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CNC / Chasing finer detail in 3D printing
« Last post by Joules on Today at 04:34:21 PM »
Moving on from the 1000hr service on one of the newer printers, I found the nozzle was badly worn, so ordered a couple of replacements.   Going right back to the 3D printed Quorn I had wanted to try a 0.3mm nozzle to see if detail could be improved, especially in the area of ringing where you get echos in the print process and small text or details carry ripple or shadowing.  I serviced the other printer prior to fitting it with the 0.3mm nozzle and started doing some testing.  Just 10x10x6mm cubes, to get the filament feeds and speeds right, make sure everything is running concentric.  It is now dialled in to about 0.015mm all round.  I needed something I would normally use, and that is my inlaid text on prints.  The 0.4mm nozzle really starts to struggle with fonts smaller than 4mm, down to the 0.48mm blob size, that gets even worse as a nozzle wears and you get ooze creeping out in random places.  The font used here is 4mm tall, but should print well even at 3mm, looking how many lines I have in the thinest portions.

Test 1 below was unfortunatly done using (old) translucent filament, this made it a bugger to photograph.  I then further cocked it up by trying to use sharpie to darken the front and show off the 0.2mm deep text.  Well a few hours later after wiping the Sharpie off with IPA solvent I added some red paint to the text with a toothpick and left it over night.  Careful use of a blade scraped away the dried paint, but I still had bleed between the layers, but this time the bleed was only a couple of thou wide and not very deep unlike the 0.4mm where you get quite a deep ridge between layers.  By test 3 (same part) I had scraped the plastic back to a smooth surface, maybe 0.08mm off.  The text is now much sharper and you can just make out the ripple on the vertical edges, that you can't see with the naked eye.

Last image shows you the scale of this part, I am hoping to try some small gears now I have a blob size of 0.36mm, that being my finest detail.  I might be able to go to a 0.25mm nozzle, but you are really pushing the limits on low cost printers as they struggle to hold the precision needed at these scales.   Another factor that also comes into play is nozzle pressure, as you go smaller the pressure increases and becomes more difficult to meter, that in turn will give you random blob size and difficulty in managing changes of direction where you may need to lower the pressure with a retraction or coast, change direction and reapply the pressure.  It all starts to get chaotic at higher pressures and the viscocity of PLA is very tricky below 0.2mm, so not worth the trouble in a commercial setup.  This is really the territory of resin printers, that being said I am very pleased with the results I am getting with the 0.3mm nozzle and I can print all my design up to 25% smaller without any problems.   We shall see if it goes out of tolerance quicker than the 1000hrs on a 0.4mm nozzle as wear will also be increased with both size and pressure.

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I decided that at least I could easily solve the issue with the FXM-3 Field Coil DC Drive Card overheating by adding a fan - actually easier than making a larger, but remotely mounted heat sink, which was option 2. The heat sink is up at 415 volts so needs to be away from fingers!

240 volt 80 mm axial ball bearing fan ordered from RSComponents along with some M4 nylon stand off pillars arrived this morning while I was pushing earth about with the JCB803. This evening I drew up a simple mounting plate in AutoCAD which via SheetCAM was ported to the CNC Plasma table and cut out of 2 mm steel plate, edges bent up to form a flange for rigidity, and a test assembly performed.

All looks good, so it got a coat of Satin Black from a rattle can, and I'll probably fit it tomorrow if time permits.

I praise the day I rescued that CNC Plasma Table - oh boy does it make this sort of thing easy  :clap:
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Project Logs / Re: Taper attachment build
« Last post by PekkaNF on Today at 04:07:37 PM »
Pekka,
The slide is adjustable to get close to zero play using a gib; it runs smoothly.  The way its set up, it is free to move up and down if the way isn't lined up with the lathe bed (though mine seems to be very well aligned with those keys).
I think my final height issue was due to the relatively low precision fit of the plastic parts, or a thickness mistake on a plastic part.  I really didn't bother working out where I messed up, just fixed it.

Thank you, Ok. the gib is back of the guide. Looks all very nice.

I like your 3D printed proof of consept plastic parts. That is tempting consept.

Pekka
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Project Logs / Re: Taper attachment build
« Last post by Joules on Today at 03:22:08 PM »
Good use of the 3D printing.   Was it strong enough to try making a part ?
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Project Logs / Re: Taper attachment build
« Last post by WeldingRod on Today at 02:37:32 PM »
Pekka,
The slide is adjustable to get close to zero play using a gib; it runs smoothly.  The way its set up, it is free to move up and down if the way isn't lined up with the lathe bed (though mine seems to be very well aligned with those keys).
I think my final height issue was due to the relatively low precision fit of the plastic parts, or a thickness mistake on a plastic part.  I really didn't bother working out where I messed up, just fixed it.
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The Design Shop / Re: Mill/drill stand for Warco Major mill
« Last post by PekkaNF on Today at 01:22:05 PM »
I thought they had lost the shipment, because last update on tracking info was 7.8 and contacted Warco Yesterday. Afetrnoon I got a call from Finnish depot that I can have it tomorow morning. Took surpricingly long time for them to process it. Hope I'll like it.
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Project Logs / Re: Taper attachment build
« Last post by PekkaNF on Today at 01:10:49 PM »
Very nice! Did you got any play?

Where did that descrepancy crep in with the cross slide and taper attachment deck height?

I relieved the center to make fit up a bit easier.

Installed on the lathe with the plastic bits on top.

Crud.  A little higher than planned.  At least those parts aren't made yet...

My speciality is to add a part thickness with wrong sign....latest was to add 20 mm instead of subsract it and even put the part in wrong way, because it did not look right - and then welded it solid. :D

Pekka
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On the spindle orientation..a very odd fault..as you would think the control would alarm if it wasn't in the correct position?

It just 'hangs' with the running light lit, so I expect that it's waiting for an input from some point on the ladder logic. I just wish I could source a copy of 'Step5' software that talks to the controller and lets you examine the PLC ladder in real time. All the hooky copies I've seen so far are missing the authorisation code  :palm:
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Welcome to the forum, why don't you post a bit in the Introductions section and tell us a bit about your projects ?
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Project Logs / Re: DIY tablet computer, maybe.
« Last post by S. Heslop on Today at 11:17:12 AM »
Nice. Now it's working for reals. Got undo and redo set to keys. The problem I had is that theres a function to start the keyboard press, and a function to end that keypress. But because alot of the key combos share a key (ctrl) then having each individual function doing its own 'else - end key press' thing was mucking it up. So now i've got a bunch of integers to keep track of if a key has been previously pressed before running the release function once.

Or something. I'm not great at programming.

Now I just need to figure out what shortcuts are worth assigning to buttons.


Since the thing also works as a plain old digitizer with the display off, i'm considering the idea of ditching both my second desktop monitor and the old graphics tablet and using it to fill both roles. I'm always fighting for desk space so something you'd need to slide around and drag through the piled up junk wouldn't be ideal. Perhaps a cantilevered arm. But even if you could lock it it's not going to be very solid. Gives me something to think about while I type out this stupid function 15 more times.
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