topic Bar Support tip geometry in Netfabb Forum

Bar Support tip geometry

Anonymous — Tue, 26 Jun 2018 18:23:52 GMT

I've been playing around with Netfabb after getting fed up with support generation in Meshmixer. So far I have found it to be fairly good and relatively intuitive to use.

The support generator is seriously configurable and works quite well for auto-generation. My issue is the geometry of the bar support tips. I am using Netfabb exclusively for SLA printing and I liked the conical tip shape of the supports in Meshmixer. They worked really well and were very straight forward to configure.

In Netfabb, no matter how many different ways I have tried changing parameters around, the tip is a blob that projects out of the part and necks down (then back up to the post diameter). Is there any way to have just a standard conical tip of say 60 degrees included angle and 0.03 mm diameter contact point? I sort of got this effect by changing the offset from the part to a negative number, but this doesn't work close to an edge that I need to support where there is an undercut (thread) just below the surface.

Re: Bar Support tip geometry

Anonymous — Thu, 28 Jun 2018 00:15:41 GMT

No idea how active these forums actually are, but here is an example....

This is what I want and was able to do with -0.95mm distance from part set.

And this is what I get: How do I modify the shape and/or size of the areas circled in red? The necked down diameter is too weak and at the very least I need to be able to make that bigger. Is there any manual control over the shape of the tips?

Re: Bar Support tip geometry

steffen_anders_adsk — Thu, 28 Jun 2018 15:05:55 GMT

Hello,

Welcome to the Netfabb Forum!

Thanks a lot for the screenshots, I see what you're trying to do. In your example, it looks like you're creatively repurposing the breakaway constriction.

There is a dedicated setting for what I understand you're looking for. It's called Angle at Top. It creates a pointy tip of up to 60 ° sharpness (measured from the bar's spine axis) at the end of the bar support:

This setting should help you achieve what you are looking for.

To learn about this setting and others, visit the reference article on bar support settings in the online help here.

Also, the breakaway constriction itself can be deactivated a little further down: Set [your chosen support action] > Support Properties > Breaking point > Breaking point to No.

Best regards,

Steffen

Re: Bar Support tip geometry

Anonymous — Thu, 28 Jun 2018 15:08:32 GMT

Unless I am completely misunderstanding or doing something wrong, that setting did not seem to have any effect. I tried everything from 0 degrees to 60 and the result is always what is shown in the second picture.

Also, enabling or disabling the breakaway has no effect.

Re: Bar Support tip geometry

steffen_anders_adsk — Thu, 28 Jun 2018 15:13:26 GMT

Remember to apply the change by re-running the support script. Alternatively, if you are modifying the setting by right-clicking a support entity (a single bar, for example), mind that this change is only applied to this particular entity. You may need to highlight multiple or all entities first before using Edit entity from the context menu:

Re: Bar Support tip geometry

Anonymous — Thu, 28 Jun 2018 15:20:43 GMT

Ok, I think I got it now. The cone tip is just buried in the part (by default). Obviously I can change the distance from part, but that leaves no way to actually specify the contact area (size). Is there some way to define this that I am missing? I have found that for my printer a 0.2mm - 0.5mm spot diameter works well.

Re: Bar Support tip geometry

steffen_anders_adsk — Wed, 04 Jul 2018 15:09:09 GMT

Hi,

Yes, the burying in the part is intentional, and the way to withdraw it is by the Distance to part property you mentioned.

Mind, you can also use the settings for the breakaway constriction to replicate the pointy tip in conjunction with the Distance to part:

There is no wrong way to do this, all that matters is that the desired contact is achieved.

However, you are correct, there is indeed no direct way to specify the contact spot, but this is easily calculated from the values used to specify the tip:

Distance to part (negative) = (desired spot diameter - Width on end) * (Breaking point width - Width on end) / Height on end.

You will probably want to achieve as little intrusion of the tip into the mesh as possible, so you would choose a width on end that is only slightly smaller than the desired contact patch diameter and then go from there (although, if you print in SLA, that shouldn't really matter unless you have very thin walls where the tips would protrude on the inside).

Best of success!

Cheers,

Steffen