Originally Posted by walter Thanks for your input. You`re right, I might need to think this through 
But I still think its doable. I`ll steer away from shops that own any cnc equipment. Period. Only old manual mills equipped with DROs. Some have pretty crappy machines but somehow stay in the business and manage to do work within 0.001". They do "one off" type work, I`ve seen places like that. Some good machinist work there.... |
I'm not sure your argument about staying away from shops with CNC equipment makes sense but I will ignore it for now. The bigger issue is fitting your frame on the machine in question. If you are talking about a full size machine with a welded up frame that would be a big concern as would be stress relief.
Aluminium tooling plate you mention is perfect choice but still might need some attention, to make this right. I could do drilling and tapping later. I would avoid making bearing blocks and motor holders in shop. They can`t beat used THK or NSK product which can be found on Ebay. Router motor holders can be made by your own cnc router later.
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having used a bit of THK product I think you might be missing a few issues. Certainly the stuff is good but it often is not a good fit for the application. Ideally bearings should be solidly mounted in the end plates of the machine. How this is done can be a big design variable.
As to mounting linear bearings I have seem machines with welded and extruded frames or components where the mounting position for the components is milled in place. This is a very good idea as it flatens the mounting surface for attachement of the rails. Generallly this is done with the rails mounted directly to the frame. I could see however where this might be better in some instances if the tooling plate where between the two.
So only thing would be milling parallel and accurate surfaces for linear ways and leadscrew/motor mounting hardware. 10-15hrs at $75... Not bad. If your CNC router ends up being production machine then its worth it.
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You miss one important element which is the mounting surface for your table. Once you mill for the rails the other surfaces of interest need to be kept parallel. Some machines can take care of this after assembly others would not be able to cover the mounting surface.
Dave