Cleaning up threads

[Beanwood]

We're having some parts made in PETG, that screw together, but we're finding the threads (M35) are quite stiff.
It seems that the various layers one on top of the other are acting a bit like anti-vibration serrations in the thread.
Once they have been screwed and unscrewed a number of times they 'fit' more easily.

What is the approved method for making these smoother. I have a locknut that run up and down several times makes things a little better.
I'm thinking of using a metal thread cutting die - for the external threads, and a piece of round bar (Threaded with the die) for loosening the internal thread.

Is there a better way?

Thanks.

 

[Bladevane]

You could try offsetting the flanks in the CAD program used to design the parts.

 

[Screwdriver]

Clearance is absolutely critical, that might be in the model or the precise calibration of your printer (or both). Layer orientation is another trap remembering you don't have to print stuff exactly vertical or horizontal. Even for circular or threaded objects, they can print at 45 degrees to optimise strength and the propensity to stick together as the layers mesh.

There are also slicing options such as exactly how step compensation is made (inner/outer/middle), this is especially important for intersecting components since they will both either "overfill" or "underfill" the inevitable stairstep you will get with any ramp/sloped surface.

After all that, a dab of silicon grease does wonders.

 

[Beanwood]

Clearance is absolutely critical, that might be in the model or the precise calibration of your printer (or both). Layer orientation is another trap remembering you don't have to print stuff exactly vertical or horizontal. Even for circular or threaded objects, they can print at 45 degrees to optimise strength and the propensity to stick together as the layers mesh.

There are also slicing options such as exactly how step compensation is made (inner/outer/middle), this is especially important for intersecting components since they will both either "overfill" or "underfill" the inevitable stairstep you will get with any ramp/sloped surface.

After all that, a dab of silicon grease does wonders.

This was where my mind was going - print it on an angle - but as this was designed for us (I've decided CAD is just too difficult for my simple mind, so paid a designer) and will be getting produced in bulk (Think low hundreds) by the supplier, I'm probably limited in physical printing configurations if I'm going to keep costs down. Hence - what can I do post production.

I should also have mentioned (My list of demands is growing!...) I'll be unable to ue any type of lubricant as these are for scentwork - and the dogs could confuse the odour of the grease/oil with the target odour.

 

[Screwdriver]

This was where my mind was going - print it on an angle - but as this was designed for us (I've decided CAD is just too difficult for my simple mind, so paid a designer) and will be getting produced in bulk (Think low hundreds) by the supplier, I'm probably limited in physical printing configurations if I'm going to keep costs down. Hence - what can I do post production.

I should also have mentioned (My list of demands is growing!...) I'll be unable to ue any type of lubricant as these are for scentwork - and the dogs could confuse the odour of the grease/oil with the target odour.

Yes you probably should mention you're paying a professional. They should be able to answer these sorts of questions.

Am I right in thinking that you paid someone to produce a printable model which you are hoping to print yourself? Reject it as not fit or purpose if it's not working.

 

[Beanwood]

Yes you probably should mention you're paying a professional. They should be able to answer these sorts of questions.

Am I right in thinking that you paid someone to produce a printable model which you are hoping to print yourself? Reject it as not fit or purpose if it's not working.

Nope I am not printing this myself.
I pay per hour for design- and the recommendation was it gets easier after several uses- however I want to provide a premium product from the start. I don’t know if this is normal for a 35mm thread?

 

[iNf]

(I've decided CAD is just too difficult for my simple mind, so paid a designer)

If you want try again, Onshape is a lot less intimidating than F360. I think it was @Dr.Al who recommended it on here.

 

[Beanwood]

If you want try again, Onshape is a lot less intimidating than F360. I think it was @Dr.Al who recommended it on here.

Thanks - I migh well give that a go. @Dr.Al is well up on my list of respected members just now, having allowed me to get a free milling machine and flypress