I actually went through several iteration of this design – initially I was going to cut the hole for the silicon coupler on the pillar drill while the acrylic was held at an angle. Not only did I forget to turn the camera on but the hole-saw left a really terrible cut.
On a positive note the CNC is cutting the plastic quite well and the finish looks very neat.
The second attempt had me drill the mounting holes for the adjustable arm in the wrong place which meant the bit hole was in the incorrectly aligned. I tried to CNC router this out again but this is the sort of machine where you really have to get things right the first time.
I decided to use cup and rubber washers to hold the material down. I am still uncommitted to a single software and using Easel – which while improving still behaves unpredictably. To keep the cuts clean I decided to not use tabs, cutting and securing the smaller shaped before cutting the larger.
I also became impatient – increasing the feed-rate and pass depth which meant I lost steps during one attempt. If there is a moral to this – it is don’t use valuable or limited material when CNC’ing when you have not finalised your design.
Each time the design slightly evolved and I was eventually left with these two pieces.
I drilled, tapped and screwed them together – after which I used a thin solution of liquid solvent cement to brush down the cut edges. This acts in a similar way to heating cut acrylic – slightly glossing and hiding any cut marks.
I took the flaps from the original extraction hood and added them to the new one. I later cut each individual roll to half their width which was a less than 1 cm – to increase flexibility.
The coupler was held into place with hot glue – not really the neatest or most secure way to do this considering not much sticks to silicone. I compressed the coupler a little and once the hot glue cooled it created a tight friction fit.
Finally I checked the extraction by sliding a board with some debris under the hood – which was all vacuumed up. I then cut a square checking the size against the original file – updated the steps within the firmware and re-cut the same shape. The accuracy is as good as I can hope it to be.