Omar Seif El Eslam - Fab Academy 2022

Computer-Controlled Machining

Assignment requirements:

Group Assignment

Test runout, alignment, speeds, feeds, and toolpaths for your machine.
Document your work (in a group or individually).

Individual Assignment

Make (design+mill+assemble) something big.
Extra credit: don't use fasteners or glue.
Extra credit: include curved surfaces.
Post processing → sanding, painting.

Learning outcomes:

Demonstrate 2D design development for CNC production.
Describe workflows for CNC production.

Assessment criteria

Linked to the group assignment page.
Documented how you designed your object (something big).
Documented how you made your CAM-toolpath.
Documented how you made something BIG (setting up the machine, using fixings, testing joints, adjusting feeds and speeds, depth of cut etc.).
Described problems and how you fixed them.
Included your design files and 'hero shot' photos of final object.

Group Assignment

In this week we want to design cool designs in meter scale, we had a small CNC router machine in our lab and had access to a big machine in another workshop.
So we started our week by testing a small parts using our machine.

Toolpath generating

Our machine has openbuilds control kit, so we used openbuilds cam to generate our toolpaths.

First step is to go to openbuilds CAM online and open your vector file.

Select the vectors you want to apply the toolpath on, we wanted to test outside path, inside path, onLine path for profile cutting and pocket area clearance.

Set the Endmill and workpiece, tool diameter, Z steps/Cut depth per pass, final cut depth/finish depth, feedrate for X/Y and Z(plunge).

To set the feed rate there's a charts for each material to know what is the maximum feed to use when machining.

We used this website to determine the feed rate we can use, we were too carefull so we set a 200 mm/min feed rate which is too low but still we wanted to be in a safe zone.

Then click on Save button in the Toolpath tab to save the gcode.

Machining

We used openbuilds control software to operate our machine.

We use same setup as PCBs to fix wood sheets on our small machine, tape + double face.

We used 3mm diameter endmill, Set the X/Y and Z zero points where the gcode will take it as the start point.

Run the gcode and enjoy watching it.

Then we measured the outer dimension for each shape to calculate runout and the machine were pretty good with less than 0.05mm runout.

Practice

I had an idea so I started to design a small test part to check if it will work fine.

Design

I wanted to design something that flex to make angel of 90 degree, our instructor suggested that we design a small box and apply parameters we tested in it.

I designed the side of the box and using Flex feature in solidworks I got the inner raduis of the curve to calculate the arch length to be able to design how much of material I will remove and leave.

Toolpath generating

I didn't want to use openbuilds CAM like we did in the group assignment to explore other options.

I have tried fusion 360 CAM but at the end I couldn't export gcode compatible with our machine, So I used mods and it worked with few errors.

I saved my design as STL then in mods > programs > open server programs > machines > G-code > mill 2.5D stl.

Then set the setting to for the pocket clearance.

Then I exported another STL with the outline only and made another toolpath with mods for profile cut.

Machining

I used openbuilds control again here.

Same steps for setting up the machine and workpiece.

Obviously you can see the trials in the pictures.

Post processing

When I removed the part from the machine bed it didn't flex it was hard and tending to break if I exerted more force.

I poured a hot water from the boiler on the section I want to bend, after that it got bent really easy, So I fixed it with a clamp and left it to dry in that position.

Conclusion: after this practice I'm sure now MDF isn't good for flexing so the suitable and available material is plywood So I decided to manufacture the assignment design on a plywood.