This blog is mainly about Telescope making, and some things about my politics. At last we finally have a President that can say "Fool me once; shame on you. Fool me twice; shame on me." instead of mixing up with an old Who song.

Sunday, June 29, 2008

Moderation is for monks

I've been trying not to spend so much time lately on telescope making, and for several very good reasons.

My boss sent out an email and said I have to renew my Lotus Domino certifications by August 4 (a black day! its my one year anniversary of breaking my leg and foot!). And while its a little easier at work, gas is over $4.05 a gallon, and I have been taking MARTA to work most days which means getting up before natural man was meant to, and coming home on time for once in my life. It does allow me to pull out my laptop and study though.... and boy do I need it. I had no idea how far behind I am -- two major versions of Domino, oy.

Then there was my 16th wedding anniversary. With the gas prices and the budget kinda tight, (more on that towards the end of July) we decided not to go down to Tybee Island near Savannah this year. We love going down there. It' where Susan's father's ancestors came from (they were Hugonots and Salsbergers -- yes, Susan is undeclared DAR). They are all in that graveyard in Savannah where we go now and then and spruce up the family plot. She offered, and I will likely take her up on it when the time comes.

But instead, we went to the north Georgia mountains. Our neighbors, Cathy and Debbie have a cabin up in Helen that they let us use now and then, and so we went there. Nearby there is the highest mountain in Georgia, Brasstown Bald. Here is a picture of Susan nearby there. Neal's gap is a couple miles behind us. It's near the beginning of the Appalachian Trail.

Brasstown Bald is the place that the astronomy geeks in highschool went from our local observatory , Fernbank Science Center one time. I was one of them, and we spent the night up there with our telescopes and cameras. It was so dark that night, that after about 1 or 2 in the morning when we all got up and went out, we could actually see the shadow that was being cast by the light of Jupiter. Astounding! Here is a picture of me near that spot at the top from when I was 16, right before a cloud arrived.

Of course. while we were there on the mountain last Saturday, I had to regail my wife with that story. :) We did spend a wonderful evening up in Helen, and finally I was able to point out Hercules, Corona Borealis, Serpens, Bootes, Draco, Cygnus and Scorpio.

So, not being able to spend as much time making telescopes as I want has gotten me feeling like a monk. But today, I was able to get out in the shed and do something. I have been stymied by the decision about whether I should use "Dental Stone" to make my tile tool. I kept trying to find a local supplier, to no avail. My dentist was willing, but jeez louisse, its $47 a pop for the stuff she has. And if I get the cheaper stuff online, I still have to pay shipping. So I opted for making one out of concrete instead.

One of my new online ATM buddies, David Harbour, swears by it, and he has very specific instructions about how to go about it. I haven't been able to follow it to the letter as he would hope, but I am close. For one thing, I couldn't find the 1" hex shaped tiles, so I used 1" square ones instead (really hard!). For another thing, I used the pre-mixed mortar mix instead of the playsand and portland cement mix he suggested.

Also, I am using a different technique for the cofer dam into which I will pour the mortar.

But I will be doing that is the same, is using match sticks to evenly space the tiles after removing them from the paper/nylon mesh backing. I am glad I read his instructions, or I might have actually tried to burn the paper backing off. That would have resulted in chipping and flaking of the tiles in the long run.

I thought that the glue they used was some sort of polyester stuff, but as it turns out it was totally disolvable in water. And while that is ok for a bathroom wall or floor, I am not sure I trust that with my tile tool, so I soaked it off as David instructed, and it came off with no problem at all (amazing how easy it was). And without all that paper and glue, I just know that the concrete will stick a lot better.

The match sticks were a little bigger than the cracks on the original sheet of tiles, so my original cutting and shaping had to be adjusted slightly, and I had a few excess tiles after it was all said and done ("Everything to excess, moderation is for monks!" - R. Heinlein). But I got them all on there and the match sticks made it all very easy. Because the tiles are square, I was able to keep things really lined up, and there are no gaps where the cement will come up to the level of the top of the tile when it is done. Because of that, there will be less prep work before drenching it in wax. For the wax, I have some "Gulf" canning wax that has been sitting up in the kitchen cupboard for about 12 years.

Anyway, as usual, I have some pictures of what I have done:

David said to use a cirle made from a black plastic trash bags to cover the mirror with. Well since he wrote that the only kind of trash bags you can get are the sort with the little indentations in them that keep them from breaking. Unfortunately you can't use them for this, because you can't squeegee the water out from underneith it. So, I used the kind of plastic bags you get at the grocery store in the vegitable aisle. The work really well, and you can get all the bubbles out. But they actually are somewhat porous. Who knew? So I used two layers, worked fine. I flattened out a little skirt all around the edge of the mirror In this picture I've lifted it up a little bit so you can see it, otherwise you couldn't tell in the picture.

Here are the first few tiles that I removed from the backing paper. The glue was hard, so I started by scrapping off as much as I could with a box knife. I thought I would try to soak the rest of it off in some sort of solvent.
I cut the original square mat of tiles
into a circle back in May, which is why this looks like a circle segment.

Here is the rest of it. As you can see, there is a sort of nylon mesh covering a diamond pattern paper substrate attached to the back of the tiles. After a while of scrapping the glued on paper with the box knife I sprayed one down with water to soak, and found out that it came off really easily if you let it soak about 15 or 20 minutes.

Here are the tile soaking in the water. In the top right of the pan you can see how far I got with scraping the paper before I found out how easy it was to soak it off in water. It came right off with my finger nails, but for the most part I still used the box knife anyway. Simple rubbing with my fingers and rinsing in the the water got the remainder of any globs of glue, particularly off the edges too.

Here they all are after cleaning, and still a little wet. The white parts are probably leftover glazing from the final firing of them I guess. Not much more that a discoloration and a little roughness. Not glassy or anything.

Here are the match sticks. In my setup there were two sizes, 1 inch, and full length (without the match heads). Cutting them is easy without resorting to tonail clippers. I found that a nice sharp chisel works fine, but that masking tape is a godsend. Neatly layout about twenty matches at a time and tape them down to a piece of wood. I had some scrap oak. then tape over their heads and whack it with the chisel. The tape keeps the heads from flying all over the shop and possibly igniting. Then line them up so they are about 1/32 inch over the edge of the wood and tape them down to that. squeeze them between another piece of wood in a vise and file them down with a rasp or some sandpaper (or both) until that overhang is gone and then tape a couple of tiles over them flus with their ends. Put that in the vise, and with the box knife cut on the other edge of the tile. voila, perfect 1 inch match sticks all taped together and ready to use without falling on the floor. For the long ones, you just leave them as is without further cutting them.

Here are the first few tiles. I layed down a straight edge made from the same material as the red and white cofer dam. it was a a cheap "For Rent" sign I found at Ace Hardware. but the plastic is thick, about 3/64". Horizontally are the one inch match sticks. Vertically (parallel to the white plastic straight edge I taped down) are the long match sticks. The "Kroger" logo is from the plastic bag over the mirror.

Here are the tiles all laid out on the mirror surrounded by the cofer dam. (1017 uses for duct tape and bailing wire). The sharpie is pointing to one of three "extra" match sticks. They are marked with dashed lines on them. They were really helpful in keeping things aligned as I put the tiles in place. I'll take them out right before I pour on the concrete. Here it is, ready for the mortar. One thing I like about this method is that the tiles seem to stay flat on the mirror. When using the mesh, there were several that were actually pulled away a little bit, but not anymore. Alas time slipped away from me, and so the mortar will have to wait until next week to do its magic.

This is what happens to all the match heads. I figured that the safest place for them was in the water I soaked the tiles in. Next to that is the hammer that my grandfather used to build a sandbox for your truly when I was 4. He gave it to my father when he died, and I got it from my father when he died. We have no kids, but I will likely pass it onto my nephew or neices. The green handled tile nippers are new from Lowes, no story here, yet :)

More picture next time.