2 replies to this topic

[David Dakstar]

I am figuring a 20 inch f/4.1 mirror with a sub-diameter 10 inch pitch lap. I want to use a W stroke more.

 

But I am not sure exactly how to do the stroke correctly. I need to deepen the centre and middle zones compared to the outer zone. Should I do a narrower W stroke nearer the centre and a wider one further out? Or keep the stroke the same all the way across the mirror? I have read explanations for the W stroke MOT. But cannot find any for TOT.

 

I am using a powered turntable rotating at around 3 rpm and figuring by hand. I have been using centre over centre strokes with various offsets from the centre, but I think a W stoke should give a smoother surface.

[PrestonE]

I find it easier with a Powered Turntable to do the Offset

and do say 30 seconds with one length, 45 seconds with another

ect...

 

Easier than trying to keep a W consistent...

 

Though, I actually use the Overarm and change the stroke and time

depending on what I am trying to do.

 

That is How Carl Z does it.

 

Best Regards,

 

Preston

[Scott E]

The narrower the W and the shorter the strokes, the faster you'll deepen the center. That could lead to a zoney surface but don't worry about that till you're near the end. At that point you'll need to cover the whole mirror pretty evenly. You'll start to get a feel for how your tool works in time. Every tool is different.