Sunday, February 8, 2015

Ok the first mini mill design candidates are ready



I have a candidate for the mini mill design ready for review. I need another set of eyes on this thing, someone who knows their stuff before I release CAD renderings everywhere.

If you are that guy, and would be interested in giving it a once over let me know and I'll shoot you a file in 3D PDF.

These are the design goals:

As little to no China parts as possible.

This means that I am not using pre-made linear guides, no factory smooth rod, no china ball screws.

 Second the price has to equal or beat cheap China mills.  Those $300 mechanical only machines or the $800 complete machines.  

Third,  as little 3 axis machining as possible.  This means that most parts will be run on the fiber laser, CNC bender, lathe, and water jet.  

Four, obviously Japan parts are out too cause of cost.

Spindle not included in the final cost.  Right now, I am contemplating some sort of non China made spindle or fabricating something using a DC variable speed motor like the ones used on car heater fans.  I can control DC motor speeds easily enough with a simple transistor and the RAMPS board.  (not gonna explain in detail how to do that, if you know basic electronics you know what I'm talking bout)

In order to save costs, a couple corners will have to be cut. These can be easily upgraded if you have the need for lots of machine time.  

Drive mechanism will be 12mm stainless threaded rod. Since the tool travel is only a foot, it should not be much of an issue.  Secondly it will have Delrin nuts and Delrin bushings.  If this ends up being the production machine, I'll throw in the files so that you can make your own replacement parts.

Guide rods right now are 3/4 inch stainless rod.  I got a supplier who has really straight 3/4 inch round bar stock, and I can put ii on the lathe to make sure each piece is straight when we turn down the ends.  I figure that it is plenty strong enough and better than the 12mm chromed steel I'm getting now for the printers.  

The whole thing bolts together.  Absolutely no welding, no corner brackets. Just m3 and m6 bolts.  

It is designed to be able to run cutting oil in it.  As such there is no drive mechanism on the bottom. Every axis moves from the top.

Shoot me a PM via the contact form.  

I'm still making the other printer/mini mill, but I'm seeing right now that it will not be strong enough to cut steel parts for those steel parts we will be needing if you know what I mean.

Superficially it guess it resembles the ghost gunner machine in that the frame is a steel box.  I have no idea how the ghost gunner design looks on the inside, other than a couple photos of some defective frames.

Below: Not my design.  Although I have had stuff made here.