Sunday, 8 May 2011

CNCing the first part

I decided the best thing to do would be to make the Top Plate first. It is probably the most important part of the engine - It supports the main A frame and also houses the power cylinder & power piston.

If i get this part wrong the rest of the engine has no chance of working.

The Top Plate can be seen in the image below, its the eh..... plate on the top :)

 As you can see in the image below it also has 2 two millimetre thick pieces of plastic that screw into it, these are for the A Frame to slot into.

So the Top Plate needs 10  micro millimetre precise holes milled through it and one large hole for the power cylinder.
So lets go :).

First the holes for all the screws and the single hole for the power cylinder have to be made.

This is the AutoCAD file that i created , i have the points where the CNC machine will mill highlighted in blue so they can be seen, they are only single points in AutoCAD and would not be seen otherwise.

The CAD file is then converted to a dxf (drawing exchange file) and sent to LazyCAM. In LazyCAM i set the depth that i would like the CNC machine to go through the aluminium, the speed at which i would like it to cut, the direction of cut and also the order in which i would like it to do things, all these things can be changed.

Once i am happy with the Cam file, i ask LazyCAM to create the GCODE for all of the parameters that i have set above. When that is done i open Mach 3 and load the file that LazyCAM has just created, here it is shown in the screen below.

If everything looks good there i hit the "Cycle Start" button and Mach 3 takes control of the CNC machine.

Once the holes have been drilled the top plate needs to be cut away from the aluminium sheet that it is made of, this is just a circular cut that will be done in the same fashion as above - circle drawn in AutoCAD, file sent to lazyCAM, file sent to Mach 3 and then the CNC machine cuts the circular profile.

And here is the final product after cutting, i'm pretty happy with it (apologies for the picture quality, i need a new camera) -

In the next post i'll show a video of the machine cutting the displacer, get the ear muffs ready, its pretty loud :)

Saturday, 7 May 2011

A video of the CNC Machine cutting the Displacer

In this post i am going to show a video of me cutting the displacer out of 7 mm foam.

The Displacer is used to shift air from one side of the main cylinder to the other.

You can see it doing this in a video i made below, there's no need to watch the whole video, just enough  to get an understanding of what the displacer does.

The Displacer i cut here will only be a preliminary design, it may need to be modified when the whole engine is complete to allow for better air flow etc.

Here is the video showing me cutting the Displacer from 7mm foam using a Taig CNC Mill -

If you would like to follow my progress making this engine more closely go here

Homemade stirling engne