6 replies to this topic

[strdst]

I'm considering ways to replicate a broken lock knob on a very old scope. The original seems to be cast iron. Since it came to me broken I wonder if it was pig iron...brittle? I can't remember if the pieces came with the kit or not. One of these days I'll do an exhaustive (exhausting) search for remnants through my telescope debris, but until that day arrives...

 

I'm entertaining these solutions...

 

One would be to locate a farrier to pound out an end of a shoe into a general shape then I could sculpt the metal with a file.

 

Or make a casting of clay and find someone with a forge. I read using a cutting torch to melt iron for casting isn't recommended.

 

Or find a jeweler to make the casting and go with silver or gold. Hmmm, maybe not...although...

 

Or have it 3D printed in metal or plastic (metal preferred).

 

Or, and this is one I could do at home, make a mold in Fimo or Sculpey clay using a good knob and fill with JB Weld. Then finish with a file and drill for the threaded shaft.

 

I'm leaning towards the epoxy idea. My experience has been very good with JB Weld but perhaps there are other materials that would be better.

 

So I'm wondering what some of you might think would be a more elegant solution?

 

For some of you younger folks, that's a half dollar for scale. 

 

TIA, keith

 

 

 

 

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[Astrojensen]

That looks VERY easy to make from a piece of flat iron. Cut to rough shape with a hacksaw or angle grinder. Drill a hole for the threaded stud, with a perpendicular hole in the knob at the end of the stud hole. Put the threaded stud in, weld the perpendicular hole shut, to secure the threaded stud, and file the knob down to final shape. 

 

Easy. 

 

 

Clear skies!

Thomas, Denmark

Edited by Astrojensen, 10 February 2025 - 03:14 PM.

[ccwemyss]

Or buy a small piece of steel or aluminum plate from Online Metals, drill a hole in one edge for the shaft, cut and file to match the profile, then drill cross-hole to match the cross hole in the shaft, and put a new pin through.

 

McMaster also has four-arm iron knobs that you might be able to cut down.

 

https://www.mcmaster...le-hub-knobs-6/

 

Chip W. 

[clamchip]

Maybe something close like this?

  https://www.mscdirec...etails/07108459

 

Robert 

[strdst]

That looks VERY easy to make from a piece of flat iron. Cut to rough shape with a hacksaw or angle grinder. Drill a hole for the threaded stud, with a perpendicular hole in the knob at the end of the stud hole. Put the threaded stud in, weld the perpendicular hole shut, to secure the threaded stud, and file the knob down to final shape. 

 

Easy. 

 

 

Clear skies!

Thomas, Denmark

I do like easy but I'm thinking the clay mold/epoxy build up might be where I'll start. The bottom of the mold should hold the shape (1/2) and the top will require sculpting. I'm thinking I can build it around a dowel where the threaded shaft should go. I don't want to epoxy the shaft in place in case it was a bad idea. I'm pretty sure mid 1950's Japanese threads are hard to come by. If it works, I can use the dowel to hold the part as I file, then burn the wood out in the wood stove fire. I'll report back sometime if it works (or not).

 

Short digression. Thinking about melting metal, forges, furnaces brought up an interesting memory. 60 years ago in 7th or 8th grade (Jr. High), I took a drafting class. The classroom was shared by the kids in metal shop. Rough bunch they were. The "teacher" spent the class period studying the L.A. Times stock page. I mean every day. He must have saved Saturday's paper to read at "work" on Monday. He seemed to use the newspaper to insulate himself from the kids who were trying to learn skills or wanted to just dork off. Enter dork off...

 

So this rather large, intimidating sort of guy (Paul, I think) in metal shop one afternoon holds a steel rod maybe 3/8" diameter in the furnace and I suppose when it didn't melt away he became bored. So as teach is studying the stock page, he makes a slow walk around the classroom and sidles up to my drafting table and asks whatcha' drawin'? I don't remember what my response was. Either I ignored him or said something smart a**. And of course his response was to lay the still glowing rod across my bare forearm. My skin bubbling and smoking, me yelping, teacher annoyed he lost stock price concentration, and big ol' Paul claiming he didn't know it was hot!  Carried that scar for years but couldn't locate it tonight. It was kinda cool, a conversation piece I suppose. So thanks Paul, well done! And I mean well done!

[strdst]

I'm quite sure this thread has limited, if not nonexistent interest, but I started it and might as well continue, right?

 

Silence.

 

Maybe it has some value in that it celebrates the ridiculous projects we take on in the name of classic telescope restoration...love. It is love and responsibility, right?

 

Maybe. And perhaps I just need something to do in the winter dreary, the hunger months, while feeding the wood stove, avoiding the news cycle. The vegetable garden won't need my attention for a while yet. Of course my sweetheart has my attention 24/7 but with her 40+ hour work week and my retirement status leaves me with time or tools on my hands. Mostly time.    

 

I approach these little telescope projects with few tools and no skills. That might be inspiring to some. That would be cool. I wrote a thread a long time ago about fashioning a lock knob for a Swift telescope out of a screw, a bunch of nuts, a file and a drill. Maybe I titled it "Counting Flowers On the Wall"? A lot can be done with a little. I occasionally find well knapped arrow and spear points left from the previous peoples that walked, hunted, fished on what I now call my place. Inspires me. I also have found what I'd call knapping fails and that inspires me as well.  My skills haven't developed much. Thousands of round and flat file strokes, a too many battery charges on the drill, (always quits when you are so close to done!) Primitive but it gets the job done. Knapping a cast iron Nippon Kogaku replacement knob. I like that. Wouldn't broaden the interest here but it does sound cool and it pretty much describes what I've been doing. 

 

Some photos...

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Edited by strdst, 18 February 2025 - 02:02 AM.

[strdst]

After hours of the scritch scritch of the files I'm finally there I think. I have another rough bun in the oven if this one fails.

 

This Nippon Kogaku came to me from a wonderful, maybe crazy man. Maybe not. It was 15 years ago. He believed through a lucid dream he was invited upon an alien spaceship and was shown a propulsion system that he called scroll technology. He spent years trying to develop it. I believe he thought he got it down. But of course there wasn't a market. Too much oil corporate push back I suppose. He thought it would furnish free energy for all, forever. 

 

Besides his scroll propulsion belief, he taught me of synchronicity. We had it in our on-line relationship till he passed. A few good years. I miss him. I think he would enjoy my last photo. The top of the frame of my heat pump. Synchronicity dear Nicholas. Miss you!

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