Author Topic: My last attempt at print was nearly spot on. Nearly  (Read 1763 times)

Offline A7er

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My last attempt at print was nearly spot on. Nearly
« on: August 07, 2022, 06:05:45 PM »
I changed some of the default settings I had used in my first print. I slowed the raising of the plate between layers to reduce the effect of the suction between the plate and the FEP film. I also increased the time between layers to allow the UV light to cure the layer of resin. I pressed print and busied myself. 2 hours later I could just see that the build plate had something on it. All 4 parts had printed almost perfectly. I say almost because the surface finish where the supports were was awful. Some of the parts had 4.1mm holes for set screws. A 4mm set screw slid in with hardly any play. 2 of the parts had flanges on to locate in a recess in another of the prints. These weren't a good fit. The rough surface, is unimportant, the holes are OK, but the flange fit is something of a concern. I think I might scap the flanges and use dowels instead.

How accurate should a resin print be?

Offline BillTodd

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #1 on: August 08, 2022, 03:12:54 PM »
My experience with Elegoo Saturn ...

There is always some shrinkage as the polymer cures and cools (the process has some similarities to casting)
Avoid thick blocks where possible and watch for suction cups and other large areas that can pull the model out of shape .
Correct orientation with proper support is vital.

For accuracy it's best to check the slicer's calibration, the number of pixels per axis verses the actual display size.

If you are designing your own models, try building in sacrificial supports on the underside edges (i.e. you create a virtual build plate under the edge/face)

Expect to have to fiddle the sizes in the model. That said I find M3 and larger threads can be printed fine without compensation.





Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #2 on: August 08, 2022, 08:07:00 PM »
I am slowly getting to grips with the resin printer. I think it fair to say it's more difficult to get right than an FDM printer like my Ender3.

Offline BillTodd

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #3 on: August 08, 2022, 08:39:42 PM »
Yes, it's very different to fdm . Its upside down with all sorts of extra forces (not just gravity) to deal with and a few deep pit-falls for the unwary.

Satisfying when you get it right though. I been using it to make parts for an fdm printer, including a printed extruder https://www.madmodder.net/index.php/topic,13435.msg161507.html#msg161507

Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #4 on: August 08, 2022, 10:33:16 PM »
My Ender3 got a bit of use this evening. I was trying to enlarge a 2 piece piston pattern in diameter to allow for machining the final cast part. I tried coating the existing pattern halves with epoxy putty. It didn't look right. So I peeled the putty off, it hadn't fully hardened, and created a "shell" to glue to the piston halves in my CAD program, exported the STL to Cura and used the Ender to duplicate and print two copies. No mess or fuss and I could see what was going on all the time! I used a layer height of .16 so the finish is quite good. A gentle sanding should be enough.
I have also produced a sliced file for the resin printer to try tomorrow, using my Elegoo water washable resin that was delivered today.

Offline BillTodd

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #5 on: August 08, 2022, 11:58:01 PM »
I've not tried the water washable stuff. It doesn't have a good press :-(

Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #6 on: August 09, 2022, 05:48:14 PM »
My latest attempt at printing was a total failure. I used resin settings from watching a few youtubers, that was mistake number one. Mistake number two I didn't see coming. I printed two of the parts directly on the build plate, no supports. They printed perfectly. They are the core moulds for the inlet and exhaust ports. The tract on the CAD drawing is 8mm dia. When I had washed and cured the two parts I could see that the ports didn't look right, they were oval, not round. A check with the calipers showed that they were .2mm undersize in one direction, but .75mm undersize in the other. The .75 is shared between the two parts across the parting line. So even though they printed, they are scrap.
I will try another print tomorrow.

Offline BillTodd

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #7 on: August 10, 2022, 12:13:07 PM »
It's well worth running a couple of calibration prints.

Eg.

<a href="https://www.youtube.com/watch?v=o2ySL-Sw8QI" target="_blank">http://www.youtube.com/watch?v=o2ySL-Sw8QI</a>


Or, the one I prefer.

https://ameralabs.com/blog/town-calibration-part/
« Last Edit: August 10, 2022, 12:22:08 PM by BillTodd »

Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #8 on: August 10, 2022, 12:51:13 PM »
I have a print running right now. I beefed up the supports to see if that would help. I will check out the calibration links later. I have watched a video about their use. Thanks.
Lee

Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #9 on: August 10, 2022, 03:43:42 PM »
The latest print was almost perfect. There is a small amount of work to do on one of the parts, it was slightly warped, but it bolts to another part to make a core mould so the warp should get pulled out. I have another print running now. It should be finished by 6.30 this evening. A 4h30m print on the resin printer would take nearly double that on the Ender3. I put the same files through Cura and Prusa.

Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #10 on: August 12, 2022, 02:10:35 PM »
BillTodd
I downloaded and sliced the Amerilabs test print and printed it on my Mono 4K. It was awfull! My settings must be a mile out. I will change them and try another print. Thanks for the link.

Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #11 on: August 12, 2022, 10:22:20 PM »
I adjusted my printer settings and tried another Amerilabs print. Much, much better! I have changed the settings just a bit and will try another print tomorrow.

Offline BillTodd

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #12 on: August 12, 2022, 11:03:32 PM »
BTW if you are using chitubox  , make sure you have the latest version (1.91?  Much better than earlier ones)  .

What out for the print size compensation adjustments they don't seem to work very well at all. 

Scaling in slicer or cad is better.

Bill


Offline A7er

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Re: My last attempt at print was nearly spot on. Nearly
« Reply #13 on: August 13, 2022, 05:33:31 PM »
Bill,
I couldn't get chitubox to run on my computer, it kept crashing. I can use Lychee which has more features than Prusa or Photon workshop. But I am wary of using something that requires an internet connection to check its "free" licence. I use Prusa then Photon. It seems to work. My last print that I mentioned I was going to do after getting a really good print, wasn't as good, so back to the previous settings. When I am happy with the settings I will re-print one of my earlier attempts to see if it is better. I think it will be.
Without the Amerilabs link I would still be wondering what to do. Thanks for that.
Lee

 

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