3D Resin printing T2 (m42 * .75) thread issue.

[Mr_Cat]

I'm looking to hook a ASI120mm mini camera onto my guide scope. 
The guidescope has a 42*.75 male thread but all the adaptors I have in my box end up also with a male thread.. so I need a female T2 to female T2. Easy enough I thought, someone is bound to have done that so I went looking and I've printed a few adaptors but none of them really thread properly, So then I thought make something specific  - find a STL with a female T2  / slice the threaded section off / copy / rotate / join / export  / slice / print. I started on a layer thickness of .050mm and ended  dropping it to .030mm  but no better (despite the print time going from 45 mins to 4 hours..)
Any suggestions ? 
 

[Dr_Ju_ju]

a few quick questions...  

1st off, if you just print the original stl model file, does it fit ok ?, 2nd what software are you using to 'form' the full model file ?, and 3rd what slicer are you using ?? 

I have to admit that I don't use resin printing, so can only offer general suggestions, but personally I would design the complete adaptor in OpenScad and then print the resultant object.

[vlaiv]

+1 for designing your own model.

Also, you need to do some tests / calibration to figure out tolerances of your printer and then adjust the model for those.

I often use 0.12mm layer height for 0.75mm pitch, so you don't need to go very fine (and waste time) - 0.05mm will be more than sufficient.

As far as I know - there is difference between different types of resin in amount of detail they can pull off - so it's worth checking out what type of resin is best suited for this work.

If you wish, I can design wanted adapter for you in FreeCad (which is open source) - in parametric form so you can tweak tolerances later on to suit your printer?

[Mr_Cat]

Thanks for the replies guys ! It's triggered some thoughts so some of my answers below are only as a result of your questions

Answers 

1st off, if you just print the original stl model file, does it fit ok ?
>No, while the alloy male will fit, it just doesn't seem to sync into the thread properly. It's almost like if you looked at the thread from the front the X/Y are scaled fine but the Z is shrunk...

2nd what software are you using to 'form' the full model file

> Just using tinkercad  I used to 3d model a long time ago (early 90's)  so I'm taking a gentle path back into a full CAD package

3rd what slicer are you using

> using Anycubic photon workshop to slice it - the 3d printer I was given is an Anycubic Photon mono and I'm using AnyCubic resin. This was recommended to me by the previous owner as a good starter. I've been suggested to move onto Lychee.

Also, you need to do some tests / calibration to figure out tolerances of your printer and then adjust the model for those.

>I am making a bracket to slide over the vixen bar on my 925 to hold the ASIAIR and dew controller and was surprised how much the finished product was smaller than in the package. For a 43 mm dovetail I ended up printing 45mm / 45.5mm  and 46 mm clamps to test the shrinkage (45mm shrunk by 1.75mm)

I often use 0.12mm layer height for 0.75mm pitch, so you don't need to go very fine (and waste time) - 0.05mm will be more than sufficient.

>That is great info thanks. I only got a litre of resin to start with - I blew through that real quickly and didn't have enough to print a cones of calibration to get the exposure right when I reduced the layer thickness - so I didn't go to "extreme". 2 litres or resin arriving tomorrow so I'll get some baselines for the resin / printer / layer thickness / exposure time  and move over onto Lychee.

As far as I know - there is difference between different types of resin in amount of detail they can pull off - so it's worth checking out what type of resin is best suited for this work.

>thanks - yeah I spotted draft resin can only take a certain level of detail but the one I am using should be fine.

I think what I'm seeing in your answers guys is that I need to sort out the shrinkage !

[vlaiv]

6 minutes ago, Mr_Cat said:

I think what I'm seeing in your answers guys is that I need to sort out the shrinkage !

Yep, that would be sensible place to start - to get fairly good dimensional accuracy.

 

[Mr_Cat]

Just now, vlaiv said:

Yep, that would be sensible place to start - to get fairly good dimensional accuracy.

 

I'm just thinking something simple like a tube - 50mm ext diameter, 42mm internal, then on the Z axis slice down half the tube 1mm slice , 2mm, slice  4mm slice, 5mm slice so I can compare all the axis.

 

[Mr_Cat]

so - 48mm outside diameter, 42 mm internal diameter, down to 20mm outer, 10 mm internal, slices at 1 cm intervals of .5mm, .75mm, 1mm, 2mm, 4mm

Once printed I can measure it, check the slices with feeler gauges etc.

Weird way to have fun tbh !!