Anycubic Photon

[Mark W]

It should be noted that unless the screen resolution (pixel) is not the same as the Z travel, one is not printing a true cube any longer.  Unless that is what hardware resolution is referring to?

Can you elaborate on what you mean? 

A voxel does not need to be equilateral to make a cube. 

[Lemosteam]

No but it might mess with your dimensional stability.

A true cube is likely best as a voxel, so if your pixels can match your Z axis increments it is easier to predict.

@Chris333 touched on this somewhat when he mentioned a higher resolution screen.

[Chris333]

How exactly does being a perfect cube help? I mean building blocks aren't cubed.

[Mark W]

Sometimes I think John's just trying really hard to resist buying his own Photon, by convincing himself that these things are issues.   


Anyway, I notice Amazon lists Anycubic Grey resin will be back in stock on January 9th! 

[wvgca]

Anyway, I notice Amazon lists Anycubic Grey resin will be back in stock on January 9th!

at what price ? and size ?
the amazon.ca site shows anycubic brand 500ml out of stock, but its $48 cdn  ??

[timwatson]

Found a source for the 10 micron step resolution. 

https://github.com/Photonsters/anycubic-photon-docs/?fbclid=IwAR1ROCB2ZNgz86gyXfDXVvd6kPrV3kBen0u1N1Dy9RKRTk-GDut-YakatV0


https://i.imgur.com/9vLKEwL.jpg

Based on the threads and stepper motor type, each step of the motor can correlate to an exact 10 micron step in Z. 
So any layer height that is not an increment of 10 microns can actually reduce accuracy in Z height as the stepper tries to interpolate with half or micro-steps, sacrificing torque and risking "magnetic backlash"

https://www.micromo.com/technical-library/stepper-motor-tutorials/microstepping-myths-and-realities?fbclid=IwAR3cr2sr0Ev18QRVoBfUIeJiqoJOFqxGlAzfIsLBxowOyvfGT_fjmbilivw

By swapping out a 9 degree stepper and a 1/32 stepper driver and hacking the firmware you should be able to half the stepping in the z-axis ... this is a nice find. If you don't hack the firmware and made those mods your z-height would be half.

As far as Lemosteams comment you can change the "physical scaling" of all machines to do proper dimensions. Z-axis included (provided the hardware can). The only things that need to match (which is what I think Mark is getting at). Is the slicer z and the physical hardware z axis increments needs to match.  So .025 would ultimately be rounded to .03mm or .02mm.

I have yet to print at .02mm but I'm going to try it.

Also the comments on the grey resin were just cautionary - it appears clear resins have no dimensional issues. Something to keep in mind is all.

[narrowminded]

Sometimes I think John's just trying really hard to resist buying his own Photon, by convincing himself that these things are issues.   

Don't tell him but at the very least his detail parts and especially his trucks would benefit tremendously from this process and the convenience of having good parts to inspect shortly after the idea strikes would be so valuable.   If you think he's a prolific producer of exquisite parts now just wait 'til he gets his hands on one of these! 

[narrowminded]

I printed a knuckle coupler to use as a transition coupler from standard knuckles to the link and pin pocket.  It's one piece with no centering spring, free swinging, so needs to be manually coupled, not automatic, but hooks right up.  It appears to be good but has yet to be functionally tested running in a train.  The forward pull is not a concern but backing a string through tight radius turns is where there is at least some concern.  The couplers tend to align themselves when mated but in reverse, in compression, it may get weird.  I'm also running these with metal wheels but no added weight so they are extremely light.  I could add a small cylindrical weight in the bottom of the hopper which might help with performance but I have run some Shapeways hoppers with no more than metal wheels and the performance was reliably good.  Those are rigid couplers and behave well from car to car but the overhang at the loco limits the radius that it will handle.  The bigger the overhang, the broader the required radius.  The weight wouldn't be much but when viewed as a percentage change it would be significant.  Time will tell. 

I guess these couplers could be used in lieu of the links and pins too if I should decide to make them for others and that was their preference.  I could also just print the couplers in place on the frame if the link and pin option was really not desired but a little detail goodness is lost doing that.  But if the links and pins weren't going to be used it would be a lot easier than making and assembling all of the individual pieces.  

It's so nice having these problems rather than no real option at all.

[MK]

Pictures?

[narrowminded]

Also the comments on the grey resin were just cautionary - it appears clear resins have no dimensional issues. Something to keep in mind is all.

And that was mentioned in the discussion link about the dimensional changes with colored resin.   The main reason I like the colored resin is the ability to see the detail without having primer on the part and am willing to adjust the dimensions to correct for the error when it occurs or matters.  And there are some parts, like the links, that I would like to use as printed, not requiring painting.

And just to be clear, this isn't an error that occurs arbitrarily.  When the same resin is printed with the same set of curing parameters the dimensions are consistent and repeatable.  That's been my experience this far.  And I'm starting to get a handle on where the errors will occur and how much to correct.  I suspect even that will be very predictable as my experience grows but worst case, so far, print a test piece, measure it, make the dimension change based on the needed correction, and then print as many as you need.

[narrowminded]

Pictures?

Soon.  I'm actually looking at some adjustments and adding some cosmetic details as we speak.  I will also be trying black resin.  These first dozen test pieces were printed in gray as it was in the vat.   The changes are a slight change in the coupling height, a slightly shorter knuckle height, a little shorter than a standard "Z" coupler, and then some cosmetic detail.  No further change is needed to the functional dimensions.

[Mark W]

...dimension of .015" and the flanges are .008",...

..leave .012", ...

.028" wide x .008" thick with the "tee" at .015" x .008". 

..They are .010" x .012" cross section .015" diameter .... 
pins were .030" inside, now .020" and .010" cross section. 

https://i.redd.it/7js62q0xw7821.jpg

 

[Lemosteam]

Sometimes I think John's just trying really hard to resist buying his own Photon, by convincing himself that these things are issues.   


Anyway, I notice Amazon lists Anycubic Grey resin will be back in stock on January 9th!

No, what I am suggesting is that your X and Y axes will not have the same resolution as your Z, unless the pixels get smaller.  So you are only gaining resolution in one direction (Z).  A higher res screen would provide smaller stepping (aliasing) in the X and Y as well, improving curves and angles when the sections are cut.

Plainly put, why improve Z axis resolution when the X and Y remain unimproved?

None of this is meant to discourage anyone or "create" issues, just thinking in terms of overall print resolution improvement.

[Mark W]

Plainly put, why improve Z axis resolution when the X and Y remain unimproved?

Which would you choose? 



https://i.imgur.com/KkIGcRe.jpg


https://i.imgur.com/za5BVk2.jpg

[narrowminded]

https://i.redd.it/7js62q0xw7821.jpg

 

I know.   But I'm old, retired from a life of machinery work, still doing machinery work but for fun again, think in inches and degrees F, and am exercising this last little bit of stubborn silliness.   Bear with me as it won't last too much longer. 

And I often do include metric dimensions but will always put those in the parenthesis, not the inches... unless I don't.   And as I experienced for a few decades now, all I need to remember is where the "ON" button is on my pocket calculator, the number .03937, and all is good and with more decimal places than any sane person needs while making finely fitting and functioning parts.