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John

Making a tube ring round again

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One of the tube rings on my new-to-me Orion Optics 300mm F/5.3 newtonian has a shallow sort of kink in it so that it does not sit nicely around the tube but presses into it at one point. The tube flexes so no damage has occurred but I'd like to return the ring to it's proper shape if I can. The ring is around 4mm thick steel and my vice / mole grip approach is just not giving enough "welly" to get it back into shape. What sort of tool would be needed to return it to the circular shape ?.

In my mind I see a sort of vice comprising two very sturdy upright metal rods / posts with a small gap between them being the sort of device that might enable you, with some muscle, to partially straighten the ring initially and then curve it again, without the kink this time. Am I thinking along the right lines ?

The scope is a few years old and I'm it's third owner I think.

Thanks :smiley:

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In my mind I see a sort of vice comprising two very sturdy upright metal rods / posts with a small gap between them being the sort of device that might enable you, with some muscle, to partially straighten the ring initially and then curve it again, without the kink this time. Am I thinking along the right lines ?

Hi John, back in the 60s, I worked as a sheet metal worker in an engineering factory. I learnt a lot of dodges that would have made my school metalwork teacher cringe, we learned everything 'by the book' in those classes.

One of those dodges was similar to what you describe. Two fat steel rods clamped upright into a sturdy bench mounted vice, and a bit of experiment would sort your problem I think. That set up gives a lot of leverage. Perhaps a gap of an inch or two (ahem centimeters :rolleyes: ) may work better. If it where myself, I'd find a bit of scrap metal to try. A couple of fat bolts could substitute for the steel rods, padded so as to not damage the tube ring.

Hope you sort it, Ed.

Edited by NGC 1502

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hi John

The rings on OO scopes are quite strong as you have found. I'd suggest a home made tool that will probably do the job. get two pieces of 3x2 and in all four ends drill some bolt holes (M10 I'd suggest) about 2" in from the end and central. Get two length of M10 threaded rod (or a bolt long enough for the task) and six nuts and washers - four nyloc and two normal would be good. put one inside and one outside of each wooden piece out the rod through the other side and then the nut on the outside

put the ring between the two wooden lengths and sequentially tighten the normal nuts until you get the desire shape. this will create a gradual pressure/bend and prevent problems.

I hope this makes sense. the wooden pieces act like a vice jaw with the ring inside.

all that said I am not sure how bad the kink is but do check your other 10" tube tings as I suspect this slight kink is normal for OOUK rings as I seem to recall all my scopes have it too.

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Ed and Shane,

Thanks for the helpful replies - I think I'm going to try and build a simple tool to do this job. It's just getting something which will hold the ring tight and allow me to apply some brute force - I can repaint and re-felt the ring if any damage is done to the finish.

Shane, I agree re: the OO tube rings - the other one is not entirely circular either but it's just this section that presses into the tube wall that I'd like to fix. The tube rings for the 300mm are much heavier duty than the ones on my 250mm OO newtonian !

Thanks again :smiley:

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I think i would place 2 large bolts/bars inside the vice jaw attached (cable tyes)to the back jaw, a third bar in the centre of the other jaw, let the power of the vice do the bending, you may be able to insulate the tube ring from the bars with a doormat made from rubber or some thing along those lines...

Edited by Tinker1947

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Hi,

What you need is a car body work former (Dollie) as some have curved bits that will match the diameter of the bracket, Place the former in a vice then place the bracket on top and whack it into shape with a rubber hammer, if you cover the former with cloth it probably won't even damage the paintwork of the bracket.

http://www.frost.co....ork/dollie.html

jeff.

Edited by Jeff RV

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I would also go for heating especially if you are prepared to repaint and felt.

Brute force usually = oops, with heat you can apply gentle force.

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Thanks for the further suggestions folks :smiley:

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