Tuesday, 29 March 2011

This sucks

I tried my homemade vacforming machine last night with disappointing levels of success.

I drilled a 32mm hole in the side of the box and attached my DeWalt shop vacuum.

I then clamped a sheet of 4mm acrylic into the holding frame

and placed an inverted ceramic pot on the vac bed as a test pattern:

And placed the sheet in the oven at gas mark 8 for 10mins. I was hoping to observe the sheet and, when it started to sag, remove it. The problem I had was that the sheet was too thick and didn't get hot enough before the MDF mount I was using started to char.

As the kitchen filled with the smell of cooking MDF I decided to give it a try anyway:

The thick, partially heated sheet was sucked down by the bed but was not hot enough to be pulled down onto the sides of the pattern. As a result I got this:

I also noted that the MDF mount had shrunk and was no longer gripping the sheet.

Next time I am going to:

1. Use thinner 2mm acrylic.
2. Make a metal mounting frame which will neither shrink nor smell.
3. Drill some more holes in the bed.

Going to be a while before attempt 2, my RepRap bits turned up today ;o)

Sunday, 27 March 2011

Killing time

Whilst I am waiting for some parts to arrive for my RepRap, I found myself with an hour spare and decided to try making a vac forming machine.

It has a small footprint and is made from 12mm MDF. The clamping frame to hold the plastic sheet is 6mm MDF held together with 8xM4 bolts.

I haven't had chance to try it yet as I don't have any plastic sheet. We used to have a vac form department at work years ago but they outsourced it, so no free test sheets from there.

I intend to use it to make the domes for the Milestag sensors from acrylic sheet used on greenhouses.

Here are some pics:

Here is a side on view showing the clamping plate:

Friday, 25 March 2011

Finishing Touches

I completed the sensor head mounts this weekend. As I showed here I fastened hook velcro to the sensors. I attempted to sew some 50mm loop velcro to a camo hat I bought from Blue Moon Guns of York for £1.99. But after 30mins of inept stiching my wife caught me and with a Bradford 'give it 'ere' she managed perfection in 15 minutes what took me 30 to ruin:

Here's the complete system. I still need to cover the connecting PCBs on the hat and wire from the gun but I'll make some enclosures to do that when I've got my RepRap built:

Friday, 4 March 2011

Sensor testing

Today I tested my homemade sensor PCBs. I had made a mistake with the connecting curly cable in that the leads were reversed. I fixed this by simply reversing the connection order at the gun end PCB.

Here is a video of the test showing shot detection and hit LED activity@