Week 07: Computer-controlled machining¶

Ironing Stand¶

Ironing Board — Designed and milled an ironing stand. TBD.

Assignments¶

Group assignment:¶

do your lab’s safety training
test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine

Individual assignment:¶

make (design+mill+assemble) something big (~meter-scale)
extra credit: don’t use fasteners or glue
extra credit: include curved surfaces
extra credit: use three-axis toolpaths

1. Group Assignment¶

We traveled 240km to FabLab Hamamatsu where we can borrow the big CNC machine.

FabLab Kannai group work page

I was first much intimidated by the large machine and the big noise, then realized what an amazing opportunity it was to design and build very large things, as long as you follow the safety procedures. Thank you Take-san of Fablab Hamamatsu for the very warm welcome and the training.

Safety procedures include:

don’t wear loose clothes
protect yourself with goggles, etc.
securely chuck the blade.
secure the board with nails before cutting.
know how to stop the machine with physical machine button as well as the software button
don’t leave your eyes off the machine while it is working
clean the debris

FabLab Hamamatsu

2. Individual Assignment¶

2-1. Design¶

I designed an ironing stand based on a design in a beginners wood working book, with the following changes

Unified the board thickness to 18mm
Instead of nailing the parts together, made the parts to press fit.
Made holes on the top table so that steam iron can be used (together with felt mat and cover sheet.)

First I made a Fusion model in 3D.

We went out for shopping and selected a nice laminated pine board of size 910 mm x 1820 mm.

2-2. Create CAM Toolpath¶

I received advice from Tamiya-san to use the dog bone technique considering the diameter of the end mill.

I made the design change after we arrived in Hamamatsu, but it took me more time than I had expected.

Before coming to Hamamatsu, I found a way to automatically arrange parts flat with Fusion Manufacturing mode, however, could not find a way to export the flat model in ai nor svg file format.

Tamiya-san taught me that the easiest and quickest way to export the paths is using Shaper utility on Fusion and exporting the faces one by one as SVG and place them on Adobe Illustrator. Saving the ai file in the old CS format is important to be used with the Cut2D software in the next step.

It was almost evening when we started cutting wood. First, we uploaded the Illustrator file to Cut2D. CUT2D

Then configured the pocket toolpaths, profile toolpaths, and drill holes, and then exported the toolpaths to Mach 3D, the machining controller.

2-3. Milling¶

First I drilled the holes to fix the workpiece. And then fixed the workpiece with the screws. fixing

The machine was controlled using Mach3 CNC software, and I used the same setting as the group assignment.
- Spindle speed: 10,000 RPM (reduced to ~8,000 via override) - Feed rate: 2400 mm/min (reduced to ~1440 mm/min via override) - Plunge rate: 600 mm/min Overrides were used to safely tune cutting conditions during operation.

Mach3

Then, loaded the rest of the toolpaths to the controller. pockets done honeycomb

I found the pocket was too deep and there was a cut trace while the endmill is moving between cuts. Apparently z-axis setting was not optimal, so that we fixed the setting of the machine and cut some extra. Some trial and error, and it was 21:30 at night!! I decided to bring the work pieces home.

back home

And only after I tried to fit the pieces together I found that I totally forgot about the clearances....😱 The pieces do not fit each other!

does not fit

Since then, I have been filing the parts forever … I think I am almost there… then, found that I manually make some holes… I will add the final assembled version when it is ready.

almost there

Reflections¶

This was my first time using a large-format CNC router, and both the machine and the venue were new to me. I was initially intimidated by the size and noise, but I quickly appreciated what an extraordinary opportunity it was to design and machine something at this scale. My expectation was that the main challenges would be learning the safety procedures and the software; the actual bottleneck turned out to be the design itself.

Several things went wrong. I was still making design changes after arriving at FabLab Hamamatsu, which cost significant time and added unnecessary pressure. I had forgotten to incorporate press-fit clearances in the parametric design — something I only discovered when the pieces would not fit together at home. The z-axis offset was also misconfigured, leaving tool-travel marks across the surface and making some pockets too deep. The honeycomb venting holes were far more complex to mill than a simple drilled pattern would have been.

None of it was catastrophic — patient filing and sanding brought the pieces close enough to assemble — but all of it was avoidable.

Next time: finalise the design and get it reviewed before the machining day; use the Shaper utility + Illustrator SVG workflow for 2D layout rather than Fusion Manufacturing’s auto-arrange feature; build clearances into the parametric model from the start; and use drilled holes for ventilation rather than complex cut patterns. The large CNC is an incredible machine once you plan carefully enough to use it well.

Design Files¶

Checklist¶

[x] Linked to the group assignment page
[x] Reflected on your individual page what you learned of your labs safety training
[x] Documented how you designed your object and made your CAM-toolpath
[x] Documented how you milled and assembled your final product (including setting up the machine, fixturing, feeds, speeds etc.)
[x] Described problems and how you fixed them
[x] Included your design files and ‘hero shot’ of your final product

Reference¶

Kantan Mokko Style (book: “Simple woodwork style”)

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