The Shop > Tools
Anybody build Dan Gelbart angled laser centre finder?
Arbalist:
I couldn't see any interference rings with the setup I used. It may be they are still there, just too feint to see? I have another mounting prepared ready to drill when the micro drills I've ordered arrive so we'll have to see what happens with that. I can't see the need for a prism unless for some reason you really want to mount the Laser horizontally? Adding a mount to house a ND filter and a reduced aperture increases the bulk somewhat but it's still small enough to use. The other Laser I've ordered is very much smaller so it will be interesting to see how compact this assembly will be. I'm still favouring a button cell, maybe a CR2032 if it lasts long enough.
PekkaNF:
As you see on the bottom picture, interference artefact is not that visible on reflected light at 200 mm distance, but I assume that dot appear bigger because of that. The picture where interference shows is the same beam, but at three metres trough matte glass. When I viewed at laser side the effect was not very clear just a bigger dot (about 2-3 cm). But at the other side the effect is very clear. Last picture shows the interference nicely (Picture is taken at a angle, because head on the picture was just just a big blow of red light, but vhen observed the rings were very consentric and all around the central dot). But the dot was really round, only the interference rings to make it too large.
I'm testing the prism, because I want to slip the indicator at the end of the spindle and there is space only to very thin object. Therefore my preference is to make this flat, but if that is too much trouble or the smaller laser is not small enough, then "Plan B" is to fabricate one that will slip over dedicated ER holder - not as versatile, but plenty of headroom.
I don't know much of the pinholes, but I think that thinner the material you have the better the results are. I could not find my very thin copper foil, but I should have somewhere a little of thin brass shim stock and I was thinking of comparing that with domestic aluminium foil - hole pricked with a needle.
Pekka
Arbalist:
Interesting about the foil. I'm wondering about how to make a fixture for centering the hole on the lathe. I have some steel shim stock somewhere that may suffice. I think in one of the videos linked earlier someone was using the edge of razor or craft blades to chop the laser image.
PekkaNF:
--- Quote from: Arbalist on April 27, 2015, 08:09:02 AM ---Interesting about the foil. I'm wondering about how to make a fixture for centering the hole on the lathe. I have some steel shim stock somewhere that may suffice. I think in one of the videos linked earlier someone was using the edge of razor or craft blades to chop the laser image.
--- End quote ---
I linked one video where instructor was using razor blades on magnet. pretty smart really, razor blade edge is pretty sharp and on magnet you have an adjustable iris.
This foil I haven't tried, but I read it somewhere. I noticed that it was easy to prick the hole on black cardboard and then pretty damn hard to align it to the beam. Hmm. Could a copper/brass metal foil be glued on a washer or something that has few mm hole and the pin hole middle of it? Thicker carrier should be easier to align and hole on the carrier should give better visual where about the beam should hit. Pity that local bolt shop does not have setscrews with pinholes on them. I have used some hydraulic orifices that were like that, but the bore was too long for this.
Any small plumbing fibre washer/cap olive fitting?
Pekka
Arbalist:
Thinking about it some more you could make a housing for the Laser similar to one I posted earlier. The ND filter slips in the bottom of the housing below the Laser. The aperture could be drilled out somewhat bigger then a piece of foil could be glued on the outside and then drilled with a small hole on the Lathe.
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