Turning Problem

[needleworks]

Ok guys, I am having another problem doing a simple turning operation.

I am trying to make a small brass pulley for a friend, the problem I am having is that cambam is adding some "extra moves" at the start of the part which is ultimately ruining it. I am using a 6mm button tool and taking very conservative cuts. If my attachments show up, you can clearly see them 

[EddyCurrent]

It's the "Roughing/Finishing" parameter.

"Roughing / Finishing    

The Roughing / Finishing property is used to select the machining method. If Roughing is selected, a number of straight passes are used at each depth increment, down to the source shape + roughing clearance, followed by a single cut at the roughing clearance distance that follows the shape. For Finishing, a single cut that follows the shape at the roughing clearance distance is used. "

It looks like setting both to "Finishing" is no good because the "Roughing" pass removes all the material down to the profile + clearance.

I tried it on CamBam 0.9.8 with same result, also tried moving it to right of Y0, also tried removing all lines other than 12, still no good. 



The attachments were perfect. 

[dh42]

Hello

the only way I found to remove the unwanted toolpath with roughing with this tool diameter is to modify the polyline ... or to use a tool with smaller Ø (you're using a round insert ?)

++
David

[EddyCurrent]

David,

Is this a bug or a feature ?

[needleworks]

Hello

the only way I found to remove the unwanted toolpath with roughing with this tool diameter is to modify the polyline ... or to use a tool with smaller Ø (you're using a round insert ?)

++
David

Once again David you may just have saved me a lot of heartache and swearing ! Your version certainly looks better than mine, I will try this as soon as I get a chance. And, yes I am using a round insert.

[dh42]

David,

Is this a bug or a feature ?

I don't know ... I think it's a bug ... but I'm not an user of lathe mop ; I tried to define the area to machine with a stock, but it work only in one direction. If the stock is longer than the piece why can machine some pass at the right side on the front of the piece, but if the stock is shorter the toolpath always start at the beginning of the polyline. If there is no stock defined the front machining go away but only in front of the piece, toolpath "debris" remain

++
David

(edit: same on CB0.98)

[dh42]

on those pictures we can see where is the tool with this profile ; the yellow polyline is the "roughing clearance" of 0.2mm (pic3)

on pic4 I added a line to the center and we get a facing pass

difficult to be sure that it is a bug or not, but maybe the lathe operation needs some improvement 

++
David

[EddyCurrent]

I'm not a CamBam lathe user myself so had a better look at the Help file.

It shows the profile line extending from the chuck centre line along X to the end of the cut on the left.

When you make one polyline follow this path it still does the 'dance' but does not spoil the workpiece, see attached images. ( I moved it to the right of Y so the single profile polyline could be clearly seen)

Edit:  Ha ha David, you posted a millisecond before me 
Probably not a bug if the drawing is correct.

[dh42]

It shows the profile line extending from the chuck centre line along X to the end of the cut on the left.
When you make one polyline follow this path it still does the 'dance' but does not spoil the workpiece

Yes it should works too and I've tried this the first time, but not satisfying with the useless pass that remain ... so I added the small line that return to rear to remove them

++
David

[needleworks]

Oh dear, what have I started 

I managed to get back out to the garage and gave the part a try using David's suggested method, the part ran perfectly and was a complete success !

Thanks again guys for all your help.