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Posts Made By: Ed Jones

April 13, 2004 02:52 PM Forum: Telescope Making

Have you silvered a mirror?

Posted By Ed Jones

I'm looking to talk to anyone who has actually done silvering. I'm trying it but am having some problems with staining.

Ed

(glad to be back on Astromart Forums)

April 14, 2004 03:39 PM Forum: Equipment Talk

Silvering.

Posted By Ed Jones

Has anyone on this forum ever silvered a mirror? I need to talk to someone who has or can connect me with someone who has.

Ed Jones

April 18, 2004 06:38 AM Forum: Telescope Making

Vladimir please check this out.

Posted By Ed Jones

Vladimir, what do you think of the performance of this Newtonian? It has astigmatism slighlty less than half the coma of an equivalent parabola but is that good enough? The obstruction is .24.
Ed Jones

May 6, 2004 06:32 PM Forum: Pictures of Me and My Telescope and........

Dob from hell OTA comes together

Posted By Ed Jones

Bizarre scopeII OTA is coming together nicely. I still need more coats of urethane and black paint on the middle section. Hopefully I'll get the rocker box cut out and assembled this weekend. Hope to be done by June 10th. You ain't seen one like this I bet.
Ed

May 10, 2004 07:43 PM Forum: Telescope Making

Re: Turpentine dissolves stuck pitch

Posted By Ed Jones

Andrew,
Too messy! You could have just stuck it in the frig and then the freezer, pitch is easily stripped from a lap when frozen. Chances are your mirror might have separated without destroying your lap as well. Try it next time in a plastic bag to recycle your pitch.

Ed

May 14, 2004 04:44 PM Forum: Telescope Making

Pizza method, step1

Posted By Ed Jones

Andrew,
Sorry for the delay, I had to shoot some pictures for a demo.
Pizza Method -
The usual method of making a pitch lap is to put tape around the edge of the tool and pour pitch into this mold and then press it to conform to your mirror or lens. This layer is lens shaped so you have to move (by pressing) pitch from the middle of the lap to towards the edge to end up with an even layer of pitch. With my “pizza method” you pour a flat layer of pitch into a mold and then let it sag when it hardens like taffy then drop the tool down and on top so that it sticks. There is no advantage for a flat lap but if you have a curve it will save you a lot of pressing. Also you never will never have to worry about your tool and lap sticking together.
Precedure:

Step 1.
Cut a piece of aluminum foil bigger than your tool and fold it around the bottom side of the tool. Trim the edge with sissors to an even length. Carefully pull it off the back to form a mold. Make sure it lays flat on a flat and level surface. Take some solvent on a small cloth and rub it on some pitch then wip your tool with this cloth. When it dries you’ll have a surface that the pitch will stick easily to.

Here is a couple of lenses I needed laps for:

May 14, 2004 04:48 PM Forum: Telescope Making

Step 2

Posted By Ed Jones

Step 2:
Pour the pitch in your mold hot enough to flow well. It’s good to have your tool warmed up a little too so it doesn’t freeze the pitch too quickly.

May 14, 2004 04:50 PM Forum: Telescope Making

Step 3

Posted By Ed Jones

Step 3:
When the pitch gets the consistency of taffy (and don’t wait too long) slide the pizza off onto your mirror curve. Fold the edges of the foil back and drop your sticky tool onto the pitch evenly. Now press as you would normally. If the pitch is too hot it will squeeze out the edge too quickly so just wait a little or press with less force. If you do it right it will mold into shape easily with much less pressing. Make sure the pitch has stuck well to the tool. When cool you can pull the foil off the pitch as easily as pizza dough. Now you can trim the edge and cut the channels, I prefer a hot knife for this. Hot press it again (after you cut the channels) against a piece of garbage bag plastic and you are ready to go. If you screw up just throw it in the freezer and strip it off and try again.
I’ve done this for years and the only disadvantage is that foil comes in 18 inch widths max.
Your saw it here first folks. Good luck, gotta go, pizza’s here!
Ed Jones

May 15, 2004 07:39 AM Forum: Telescope Making

Re: Pizza Method

Posted By Ed Jones

Andrew,
I thought this up years ago and I haven't seen it published or used elsewhere. I'm basically lazy and will always try and find the easiest method as long as it works. This method is not useful for flats but is meant for more strongly curved lenses and mirrors. lenses especially have stronger curves and the masking tape method is totally useless in many cases.
The channels in pitch allow the pitch to flow as it conforms to the curve and the size of the squares is a function of both the pitch hardness and thickness. If your pitch acts too hard (no flow) then you must either add more channels or pour it thicker, still better is to just remake it adding a little solvent to make it softer. On the other hand if the pitch is too soft it will flow too fast and you should pour it thinner to compensate. I think the thinnest possible pitch will give you the best sphere as long as it still flows. I think what you are refering to is that primary ripple is related to the spacing of the channels. I make my channels by eye and they are never the same width and more importantly keep the channel width small to prevent this.
I polish with cerium oxide and finish with Opaline. I got tired of turning everthing including myself red and Opaline actually does better job and doesn't scratch.
I'd never make an F/4 Newt., too much coma, too hard on eyepieces more difficult to figure.
"Any tips for slower f ratios besides a tester?", you mean testing tips? For the first time mirror maker I recommend the conjugate null.
Ed Jones



May 22, 2004 06:08 AM Forum: A Day in the Life of the Administrator

Question

Posted By Ed Jones

Herb,
I have a box of glass blanks all the same about a dozen pieces. How can I sell these by auction? Do I pay $4 for each one I sell? My wife is cleaning house.

Ed

BTW nice job on your site.