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Great stuff Rich I look forward to the progress report

Thank you for that Raymond. Nice to know that the Ronchi test was the main tool you used in the making of your superb mirror as some don't really like it. In my opinion it's easy to set up, use and is not over complicated like some of the other test method's mentioned which is all good for someone that is an amateur. If it produces a mirror that is close for me then the last stages will be a null test and finally an auto collimation test by experienced eye's. Back to technique, as I work the mirror it is rotated randomly between wet's to avoid astigmatism and hopefully produce a figure of rotation Explaining your test methods and how you had to rework your mirror to end up with the finished item is a help as it proves it can be done several way's. Much respect for finishing a lovely looking mirror Damian

Hi RickI normally leave the mirror after washing it off under cold water for a couple of hours but then retest just before another session so it will be tomorrow morning when I have another look. As you say the edge is getting nearer but it's so hard to judge changes Damian

I've just been busy with the camera again before I get ready for work Here's the result's of this morning's efforts Inside ROC Outside ROC I have used the same W type stroke as before deepening all the curve but the last half an hour I just worked across the middle 1/3 of the mirror with approx 1/2" overhang in a attempt to push the TDE out. It's also flattened the hill a little More thinking this aft before returning to the fray tomorrow morning with renewed vigour Damian

Great info Ron. I have read about the way the facets work before but cannot remember there is a full page on the web about it somewhere? Tex also has a bit in his book about the surface quality using various type's of lap although the picture's are quite dated now it does give a good representation of what it looks like at a microscopic level. I have done another 2 hour's today so the mirror is just settling before I put it to the test again, I like the bit about giving it a quiet talking to although I must admit it's not responding well to the expletive's that I sometime's use I shall post some image's although I do believe they may not be much different to the one's above in the TDE battle Damian

Hello John, A lot of thought's there thanks and just to elaborate on a few bit's which I have touched on in previous post's which maybe you missed??? I'd be surprised myself if I made a full size lap as I would probably need me to spend quite a bit of time in the gym to push it across the surface, the amount of drag on an 18" lap is phenomenal and I have 40kg of weight on the base of the table and the suction still tried to lift the legs. It's hard work I will give thought to the test you mention as the diffraction around the Ronchi image's is quite severe so other method's may be needed although the Ronchi does show a lot. Several people have already commented on lap making via the 'Tex' cutting squares method and it is something I will considered if I make another lap. I'll probably have a go at it as I have tried several other way's (in previous post's) although everything is good in theory and I suspect it will end up a very messy affair I'll definitely agree with you on a few of your point's . The pitch bit, that it stick's to everything mostly what you don't want it to hot or cold! That you have never made anything as big as this by suggesting working mirror on top or making a full size lap both of which just aren't practical or feasible due to the physical effort needed to use them The creation of micro facets is a good idea, either by the onion bag method or by placing the wet lap on greaseproof paper whilst pressing which wrinkles the paper and after several uses create's micro faceting Damian

That look's very nice Raymond and a pleasure to behold, certainly inspirational On a testing point did you use a matched Ronchi test for it to start with? and obviously other test's? Could you explain your testing as it's obviously produced a very nice mirror as can be seen from your image. I one day hope to be in the same position of being able to say been there done that and I have the picture's and test image's to prove it. Well done and thank you for sharing it with us, can we also see a pic when you get it coated. Damian

Cheers John I've yet to start the build of mine but it'll be on it's way soon

Thank you everyone for the encouragement and kind words.Ron, I have looked at Mel's page a few time's it's amazing the amount of literature you read when you get into all this. A lot quote Texereau as the be all and end all of mirror making.It's not the case just another way to do it. It's all helpful especially the encouragement and interest of others on here. I have found a few site's on mirror making and logs of people's battle's with mirrors. I have had many a battle with enthusiasm and have my occasional low points but always end up at the same conclusion that time and effort will sort it out.I just sometimes can't see the wood for the trees More work possibly tomorrow but definitely on Friday and the weekend. Cath as Peter say's I'm working towards a sphere then I can start the exciting (in mirror making) bit of parabolising Damian

Battle has continued over yesterday and today so another 3 hour's of the turned edge. Here's the outcome Inside ROC Silly me I had a cup of coffee stood not too far away in the image so there's a little thermal distortion on the lower side of the middle right hand band Outside ROC I'm not too sure there has been much change so may have to think about different tactics? I plan on another 3 hour's and see what things are like then? Damian

I'm looking forward to that too and like the rest it will probably be a fight all the way! More work on the turned edge today Damian

Managed an hour through the day but it's time for work. I'll carry on tomorrow with a test first thing to see if things have changed then probably another couple of hours of going round in circles as that's what mirror making is all about Damian

I'll agree fella as were well into our second year of this! Hope the channels are now cut

Thanks Nigel, I'm going to carry on with the stroke I'm doing at present and hopefully the edge will behave itself soon? although that maybe another 10 hour's work or so? I shall then make a start on the central hill and hopefully onto a sphere. I will consult John on the way to go about the next stage although a sphere is my first goal. Damian

Thanks Rick it's been a battle of I think 17 hours up to now. I agree the diffraction make's it look far worse than it is and when you move closer to ROC with less lines it amplifies it even more. I'll put the focuser on the build thread when I finally get there so it all ties up with that. Making a few changes which I've been thinking about on the next build it all depend's how long the mirror take's. Damian

Today has been another 2 hours of edge work and I'm sure things are improving albeit at snail pace. More image's after the last session Inside ROC Outside ROC Was hoping for a bit more work than I managed today but as usual side tracked onto dad's car repairs. More work tomorrow all being well but I have my own car to sort out and wait in for the delivery of a lovely focuser for the scope build Damian

I've done it all by hand as I wanted a true reflection of what can be done with basic tooling. It's not gone too bad up to now

Hi Derek Yes I've seen the video's of Gordon definitely good to watch and it does show the work involved in making a large mirror. Only thing it doesn't portray is the time scale and mental strength you need to see it through to final conclusion. It's taken a lot and will take more before I'm finished. Done another 2 hours today although was hoping for more but had my dad's car to fix so cut short today. I'm still battling the turned edge and get to a sphere so I can actually start the figuring process of creating the parabola. Long way to go yet with the edge problem though. Damian

Result's of today's session Inside ROC Outside ROC Got to admit it's difficult to see any difference Tomorrow is another day with the new cerium oxide stock so I'll carry on with the polishing Damian

Cheers James. It really is testing at time's and I wouldn't be where I am without good support Damian

Cheers Guys,I've been trying to work the edge with the 10" lap starting at the edge and working inwards in a tight W as glass need's removing all over to bring the surface down to the bottom of the turned edge. I'm obviously working the edge more as you say the oblate centre proves this and can be dealt with later. It's beginning to show progress but as John said don't go mad. Looking forward to this aft and tomorrow to see how the image changes fingers crossed it will show more improvement. Damian

Morning all, I've steadily worked away at the mirror and here are the latest Ronchigrams. Roughly 12 hours since I started to work on the TDE Inside ROC Outside ROC I had a few speck's of moisture on the mirror centre from where the lap had been pressing on top in the image's . The turned edge is improving but I'm also getting a hill forming in the centre which will be dealt with once the edge is sorted. I was running low on Cerium Oxide (2.5uM) Wednesday so yet again .5Kg more ordered which hopefully will see me to the end but only time will tell. More work this afternoon Damian

Thanks for the image Ron hopefully I will one day see the same reflected back at me. At present it's a battle with the edge and then hopefully achieve a nice sphere. The battle is still raging and it will be quite a while until the war is won. I will be using a matched Ronchi test but this will be backed up hopefully in the end by the Ross Null test and then the final test by John on his test equipment. Long and winding road to travel as yet. Damian

After this mike I'm gonna have a few! Make sure I bring some up that there Galloway to celebrate

Just a couple of pic's of the 10" lap in action, I apologize for the blurry shots think the camera is as dizzy as I am after all this going around in circle's It's working well just an addition to the thread whilst pressing again Damian