Rockets!

Space X made it and so can you (not) with this rocket! I designed this because I wanted to try out different shaped rockets and see which flew the best. I'm a bit stymied right now though because the rocket isn't airtight enough! It's quite tight, but in order to build up enough pressure to take off I think it needs to be really airtight. I've got some theories about how to improve it, but right now the 3D printing is leaving little holes in the build.


Rocket Fuel
This rocket doesn't burn Ammonium Perchlorate Composite Propellant, kerosene or liquid hydrogen. No this uses the power of Arm and Hammer along with vinegar as an oxidizer (correct?). I've had a lot of experience with this fuel mixture resulting in a lot of frothed upon clothes, heads and hands. It's simple and fun but when the explosion goes off with you around you end up smelling like a Fish & Chip shop!


Next Steps
The rocket printed out well and a lot of people like the design. It could almost do just as a toy, although I need to trip the fins to be less pointy. What I need to do next is get the rocket airtight. My plan is to print an inner combustion chamber that is a simple cylinder. Based on previous prints of this shape it ends up very airtight. This will either fit into an expanded rocket shape, or maybe part of the design. Back to the drawing board!

Patents and 3D printing

I'm an inventor and I have at least 9 patents to my name, so I was interesting in what patents are out there for 3D printing. It looks like Stratasys has been working in this area for a while, but I noticed that their original patent is now no longer under patent protection:


5121329 Apparatus and method for creating three-dimensional objects was filed in Oct 30, 1989 and issued Jun 9, 1992.


For patents issued before June 8, 1995, the patent term is either 17 years from the issue date or 20 years from the filing date. That means this one ran out in 2009. And it's a doozie too because it basically covers CNC based plastic deposition printing!

Pro 3D printers

I started this thread on the MakerBot Google group as a discussion about how to improve MakerBot and what might be added. I've been looking at pro printers and one problem I can't work out is why they are so expensive! Are they particularly difficult to make, or do they just not sell that many?

Rillakuma Bears Multiply

http://www.thingiverse.com/derivative:2635
I was very pleased to see someone else had printed out my bear model. It's actually quite difficult to get it to look good, but I think the pink one works! I made this bear for my daughter and based it on one of the many bears she has. She is リラックマ nutty!

Self-printed Makerbot

This is very awesome. Someone very patient took the time to design, print and assemble a MakerBot made out of parts a MakerBot had printed. I'm not sure if he gutted the old one or built a copy. I think the time to do this is probably not worth it given the fact that laser cutters can punch out the case quickly and cheaply, but if the only tool you have is a Makerbot, then this is very cool.

Jigsaw Cookie Cutter 2

I printed out the cookie cutter and learnt a few things:

• It would be better to print upside down because the bottom layer on the heated build platform tends to be squashed and as such doesn't make a good cutting edge
• The cutter is too small for a good sized cookie (yum, cookies...)
• The edge at 1.5mm is way too thick and according to a cook I asked, not good for making cookies

Also, a tip to anyone doing printing of objects that have thin walls with a fill in between: print from SD Card! If you ever see a zigzag fill going on in the output of Skeinforge between two walls that translates to a whole load of GCode and the serial link is just not fast enough. As a result, your walls are going to get over full and pudding out. Using the SD Card will give you a zippy fill.

So, now I've redesigned my cookie cutter to have really thin walls. In fact it's 67 layers, one layer thick! Let's see how that prints out!

Screen shot from netfabb showing the new STL file. I use netfabb for quick and dirty STL file fixing. It is very good at it.

Jigsaw Cookie Cutter

This took me a lot longer than I thought it would! My first attempt ended up with the protrusions and indentations being different sizes. This was all due to the wall thickness not being zero (a perfect cookie cutter). The wall thickness is 1.5mm which seems thick to me, but I took it from another cookie cutter on Thingiverse. I think it may be possible to thin it down considerably, but I want to see how it performs first.
The other element I added was a curved taper to the Z-axis. I did this to add a bit of style but it also enables, or should enable multiple cookie cutters to be stacked. I'm dying to print this out and see how it performs stack-wise and cutter-wise. It was also a terrific learning experience on Rhino. I found out how to extrude walls to make solids and how to use the Taper function!