polishing tool dilemma

I am back doing my 8'' f/6 mirror after 2-month break. ROC is perfect, I did sharpie test for checking T/M contact. I started smoothing with WAO already and moving at decent pace.

I would like to ask you guys about your preferences for building a polishing lap.

1) Is it better to apply pitch squares individually or pour pitch in a cast and carve channels in it?

2) What is the best way to fasten individual squares? Beeswax or turpentine? Where can I buy those?

3) Finally do you have some tips & tricks about polishing? I know general rules from Texerau's book and some web pages, but it is always good to know other mirror makers' opinion

Thanks!

Marcin,

I personally had great difficulty with individual pitch squares. I couldn't cast uniform thickness strips from which to cut the squares. Cutting of the squares and fixing them to the tool was very messy. And too much channel maintenance during the first pressings just to get good contact.

SO, I ended up doing it this way.
I built a paper and tape dam around the tool. Poured in the melted pitch.

PROBLEM: Mirror is concave, cooled pitch is flat.
Several warm pressings were required to squish a little pitch out the sides and raise the center until good contact.
MY weapon of choice was a HEAT LAMP. They are a great way of softening the pitch with good control.
When good contact was achieved, I formed the facets with a PITCH FACETING MAT. A grid pattern pressed between the mirror and lap to form the facets. They eliminate a lot of channel maintenance though trimming of the edge of the tool is still required. At the end of each polishing session I would warm the pitch with the heat lamp, spray the lap with water, place the lap mat in place, press with mirror and cover with a wet towel. About 1/2 hour before my next session I would remove the lap mat and cold press with a little weight.
Newport glass sells pitch faceting mats, Willman-Bell used to and still might. I made one from the side of a laundry basket. Highly recommended.

Two tips:
1) Perhaps stating the obvious, but, before you start thinking parabola, bring the mirror to the most perfect and smooth sphere possible. Try to parabolize directly from this sphere. If you miss and corrections get too complex don't be afraid to work back to a sphere and try again. Patience me boy, patience.

2) Enjoy.

Bob

Aside from his quirky personna, Richard Schwartz has a nice and efficient method.

http://megspace.com/science/sfe/i_fa.html