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John S and Adam's CNC Crankshaft code

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JasonB31/08/2019 08:26:43
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The subject of the CNC crankshaft cutting code that the late JS used to run as a demo at shows has come up on MEM forum.

Does anyone have a working copy of the code that they could let me have, it seems the one in circulation does not cut enough metal as the downfeed per pass is too small. Or if you know what other forums JS may have posted it on, I have seen the post on this forum.

I have enquired wit Ketan but need to wait for Ian to return for an answer.

Thanks, Jason

Edited By JasonB on 31/08/2019 08:28:34

Emgee31/08/2019 09:23:11
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Jason,

I see in 1 post it cuts 1mm per pass and in another the code posted at your linked page worked OK with Mach 3.

Emgee

JasonB31/08/2019 09:52:48
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Emgee, I don't think anyone has got it to cut, the guy who says it ran OK in Mach3 was air cutting, when he later tried it on metal he got the half moon cut as per Vixen's (mike) posts see his reply in this post

Baz31/08/2019 11:07:32
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JasonB, I have a copy of the code but at present I am in sunny Devon on holiday. When I get home you are more than welcome to a copy of it.

JasonB31/08/2019 13:10:30
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Thank's Baz, will PM my contact details.

Vasantha Abey01/09/2019 05:03:14
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Dear,

I am from Sri Lanka and if you can let me have a copy I will appreciate that too. I tries to make a Mitusubishi Evolution Crank shaft from a a billet of EN19 steel. I tried a 2d sketch of pin and journal plan view on Solid works, and the curser allows the coordinates to see at the bottom.You can divide the contour to say 60 points, note down the x,y points.

later you can write a G code program, switching y axis to z on you MS Note pad. keep the x as 0. Of course you need a 4th axis to turn the crank shaft. This is a very difficult process, but you can do it. The end mill on the spindle need to rise and fall during the rotation of the dividing head. I have used a servo motor driving a toothed belt that slips on an aluminum toothed rim tightly fitted to the pheriphery of the divider plate. The servo motor also has a toothed wheel and with an encoder. The cnc mill has a Centroid CNC 4 axis installed and the mill is an OKK Mill.

Remember that the pin travel like a clock hand and round the center of the journal . On solid works 2D drawing, you have to draw at least 20 circles or more right round the journal center and circles are in orbit. Then you can use the curser to plot suitable cordinates on top of each circle and write a gode program. the X cordinate should be made Z. I will soon send you the G code program I used but to day is Sunday so will do it on Monday.

John Pace01/09/2019 20:33:07
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Posted by Vasantha Abey 01/09/2019 05:03:14

Dear,

I am from Sri Lanka and if you can let me have a copy I will appreciate that too. I tries to make a
Mitusubishi Evolution Crank shaft from a a billet of EN19 steel. I tried a 2d sketch of pin and
journal plan view on Solid works, and the curser allows the coordinates to see at the bottom.
You can divide the contour to say 60 points, note down the x,y points.

later you can write a G code program, switching y axis to z on you MS Note pad.
keep the x as 0. Of course you need a 4th axis to turn the crank shaft. This is a
very difficult process, but you can do it. The end mill on the spindle need to rise
and fall during the rotation of the dividing head. I have used a servo motor driving
a toothed belt that slips on an aluminum toothed rim tightly fitted to the pheriphery
of the divider plate. The servo motor also has a toothed wheel and with an encoder.
The cnc mill has a Centroid CNC 4 axis installed and the mill is an OKK Mill.

Remember that the pin travel like a clock hand and round the center of the journal .
On solid works 2D drawing, you have to draw at least 20 circles or more right round
the journal center and circles are in orbit. Then you can use the curser to plot suitable
cordinates on top of each circle and write a gode program. the X cordinate should be
made Z. I will soon send you the G code program I used but to day is Sunday so will
do it on Monday.

Hi Vasantha

Having done some of these type of plotting type job i know how tedious
it can become.All is not lost as you were doing it this way i will assume
that you may not know this as follows.I use an early cnc system "Compucut"
a Dos based unipolar system and an old drawing system Draft choice for
windows .The Compucut system has a file "circdata" in which
the basic units are inserted and produces a plot file ,this file is then
converted into a relative file .The file takes the form of PR nnn,nnn;
which Compucut uses " HGPL" . Using find and replace in wordpad this is
converted into the format 3R nnn,nnn,nnn; like you the the x axis is
all 000s and the y axis and z axis is using the data.
Most likely the drawing system you use will have a polygon function,drawing
this and saving the data it can be exported and the file produced is the same
as the circdata that i use ,perhaps the easy tryout is to draw an 8 sided form
and see what is produced. The compucut circdata has an odd quirk in that
the data starts at 0 deg in the 3 oclock position moving anti clockwise so to
use it for this crankpin the 1st quadrant is cut and then pasted at the
end of the file to start at TDC At 0.5 deg resolution the Compucut version
gives 720 lines for one rotation.the test piece in the photo is at 4deg and
has 180 lines only cut in wax just to tryout ,as in your post the axis of the cutter
tracks the centreline of the pin ,the pin diameter is determined by the distance
of the cutter relative to the axis of the pin.

Johncrank pin.jpg

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