Grinding your tool

[koputai (Jason)]

Folks,
Many years ago I bought an 8 inch mirror grinding kit from Astro Optical in Sydney. It was a very comprehensive kit, and came with two full thickness 8 inch blanks.
I started out and did many hours grinding and now have the first grade abrasive done, and have a mirror with the right depression depth, and a tool with the corresponding peak.
Now, I see this as a bit of a waste.
Is it possible for me to finish grinding from here in with a different tool? One that isn't another 8 inch blank?
Could I then feasably use the 8 inch tool I have as a blank for another mirror?

Cheers,
Jason.

[rmcpb (Rob)]

Make a tile tool molded on your mirror and run on the rough grit for a while longer to get it bedded in then go up through the grits.

[Garyh]

Hi Jason,
If you have already hogged out with the tool, you might as well go through all the grits etc and finish of the mirror with it.
Make a plaster tile tool for the glass tool and make a second mirror with that..But I suppose you will have to get the back flat again which will be a bit of work!
cheers Gary

[madtuna (Steve)]

Grinding your tool



am I the only one with a dirty mind?

[GeoffW1 (Geoff)]

Originally Posted by madtuna

Grinding your tool



am I the only one with a dirty mind?

Absolutely not but no-one wants to be first

Cheers

[koputai (Jason)]

Originally Posted by Garyh

If you have already hogged out with the tool, you might as well go through all the grits etc and finish of the mirror with it.

Yes, good thinking, might as well.

Make a plaster tile tool for the glass tool and make a second mirror with that..But I suppose you will have to get the back flat again which will be a bit of work!

Would that be purely for mounting reasons?

Cheers,
Jason.

[Garyh]

For both mounting and grinding you will need to keep the back flat or you will get astigmatism. Depending on your blanks if they are out of sheet glass or especially moulded blanks you will have to grind the back flat anyway.
I very roughly did the back of my 6" mirror to knock off the high spots (moulded blank). Knowing better I should have spent a good hour or 2 getting it nice and flat!
cheers Gary