On Jan 15, 2009, at 10:38 AM, Tom wrote: > Jon Elson <el...@...> writes: > > snip... > >> This is for a ** V8 ** bike? Is this a showpiece, or something >> somebody >> is going to ride a lot? >> >> The milling of parts like this tends to leave sharp inside corners >> that >> worsens the problem. You might be able to get a stronger part by >> using >> a bull-nose end mill to get rid of the sharp corners. >> >> Jon > > Hi Jon, > Yes my customer is making 10 more of these trikes, there are 6 or 7 > currently in > his shop. > Yes, they get ridden quite a bit, as they handle really well, and > are very > comfortable to ride in for days at a time... not to mention super- > fun fast;-) > > I agree re: radiusing the inside corners. I might possibly even get > rid of the > lightening pockets altogether, since the sum of weight saved would > amount to > only 10 oz or so - this is a heavy trike anyway. (See my response > to Gene's > comments) > > Tom
7075 only buys you something in bulk parts. I have no idea where the division between bulk and thin wall comes. I'm not so concerned about dynamic stress as I am about fatigue cracking. Decent radii on the corners will certainly help. One trick is to machine the part out of plexiglas and then heat to stress relieve. Then stress the part and view with polarized light; one can see the stress points and engineer the design to compensate from that knowledge. Boeing used a lot of 4340 and 300M for critical parts. Good luck. Dave > > > ---------------------------------------------------------------------- > -------- > This SF.net email is sponsored by: > SourcForge Community > SourceForge wants to tell your story. > http://p.sf.net/sfu/sf-spreadtheword > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
