Reflective Break

Ok, so it kind of got cold this past fall and then Christmas and New Years and then all the other stuff, politics-wise. And I ran out of polish anyway (got some more now though). And a huge bill on my truck has pretty much left me in the design phase again.

So I've promised myself and several friends, that I would be starting out with a Steam Punk telescope. Cherry, brass, inlay, carving, maybe some leather and gold leaf (! right). I saw some nice minimalist designs that I liked, Jan vanGestal's 30cm in the Netherlands has a really simple 6pt mirror cell, I am designing a similar 4pt one. Another guy named Tim Nott in Australia, has a 16" tri-dob that he did a great job on, and I was seriously considering it too. It's a truss type OTA, but also liked the Pletestone cantelevered design. no links to that anymore :(. And before all that I saw a really nice design "Captain Nemo" by Anthropologist Ross Sackett. Featuring beautiful wood, brass, inlay, metalwork, and even gears and chains, its a marvel to look at and an inspiration, and I said "someday".

I went about scratching around other designs, like this partially completed one:

(click to enlarge them) It has a very open structure. In fact, the mirror is just laying there on its four points beneath it, and two on the side (against which it rests when you tip the whole thing away). It would work fine, but its kind of unsafe for several reasons. Most importantly, its a magnifying mirror. That means if I leave it out in the sun during the day it could blind someone passing by or start a fire very easily - even without a reflective coating. Also, it could get damaged by a stick falling from a nearby tree, or sand kicked up. Being so open like that has the nice feature of being very light weight though. But it has lots of very odd angles to it, and frankly, I am not up to the task of getting those very well, so early in my wood working experience.

But it gave me some good ideas. First, its a tri-dob. I like that. It mans that the mirror and the telescope above it sit in the middle of a triangle which is very stable and low to the ground. Also the two cresents are smaller than a traditional Dobsonian, and there is a center one of bigger diameter under the mirror. If I ever wanted to motorize it, then all I would have to drive would be that center rocker, and not two outer ones. The secondary mirror holder would have been a wire spider like Jan vanGestal uses.

This led to another one that is more enclosed version of the same thing. here is what the mirror box part of it would have looked like:

I threw some nice cad formatting in there to see what it would look like. Basically its 1/4" plywood bottom, top and sides. The three crescents are the same though. This design would be really easy to put a flip up cover so that the mirror would be protected when not in use. Popping the mirror out would be simply a matter of lifting it out with a little cradle tool so that I could store it in its storage box. I really liked this design. But again, its beyond my ability. All that curved wood is made by laminating and building up my own thick plywood from thinner plywood. I could do it after a few prototypes, but I have no experience with that, and it would look like crap with all kinds of compromises and rationalizations on my part before I got done. The other thing with this is the trusses. While they make the assembly very stiff (just like my mirror grinding stand in previous posts here), they are hard to put together right. This wouldn't be the case if I could simply put it together and leave it, but I want this thing to be portable, so they have to be easily disassembled each night. Making the hardware that will let you do that, and still be strong enough would be a difficult undertaking. Six truss poles is better than eight of them, but not by much. I made that design with TurboCad drawing software if you are curious. Fun stuff.

So, I went back to the drawing board - virtually - and decided that I needed to re-learn a lot of things that I haven't had to use since I was a college kid at GT. Things like stress, strain, elasticity, tension, compression, beams, moments of inertia, moments of insanity. What I really wanted was something that was strong enough, and stiff enough not to act like an archers bow every time I touched it. What it looked like afterwards could be 'art' if it looked wierd, or 'design' if I could make form follow function. Basically, a statement of excentricity - my favorite thing!

Then I looked on my Barack Obama calendar and there for January 30 is a quote by Nelson Mandela. - "There is no passion to be found in playing small - in settling for a life that is less than the one you are capable of living". Ok, so that clinched it. Back to the Steam Punk telescope, just do it.

Looking for inspiration I checked back at Ross' website and saw that he had updated it to include other designs I was unaware of. He also had some engineering pages that confirmed a lot of what I was discovering, and I became convinced that his "Moonsilver" series of scopes were simple enough and customizable enough that they fit right into what I was thinking.

So, my aim is to make a telescope that looks something like these images. I made them with Google Sketchup. Its a free program that really helps in visualizing what you want to make, and it allows you to make sure that all the moving parts won't knock into each other. Here is my interpretation. Or you can actually download the sketchup files and use them yourself. (they are copyrighted by me, so ask before taking. I'm into open source, so they are copyrighted so as to maintain that. contact me for details). Anyway, here is a link to the .skp file. http://sketchup.google.com/3dwarehouse/details?mid=414cd6f6aac16df818f475bed8b50d3

A view from the rear-side. This is what it would look like as you walk up to it. the eyepiece is in the brown thing at top left. That is connected to the base by a bent aluminum pole. Its bent so you back won't be.

Viewed from the other side - front side. the black circle is a light baffle that leaves the optical train unencumbered. It is mounted on its own smaller tube and is easily removable if its not needed for the night - like up in the north Georgia woods. Here in Atlanta, though, its needed, as there are too many street lights near my house.

Looking at it from the front. The diagonal mirror is held by a single curved piece of 1/8" aluminum. I might make that brass, and carve it :) What I don't show here is the lid for the mirror box.... details, details.

From the left. Here you can see the single crescent

(instead of three with the other design), and the attachment arm between the pivot point and the mirror box. This arm has attached to it the large 2.5" bent aluminum strut tube. The smaller bent 1/2" tube for the light baffle is attached to the end of the crescent. This is probably not a great idea, and I amy change that. The holes in the cresent do two things. they make it lighter with no loss in strength, and they make it look cool. Probably need some inlay here.

A view from the back. The septgonal mirror box

will have mirror columnation and safety screws in the bottom of it to adjust the mirror with.

One thing to note here is the two platforms at the bottom. The top of them has a 16 gauge steel plate attached to it for smoothness. It rides on the bottom one with roller bearings. I haven't decided how exactly yet. But it has plenty of room if I want to motorize it.

A view frm the right. Here, the vertical arm with the pivot point in it (a 3/8" bolt) rests on the base. At the end of the pivot arm is a carving like on a fiddle head or old time battering ram!

A view from the top. As you can see the base

rings are just that, rings. I may change that, because I probably need a vertical pivot point. But maybe not.

Again, you can see some holes, this time in the mirror box. Same reason.

Redo

UG!

I turned the edge of my mirror. I got over anxious and went too long and hard with parabolization. It gouged a hole in the middle and turned the edge. And while I made significant progress towards making the center and other zones pretty close to 1/4 wave P-V, I was never going to be able to fix that turned edge and keep the paraboloid.



So I polished out the edge, center be damned. Now the center is slightly raised, but overall its a sphere. Slow 30 per minute 1/3 W strokes. Six one way six back 4 times in one place. turn the mirror 90 deg CW, turn around the barrel 45 deg, do it again - around the barrel twice that way. Finally, no turned edge... I think.

Here are pictures, let me know.

What appears to be a flat center sloping up at the edge. Click for a bigger image and you can see perhaps there is a darker shadow on the right, but no matching bright ring on the left (KE is positioned on the right)

Here is a ronchigram. It's made from a transparency that I reduced down on a copier at Kinkos. 40 lpi. This is inside focus.

This is further inside focus

This is outside focus.

I'm not seeing the tell tale curls at the ends of the lines indicating a turned edge anymore. I sure hope I got it licked.

Testing my 12.5"

Back in an earlier post I was talking about the foucault tester I made. Well, I tested my mirror with it this weekend, and the little green LED was just not bright enough for my old eyes, so I got a big huge jumbo white 28 cp LED, and rewired it with a rheostat so I could control it. So much easier now, and I have some pictures. In fact, videos too.

Say hello to my little movie.



And this one too. I have a couple of questions, and I hope to get some of the ATMs on the ATM list to watch and comment.



And these pics in no particular order. As usual, click one to get the full detail shot.

Note the roughness on the first two shots. That is the kind of finish the polyester polishing pads give. Its pretty rough, but should polish out without too much hastle when I switch to pitch.



This one has a funny way with it. At first glance it appears to be a bowl with the light source to the right. Then, blinking my eyes it appears as a mound with its light source to the left. Both of these are tricks, of course, because the light source is actually right below the camera lens.
There appears to be bleed through in the shadow that shows the line of mounting holes in the mirror stand for other size mirrors. I think I will put a white (or maybe black?) card in behind the mirror next time.

The glare is where I got a little ahead of myself with the new bright LED and didn't baffle it very good.

Polishing my 12.5"

August was cool. A few days got above 90 but mostly it was in the low 80's and even into the 70's I managed to finish up the fine grinding on my scope in the evenings, in one or two cases I was done with only an hours worth of work, but even still, I kept at it for at least 2 hours on each grit. I did this partly because I wanted to get the ROC as close to 137.5" as possible before going to the next level, even though there were no pits left. At one point, I think it was the 320 grit, I was thinking that I was going to run out of tile. It got awfully close to the concrete. In one place I actually had to dig a grain of sand that was at the same level as the tile and re-seal it with hot wax. But that worked, and the subsequent grits didn't wear any more tile away that I noticed.

Finally it was major clean-up time before going to the polyester polishing pads and Cerium Oxide. I was getting absolutely paranoid.

Then I applied the pads. They look like those flowery bathtub thingies that keep you from sliding around in the shower. I put them in an off-centered hex pattern all over the mirror and cut them where they ran over. I put about a 1/2 teaspoon of CeO2 on it and within two times around the barrel it was already a noticeable shine. But the drag! Man it was like pushing a car around. So I washed off the CeO2 and removed 3 or 4 pads and that made it much easier. In total, I have spent about 3 1/2 hours on it now, and there are no pits left from edge to center. I tried the 10x magnifier - nada, sun test -nada, the lazer test - nada, and I finally found a little hand held microscope down at Radio Shack that goes all the way to 100x. There are simply no pits left... except one set in the very center.

Once while I was polishing and getting over zealous I let the mirror tip over the edge of the tool, and it sheared off chunks of tile. I stopped immediately, cleaned everything and inspected, and sure enough, small scratches. It wasn't too late, I could have gone back to fine grinding, but I decided to continue for a few more whets to see if they would clear up by themselves. Well, for the most part they did, but there are still a couple of the strays, 2mm long, in 2mm patches. But they are within the shadow of the secondary mirror, and one of them would be covered up with an alignment ring eventually anyway, so I'm just going to ignore it and go on.

I really recommend using the pads. It shortened the amount of time I needed to polish the mirror tremendously, and perhaps got me to the point where it is fully polished. I might not have gone that far had I done it with a pitch lap and been tempted to start figureing too soon.

So now I am ready to start getting the shape to a sphere, in preparation for getting it to the shape of a paraboloid. And for that I will need a pitch lap. But while I am waiting for the Lap mold to arrive from Kevin McCarthy at http://www.pitchlaps.com, I can practice using my Foucault tester.

Political things: McCain proves daily he lacks the capacity.

I said that this blog would be about politics and telescope making, but I haven't done much about the former. So, here goes.

In the evening this past week, of course it was the Democratic Party National Convention on TV. We spent the final night down at the "Thinking Man's Tavern" with the Drinking Liberally crowd. It was an exceptional time and I am really motivated now to go out and campaign for Obama-Biden.
I don't think the Republicans will be able to match it. In fact, I think they are going to fissle out because of Hurricane Gustov. Bad luck there. Just remember, it wasn't our idea to pray for rain for their convention. But while God may not fiddle around with our petty conventions, we do.
With McCain's pick for VP, I'm simply amused and almost embarrassed. There are plenty of people that don't have the credentials to be President in the Republican Party. But to pick the one that has no credentials? Good grief! Imagine Biden and her in a debate? He would loose simply because everyone would feel sorry for her. If I were Biden I would refuse to debate her. Not the same league. Not even the same game.
McCain could die. He may get cancer again, or a heart attack, or meet up with some nut job or have a bad case of the flu and not pull through. He knows this and he picks some cute gal from Alaska.
He sure likes the cute gals though, doesn't he? His first wife was a divorced swimsuit model but got injured in a car crash so he dumped her. Then there is Cindy with the looks (once upon a time) and money (and drug habit and thievery of them in recent memory). Now it's Sarah who still has the looks and is being investigated for abuse of power by the FBI who McCain has designated as his stand-in should he be deemed unfit. He sure has a knack for picking good looking but flawed women. But that's ok, he was in a prison camp, they all did that (not!). Remember Stockdale, Ross Perot's VP pick? He was in the same camp. He was a hero. He never used it as an excuse. James Risner was in the same camp. He was a hero of Vietnam and Korea. He never did crap like that. But while some of these guys were qualified to be President, being a POW is not what made them qualified. McCain who is certainly qualified and has the credentials is that way, not because of being a POW, but despite it.

This guy isn't a maverick, he is a wannabe playboy that happened to do a heroic job as a prisoner by helping his fellows there. He made a noble decision that I am not sure I could make, staying in a Hanoi prison when offered early release, and he chose not to. That shows he has character, but it alone does not qualify him to be president.

If he were a maverick, then Biden would have to debate a worthy opponent. He could have picked the governor of a real state like Romney or even that party traitor Lieberman from Connecticut like he wanted to. But he did what the party hacks told him to do - maverick no more. Just more of the same.

Ask yourself... Hell, ask "the google" -- "What has McCain accomplished in his 19 years as a senator"
-- Tried to rein in the tobacco industry. big success there eh?
-- Campaign Reform- yeah right. McCain/Finegold was a rousing success.
-- Limited big corporations liability due to Y2K software bugs. Remember y2k? Wow that was bad. I fell for it too. plenty of old canned corn in the crawl space.
-- He won the Line Item Veto battle at last! Struck down by the Supreme Court as unconstitutional. Oops. Republican Senator Arlen Spector of PA and head of the Senate Judiciary Committee once said McCain just has other interests than law. Yet, he's a senator, whose job it is to pass.... gas? no, "laws". And as POTUS it will be his job to enforce "laws". I would think that he might be somehow interested in the subject and know something about it, but appearently he knows about as much about the law as he does about economics.
-- McCain led the fight to strictly limit gifts to senators and their staffs and to cut back on junkets paid for by special-interest groups. Thats nice. It appears he is still in the pocket of washington lobbyists despite the ban though. A real 22 year insider he is, not that he has done much with it. That's leadership for you.
-- In 1997, he brokered a deal between the networks and family groups to establish a voluntary TV ratings system. Does anyone care any more? Did it actually do anything? Did people change their viewing habits because of it? It was specifically designed to be used with the V-Chip, which was mandated to be built into all television sets manufactured since 2000, but the guidelines themselves have no legal force, and does not apply to news or sports programming (like WWF although they use it).
-- Last year, McCain co-sponsored a bill by Sununu of NH, the Internet Tax Freedom Act, John Conyers sponsored it in the House where it was opposed by 2 people. The Senate hasn't voted on it. That's leadership eh?
-- Back in 2000 after he dropped out of the race back then, he passed some legislation for Boxing reform. Is that violent sport still around? oh my. I guess that's leadership... for a minor niche industry. Good work John!

Reagan or FDR -- They inspire, they are visionaries that show us what we can do. LBJ or Eisenhower they know how things work in government. They are mechanics. They steer millions of people to do great things.

McCain is not a dreamer. He doesn't motivate people to action and make things work. He is a survivor -- only a survivor. He survived a horrible prison camp with its torture. He kept his head above water in the Senate for 26 years.

But lots of people merely survive. but that doesn't make you a hero. Lots of people are heros. But that doesn't qualify them to be decent President.

The world and America needs to do more than survive the next four years, we need to transform ourselves into what we will be for the next 100 years.

McCain lacks the capacity.

Obama has it. Now in this time and place. And we will grow and transform ourselves and our world.

Other things

August was one of "those" months...whatever that means... Well I guess I could say, since this is a web log and all. It was a relatively cool month and everyone commented on it. I found myself having to defend against attacks on global warming theory, but as nice as it was I wasn't too convincing. Gas prices even went down, and I didn't take MARTA to work nearly as much as I had intended. The end of July was pretty hectic with all my IBM/Lotus certification exams I had to take, so it was nice to take a breather at the beginning of August to work on the design of my telescope. And then there was the Olympics, which I swore I was not going to watch, but I got sucked into it anyway. I used to be on the high school swim team so that has always interested me. (yes, geeky Uncle Bill once played varsity sports)

Susan closed our shop Nease's Needlework in Decatur. We are going strictly on line from now on. But after 9 years and a bad economy and lack of heart we were just not making it. It's a sad thing, as we were continuing a legacy in the town that went back to 1973 when Mrs. Dennis started Dennis-Art Needlework. But the good news is that we are still on line as we have been since the start. But we won't carry knitting patterns or yarn anymore. That was because of the deal we made with the person we sold the store to! Yes, the town will continue to have its shop for a few more years I hope. Susan sold the yarn and knitting inventory to one of her employees and she is taking over the lease and she is bringing in a new line of business - spinning. That means, Spinning wheels, bulk carded wool, dying supplies, classes on how to do it, and the whole shebang. Carrie has named the place "Sheepish" -- because all the cute names are gone. yeah right, like that's not cute. I hope she does well, and when she gets a website going we'll put a link up. I might even try my hand at spinning. (after I finish my telescope).

We spent last weekend moving all the needlework and cross stitch and framing and flosses and related stuff and their shelves and "Oh My God I Forgot All About That" items. Susan rented a 10X30 storage unit into which we piled it all. We didn't get finished with moving everything until Wednesday. That meant we spent the time dodging intermittant downpurs from the remains of Tropical Storm Fay that went through here.

It's well organized actually. There is no electricity except the automatic overhead flourescent light, so she can't actually do work there other than retrieve stock and box it up to send to customers etc.. We can get to everything, but there is still work to do. Susan will be taking a few months off before finding a part time job. Whe wants to beef up the marketting of the website and make a good go of that and sell a lot of the things we don't want to keep on eBay.

With the nice weather and even a lot more rain than usual all summer, the lawn greened up pretty good, so I've spent a bunch of time puttsin' in the yard.

And of course the mirror, always the mirror. It's been cool enough to spend a lot of time on it. I've finally gone down through all the grades of grit in the fine grinding and started polishing.

Whet the hell

I made the new tool. and little did I know that I would run out of #80 grit. But not before I got the tiles on the new tool all in contact. Here are some pictures of the tool after I started grinding with it. They progress from "a lot in contact" to "almost all in contact". I the former, you can still see where some of the grit has attached itself to the wax leftovers. As it progresses, you can see how all the tile glazing begins to go away, such that in the second to last picture, its only in the center of the tool, and in the last picture its virtually gone.

After conferring with the gents on the ATMLIST, They all agreed that I should jump ship and go with the #120. So what the hell. I cleaned up the shop thursday night, I did it. And it's working the charm. Currently I am fighting to get rid of one really nasty pit , and to get the focal length about an inch or less longer than it is right now. The way I figure, if I keep the tool on top, and go through about 3 or 4 more whets, the big pit should be gone, and the FL should be just about right. I'll bet that I get onto the #220 tomorrow evening.

So I went up to the disposable tool store today (Harbor Freight) and got a few things. A new dusting brush for my workbench - last the last one, and the one that I was using is really for scrubbing floors... (wrong tool). And I got an old fashioned red liquid thermometer to hang up out there (it hit 86 degrees today). I got a 10x magnifier and an LED flashlight and a new apron and some new blades for the box cutter. And some other stuff I forget right now.

$24 even for cheap crap. Lotsa cheap crap. And the way I use it, it will never wear out. I love that place. Sure its made with cheap Chinese slave labor, but what isn't anymore? I am so bad sometimes. But I gotta do something to feed my leftist guilt, eh?

-Bill

Mirror Mantra

Sailors on tall ships had them while trimming sails. Old Irish women had them while weaving cloth. Field hands had them while picking crops. Chain gangs had them while tarring roads. Bakers had them while kneading bread. Hikers had them while on the trail. When I mow the lawn, I have several. There is even a modern one for computer programmers. "Working 40 hours on the Xerox line" by Stan Rogers.

Chants.

And thus, today, when I dosed my new tile tool with a charge of #80 grit and some water and started the old back and forth, these rhythmic songs started creeping into my brain like a slow distant freight train.

It was hot out there. About as hot as I would attempt it. Over 90 degrees in the shed by the time that I called it quits at 3pm. My hands were wet with water, and that helped, but boy, I really need to wait until after August for this thing. Or at least wait for a cloudy day.

But to keep going and to keep even pressure and even strokes, it was the meaningless mantra going through my head that eased all the work.

I don't like music when I work. I find that I get into listening to music way to much. I ponder it when I do. Maybe it's that I don't like things to interrupt the music. But when I do work in my shed, on the telescope or whatever, or when I am programming, I like things very quiet so that I can concentrate. And then the voices start in my head. I talk to myself in meaningless ways - giving myself encouragement, and admonishing myself on mistakes made. Or I count how many strokes it takes to make one round (between 60 and 73). There is the rhyme and rhythm of counting that all blurs into simple meaninglessness after you miss-count but continue making the noises in your head anyway, just for the hell of it, and because you aren't done yet.

Porter was wrong. The mirror isn't the thing. Its the cadence... now that, the cadence is the thing.

More pictures next time. They are out in my shed in the camera on the workbench, and I am too hot and too lazy to go out and get it right now. Not too exciting. Same old tool. I have it wrapped in clear packing tape now, and I'm not so sure I like that idea too much. The slightest wrinkle causes little tunnels where grit can reside. So when I finally get to the #120 and later ones, I am going to have to strip all that off, clean the tool and start over from the wax stage each time. I keep telling myself that I did manage to save a lot by not using dental $tone. I'm cheap - its worth it.

Where I left off with the mirror was hogging it with a 2" pipe cap. I thought it would take forever to get this new tool to the point where every tile is fully touching, but after today, it looks like most of them are there, and even some of the ones I thought would simply never make contact are half way there. I'm pretty impressed with tile tools, let me tell you.

All of the worry about having the tool stick - like when you have two peices of glass - is completely gone. You spend your time grinding instead of worrying. You start thinking of how you can press down on it more, rather than thinking how much can this this sucker drag. I am truly amazed.

After a while, I noticed that the glazing was being removed in a ring around the center of the tool. It was a stark reminder of how grinding of the mirror really works.

If the tool is grinding away at an annulus ring, then the mirror on top, must be grinding a hole in the center to match it. Sure enough, when I took my first spherometer measurements, it was .038 in the center and .036 at the edge. .038 is a little too deep for me, and I wanted to remove that hump of glazing on the tool, so I tried it about 10 rounds with the tool on top. I was worried that the packing tape would be slippery when wet, but it was actually just fine to hold on to, dry hands or no. After 10 rounds, I checked it again. .0365 in the center, and .0345 at the edge. And I got rid of that glazing.

One thing I noticed was that using a big tool like this makes the surface a lot more even than you can control with a 2" pipe cap or 3" flange. As my data proves, the numbers were all over the board. But with just a gut feel even after such a short time "lapping in " my new tool, its obvious that these kinds of anomolies will subside. I checked all over the mirror, and its really very even from the center all the way out to the 10.5" ring. None of the measurements I took inside that ring varied from .0365 at all. At the 11" ring, none of them varied from .0350, and at the edge, none of them varied from .0345".

So, the next plan...
1. Wait for a cooler day.
2. Grind with tool on top for a while to get the the measurement between .0320 and .0325 all over if I can.
3. Switch up to #120 :)


-Bill

Waxen it down

I might be movin' to Montana soon
Just to raise me up a crop of Dental Floss
Raisin' it up
Waxen it down
In a little white box
I can sell uptown

-Frank Zappa, Montana


So I have the tool now, and I sealed it with some deck sealer I had around and let it dry. It says its for concrete, and it says you can clean it up with soap and water.

right...

I tried soap and water. The brush felt like I put rubber cement on it. Then I tried MEK. It just stank. Then I tried alcohol - worthless. Finally the old standby, paint thinner - it did the job. oy. But the tool is sealed at least

Then I levelled the tool and put a packing tape dam around the edge. Levelling is very important, since I would be pouring liquid wax on it in a bit.

After melting two bricks of the "Gulf Wax" used for canning preserves and such, I poured the wax over the tiles and let it congeal. It was about 1/16 to 1/8 inch thick. And while it was still soft, I scrapped it off with a little wooden scrap wedge that was handy.

One thing I noticed, was little bubbles in the wax, and I was disappointed in them. This kind of wax has a lot of that anyway, but here it seems like a place for disaster to hide. So after I scapped off the wax, I took out my low wattage (10 watts) fine point soldering iron and remelted all the channels to let all the little bubbles pop to the surface.

Bubble free, and with wooden wedge in hand, I scrapped 1/32" of wax out of the channels. It just came right up. I noticed that some of the wax was coming loose around the edges, so I packed it tight and took the propane torch to it and light (ever so lightly ) wafted the flame and sealed them.

Alas, I let it drip down the side of the tool once or twice. And while I could peel it back off, there is always some wax left. Paint (red acrylic - leftover from my front door) doens't like to stick to wax much, and so, this morning, when I went out to paint it, I scrapped off as much as I could and painted it anyway. I hope it work, but I have a feeling that it will peel before too long. I will put another couple of coats on and then wrap the whole thing in several layers of packing tape as David suggested.

Here is a video of me scraping wax. Its pretty easy when its warm.

Here are some other pics.

I put a couple of bricks under an old kitchen pan. That and the wax and the torch and some tape is what I used.

Here is what the wax looks like when you scrap it off. I did it diagonally with a little wooden wedge I had laying around. If I had done it normal/parallel to the channels it would have caught in them in an uncontrolled way.

Here it is after removing the wax and the dam.

Closeups of the wax after scraping 1/32" from the channels.

No animals were harmed in the making of this mirror

I rewarded myself for having handily passed my first certification test by working out in my shed on my grinding tool today. Plenty more pictures. It rained like crazy today. Very odd for July in Georgia. On loud thunderbolt made the lights flicker and we lost a small branch out of one of our sweet gum trees. I normally collect rain water around here for garden irrigation (because of the 5 year drought) and I used some of it to fill my tub of water.

Anyway, David Harbours method of creating the grinding tool is a charmer. I slid it off the mirror friday evening after I got home without a hitch. Today I pulled out all of the match sticks, and the aluminum foil and wirebrushed any loose cement and picked at it with an awl. I finally bevelled the sharpest edges around the outside edge with the sharpening stone.

Unless you count insects, I didn't harm any animals. But man I hate wasps, and there are a couple of dead ones in my shed. And an ant that decided to crawl under my wirebrush. Oh well. Albert Schwitzer, I'm not.
In no particular order, some things I did or noticed with some comments. This is the edge after removing the dam. It has some puts that I will fill before coating with the water seal.

An edge-on view of how one row got a little skewed from the rest.



Edge on view of the smallest of the partial tiles. notice that they are a little slanted down to the left. Eventually they may come into contact maybe.

This is the right after removing the dam around the outside. you can see that I have removed some of the match sticks which were still wet. There were surprisingly few places where little "posts" of cement occurred at the intersection of match sticks. I guess its because I used square tiles instead of hex tiles like David did. Around the edge in the gaps are wadded up aluminum foil. If I were to do this again, I don't think I would use that, as the aluminum seems to have chemically reacted to the pOH of the concrete and got brittle, mushy, or flat out disintegrated. I had to scrap most of it out. I think I would try somthing non-porous, like silly putty or something.
Here is another shot of one of the chunks of foil.

Here it is with a third of the sticks removed.

And here I am using the awl to get the others. its really a matter of flicking them out of the way. Once that is done there were several places where cement extended down to the face of the tile. But there wasn't much of that, and a stiff wire brush got it all.

Like I said, it rained to beat the band. Here looking across my back yard. The camera was up under the brim of my hat.
I Thought I would rinse it off in the storm, but soon realized that all I was doing was getting grass on it. So I brought it back in and dipped a few gallons of water from my rain catching system into my wash tub. I stayed a little dryer that way too, heh!

This is how it looked right before rinsing it. I did the back of it too. It was a little mottled. the deepest indentation on the right is about 1/8 inch. Later I ground it over an old round concrete stepping stone. Smooth as err... concrete now :)


Here is one section of where I bevelled the edge.

Here is a little chip on one of the tiles. Hope it doesn't hurt much.

No leftovers

At 16 years of wedded bliss, I can say that I don't mind leftovers anymore. Susan is a really good cook, and its par for the course I guess.
But when you take apart a lawn mower or a printer, or some other thing with screws, gaskets, washers, springs, levers and opto-interrupters (not that the lawnmower has that) and you start to put it back together again, I can't help but get two mutually exclusive yet sinking feelings in my stomach...

"There aren't enough parts here to put it back together..." and "I screwed something up, because there are two many parts here."
When I get both of those feelings at the same time, then I know I am doing it right and all will work out well.

So when I estimated how much dry mortar to dip out of the quikcrete bag to put into the wheel-barrow... and wondered if it was going to be enough... and got that feeling... I threw a few more scoops in for good luck. Funny thing about luck... if you get it, you are lucky. Well, I got lucky. There was just enough leftover to fill a crevase by the door of my shed that I keep meaning to fix. Oh happy Friday. (well Thursday, actually, but tomorrow is the 4th :)
After filling in a few of the places of missing tile with tin foil as suggested by David Harbour, I pulled out all of the interim stabalizing match sticks and made ready to pour.

Here is the bag of Quikcrete Mortar mix I used. I estimated that I would use about a quarter of it, and then upped that to on third. Yeah, go ahead, call me a wuss. I put it on a hand truck to get it from my pick-up down to the shed. Easier that way.

Here is the water jug. I used the amount of water that was between the black marks to mix with the mortar mix. The instructions say that you should be able to have 1/2 inch of the stuff on a trowel, and that you should be able to hold the trowel vertically. That seemed too thick to me, so I added a little more water. It was about twice as thick as a slushy down at the 7-11. (we don't have 7-11's down south anymore. But I remember :)

And here it is after I added the mortar. I ladelled it in there, starting from the center and working out, so that there would be no bubbles. It was about 1/2 inch thick as I worked to the edge. After that, I just piled it on, wondering with ever coop full if there was going to be enough. It was hot out there in the shed today, about 90 degrees. I was already sweating, but wondering if I had enough mortar made it worse. And there is nothing worse that having to make a second batch, because you never get it the same consistancy.


One thing I had to do was to level the mirror. If I had listened to Francis O'Rielly, I would have done that beforehand. But of course, I am stubborn and want to learn from my own mistakes rather than the wisdom of others. I'm such a toad.

Its about to storm here in a few minutes, and I left the tool just as you see it here, unwrapped. I'll go out later on for one last screeding and close it up with a damp towel inside and wait a week and see what I get.

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.

-Bill