Archive for February, 2013

Solar seed warmer to get a jump on spring

Spring is coming… here is a tiny little hacklet from the bench of Tim.

I live in New England. I don’t mind it here, but the growing season is a bit short. So here is a scheme to give outdoor direct-seeding a little head start.

Seeds for many food plants, such as melons and peppers, will not germinate until temperatures rise above a certain point consistently. They could in theory be started indoors, but I’ve never had good luck with this in a prison-windowed New England house: even if I remember to water the seedlings consistently (hint: I don’t), regardless of how well I position them in my best south-facing window, they still end up weak and spindly for lack of sunlight. If they don’t outright die when hardened off and transplanted, they seem to go into some kind of shock and stop growing for several critical weeks. I’ve found direct-seeding outdoors is a lot more reliable overall. The tradeoff is that by the time it gets warm enough long enough to trigger germination, they will not set fruit until the tail end of the growing season. What a pain!

The previous homeowner was nice enough to leave behind some things, including some solar garden lights. A quick tweak to them makes them into seed warmers.

Solar garden light converted into a nighttime seed warmer

Solar garden light converted into a nighttime seed warmer

String of low-valued resistors insulated with black heatshrink

String of low-valued resistors insulated with black heatshrink

Assembled view of the seed warmer element

Assembled view of the seed warmer element

Ingredients:
1 old solar garden light
Heat shrink tubing
A few low-value resistors (5-10 ohms)
Small bit of copper tubing

Process:
Sould be pretty self-explanatory from the pictures.
solder one to a few of the resistors in series to achieve the desired length. Connect to each end of the resistor string with some thin insulated wire. Heat shrink this assembly so that the wires exit on the same side (the heat shrink will prevent the bodies of the resistors from wearing through against the tubing and shorting out). Cut a piece of copper tubing to a sufficient length that this can be stuffed inside. For best results, the assembly should be a snug fit inside the tubing to ensure good thermal contact. Finally, seal the ends of the tubing with RTv or similar watertight material, and optionally coat the copper with something to prevent corrosion.

Remove the LED from the solar light, and wire the heating tube in its place. DONE!

Now, when you plant a hill of outdoor seeds, drive the heating tube into the center of the hill, and place the solar light off to the side a bit (so it is not shading the hill). The sun will help keep them warm during the day, and the heater will take over during the cold nights.

Notes:
How much heating will you get? Short answer is “it depends”. In theory, you can measure the voltage output by the light unit and use Ohm’s Law to calculate the power dissipated over your chosen resistors (power in Watts = I*V = V^2 / R). Depending on the design of your solar lights, the output voltage may not be remotely constant or easily characterized, and the circuit inside may have its own current-sourcing limit, reducing your total output. The actual amount of heating you get may be pretty modest. You will not (and should not) find the tube uncomfortably warm to the touch during operation. Fortunately, dirt is a pretty good insulator.

Some plants just plain don’t like to grow in the cold, even if you can trick them into germinating early. For better results, combine with a coldframe to keep the aboveground bit a little warmer too.

So, it appears MakerBot have gone full evil now…

We shuddered when it was announced that MakerBot were taking the next version of their RepRap-based printer design closed-source. We crossed our fingers when the CEO responded to the flap saying they’d be “as open as possible“. We watched with popcorn the various flaps about Thingiverse, legal mumbojumbo, attribution and moral rights.

But now this. MakerBot has been awarded a patent on the conveyor belt. (Specifically, use of a conveyor belt “with a 3D printer”.)

I don’t know about you, but I can’t possibly think of any device for converting a computer file to a tangible work product that uses rollers to clear its work product from the work area to make room for subsequent work product. Certainly no such analogous device exists, or else 3D printers wouldn’t have such a clever and unique name.

While I am here, to forestall successful patent attempts on other obvious means of clearing work product from a work area, I hereby disclose the following novel invention:

1) A work producing system and method comprising a work producing machine, a means of executing stored instructions (sometimes called a “computer”), a set of instructions (sometimes called a “program”, or “software”) that instructs the work producing machine to produce a work product responsive to a description (sometimes called a “file”) describing the work product, a means of conveying said description to said system, and a means of conveying said instructions to said machine. (The system description may optionally include such novel and non-obvious components as RAM, a CPU, wires, wifi, power from the power company, etc.)

2) The claims in Claim 1 where the work-producing machine further includes a method of clearing prior work products from its work area.

3) The claims in Claim 2 where the work-clearing means includes a pushing means to push the old work products from the work area.

4) The claims in Claim 2 where the work-clearing means includes a pulling means to pull the old work products from the work area.

5) The claims in Claim 2 where the work-clearing means includes a scraping means to scrape the old work products from the work area.

6) The claims in Claim 2 where the work-clearing means includes a gravitational means to remove the old work products from the work area. An example of such a means is a tilting means which tilts the work surface, a rotational means which rotates the work surface to a nonhorizontal position, or an antigravity device which causes a local gravity inversion in the vicinity of the work surface.

7) The claims in Claim 2 where the work-clearing means includes a vibrational means to shake loose the old work products.

8) The claims in Claim 2 where the work-clearing means includes additional work surfaces which can be exchanged with the work surface on which work products have previously been produced, and a means of exchanging said work surfaces. (The unused work surface may, for example, be physically exchanged with the used work surface of the same machine, or exist in a second work-producing machine which takes over work production jobs while the first work surface is full.)

9) The claims in Claims 3-7 inclusive, where zero or more said means are combined in such a way as to improve the reliability of clearing work products from the work area.

10) The claims in Claim 9 where the pushing means further comprises a solid object configured to move across the work area, thereby pushing work product out of the work area. Compare “broom”, “push bar”, “squeegee”, “bulldozer”. Since patent examiners have the imagination of a goldfish, I should point out at this time that moving the work surface with respect to the pushing device is the same as moving the pushing device with respect to the work surface.

11) The claims in Claim 9 where the pulling means further includes a magnet. Magnets are magical. (Computer-controlled electromagnets are even more magical because computers are magical and electricity is magical.)

12) The claims in Claim 9 where the pulling means further comprises a suction mechanism and a means of moving said mechanism into contact with the work product and to a location outside the work area. (Compare: “vacuum pick and place”)

13) The claims in Claim 9 where the combined pushing and pulling means further comprises a robot arm and a means of moving said mechanism into contact with the work product and to a location outside the work area. (Compare: Industrial pastry sorting robots). Since I may have been unfair toward goldfish in Claim 10, I should point out that the non-difference between moving the work surface vs. the pushing device also exists for a *pulling* device. Or basically any other device or combination of such devices.

14) “Pushing”, “bumping”, “kicking”, “nudging”, etc. are the same thing. Just throwing it out there.

15) The claims in Claim 2 where the work-producing machine is configured to produce works which are of a 3-dimensional nature.

16) The claims in Claim 15 where Claims 3-14 are restated here by reference.

17) The claims in Claim 16 where the system further includes a means of collecting the removed work products (sometimes called a “bin” or “bucket”).