Scratch Build – In Progress The Dragon Reborn [25/09/12]

Just out of curiousity:

Was the mill bit new? What rpm and what feed did you use?

 

The 1 mm bit? Yeah It was pretty much new, I think I used it for a bit of wood before.

The problem was there was there was no instructions or anything with it so I had to guess feeds and speeds I think I set it to 20000 rpm and I think the speed was about 2-3mm/sec it was ridiculously slow but I didn't much fancy breaking the bit. Honestly I could have probably pushed a bit harder as it was kind of grinding its way through more than cutting.

 

Ok so the results are in... And it doesn't look too good I'm afraid

While it has curved a bit its not the smooth continuous curve I had hoped for:


I have one more thing I can try before I do away with the curve section of the silhouette entirely.

as a teaser here is a preview how the piece will fit:

 

I have some experience bending acrylic and I have a couple suggestions. Getting an exact radius in fairly thick acrylic is a real challenge. I would go back to using the heat gun, you will have more luck heating just the part you bend for something like this. To get a better bend you would need to cut a larger piece, and trim it down after you bend it. You need more material on the short side so you can have something to clamp to while it cools. You also may want to cut it a little wider than needed and trim it down after bending, since the material will always shrink and deform slightly right at the edge when you heat it.

 

Thanks for signing up to tell me that shinji2k. As you say the plastic has deformed quite a bit and shrunk from its original size and so doesn't fit the space as it did before. So yes I will be bending a larger piece and then cutting it down .

In other news I finally broke down the ad hoc setup where this will eventually go in order to test fit some of the parts.


Unfortunately ran into a slight problem with the motherboard in that the holes didn't line up with the ones that I had previously drilled..


Marked where the holes should be:


So thats another job that needs doing. Sadly now not the most pressing...

I've just put together the whole setup for the first time with the Mini PSU that this project was virtually based around.

While there is power getting from the brick too the board (the little LED is on on the plug which connects the brick to the board) when i try to turn on the computer or even jump the PSU (wire from the green cable to any of the blacks) nothing happens...

Sadly it was bought from someone on here who said it was taken from a working computer although I've only now gotten around to testing it (needed a 4 pin male to male cable which I've only just made up)

So now I need some help. I need a PSU to power this thing.

EDIT: Ok maybe I was a little quick to judge but it seems the power brick is only putting out 2.4V. Whether its supposed to do that or not I'm not sure...

Should I just buy a new one which should work or try and buy bits for this one?

 

Looking good

What is the mill you're using? I've been looking for a cnc a long time now, but my wallet refuses to get me one of them. I hate these wallets that eat all your money..

Keep up the good work, bro

 

Sorry the bend didnt go too well, I did forget to mention i was only bending 3mm acrylic so the thickness will effect the timescale for heating it up...

If u can get a heat gun then try bending it a bit at a time like was mentioned earlier. at least then ur only working on the bend and not softening up the whole piece.

 

Thanks Razbit. The mill is one I bought off ebay to be honest. It was relatively cheap.... compared to the likes of the Bridgeports which some guys have around here. But to get it working the way I wanted and so on has taken a lot of money, and I'm about to throw even more money at it to turn it into a 3D printer .... so yeah these things are big money pits.

I am working with 3mm plastic too but its weird as like I said it doesn't go soft when heated it just goes rubbery so you have to bend and hold it until it cools, and if you reheat it it springs back to its original shape. So my current plan is to bend a larger than needed piece then cut that to the required size.

In other news I plugged my laptop brick into the PSU and it seemed to work fine (I jumped the PSU and the HDD's and DVD spun up) so it is just a bad brick not the PSU as originally feared.