How was this part made

[Wongster]

Hello guys,

I just received some stuff from China which I ordered for rebuilding an old 3D Pinter. The 3D printer is a Mini Kossel using 20mm square aluminium extrusion as it's based.  The parts I shipped in include some aluminium corners for its base and top. These corners are to hold the alu extrusions together to form the frame of the printer. 

While inspecting the parts, I was wondering how they were made. The bottom corners are 60mm in height and the square hole for the alu extrusion has rather sharp corners. My longest mill wouldn't be able to mill so deep. I guess it's done in halves - flipping over the part after one side is done using the 2 round holes as index or a fixture with the profile milled in. .

But the square hole is a challenge to my inexperience mind. 

All the holes are clearance holes. Kind of a pain to set them up for drilling. 

Some pics:









Any thoughts?

Regards
Wongster

[Mayhem]

An extrusion is formed by pressing the material through a forming die. It will be made by the length and then cut into the desired lengths. The additional holes will be drilled and tapped.


This will give you an idea of the process:
https://www.youtube.com/watch?v=iiGlq7408ME

[Wongster]

Thanks. Meaning this piece is also extruded instead of milled? The extrusion I mentioned is the profile that goes into the square hole.

[Mayhem]

The part shown in your OP look to be extruded as well. That would be the most economical means to mass produce them.

[Dr Stan]

Extrusion is also my #1 conclusion if the production quantity is high enough.  It probably is if one assumes the extrusions are along the same lines as those used a lot in automation.

Lost wax casting is my 2nd guess.  However it would require broaching the sq hole to keep the corners nice and square.

In either case all the holes would be made in a secondary operation(s).

[dallen]

Look at the part if the holes are drilled in it then its more than likely an extrusion, if they look like they were cast in it then its probably been injection molded, or die cast which would put all of the hole in it with no more machining being needed other then to probably painting/coating.

[Wongster]

If I'm to try my hand at machining this, how should I approach it? The aluminum profile I'm using has corners with radius of about 1.5mm. But my 3mm endmill maybe too short for this 60mm pc.

[PixMan]

If you're making a one-off, you could drill the corners with a 3mm drill, then the mill bulk of it with a long 6mm or whatever you can find. Then draw file the match between the hole and the milled surface.

[Dr Stan]

IMHO I'd just buy additional corners.  Unless you're looking at a quantity of 100 or more the amount of time to make one or two cannot be economically justified.  Spend the time on other aspects of the rapid prototyper's repair.

[Wongster]

Thank you all.

It is definitely cheaper and save time to buy. The thought of making a piece is just for fun. To test out my hardly use A2ZCNC mill lol... but Dr Stan is right, i should focus on the the rebuild on the mini Kossel. Maybe when I've nothing much in hand, I'll try making one piece just for fun.