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Topics - Davetech

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1
Think Tank / Soda Bottle Lighting
« on: July 26, 2009, 02:01:09 PM »
Crazy ideas, huh?    Okay, here's my contribution.

I stumbled on this YouTube vid:
   and decided to try it.

It works!  It works better than I expected! 


I mounted the bottles at different depths to see which one would put out more light.  The video says to cover the bottle caps with a light shield to prevent ultraviolet from breaking down the plastic. I haven't done that yet.



The bottle on the left appears to be transmitting more light to the interior. I made wire hangers from baleing wire that just hook over up at the roof and wrap under the bottles. It is so thin it is not noticeable. It, plus the tight fit of the 3 liter bottle, plus the silicon sealant combine to hold the bottle securely.

The 3 liter bottle needs a 5 inch hole and I happen to own a 5" metal cutting hole saw that I can use with a 1/2" drill. This was left over from the days when I had a car stereo repair shop and I installed speakers in car doors. It makes a perfect hole for 3 liter bottles.

Now, this idea seems to only work for roofs that have no attic beneath them (unless you want the lighting for your attic, which ain't a bad idea) but I have thought about combining the bottles with a "light tube" to transmit the light through the attic into an interior room.

Light tubes are expensive if you buy it from a home improvement center, but back when I first got interested in solar, I bought some mirror finish mylar on a roll from Worm's Way (online gardening supplies). I think a decent light tube can be made by lining the inside of a regular heating duct with the mylar. That's one of the projects I have on my back burner.

As it is, I tried the idea on a shed that used to house my lawn mower, then it was a small work shop, then it became a junk room. When I came in, even in the middle of the day, to find a particularly pretty piece of junk, I'd have to turn on the light to see well. With two bottles, and partial shade, there is still enough light coming in that I usually don't need to turn on a light. I still plan to add two more bottles but that would take me about an hour so I've put it off.  ;D




2
CNC Questions and Answers / Setting up limit switches
« on: July 15, 2009, 04:25:40 AM »
I'm making progress on "Tom's Easy Mill".  I'm to the point of setting up limit switches after building the Z-stage and then rebuilding it because it was oogly and I didn't like the first one.

The little instruction booklet for the driver board, which I have misplaced >:(, did not say whether the limit switches should be normally open or normally closed. But it did show separate limit switch inputs for each of the three stages.

I had charged ahead and wired them as normally open, but then I read a post where someone was talking about their system and their switches were N.C.

Is there a standard? I know I can find out with a little experimentation, but I didn't want to apply power to the board until I have everything right. I've written to the seller but no answer back yet. 

To show my noobness, I also just assumed that two switches are required for each stage... one at each end?  I wired them in parallel since they were N.O.

Another question I have is about placement of the Z-stage switches.

Placement of the switches for the x and y stages seems straight forward, but placement of the bottom z-stage limit switch seems critical, where you want the mill bit to be able to reach the maximum working depth without going too far and touching the stage platform. Do you normally have the work piece sitting on top of a scrap piece of wood or something and just set the limit to be at the surface of the scrap?  Should I make that switch height easily adjustable?

Yesterday, the mailman brought my parallel cable gender changer so I can now hook the board up to the computer. I'll be ready to apply power once I have these switches set up correctly. I had been wondering how the program knew where it was on the board. I found in the K-cam documentation that it figures out where it is when it is first started up by seeking out the three limit switches and bumping them three times to make sure it knew where the limit was. I don't know if other software does it this way or not... cause I'm a noob :P. But that does tell me I can't experiment until I have the switches in place.


 




3
CNC Machine Builds / Building Tom's "Easy Mill"
« on: June 19, 2009, 04:37:44 PM »
I've moved these posts over from the Heliostat section because I felt like I had highjacked the thread.  :-\


Okay, enough of this nonsense of wasted time on trying to get boards etched for my heliostat controls.  You have probably seen this by Tomtechart, but if not, you are in for a treat:



I've been wanting to build his "Easy CNC Mill" for some time, but I put it on the back burner.  Now I have  moved it to the front burner. Just got back from spending $55 on black pipe and threaded rod, so there's no turning back now!




I'm starting to feel like old Don Quixote charging at learning curves.  But it's fun.



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