mapstar

Testing resumed today and I took the following images More work this morning although I have to go to work worst luck! Damian

Thank's for commenting Nigel I have tried a slightly different stroke on the second session and this has been a tight W as you say about an inch overhang working towards the centre with the lap overhanging the mirror about an inch at the end of each stroke. As I read it the glass needs removing across the entire mirror to bring it down to the edge without creating a deepened centre which will be difficult to correct as Ron say's . The edge seem's to be improving to me. I shall have another session before the day is out using the same stroke then leave leave it overnight to settle and take image's Damian

Cheers Mark although I wish that was true

Thank you for the advice Ron Yesterday I worked for the first time with the smaller lap for a total of 3 hour's through the day on the mirror cooling and testing between sessions. The surface to be honest hasn't changed that much at the edge but the middle now has a bump forming and overall the surface is rougher so to say Stoke yesterday was at an approximate 5" from the edge with very little overlap. More work today so as the mirror is cooling off I thought I'd add a bit to the thread. Damain

To be fair Paul I struggle with them, as you say more experienced eye's know what they are looking at. done a couple of hour's with the smaller lap today but I can say the mirror is now looking a little less smooth and I'm going to have to really study the image's to see if the edge is getting better. One thing I do know the middle now has a hill!

Thanks Nigel, good to have a second opinion and confirms what John said. I've just done ten minutes after an initial hour long wet press. The lap is not quite working so I have warmed it and I'm going to wet press again for an hour with weight on whilst moving it around to stop sticking. I've taken some test image's before I start so I can compare the progress later once the mirror has cooled. Damian

I forgot to add I also took some foucault images. I had the Knife edge on a slant as I attached it to the tester with blu tac. Think I must've had a big smudge on the mirror too? I took these on the 13/02 And these on the 21/02 Quite difficut to get decent image's and to interpretate as to what's going on but the first set show the edge quite well Damian

After polishing a second time it was the beginning of February and so I again tested the mirror using the 133 Lines per inch Ronchi screen. I was working inside the radius of curvature 7th feb 11th feb 15th feb 19th feb 20th feb 21st feb 22nd feb 23rd feb I had been using the 18" lap to work through the centre with about a 2" overhang. The image's show I have an edge problem (rolled) which I have steadily worked further out but now seem to have come to a standstill. I also began to take image's through the radius of curvature all of which was quite difficult to do as my photography equipment isn't exactly brilliant (note to self there upgrade camera) These image's were taken on the 23rd of February. The travel is about 30mm from inside ROC to outside ROC in about 5mm increments. After discussing this with John he advised that the edge was the first thing to sort out and the middle could be dealt with later.So I made the smaller 10" lap to work with minimal overhang, the centre of the lap on average 5" from the edge. Once I have tidied the lap up and cut the channels I will cold press with lot's of weight and make a start. After about an hour I will then clean and test to see if the edge is getting better and post some more images. Damian

Hi all, Thank you all for the help and advice about the smaller lap . I know this method work's for some so I will as Rick says 'try it and see how things go'. Out of interest on this I did do some calculation's on the actual difference in the lap thickness between the edge and middle making a 10" lap. The result is just over 1.8mm between the side and the middle thickness of the lap. I should imagine that this could be the difference between one side of a lap to the other if anyone's lap does not sit entirely flat whilst making? How many use a spirit level whilst setting up and on the back of the lap when casting? I shall see how it perform's over the next few day's and revert to a different method mentioned above if it does not behave. Damian

I hope I can finish it off to everyone's expectations so no pressure! I've got one of those imaging balaclava's like kenny has to stop hair loss he he More this weekend as I've been on with other things most of this week. I have picked myself up from the lap incident and optimism is coming back again Onwards and upwards and thanks for the continued support it's much appreciated. I'm sure messing about with all those imaging cable's would drive me nuts, I do enough of that at work :-D

Ha ha cheers Derek I get to spend lot's of time (and money) on it as there isn't a missus Mapstar so the foil would be very safe I think I may do one in my next decade on this earth (it's gonna take me ten years to get over this one!!!!) Cheers Pompey Monkey I'll be carrying on this weekend so look out for update's Damian

Thanks Nick glad your enjoying The notes and I'm sure one day you'll get to see the results. Cellotape is a good suggestion thanks. Unfortunately the pitch being hot make's the glue on the tape melt and let go. I used Gaffer tape in one of my much earlier pours and learn't my lesson there. White spirit is definitely on the shopping list Ron

Unfortunately I'd run out James so used normal width stuff over lapping it on the mirror. Unfortunately The pitch ran underneath during my bit of a disaster

Thanks for dropping by Derek and I agree it's very tedious at time's and enough to test the patience of a Saint.(although being an imager patience shouldn't be in short supply) The pitch is poured onto aluminium foil on top of the mirror, so come's off the mirror quite easily unless like mine it goes under the seam in the foil and sticks to the glass itself. I think the stuff just doesn't like me although the feeling is mutual Damian

Lovely story there Ron and I can quite sympathise with the pitch and rouge get's everywhere analogy. I'm finding it does very quickly. John has mentioned David quite a few times and recounts very fond memories of him. Please don't think you are interfering as it's a pleasure to read the experience and interest in the subject people have. Feel free to pop a comment in as I'll always welcome them Many thanks Damian P.s. hope you do make another mirror, although I won't be blamed for any divorce proceeding's

Hi Ron, Many thanks for the kind word's and encouragement all of which is gratefully accepted especially when at a low point. I've managed to cast the lap and although not pretty I'm sure it will work. The lap is 10" in diameter I have read of the method you describe before and it is also in Texereau's book or something very similar as I recall. I have tried a couple of methods up to now and thanks for the suggestion on the way you managed to make your's as there is always more than one way to complete the same job some much easier than others. Casting lap's is one of my least favourite bit's of mirror making and I'm always apprehensive when it come's to doing one. As far as this bit is concerned I'm not on my own as Rich hate's it too.Finger's crossed I can complete this and show it can be done but a few more knocks to take along the way Damian

The cold light of day has revealed the turps has dissolved all the pitch into an oil like sludge on the mirror. After going through several sheets of kitchen roll it's had a final clean and wash with detergent I've inspected the surface and I seem to have got away with no damage The lap isn't pretty but it will work although I will try to clean it up a little more. Damian

It may even drive me to drinking whiskey!

Cheers Ian I hope your right and I still have some teeth left! Damian

I think it probably would Daniel except there's a slight hitch in that. I can't get the mirror in my fridge :-( The turps seem's to be doing its bit. I'll leave it to soak and then give it a clean tomorrow.

Cheers soupy. My second attempt at a lap was a complete disaster with the pitch actually getting onto the mirror I have managed to get the lap and most of the foil off and now it is soaking with turps sub's to dissolve the pitch. Another set back which if it means going back again due to scratches will be a massive blow :-(

Had a go at casting the new lap and as always it turned out to be a disaster. I hate pitch!!!!!

I may do that Nigel. I didn't do it with the last lap though Damian