Designing the chasis for final project

Design

My final project needs a hard frame for making the extruder work, so I decided to make it out of aluminium. I got 1/4" by 3" aluminium plate. It was 180cm long, and I made all the parts in my design to interlock using a 6.5 width tolerance. This is the design. The aluminium will hold everything together.

The idea is to make all the interlocking with cutouts in corners, which need to be sized according to the diameter of the endmill. Since I'll be using a 3/16" endmill, then the cutouts must be a bit bigger than that. Everything will be held together with M5 screws. The assembly detail will look like this:

It's important to note that I gave it a tolerance. Also, I waited until I had my material to measure its exact width.

• material width: 6.3mm
• slot width: 6.45mm
• fit: very snug, but not impossible to get in.
• runout: 0.15mm
• mill slot arc radius: 3.3mm

Nesting
After that, I nested the parts on the outline of my available sheet, taking care of having enough space for the endmill to cut well between parts.

Toolpathing

I used enRoute to make the toolpathing and cut file. I used the following settings:

• tool 1/4" square endmill, 1 flute, upcut
• passes 6 passes, 1.2mm depth per pass
• rpm 10000rpm
• speed 10 mm/seg

Cutting the file

Drilling the holes

I set the piece first to drill the holes, which I later used to fasten it to a sacrificial piece of scrap with wood screws. For the drilling I used a 5mm DRILL BIT, not an END MILL. The drilling could have been done in one pass, but I used two passes.
I am using EnRoute software. The drilling part used 500mm/min penetration speed. And the two passes are half of the 1/4" aluminium sheet.



Cutting the parts
For the milling part, cutting the parts, I am using the 1/4" one flute carbide end mill.
The feed speed is 700mm/min which is about 10mm/sec. I am using 6 passes, so 1.2mm per pass, and the tool spins at 10,000 rpm. I am using conventional cutting.
You have to move the toolpath start point for each part, so that you maximize the screws holding down each part.



The final pass still needed to cut alittle more into the part, so I sent another pass with a little bit more depth.

The piece was then securely fastened. And everything went smoothly.



As you can see in the video I'm using cooling liquid with a syringe. I'm just periodically spraying rubbing alcohol to the endmill so that the temperature does not increase rapidly and start getting melted chips.
Also, the endmill is cutting on upcut, which helps a lot in getting the chips away from the toolpath as fast as possible.
This is the final assembly with the tube and some of the final parts.


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