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M250cnc
20-01-2011, 10:53 AM
Or as i call them by their technical name thingamabobs. These were made on my Harrison M250 lathe converted to CNC.

Control software Mach3, Cad/Cam OneCNC


http://www.youtube.com/watch?v=1UWrYydJG0Q

Phil

h4ppy-chris
20-01-2011, 11:41 AM
what are they for?
it does look like you can have hours of fun with them :rofl:

Lee Roberts
20-01-2011, 12:29 PM
Nice, they look like fun!

Jonathan
20-01-2011, 12:39 PM
Nice...I once made cylindrical version of that.

How did you hold it in the chuck? Soft jaws machined to fit?

Very effective, though kind of cheating rolling them with one soft surface.

M250cnc
20-01-2011, 01:31 PM
what are they for?
it does look like you can have hours of fun with them :rofl:

Well i don't know about hours, few minutes maybe. They have been made for someone to use in demonstrations and have some fun.


Nice...I once made cylindrical version of that.

How did you hold it in the chuck? Soft jaws machined to fit?

Very effective, though kind of cheating rolling them with one soft surface.

They are cylindrical, no i didn't use soft jaws and i am rolling them using shiny clear perspex which is nice and hard.:eek: :smile:

Phil

Jonathan
20-01-2011, 04:17 PM
They are cylindrical, no i didn't use soft jaws


Hmm, so did you machine them all in one operation? Or are you not disclosing how :naughty: I saw the other thread about it here a while ago.

By cylindrical I mean mine were just prisms. I did it in the lathe by offsetting the center and machining it three times.



i am rolling them using shiny clear perspex which is nice and hard.:eek: :smile:

Exactly - now use two pieces of perspex. That would be even more impressive.

steventhebrave
21-01-2011, 01:28 AM
The shapes are for me. They look awesome! Looking forward to the postman knocking.

Here's a little blog post I wrote about shapes and solids of constant width :

http://blog.stevemould.com/50p-coins-make-great-wheels/

Sent from my Nexus S using Tapatalk

FatFreddie
21-01-2011, 11:11 AM
Hmm, so did you machine them all in one operation? Or are you not disclosing how :naughty: I saw the other thread about it here a while ago.

My approach would be to turn the pointy bit and then basically part off the lightly curved face first roughing a relief down to maybe 10mm dia and then finishing the face and parting off the final 10mm in one go - if you get the tool shape right it should work ok.

Anywhere near? :-)

Jonathan
21-01-2011, 11:55 AM
My approach would be to turn the pointy bit and then basically part off the lightly curved face first roughing a relief down to maybe 10mm dia and then finishing the face and parting off the final 10mm in one go - if you get the tool shape right it should work ok.

Anywhere near? :-)

I thought it might be that, but there's no mark at all at the center of the lightly curved face.

z3t4
21-01-2011, 12:52 PM
Thanks Phil & Steve. The video is brilliant!
More here (http://mathworld.wolfram.com/ReuleauxTriangle.html) on these curves.
HTH
John

M250cnc
21-01-2011, 01:22 PM
My approach would be to turn the pointy bit and then basically part off the lightly curved face first roughing a relief down to maybe 10mm dia and then finishing the face and parting off the final 10mm in one go - if you get the tool shape right it should work ok.

Anywhere near? :-)

Maybe, getting warm :lol:

It will make it interesting for those that watch but do not participate in the threads to see how various minds work.

The piece is 48mm diameter and will not go through the headstock of my lathe.

So material cost has to be considered, it is not a secret in how i did it but just a bit of fun not to give the game away too easily. But i will let on if anyone gets close to my method.

Phil

M250cnc
21-01-2011, 01:28 PM
Hmm, so did you machine them all in one operation? Or are you not disclosing how :naughty: I saw the other thread about it here a while ago.

By cylindrical I mean mine were just prisms. I did it in the lathe by offsetting the center and machining it three times.


Exactly - now use two pieces of perspex. That would be even more impressive.

Jonathan i have never heard anyone call a prism cylindrical before. :lol:

I would have tried rolling them on two pieces of perspex but as i made them for a customer i can't really get them all scratched can i.

They are on a thick towel as i was using a glass table and didn't want to explain to her indoors about any accidents. :whistling:

Phil

M250cnc
21-01-2011, 01:31 PM
Thanks Phil & Steve. The video is brilliant!
More here (http://mathworld.wolfram.com/ReuleauxTriangle.html) on these curves.
HTH
John

John Thanks for the comments and the link.

Phil

Jonathan
21-01-2011, 01:37 PM
Jonathan i have never heard anyone call a prism cylindrical before. :lol:

I would have tried rolling them on two pieces of perspex but as i made them for a customer i can't really get them all scratched can i.

They are on a thick towel as i was using a glass table and didn't want to explain to her indoors about any accidents. :whistling:

Phil

Nor have I heard anyone call a solid of constant width a cylinder, but nevermind - I should have chosen a better word!

They must be aluminum then if there's a risk of getting them scratched.

Still thinking ...

M250cnc
21-01-2011, 02:08 PM
Nor have I heard anyone call a solid of constant width a cylinder, but nevermind - I should have chosen a better word!

They must be aluminum then if there's a risk of getting them scratched.

Still thinking ...

Jonathan, Steve Mould called them Constants of Solid Width, i call em thingamabobs.

You are correct in that they are made from Aluminium.

They are very round as you can see from this poor photo, so cylindrical to me. :lol:

Phil

Jonathan
21-01-2011, 05:41 PM
Maybe when parting off you held the piece in a revolving chuck in the tailstock. That would still leave a mark, so take that chuck and put it on the spindle and machine the other side? It should still be on center so that could work ... probably something a bit more ingenious though :smile:

Possible some sort of turning between centers was used ('save material').

I guess the question to ask is was it all machined in one operation or not?

M250cnc
21-01-2011, 06:29 PM
Maybe when parting off you held the piece in a revolving chuck in the tailstock. That would still leave a mark, so take that chuck and put it on the spindle and machine the other side? It should still be on center so that could work ... probably something a bit more ingenious though :smile:

Possible some sort of turning between centers was used ('save material').

Very cold. :lol:


I guess the question to ask is was it all machined in one operation or not?

Clues, not every one had the same operations there are some subtle differences, so you now know there is more than one operation. :naughty:

:whistling: I'm enjoying this. :smile:

Phil

jcb121
11-11-2013, 10:30 PM
http://www.youtube.com/watch?v=cUCSSJwO3GU

Shapes and Solids of Constant Width - Numberphile - YouTube (http://www.youtube.com/watch?v=cUCSSJwO3GU)

this site has become youtube famous,

who said it couldn't be done?

and who did it in the end?

interesting video also.

Lee Roberts
12-11-2013, 10:18 AM
WoooHooo :yahoo: we're famous :excitement:

.Me