Diy ground glass focusing screen

[Tin Can]

I just picked up a Jagermeister shot glass, it has a 16mm thick bottom. I bet it would work.

You can use thinner glass, but it wears down.

Look in the kitchen. I sharpen knives on the bottom of ceramic plates...

[steveo]

I just picked up a Jagermeister shot glass, it has a 16mm thick bottom. I bet it would work.

You can use thinner glass, but it wears down.

Look in the kitchen. I sharpen knives on the bottom of ceramic plates...

Would a drinking glass be flat enough? Just thinking back to my woodworking when we'd sharpen chisels with very fine sand paper glued to float glass less flat stuff caused issues.

[Ron (Netherlands)]

My glass supplier had little pieces of glass laying around, one of them was big enough and I got it for free...just try your supplier
btw the glasses used for screens are cheap too: about USD 5 for a package of 3 glasses

[Tin Can]

Would a drinking glass be flat enough? Just thinking back to my woodworking when we'd sharpen chisels with very fine sand paper glued to float glass less flat stuff caused issues.

It will become flat as you grind.

But wear a glove and don't break the glass.

[Ron (Netherlands)]

Ron, Very useful, thanks for sharing!

Questions:
What's the amount of grinding powder required for a 4x5 GG - average?
Any known good source in USA apart the bay one?
What could I use to trace fine black lines on the glass which will not go away with the first alcohol wet clean cloth?
I have tried myself grinding with sandpaper and water but took too long and I gave up,


Thanks,

Renato

Renato, you'll need very little powder for a 4 x 5 inch glass, less than 15 grams
I have bought little sacks each with 100g of powder. I used about 50g of it for 7 screens (which were on average 9 x 12 cm)
I bought it on Ebay from a UK person who sold different grades of powder, since I didn't find any supplier in The Netherlands.

As for defining lines on the screen; I found a very nice print from an original ground glass that I can have printed on translucent stickers and which can be put on the screen:



cheers
Ron

[RSalles]

Ron,

Not bad at all...
Great idea btw, Randy friend has point out a suppler for powder, but that's all different in size grains: 320+ 500 insted of 400 + 600. Does it make a big difference? I mean, results will be un-usable?
Thanks, I'm sort of drunk now, listening for Dave Bowie old disks, I'm in a sorrow you can hardly imagine,

Cheers,

Renato

[Pierre 2]

One guy published some variations a while ago.

1. For tool, use a piece of wood stuck to the glass tool with strong 3M dual side tape. It is about 1.5mm thick and its foamy so it will stick even though the piece of wood is not perfect (as long as it is dry when sticking it to the glass. Very confortable handle to work with.

2. As for myself, I had valve lapping compound on hand (available an any autopart store). Worked quite well. As this compound is mixed with oil, on the glass, i just added a few drops of dishwasher liquid and some water. The rinsing did not left anything on the glass. My little can will go a long long long way...

Ron, thanks for the drawing !!!

[Pierre 2]

Ron, any chance you can email your drawing file ?

Thanks !

[steveo]

One guy published some variations a while ago.

1. For tool, use a piece of wood stuck to the glass tool with strong 3M dual side tape. It is about 1.5mm thick and its foamy so it will stick even though the piece of wood is not perfect (as long as it is dry when sticking it to the glass. Very confortable handle to work with.

2. As for myself, I had valve lapping compound on hand (available an any autopart store). Worked quite well. As this compound is mixed with oil, on the glass, i just added a few drops of dishwasher liquid and some water. The rinsing did not left anything on the glass. My little can will go a long long long way...

Ron, thanks for the drawing !!!

What about a rubber sanding block for a handle?

I've got some lapping compound and a couple of cheap Ikea picture frames so I think I'll have a punt tonight. Even if it doesn't quite work its better than watching the telly.

[ruilourosa]

Hello

What will produce the best results (brightness / contrast / snap into focus) the finer grit or the coarser grit?

i have a toyo original screen with a fresnel, and i find it so so and i have a original shen hao screen on a TZ, i find it not so bright

i would love to make focusing more easy, specially with 65 and 75mm

a bit off forum: ecbuyonline on 3bay sells some screens, are they any good? i´m also looking to the hasselblad split screen, any experiences?

Thanks


Rui Lourosa