Originally Posted by DAB_Design Alot of questions to answer. So I'll address each....
CNC Pro - So are you trying to trim formed composite components? - Yes.
One of Many - It sounds more like nesting error. - This is the direction I'm leaning towards more. I'm sure I'm getting some movement in the wood, but I think the real problem is the nesting.
I found out something interesting a couple weeks ago that I forgot about. And I"m sure this is probably part of the problem. But it seems most of these fixtures I've been using to trim/drill the part were made using a part. In my opinion (not worth much since I only have about 2 1/2 months experience with composites), wouldn't it be better to use the mold to make any type of fixture? |
Is this a full mold cavity or a single sided lay up? If all surfaces contact the mold, there should be less chance of thickness variations. Better surfaces help register the part with less error.
I would take the parts made off from the mold and let them set for a few days. These continue to shrink some, but should be reasonably consistant as long as nothing changed too much in the molding process, not demolded too early, then post cured, which could lead to distortion etc by the time secondary operations are under way.
When I would make a plug I would wax the surfaces of the part with parting compound to get the part off the plug. Have a crude core structure ready to create the plug on, made of MDF with a few known true locating surfaces to control the parts alignment to a datum plane on the print(usually the table surface). Mix up some bondo and glob it into corners of the part that would provide the best register and on the MDF core, and place the part on the core before the bondo cures. Making sure the part actually rests on the cores original locating surfaces. I always kept the plugs surface as minimal as possible. More surface=more friction which makes it harder to get the parts to nest on the plug consistantly.
Originally Posted by DAB_Design Is this molded in or is it a trimmed cutout? - It is a molded oval shaped pocket, where the floor is trimmed out on the cnc. Make sence? |
I would suspect this groove to be an optional size knockout for the oval? Possibly a seal groove? It may not even be that critical other than keeping it intact until that option is required for the application. +/-.03 may be their ideal for location, but it sounds like they may rarely get that quality in a run. It would be interesting to know what the reject rate was before you came on board. Not that you intend to apply rocket science practices to say out-house venting shrouds for instance.
DC