What are you machining?

[grim_d]

Made a start on the double pulley for the lathes new motor so I'm ready when I've got an inverter, bored to size and marked out ready for putting the vee's and the key way tomorrow hopefully.

 

[zx9]

I might have bitten off more than I can chew!
View attachment 228906
...
Edit: More posts to follow as I progress.

A little more progress.

First time I have ground or used a form tool.



Which turned out ok especially as it was between centres, a little bit of chatter but some good cuts as well, lots of Rocol RTD was used.

This was the set up which I removed prior to setting the off axis for the taper turning.


Note cut up Pepsi can to hopefully protect the knurl, and the result.



The end which will be threaded got a bit chewed, I could not get a nice angle on the tool and resorted in using an insert tool, I should have ground up a thin HSS bit.

I am getting into HSS now.
More updates to follow when I have got the taper done.

 

[Kram]

Cheap vice needed to be squared. Facemill is great on cast just need a much bigger one and more travel. I might attempt to make one.

 

[pressbrake1]

Lump of 200mm chrome round in the dsg being made into something else round..
Machine must be 65 years old and still produces finish close to ground

 

[Hitch]

I've got a Fowler digi mic, always seems to read true, but the display constantly flashes which is irritating. Might give it a strip down and see what happens. The fast acting ones sound good!

 

[slim_boy_fat]

Machine must be 65 years old and still produces finish close to ground

Won't that be more to do with the cutting tools than the age of the machine?

 

[pressbrake1]

Won't that be more to do with the cutting tools than the age of the machine?

No

 

[pressbrake1]

Great finish. HSS?

Knux , hss wouldn’t survive chrome.
Big mass and rigidity exceptional design and overall quality equals finish

 

[grim_d]

Pulley finished.



Ground up a tool for cutting @qwakers thread when the material arrives, discovered it is a M16 X 4mm trapezoidal, just aswell I ordered 16mm stock!!

 

[Seadog]

Does that have top rake? It's bad practice, surely, because it will alter the geometry of the thread. Or have you been really clever and compensated for the error?

 

[grim_d]

Yeah it does because I ground it from something that already did. I've certainly not been clever...

I can remove it easy enough, having trouble visualising why it's no good but it's late and I'm stupid.

Edit: it just clicked. Idiot. I shall make another.

 

[minimutly]

Please explain for idiots like me?

 

[Hood]

Ok simple quick drawing, just cut side relief angle on a block.

You get this if looking down from the top.

Now cut some top rake.

And now looking from the top.

 

[Hood]

Here it is with a threading style tool
Side clearance only.

From top

Add some top rake

View from the top, dotted lines showing original angle.

 

[fizzy]

Knux , hss wouldn’t survive chrome.
Big mass and rigidity exceptional design and overall quality equals finish

They definitely help but plenty of people get very nice finishes on tiny little lathes.
Perhaps not on chrome though?

 

[Agroshield]

View from the top, dotted lines showing original angle.

So can you do it the other way with the 3D model? Start with say 5 degrees top rake and a bit of side rake and determine what angle you would need to grind at to achieve a true 60 degrees plan view.

 

[pressbrake1]

They definitely help but plenty of people get very nice finishes on tiny little lathes.
Perhaps not on chrome though?

Naturally but when you’ve got half a ton of knarly old poop swinging and a damaged used insert and get good finish it takes a good lathe.
I should re state it as ‘ dsg that’s done 65 years of work still gets exceptional finish no matter the material or condition of the tool’

 

[Hood]

So can you do it the other way with the 3D model? Start with say 5 degrees top rake and a bit of side rake and determine what angle you would need to grind at to achieve a true 60 degrees plan view.

I would imagine so but you could just as easily regrind the tool as is until it just kisses the back edge, assuming that you can accurately set the angle of the grinder you are using.
In reality the tool above is likely very close to the required angle anyway.