Barge design 2014-08-03 : Final design & first milled parts
After stalling for a few weeks (or months ...) I got back on track with my barge project. I finally managed to meet with the airplane guys to get a quick introduction to the 2.5-axis CNC milling/cutting machines we have a the MCCR's workshop.
I also reworked some details in my 3D model. Instead of using water bottles to ballast the barge down, I got four 5kg (11lb) lead ingots. This will obviously take much less volume. I decided to add extra frames to make the whole thing stronger.
Not shown below: I'll use metal brackets on all four corners and also to secure the hull bottom and the deck to the sides. I'll bolt them (with countersunk bolts) and epoxy them in place.
I also diagnosed a tiny error ... The wood I got from the home improvement store is 14mmx14mm and not 9mmx9mm. Absolutely no idea how I got that 9x9mm dimension in my mind. Well ... It was quickly fixed in what is now the latest iteration of my 3D model.
First parts were milled from 5mm plywood: one of the "closed" frames and the front plate at the bow.
General view
Deck off
Deck will be epoxied in place, of course
Side view
With frames
Exploded view
Exploded view
From below
CNC milling in progress
CNC milling in progress
From 3D model ...
... to actual parts
Two fellow members of the MCCR introduced me to CNC milling on the club's machines. This particular machine was built from scratch. It is still driven by an old DOS version of Step Four Pro.
First step is to set the absolute/machine zero and then the origin/zero of your drawing.
The Z (vertical) axis also has to be calibrated as it depends on the milling bit.
Not having my own bits yet (they run the machines like coffe machines: everyone can use them, just bring your own coffee or ... milling bits). The "teacher" lent me one of his 1.20mm carbide drilling bits.
The 5mm plywood was cut in two 2.5mm passes. Less strain on the cutter. With such a small bit corners are quite sharp and just require two strokes with a small file to be perfectly square. The produced parts are almost ready to use/glue. Quite impressive.