It started off as <SharpCraft> where the angle brackets were going to become ends of a chopped log, for when I carve it out of wood. But this works for now.

That’s the second best fortune I’ve had from a fortune cookie. The best fortune was from the previous dinner. I can’t remember what it said, but it was really great. So when this one came along I decided to document them here.

Here’s a good page on variacs: http://www.nmr.mgh.harvard.edu/~reese/VariacPage/

edit: had to recreate info that disappeared on initial posting

If I did get away from 2×4 sides, I could get 12 tops from a single 2×4. Hmm.  I need to check prices but I think I would need to get my raw materials way down under $5 per house to be able to make these for resale. Not that I plan to do that, but what else am I going to do with 12 bat houses?

I’ve made one house, but I didn’t take any pictures. I’ll make the second one and get some pictures up.  (Hey – I’m doing it just like Norm!) The overall dimensions are 14.5″W x 17.5″H x 3″D outside and 11.25″W x 15.75″H x 1.5″D inside. Look for construction details in the next post, but you can get the idea from this screen shot of the design.

Yahoo offers the options that I want. They call it “Personal Address”. It comes with five email accounts and a ton of storage for $35/year. The problem is that I already park my domain at Yahoo under a small business plan for around $10/year. So when I go to upgrade the service they tell me I can’t, but instead I can get “Custom Mail” for $26.21 per year. But that only has one email account. Why can’t I have the other plan with five?

It sounds like a simple problem, but I’ve gone through weeks of email support and phone calls. (Don’t hold the phone too close to your ear when you call them, the “Yahoo!” yodel will hit your eardrum like an icepick.) Since my registration expires in the next couple of weeks, I’m going to move everything to myhosting.com They seem like they have it together, although their pre-sales support doesn’t seem to be working on Friday nights. It’s going to cost me about the same, plus $10 per year for the domain registration.

I guess I still need to figure out how who my registrar is and if or how I change that.

I built a large crosscut sled last February (2-ft x 4-ft, need to put up pics). I made two runners out of MDF, so the sled will track straight in my table saw. I made it just loose enough to slide easily, and it worked well for a month or so. As soon as winter transitioned into spring, the MDF swelled up enough that the runners won’t even fit into the slots in my saw. I thought MDF was supposed to be stable?

This gave me a chance to destructively test my glue bond on the old runners. These were MDF held to the slick side of hardboard with year-old (at least) Titebond 2 and no fasteners. It held well enough for normal use, but I could break the bond with a moderate whack with a hammer. I didn’t knock them completely apart so I haven’t looked at what part of the joint failed. If it looks interesting and I can get some good pics I’ll put them up. Both MDF and hardboard are very good for specific applications but pretty lousy for anything else, and neither of them are structural materials, so it doesn’t bother me that I can’t glue them together well.

So now I’m making another one. My first thought was to leave the first one, make one now while it’s sticky, and then just have two, one for summer and one for winter. But I found some .325 thick ABS plastic that I cut down to 3/4″ without too much trouble. Let’s see that swell up.

Generic “sand” has a density of 1442 kg/m^3 loose or 1682 kg/m^3 packed.
(Source: http://www.simetric.co.uk/si_materials.htm)
BTW, (1682-1442)/1442 = 16% increase in mass for a given volume by packing the sand.

MDF density is 680-830 kg/m^3
(Source: http://hypertextbook.com/facts/2000/ShirleyLam.shtml)

Iron (as in cast iron or mild steel) is 7870 kg/m^3. (No source, I just converted it from .284 Lb/in^3, permanently burned into my brain from college.)

The relationship between metric and English density units is
1 kg = 2.2 Lbs
1 m = 39.37 in
1 kg/m^3 = .0000361 Lbs/in^3 = 1/27680 Lbs/in^3
So to convert divide [kg/m^3] by 27680.

As it works out, a volume the size of one sheet of MDF is
Loose sand: 1442/27680 * 49*97*.75 = 186 Lbs
Packed sand: 1682/27680 * 49*97*.75 = 217 Lbs
MDF: 750/27680 * 49*97*.75 = 97 Lbs
Iron: 7870/27860 * 49*97*.75 = 1012 Lbs
(Don’t forget that MDF sheets are an inch bigger than plywood.)

The MDF conversion was just a common sense check for the conversion, yes a full sheet of 3/4 mdf weighs just under 100 Lbs.

So since sand is somewhere around twice as dense as mdf, you can have the same mass by putting in twice as much mdf as sand. I like this because sand is messy and mdf is pretty cheap.

On the other hand sand with just enough room to shift may provide additional damping. I’m not sure about that, I’ll have to think about that one.