Re: CAD draw 4th axis part
hy, i guess the problem is that you have to keep the cutting section orientation constant, while the software is tilting it, in respect to path orientation
i could start my SW and give it a try, but anyhow, i would not aproach it like that, because i know that when a 4th axis is used, you have somehow to corelate the feed and everything, because the motion is interpolated, and not all cam's are doing it right, thus they may output the toolpath, but may fail in computing the correct feed
i would actually draw the cilinder in 2d, and output parametric code for the finishing, because i believe that you are looking for some tight tolerances, and like this i would obtain the level of control where i would be comfortable
otherwise, you may be lucky, if wall deviation is < required tolerance, and in such a case, you could machine it just like that ( for example, if you look for 0.2 tolerance and walls deviation is 0.1, then is all ok )
i am not saying that fixing SW is not possible ... i am just saying that i can do it faster in 2d + wrapping the final code ( using a macro eq, etc ), then the time required to dig for a sw fix / kindly :)
ps : i also hit into something similar a while ago, when trying to design reamers with tilted flutes ; truth is that a cut-sweep may output a toolpath <> then what a cutting tool would generate; in your case, the problem is keeping the section orientation constant, and my problem was that the section was much smaller in comparison to tool section ... maybe you should ask inside the sw forum
Re: CAD draw 4th axis part
me again : search "barrel cam mechanism" on youtube ... what you need is to obtain something some-how similar to that, but truth is that you can simulate the motion even if walls are not ||
you are looking to obtain kind of cam behaviour ( by cam i don't mean cam-software, but cam-mechanism )
when it comes to cam-mechanism, i simply compute the motion and code it directly, thus i don't go through a solid / kindly :)
3 Attachment(s)
Re: CAD draw 4th axis part
hy :) pls check attached images :
01) i sketched the path ( 2 circles dia8, conected with a tangent groove )
02) wrap-deboss ( 6mm depth ) over the od of the cilinder
03) to check the walls, i created a 3d sketch, and i have intersected the wrap-debos with a plane that contains the cilinder axis, and i have obtained a rectangle with height=6 and length>8; length would be 8 only if the groove was perpendicular on the cilinder axis
if you wish, send me the real required dimensions, and may sent a video back / kindly :)
Re: CAD draw 4th axis part
Thanks deadlykitten. Damn, I've been around motorcycle engines for most of my life but never knew that the industrial version of a shift drum was called a "barrel cam" mechanism. No wonder I couldn't find anything in YouTube. I just looked under "Barrel cam" and there are plenty of videos. Thanks for your help and your offer re a video but could you give me a couple of days to look at and digest some of the ones on YouTube first?
Regards
Re: CAD draw 4th axis part
hi skippy :)
"barrel cam" is from the field of mechanisms with cams and articulations, which were heavy used to design machinery motion
if you know them, you will no longer look at a part as an individual, but you are actually capable of undertstanding it's place inside a motion chain, and you may figure it out what tolerance is needed in order to craft it :) thus, even on a wierd mechanic organ, is possible to imagine it's motion ...
today they are less used, because most motions are interpolated by cnc's :)
that is not a "true" barel cam mechanism ... if you wish to know, it is a "restricted" mechanism, because is not 360* ... that groove is a mechanical cam contour ... whatever :)
Quote:
could you give me a couple of days to look at and digest some of the ones on YouTube first?
do whatever you wish :)
as for that part, one way to get the solid, is to open the 2d dxf ( considering that there is one ), check the contour, and paste it in sw, then wrap it on the cilinder
do you race ? kindly :)