Re: [ATM] trepanning mirror

[aki.lotjonen@phnet.fi]

Hi Joe,

Yes, it could be difficult it you do not have the core or plug, what 
ever the correct name! :) Measure the hole diameter. Drill with a 
suitable size biscuit cutter from, for example, 10 mm plate glass a 
suitable new core. Plaster it back to the center hole of the mirror. 
Ok, it would be good to grind as long as the flat core has got the same 
radius as the mirror itself. Understandable is that if the center 
hole's diameter is large, you should grind rather long time!
Another possiblity is to make 2 pcs. new disks and grind them so that 
you got about the same radius as in your primary. And the grinding work 
should not take a long time. Of coarse more work...

Rgds,
Aki




Joe wrote <nss@mwt.net>:

>
> Aki Lötjönen wrote:
>
>> Hi,
>>
>> Gregorian 8 inch f30 sounds like exciting project!
>> I have tried two methods of making the center hole to a primary as follows:
>>
> {snip}
>
>> Just
>> plaster the core back, seal with candle wax and that's it. Finalize
>> grinding, polishing and figuring.
>>
>> Regards,
>> Aki Lötjönen
>>
>> Ok, looking for suggestions on a blank I bought from surplus shed. 
>> an 8" f-4 blank,,
>>
>
> problem is  already has been cored nice beautiful core..  but now 
> what should i do with this gaping hole in the center,
>
> Sure would make grinding easy with MOT  just add grits & water 
> through the hole he he eh
>
> But seriously,,  what's the best procedure when no core is present?
>
> Joe
>


_______________________________________________
ATM mailing list http://www.atmlist.net/