80mm long focal length refractor

[savarin]

At last I can get back to scope work.
Now I have the 4 jaw chuck I can bore out the bearing shell.
There was just enough clearance between the end of the bracket and the lathe bed.
It was a hell of a job getting it centered, the slightest pressure on one jaw sent it way out of alignment



Both brackets bored and the bearings turned up in delrin.
The 3x8 mm holes are for the cross pieces that the clamp bolts will fit once the slots for them are milled out.
Then they have to be split in half. I think I will use the two angle iron guides again for that.

These were shaped with a file and small flap disk.
I cant make up my mind whether to bore a large hole in each side plate or not. No function just for looks.

 

[savarin]

No holes at this time as I think I may need the sides of the supports for some future additions.
Milled out the slots for the clamp bolts.

The large round disk is the top clamp holding the bearing support onto the vertical milling attachment.
And then 4 holes drilled and tapped 5mm and split them with the trusty angle iron guides and hacksaw.

The clamp bolts are 5mm into 8mm stainless, the one with the double cross piece is so that when dismantled in the dark it wont drop and be lost.

Like so. The nuts will be similar to the 8 knurled stainless ones that hold the rings together.

and with the tube just for looks. You can just see where the bottom plate has a half circle cut out for the scope tube to recess into when pointing vertical.

I'm very pleasantly surprised at the smoothness of the bearings and how little pressure is required to change the friction/force required to move the scope. (so far)
I'm not looking forward to the huge amount of polishing to be done in the near future.

 

[chips&more]

Nicely done! And I especially like how you used the angle iron! That’s Yankee Ingenuity at its best!

 

[savarin]

Nicely done! And I especially like how you used the angle iron! That’s Yankee Ingenuity at its best!

Thanks for that, but I'm a Pom.
Thats an Englishman living in Australia.

 

[rwm]

That is looking sharp! What wall thickness is that tubing? I assume you are polishing that?
R

 

[savarin]

That is looking sharp! What wall thickness is that tubing? I assume you are polishing that?
R

Everything will be highly polished at the end, I'm not really looking forward to that job.
I also want to use some profile cutters on all the edges I can so it will look better than dead square sections.
The tube is only 3 mm thick.

 

[Tony Wells]

Going to do a reflector when you finish this project? I want to see how that's done.

 

[savarin]

Going to do a reflector when you finish this project? I want to see how that's done.

Hmmm Tony, then I guess you want to see how this one is going eh?

The truss tubes are 12mm square steel tube. They are made but I still have to weld the diagonals in.
I have the two lazy susan bearings for the top cages.
I have the glass for the two mirrors plus the grinding and polishing machine ready.
They will be two f6 12" mirrors where the back face will be ground to the same radius of curvature as the fronts.
They will be polished to a sphere then flexed to the parabolic shape required. I have made one 8" f3.7 spherical mirror flexed to a perfect mirror to check the process.
When I finish the refractor I will be starting on these again and will start a project blog.

 

[rwm]

Reflector binoculars?! Will you have the image inverted?
R

 

[savarin]

Reflector binoculars?! Will you have the image inverted?
R

Yes but they are for astronomy so it doesnt matter although it helps if the finder scope produces the image the right way up and the correct left to right orientation but its not essential.