Building a Soup Can (KFM) Radiation Meter - part 1

[ljerd]

I have seen all videos on this of yours, and I have two more questions: When I cut those two notches at the top of the can, does it matter where I cut the notches, and how far down? Also when you said "poke a wire through a charging hole so it rests about 3mm above the foil leaves", What wire should I use? what brand and kind of wire did you use to make this?

[kmomutube]

@ljerd the notches should go directly above the "seam" and on the opposite side, directly on the "line" from the printed pattern (so the leaves line up between the stop threads) I only made very shallow notches. Another suggestion was to put a small amount of electrical tape over the edge before cutting the notch (the tape is soft and notches well) You don't really NEED the notches with thin thread that behaves well, but with fishing line it really helps to keep it from slipping around

[kmomutube]

@kmomutube Wire: can use "real" radio shack bell wire. Can use a paper clip, bent the way you see in the video - center unfolded flat and the two smaller ends folded at right angles to the center. Wrap the middle with electrical tape/bandaid for insulation. I prefer paper clip. It sticks up well on one end for charging, and the short end can be bent to go Exactly where you want it inside the can. After charging, just twist to bring the short end up away from the leaves and leave in place.

[ljerd]

It is about one millimeter larger than 8 centimeters, I cannot adjust it any better than that. is that ok?

[kmomutube]

@ljerd For the wrapper around the can to place stop threads - 1mm off probably not that bad. But for foil leaves and the scale on the top - probably want more exact. The scale is just a millimeter scale - if you have a clear plastic ruler, you can tape in place to substitute. For cutting the leaves exactly without a pattern- 1 1/2 inches wide by 1 5/8 inch tall, (3.81cm x 4.13cm). Thread fold is 1cm down from top (0.4in). "mark here" spots on thread are 1in each from edge of leaves (2.54cm)

[ljerd]

I have tried downloading every template on the internet, but unfortunately they are all not to scale. what can I do to fix this? could I somehow make this without a template? thank you!

[kmomutube]

@ljerd The best way I know to fix this is to use the "scaling" for your print driver. Use one of the templates with a measurement block (the one at the site in the video directions has a metric block - some have inches) Print it out as is. Measure what size you have. Now use a calculator and divide the size you need the block to be by the size it is (so if the block needs to be 8cm and is 6cm, you need it at 8/6 or 133%) -continued on next comment

[kmomutube]

@kmomutube Now that you know the % you need - select "print" , then on the print popup select "properties", then select the "Effects" tab (third from the left) on properties. Then change the "% of normal size" field to whatever you just calculated. print again. Measure again. You might not hit it Exactly right the first time- if it's a bit too large or too small, nudge the "% of normal size" up or down and print again.

[kmomutube]

@kmomutube If you notice that changing % of normal size has NO EFFECT on the size of what you're printing- your driver may not support scaling. There are several options then. If you have a copier that will copy larger/smaller that works. If not, you can download/install PrimoPDF or similar (a printer driver that creates a pdf file) Select PrimoPDF as your printer, select "properties" then "advanced" and change the number next to scaling. Then print the pdf file to your regular printer

[kmomutube]

not intentionally blocked. Probably something I need to enable? If I can figure out what that is, I will fix. Apologies

[jamespmadison]

I wanted to download this series but it won't let me. Do you have it blocked from downloading? Why? This is excellent info

[CrypticCRICKET]

Update on my meter: I found that my initial high meter readings were a result of humidity inside the chamber. Humidity where I live is often high. I discovered that you need to get the best seal that you can between the clear plastic cover and the can. and to seal the holes in the side of the can that the "leaf stop" threads go through. I used glue to plug the holes. It's also very important to allow time for the desiccant to dry out the chamber before expecting top performance. 5-6 hrs. :-)

[cernunnos5]

THANK YOU FOR DOING THIS VID!!! I have 2 books where this is described but they are outdated in there inprovs and difficult to visualise building even with pictures. A vidio is way better. I hope everyone sees this and I will try to find a prominent place for it on my channel

[CrypticCRICKET]

I just finished watching your 5 part series on makng the KFM. Great job you guys! I'm making one myself right now. I decided to search Youtube for videos and found your series. Very helpful! Have you guys measured any changes in levels of radiation at your home?

[kmomutube]

@CrypticCRICKET

I can't comment for all the meters we built - some are in other homes, some went to school. For the one I have in my kitchen, I can say we've seen unusual readings on only two days so far: 3/28 and 3/29 (the usual for our area is less than 1mm change in 24 hours) On 3/28 we also saw a report posted from the power plant near here that they had unusual readings they believed to be (very slight) fallout as well. Since 3/30, readings have been back down under 1mm per 24 hours.

[CrypticCRICKET]

@kmomutube Ok thanks for the information. I just made the first timed measurement with my new meter. I charged the leaves using scotch tape method and they swung out to a reading of 7 and 4. I timed for 4 minutes and took the new reading. The new reading was 4.5 and 3.5. 3 mm in 4 minutes. By the conversion chart on my can that result = .6 R / HR

I used .004" nylon thread to suspend my leaves. I found it in the sewing dept. at WMT. I need to do more reading now to be sure I'm doing this right.

[kmomutube]

@CrypticCRICKET We were very lucky in that the first few meters that were built here were with fishing line (stren original 4lb, walmart) which holds a charge very well. So when the first meter in the set was built using nylon sewing thread, it was clear something was different - it charged fine, but then rapidly lost charge while the meters on each side of it were doing fine (<1mm/24hours) With the other meters all the same and that one different, we suspected the thread was the problem.

[kmomutube]

@kmomutube Looks like the sewing thread (Singer nylon) had an anti static coating on it- making it weakly conductive. Since then, we've tried other threads and it looks like the conductive coating problem affects many brands of sewing thread. The original instructions suggested unwaxed dental floss - which has been hard to get here (all waxed floss) . So we decided to stick with the 4lb stren fishing line- 2lb would be easier to work with but thats harder to get (special order)

[kmomutube]

@kmomutube Silk beading (not sewing) thread also worked well - but expensive. We did try strips of dry cleaning bag as suggested in the ORNL notes - didn't work for us. The local dry cleaner uses anti-static bags. On the web site from the video description under the "troubleshooting" link there's an entry titled "the meter charges but falls rapidly on first use" (it's the entry that starts "don't panic...) we gathered together some notes there on thread problems we encountered