ring roller

[ch2co]

Savarin
Is this a mirror that you ground yourself? I'll be interested as to how well your parabolic deformation works. Do you have a Foucault tester to follow the
deformation process? That would be fun to watch.

CHuck the grumpy old guy

 

[savarin]

The 8" was a chinese mirror that had an excellent surface but was so undercorrected as to be almost spherical so we thought why not give it a go.
I was very careful as we didnt want to damage the coating
Due to its short focal length rather than pull the flat back I re ground the back side to the same RoC of the front surface, glued everything up and tensioned it via star test so sorry no Foucault.
I also am looking forward to seeing these mirrors change under the test and will try to video it.
Wont be for a while though, still heaps to do before I get that far.

 

[ch2co]

Take some pictures for me! Sounds like a fun endeavor.

 

[Wreck™Wreck]

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.



I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.



Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544

 

[rwm]

Holy Crap!
R

 

[brino]

I do it like so, 24" rings on a 34" aluminum plate in the gap bolted to a faceplate, 304 laser cut SS 1/2" thick. Four parts took over 30 hours including set up. Not including drilling and tapping the plate and milling the clamps.

Thanks @Wreck™Wreck for showing that setup.
I will likely never need it in my home shop but always appreciate seeing how it could be done!

-brino

 

[Wreck™Wreck]

My employer did his best to find a shop with a HBM or Bullard of appropriate size but there were no takers, no one wanted this job, we did it at considerable cost in house.

 

[Wreck™Wreck]

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.



I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.



Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544

 

[savarin]

Now thats a face plate.
Thanks for the idea, hmm, thinking.
How did you machine the faces or was it only inside and outside dia that mattered?

 

[Wreck™Wreck]

Now thats a face plate.
Thanks for the idea, hmm, thinking.
How did you machine the faces or was it only inside and outside dia that mattered?

Face halfway, move clamps to the other side and finish face, same with the diameters, clamps on outside and turn ID and face, move clamps to OD then turn and face, flip and repeat, this requires much patience but I am paid by the hour.