printed Nipkow Jigsaw

A "new fashioned" televisor, using an Arduino to drive the motor and display.

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Re: printed Nipkow Jigsaw

Postby Klaas Robers » Sun Jul 02, 2017 7:55 am

But PLA is very heat sensitive. May be you can melt the joints by using your soldering iron?

Can you place a sheet of aluminium foil between the soldering iron and the PLA disc? This will solve the transparency problem at the same time. Reopen the apertures with a needle.
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Re: printed Nipkow Jigsaw

Postby Andrew Davie » Fri Jul 07, 2017 3:49 pm

Klaas Robers wrote:But PLA is very heat sensitive. May be you can melt the joints by using your soldering iron?

Can you place a sheet of aluminium foil between the soldering iron and the PLA disc? This will solve the transparency problem at the same time. Reopen the apertures with a needle.


A coat of aluminium foil on the back-side would solve a number of problems - the transparency, but also reflecting stray light back into the 'light box' and hopefully slightly improve brightness, too. I'll tackle that after I get the mechanics of the disk printing understood a bit better.
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Re: printed Nipkow Jigsaw

Postby Andrew Davie » Fri Jul 07, 2017 3:55 pm

I printed a new set of 'pie slices' over the last few days in ABS material, and today bought some acetone and tried applying it to the jigsaw-joints. It worked quite well, although one must be careful what the disk is lying upon when you do this, as acetone melts the ABS and as it evaporates on your desk you get a residue left behind. Anyway, it's really messy and I only had a rather too large for purpose paint brush to use. But the results were excellent - a very sturdy-feeling bond much like welding rather than gluing. The video shows the thin (1.5 mm) disk being put under a fair bit of lateral stress to see how those joints line up. Also you can see the disk side-on and it appears to be flat. Certainly appears flat when lying either side up on a desk.

I'd call this experiment a success so far, so probably the next step is to print a slightly thicker disk and be a bit more careful about applying the acetone next time so it looks a tad neater. I'll use this current one for experimenting with putting the holes through with a hot needle and with a drill bit, to see how that goes. Also I need to double-check my concept of 8 rows of hole markers, correctly offset, will produce a correct spiral when the right ones are drilled through.

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Re: printed Nipkow Jigsaw

Postby Harry Dalek » Sat Jul 08, 2017 10:06 pm

looks good Andrew does not look like it would need any more support ,nothing like shake test :wink:
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Re: printed Nipkow Jigsaw

Postby Andrew Davie » Mon Jul 17, 2017 11:50 am

A follow-up on this disk; the stresses in the material due to the tight tolerances of the joins were too much, and the disk has warped.

nipwarp.jpg
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Re: printed Nipkow Jigsaw

Postby Andrew Davie » Mon Jul 17, 2017 11:53 am

Here's the next version - I have significantly reduced the "tightness" of the jigsaw, so this one is much easier to snap-fit together. Also, I've printed at 5mm thick. I will again use acetone to weld the piece together and see how it behaves. Note the central hole so I can mount on my exisiting hub for testing.

nip1.jpg
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One (successful!) experiment was to make a "slurry" of dissolved filament using acetone. Essentially a small beaker of acetone into which I placed small pieces of ABS filament. I stirred until the filament had dissolved, and the consistency was like (say) full cream milk. Then I "painted" this on to the print-bed surface which was heated to about 25C. I was very careful during this phase - I did the work under a fume hood, except for the painting on, of course - but I was careful to proceed slowly and with minimal "active" acetone exposed. I also, for good measure, wore a face mask and protective gloves. Anyway, with three 90 degree rotated coats, I deposited a very thin layer of ABS onto the print-bed - the acetone evaporating fairly rapidly off the warm bed, leaving behind the ABS. When I printed onto this, the adhesion of the print was fantastic, and there was little to no warping (as opposed to significant warping previously). It's a great solution. Only pain is cleaning the print bed after, which is done with a bit of elbow grease and a rag soaked into acetone.

I must stress, acetone is apparently highly flammable, so due caution should be used when dealing with this material - particularly when applying to heated surfaces!
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Re: printed Nipkow Jigsaw

Postby Robonz » Sat Aug 12, 2017 8:38 pm

Andrew, is there any chance of getting a DXF of your current disc? I assume its 32 line vertical scan. I have a laser cutter and will laser cut one. I could send you one too.

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Re: printed Nipkow Jigsaw

Postby Andrew Davie » Tue Aug 15, 2017 12:16 am

Robonz wrote:Andrew, is there any chance of getting a DXF of your current disc? I assume its 32 line vertical scan. I have a laser cutter and will laser cut one. I could send you one too.


I usually generate an STL file, which is fine for 3D printing - but I'm unfamiliar with laser cutting, and know that STL won't cut it. See what I did there :) Anyway, OpenSCAD, which I use for generating the 3D models, CAN 'project' a 3D object to a 2D surface for generating DXF, and I'm happy to have a play with doing this. The disc is indeed 32 line vertical scan - however, this in itself is not terribly difficult or interesting. Thanks for your offer - that's a fine gesture - how about we discuss exactly what you want/need and I'll see how we can work together to make something useful.
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Re: printed Nipkow Jigsaw

Postby Andrew Davie » Tue Aug 15, 2017 12:23 am

Well, it turns out it's pretty easy to generate a DXF file from an OpenSCAD 3D file.

First, consider a 3D model that you've designed and it's instantiated by a call to the function you wrote called (say) "my3DModel();"
Then to create a 2D version of this, you just project it to the XY plane via...

Code: Select all
project(cut=false)
    my3DModel();


That's all there is to it. The 'cut' can be true, in which case you get a slice at Z=0, or false in which case all points in the model are projected onto the XY plane.
Then you just File/export as DXF.

Once we figure out exactly what you want/need, I'll get it done.
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Re: printed Nipkow Jigsaw

Postby Robonz » Tue Aug 15, 2017 10:09 am

Thanks Andrew

I have found Gary's DXF generator
http://users.tpg.com.au/users/gmillard/nbtv/nbtv.htm

Actually I have downloaded ALL of his amazing software. What a great effort there Gary! I am sure you saved everyone hours of fiddling.

Before I make a disc I need to make a lot of decisions on size, apertures and encoder holes etc.
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Re: printed Nipkow Jigsaw

Postby Harry Dalek » Tue Aug 15, 2017 7:43 pm

Good to see you on the forum Robon look forward to seeing your projects .
Andrew sorry i a bit dim but the lined up holes nipkow hole position i don't understand these look similar to Jenkins used on he's drum monitors i still can't get my head around that one unless your using a rotating square of polygon mirror for the framing
I can see the pie disk is coming together from the prototype looking good ,i can see the future of constructing using 3d printers and laser cutting ...both sort of give the same results good to have both i suppose .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: printed Nipkow Jigsaw

Postby Andrew Davie » Tue Aug 15, 2017 10:13 pm

Harry Dalek wrote:Andrew sorry i a bit dim but the lined up holes nipkow hole position i don't understand these look similar to Jenkins used on he's drum monitors i still can't get my head around that one unless your using a rotating square of polygon mirror for the framing


OK, first they are NOT holes. They are places for holes. So on each of the 8 slices, we have all 32 possible hole positions. We don't want 32 holes on each slice, but we DO want just a single TYPE of slice that can be used to make a complete disc. After assembling 8 identical slices, the hole markers are designed such that you can poke-out (say, with a pin) 32 of them and form a perfect Nipkow spiral. Which holes to poke out? It's easy... if you consider the radial 'rows' of holes visible in the pictures I posted, then there are 4 'rows' of holes per slice. Start with any slice, and put a pin through the innermost hole on each 'row'. Now you have 4 holes on the slice. Each of those is ever so slightly staggered in distance from the centerpoint. Now move onto the next slice. Instead of poking the innermost holes, we now poke out the holes 2nd from inermost in each 'row'. And for the 3rd slice we poke out the holes 3rd from innermost, etc. The hole positions are designed such that this process will give you a perfect spiral with holes spaced correctly.

Another way of thinking about it - the complete disk actually has eight complete spirals on it, and the positions of the holes for all of those spirals are marked on the pie-slices. Each slice has 32 holes, so 8 slices = 256 holes = 256/32 complete spirals. We need to poke out the holes for just ONE of those spirals. It so happens that the holes are perfectly spaced such that you can do this - as you start from the innermost hole on one slice, the next hole 360/32 degrees around is slightly further away, and the next 360/32 around is slightly further away again. This happens for the 4 holes in a slice, and there will be a position for a hole in the next slice in exactly the right place.

Yet another way to think of it: Take a disk with a complete spiral of 32 holes. Divide it into 8 pie slices. Put them exactly on top of each other and mark on one of them exactly where ALL the holes on ALL of the slices are. You get the 'line' pattern that I have on my pie slices. Each single slice has enough holes to allow recreation of the entire disc from just that one slice.

The reason for doing it this way is that you only need a single type of 'pie slice' to enable you to recreate an entire disc. Hope this is clearer!
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Re: printed Nipkow Jigsaw

Postby Harry Dalek » Wed Aug 16, 2017 11:09 pm

Thanks Andrew staggering the hole positions like that i now understand what your up to ..
if your making the holes with a pin ,i used to do it with a hot pin but if you put your pin in a dremel that works very well , look forward to seeing it spin .
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Re: printed Nipkow Jigsaw

Postby Robonz » Sat Aug 19, 2017 3:59 pm

I think its going to be very hard to make a "not wobbly" disc using 3d printing. Maybe if you glued a piece of clear acrylic to the back it would add some rigidity. I have a good 3D printer but am opting for the laser cutter. It is yet to be proven by me, but I am working on it right now. I just posted some results a few minutes ago.

Thanks for the welcome Harry, you sound like a very social guy. I have been trawling the forum reading up on your historical efforts and Maksim Holtzman's dual drum set up. That amazed me, there are VERY clever people here!
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Re: printed Nipkow Jigsaw

Postby Harry Dalek » Sun Aug 20, 2017 10:35 am

Robonz wrote:I think its going to be very hard to make a "not wobbly" disc using 3d printing. Maybe if you glued a piece of clear acrylic to the back it would add some rigidity. I have a good 3D printer but am opting for the laser cutter. It is yet to be proven by me, but I am working on it right now. I just posted some results a few minutes ago.


I am just watching the 3 D printing going on here and laser cutting really interesting new tool idea of late on the case... disk... mirror screw slats ...and such ,i have no idea about it apart from observing but i can see they both have there strengths and weaknesses you also have the cnc cutting machine if you had all 3 you would have it made .

Thanks for the welcome Harry, you sound like a very social guy. I have been trawling the forum reading up on your historical efforts and Maksim Holtzman's dual drum set up. That amazed me, there are VERY clever people here!



No worries yes lots of old projects the old posts are a gold mine of information things that have worked and fails i do like the 2 drum monitor over the nipkow .
It is amazing how many ways there are to make a television or camera .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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