Removing a knob

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Smokedaddy
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Removing a knob

Post by Smokedaddy »

I thought I'd ask before breaking something. I need to remove a knob from my Polyvar MET. It's about 4.1275 cm in diameter and it has a slight edge on the backside to grip. I removed the set screw so that's not an issue. Do they make a wheel puller for something like this? It rotates a diverging mirror from transmitted to reflected light and more than likely unobtainable so I need to be careful. It's the knob in the middle of the screen

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-JW:

PS: there is no screw in the SHAFT either.

grgh
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Post by grgh »

presuming that there is something not working with the diverging mirror.
Why pull the Knob off when it looks as if you could access the mirror by undoing the lighting tube access panel at the rear.

Just a suggestion as i have no experience on a Polyvar MET.
used to do astronomy.
and photography.
Zeiss Universal Phase contrast.
Zeiss PMII

Smokedaddy
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Post by Smokedaddy »

grgh wrote:presuming that there is something not working with the diverging mirror.
Why pull the Knob off when it looks as if you could access the mirror by undoing the lighting tube access panel at the rear.

Just a suggestion as i have no experience on a Polyvar MET.
Thanks for the suggestion. The mirror can't be accessed that way. The plate can't be removed until the knob is removed. When farting around with this last night, I noticed that the mirror has fallen off and is inside at the bottom. I thought it was missing or that someone broke it. I can't tell if it's broken somewhere but the part I can see is intact. I suppose I'll have to machine a wheel puller specifically for this particular knob.

Image

-JW:

lothman
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Post by lothman »

could you try to lift it off with two small crowbars (coffee spoons).

Smokedaddy
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Post by Smokedaddy »

lothman wrote:could you try to lift it off with two small crowbars (coffee spoons).
Thanks for the suggestion, I tried that. I'm going to fabricate something like this tomorrow. Hopefully I have the concept correctly.

Image

-JW:

elf
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Post by elf »

Was there more than one set screw in the hole?

Smokedaddy
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Post by Smokedaddy »

No

Smokedaddy
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Post by Smokedaddy »

... got that puppy off.

Image

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-JW:

rjlittlefield
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Post by rjlittlefield »

Nicely done! Any indication why it came off so hard?

--Rik

Smokedaddy
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Post by Smokedaddy »

Nope, the shaft wasn't marred whatsoever. Polyvars are build like a tank. From what I've read they were very high quality scopes. I'm quite lucky that all the prisms are in excellent condition, all the objectives, filters, cubes, Nomarski etc. Looks like the mirror survived falling off too and didn't break during shipping. That's totally amazing. It has some damage where the clips were and elsewhere but the mirror surface/coating looks good to me. All the clips and small pads on the clips are there as well.

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-JW:

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