Magnetic optical punch

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Magnetic optical punch

This topic has 10 replies, 4 voices, and was last updated 11 February 2025 at 10:03 by JasonB.

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10 February 2025 at 21:46 #782703
Fulmen
Participant
@fulmen
I’m actually quite pleased with myself now. I just made a switchable magnetic optical punch, and it works every bit as good as I expected. And on the first attempt as well. The body is just 3D printed so I might make one in solid metal later. But that will be a vanity project, the printed one is more than good enough for me.

It uses 6 Ø6x3mm neodynium magnets and locks in place with a 30° turn of the central body:

The eyepiece isn’t exactly optical quality, but it’s easy to reshape so if anyone has a good trick here I’m all ears.
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10 February 2025 at 22:08 #782705
John Haine
Participant
@johnhaine32865
Neat! How does the locking work?
10 February 2025 at 22:18 #782709
Fulmen
Participant
@fulmen
Like this (viewed from below):

The red parts are mild steel, magnets are blue and in an alternate north/south pattern. The 6 small steel pegs are in the base as seen in the photo. The magnets and the large ring move together. As depicted the magnets are off, if twisted so the pegs align with the magnets they’re on.
11 February 2025 at 06:54 #782722
JasonB
Moderator
@jasonb
How does it perform on non ferrous? I have an O ring in the bottom of mine which stop sit sliding on many different materials.
11 February 2025 at 08:26 #782736
Fulmen
Participant
@fulmen
I have an o-ring as well to provide friction, the magnets obviously won’t work on non-ferrous.
11 February 2025 at 08:38 #782738
bernard towers
Participant
@bernardtowers37738
When I made mine a long while ago the central viewing lens was mushroom shaped so it gathered more light to make the target brighter.
11 February 2025 at 08:43 #782739
Fulmen
Participant
@fulmen
I did the same, but mainly for ergonomic and esthetic reasons. The stem is 11mm while the head is 16, I don’t know if it makes a difference or not. It works OK but I wouldn’t mind some more light. I have considered adding a light source, but I don’t have a lot of space for that.
11 February 2025 at 09:41 #782742
bernard towers
Participant
@bernardtowers37738
the bigger the head the more light gathered
11 February 2025 at 10:00 #782746
Fulmen
Participant
@fulmen
Idunno about that, I have a big’ol head and I’m still quite dim.
11 February 2025 at 10:03 #782748
JasonB
Moderator
@jasonb
I can see the ring around the edge now that I look closer.

I don’t seem to have a problem of brightness with my commercially made one which only has an 8mm dia stem and 12mm head. Though the height may come into it as yours looks a lot taller than mine which only has a 30mm high body, possibly the straight rays of light hitting the sides rather than being able to get to the bottom or the polished internal bore of mine reflects more light?
11 February 2025 at 10:03 #782749
JasonB
Moderator
@jasonb
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