After waiting a week for a first class royal mail delivery my new bevelling tool arrived and an hour was spent doing what is likely the last bevel I will need to do on the mirror unless I have to go back to 80 at a later stage.One thing you don't realise before grinding a big mirror is how many bevelling stones you need.Ive been through atleast 6 or 7 by now, a few early ones snapped but my technique is much better now :)
cleaning off that 80 grit ready for 220
heard back from john who said that I should do an hour with the 220grit and a 2" overlap then pencil test to check for good contact.The first pencil test wasn't that good so I did another hour and tested again with slower more deliberate strokes.Bingo,much much better contact now and the pits from the 80 grit were disappearing fast.1 more hour has been done with the 220 grit and two further pencil tests which look perfect and I think there are 2 small pits left from the 80 grit so I will probably do another 30-60 minutes with the 220 grit to make sure its perfect then move on to 400 grit which will probably take a similar 3 hours or so to do.600 alu oxide to finish then its time to make a pitch lap and then many hours polishing.Cant wait!!!
getting good contact
good grid waiting grinding.not a pencil but still qualifies :)
pretty much perfect contact now.this is 3 or 4 times round the table
finished curve.not 100% sure if it looks exactly like a sphere or not but I will find out eventually
Think that's if until next Tuesday now and then I need some 600 grit ordered.I move house on the 26th so likely I will end up with a couple of week inactivity as I will have nowhere to grind so will try and make my ronchi tester
upto now ive done 73 hours on the mirror and im upto 12h 15 minutes with the tile tool.the time is adding up,and its been 6 months since I started <gulp> admittedly I only do a few hours a week so ive not hammered it.
clear skies Rich