to the rigidity of the tool.

Consider a 1/4 inch tool mounted radially to the work (in a normal tool post). As the tool cuts it will tend to bend.

Now mount the same tool on its end in a tangential holder and the tool is in compression along its length as it cuts and the tool holder can be made very thick, rigid and massive to resist the bending moment and prevent flexing and chatter.

So you tend to get a better finish with the tangential tool, or, to put this the other way round, you can take much heavier cuts while still getting a good finish.

Ian

 

[georgeseal]

One thing that no one has mentioned is how the tool bit is mounted.

With our QCTP that has a horiziontal tool slot with a crash or over cut there is nothing to give. Something has to break or stall.

With the "Diamond" tool holder the bit is held by a clamp along the axis of cutting force. If overloaded then the tool bit slips down away from the cut. You don't break tool bits, strip gears, snap drive belts.

Just my thoughts on the subject
PS Am a Happy ;D ;D ;D user of mine. Have had it for about 10 years

 

[Lew Hartswick]

With the "Diamond" tool holder the bit is held by a clamp along the axis of cutting force. If overloaded then the tool bit slips down away from the cut. You don't break tool bits, strip gears, snap drive belts.

If the bit "slips' in the holder it wasent tight enough.
...lew...

 

[Cedge]

Lew
George is correct. The tool is designed to let the bit slip if it encounters a heavy bind. It's a little annoying the first couple of times you experience it, but it saves both the tool and the work piece from damage. It's saved my bacon a couple of times when I got a little overly aggressive with a cut or overshot my stopping point. Under normal stresses the bit is as stable as you could ask for it to be.

Steve