I bought the acrylic this week ($325) from Johnston Industrial Plastics and here is the guy cutting the 1″ thick acrylic (snapped with my iPhone)
I then drove down the street and dropped it off at the waterjet cutting place ($80) who cut it today. I also got permission to tape the “Flow” water jet cutter in action because it is pretty neat to watch. Here are some shots of the video footage as it cuts my acrylic:
The waterjet manufacturer has a pretty funny “Can Water Cut It” website where they cuts all sorts of crap in half like iPods, snowboards and a lawnmower.
I then dropped everything off at the university this afternoon, ready for the build next week (the protective brown paper comes off):
The only part to source yet is the vacuum gauge and I have a bid on one. (removed eBay link) I also have to buy an assortment of bolts, aluminum plates and a support for the upper shelf, but those can all be purchased locally. With the acrylic cut, all the ports now have covers.
Once the L gasket and the drill bits for the acrylic ($90) arrive, the vacuum chamber can be pumped down for the first time!
Wired published an article today that talks about Shawyer’s cavity and a paper he published at a CEAS 2009 conference earlier this week. Having read over the article and paper, there are a few interesting things to note:
- Shawyer mentions that for the first cavity, he did do some tests to eliminate spurious effects, such as buoyancy, by placing the cavity inside a hermetically sealed container. With our vacuum chamber, we should be able to push the tests one step farther.
- Shawyer still doesn’t mention what the measured results are from the superconducting cavity although the “calculated” results show a potential force of 143Kg (Holy frack!) for a 6KW input.
- His recent tests have been funded by “substantial shareholder investment”
- He mentions numerous other groups duplicating his work (our research not included)
- Two other groups, one in China and one in the USA are working on EmDrive projects. We understand that significant progress has been made in both theoretical and experimental work, within these groups. Reports have also been received of work in a further two countries. In the UK we have started the initial performance tests of our first flight thruster.
- He also published a picture of the superconducting cavity I have not seen before:
I will be sending around the latest Levitee update this evening.
One of the things to avoid with the vacuum chamber is putting too much weight on the top shelf of cart which can only support 250lbs. The vacuum chamber is roughly 150lbs and the next heaviest component is the acrylic window(s). If acrylic weighs 0.0426lbs per cubic inch (apparently), then the rough weight of the front window will be about 40lbs, assuming a 30″ by 32″ square 1″ thick piece. That leaves about 60lbs for everything else including ports, DUT and other variables. I may end up putting a strut under the upper shelf to add support.
The replacement L gasket has been ordered and I also purchased gas springs off eBay to keep the acrylic window from opening too fast.
I got quotes back for metal spinning the copper cavity and the first one came back at $2400 for the mandrel and then roughly $400 per cavity after that. Too rich. I am going to attempt to build the cavity in three pieces by strapping everything in place around the wood mold I already have and then soldering all the seams. If the tolerances are not good enough, then I will think about going the metal spinning route.
I also sent RFQs out today with regards to waterjet cutting the acrylic pieces I need and I am still looking for a preferably local source for the special acrylic drills bits required because regular bits will rip and crack acrylic.
TOF work has also kept me busier then normal this week as we have moved some websites over to a new “private” server and there are hick-ups to sort out. The good news is that the wiki documenting this project is now much snappier and in the future will be able to handle huge volumes of traffic.
Have a great weekend. I am off to Jasper for a day-long bike trip.
There are four ports on the vacuum chamber and thanks to a recent purchase of a blank off eBay (shown below), I now have two left to cover. Of the two remaining ports, one is the port through which the vacuum pump will be attached and the other will be the port used for bringing in the microwave waves. The vacuum port will be made from acrylic and it should be a simple matter of drilling a hole through the acrylic, then giving it a thread and screwing in a 3/8″ connector. I haven’t figured out the microwave port yet.
I also finished the wood mold as shown and after trying my first idea of cutting one piece to cover the entire mold, realized it is not going to work. My next idea was metal spinning and aftering annealing the copper to make it more malleable (and to keep it from wrinkling), I mounted a small piece of copper on the mold to test with:
However, when I reattached the mold I didn’t center it well enough and at 200RPM it wobbled enough to send the detached piece (shown) flying clear out of the garage.
Metal spinning is the way to go, but I have to think up a better method and maybe get a harder wood. It turns out there are lots of place in Canada that do metal spinning and I will looking at getting a few quotes too.
Got the vacuum chamber installed on the cart this week:
Here is a shot from the footage with Arash and Kashish helping:
I might also have a supplier lined up for the “L” gasket that has to be replaced on the bottom side but I am still getting quotes. For the rest of this week, I plan to finish lathing the wood mold and then building the plastic mock-up. The good news is that the cavity might not be as sensitive to the diameter of the narrow end as I thought. If the diameter is not 170mm, then it means the frequency of the TE0,1,n mode will need to be adjusted with the tuning plate to bring it back to resonate at 2.45Mhz, although, in talks with Kevin, it may affect matching.
have been feeling under the weather these past few days and I have been changing TechOnFoot over to a new billing system, both of which has meant not much done on the Levitee front. I did however work on the wood mold getting it roughly into shape as shown in the pictures below:
Wow, does working with a wood lathe create a ton of scraps:
Here is a shot from the raw 1080p documentary footage of the wood lathe in action.
The utility cart ($309) showed up this week too and Kevin sent me the measurements I need (thanks!) to get the supports installed. We should be able to bolt the vacuum chamber to the cart later next week sometime.
Over the past week, the vacuum chamber arrived at the University and after inspection, it is definitely used but in great condition, certainly usable for our purposes.
Thanks to Kevin who took pictures of it:
I will be cleaning out the inside though:
I have purchased a cart like this which can handle 250lbs per shelf and is 26″ wide and 40″ long. The acrylic will be about 50lbs and the cavity another 150lbs.
Once everything is put together, it should look like this:
The front will have the clear cell-cast acrylic hinged to the table and the chamber will be bolted to the cart with the L-shaped lips along the side (not shown in the pictures). The vacuum pump will then sit on the bottom shelf and through a hose connected to the back (or top), evacuate the chamber. All the green parts are the ones that I have in my possession already. The DUT will then sit inside on an analog scale on a shelf and, through one of the ports, connect to the magnetron source via an N-type connector. We can then film everything through the front acrylic window. The vacuum we should get is 10-3 torr.
From the extra vacuum parts which also arrived this week, I got a blank to cover cover one of the three ports. I will use acrylic to cover a second one (thanks to an o-ring among the vacuum chamber parts) and the third one I still need a port through which the signal will pass. I also have to get a new “L” shaped o-ring for the seal that will sit against the acrylic.
I also got the second of the wood blanks cut yesterday:
I spent some time trying to rough the first blank into form, but it was too off center and starting moving the whole lathe around and heating up the electric motor. I have since rough it in more with the chainsaw and it should fit on the lather much better now. I will attempt more wood work tomorrow. Unfortunately I think the grain of the wood is too course and I will need finer grain wood to get the 1mm accuracy I want.
I also got some good advice from friends (Silica, one of the guys I game with) about how to mold the copper and he suggested quenching. Heat up the copper to red hot, then submerge it quickly – apparently this makes the copper very malleable which will make forming it around the mold easier.