Lessons to learned hopefully from you.
So this started out as a 9.75” x 6” x 1.52” block of celcon. I still have 2 more ops to go tomorrow to make some more features. But this one is scrapped because of me, the material, the workholding, or all three! I held it in a 6” Kurt vise with hard jaws and parallels with 20lbs max on the torque wrench for all ops so far without issues until this one. It was just adding the wider pocket connecting to the two smaller ones below. Obviously once you remove a good portion of material things can move around on you depending on all the variable in your setup etc. but everything stayed in tolerance except the wide pocket which expanded .02” per side in the Yaxis or the smaller dimension. The z was fine except the rib in the middle, it dipped down almost .01”. Now I understand that this was a risky situation to begin with being completely unsupported in the middle and I was trying to take that risk being it was a one off and not wanting to make any sort of fixturing contraptions to make this a better situation of sorts. The plastic was relatively stiff as far as plastic normally goes but not stiff enough. That wall thickness was approximately 3/16” at its thinnest, it’s definitely the thinnest wall I’ve machined in a mill so far. My boss still thinks they’ll buy it thankfully but to me it’s a learning experience that I’d like to not repeat.
My question is how could I have avoided this or done it better and also how would you have made it?