Designing 3D printable dove tail joints?

[disneytoy]

Love 360!!!!

The other day I was designing a part to be 3D printed. Standard desktop printer. I'm pretty good at making a joint fit. 0.1mm is good enough for a tight slip fit. This has worked great with round holes and 90 degree shapes. I would just use the OFFSET function for the mating part.

So, I am trying to get a DOVETAIL to fit. The way offset works, the shrinking of the shape once printed doesn't fit?  Is there any good way of designing a dovetail so the tolerances fit? 

Thanks!

Max

PS--------------------------------

I am only trying to make one Dovetail so I can index two parts together. If I printed them as one piece it would be a mess of supports. A single dovetail would lock them together and make it very easy to print. I'd use what I learn on other FDM projects:-)

[LeonardoBN]

Hi, @disneytoy.

I will deviate from your main question firstly... What material do you use? Slicer's horizontal (XY) compensation could be a potential solution to your printing.

Do you use Sketch/Offset or Modify/Offset to design your tolerances?

If possible, you can attach here your F3D file.

[disneytoy]

Thanks!

I have an Ender 3, printing PLA. This is a small part. Dovetail may be 10mm wide. depth 5mm.  I think because I drew the first part of the dovetail, then used offset, somehow the right angles are too tight??

I essentially created a new offset plane: sketch. Projected the first dovetail then offset command.

Thanks.

[LeonardoBN]

Nice, I have a similar setup here, and I only use 3D printers for fabrication here. Nice fittings from 3D printed parts are awesome.

I am not sure if this is a good approach, but I always model with no tolerances. So I rely on my printers to be well calibrated.

If I were add in Fusion with 0,1 mm tolerance, I would model with zero tolerance, then use Offset Face.

In this example, I offset the three faces of the white body:

[laughingcreek]

everybody's just going to be guessing with out a little more detail.  where its the problem? can you describe it with a diagram or a pic?  attaching an example file wold be helpful also.

guess 1-sometimes the outside corners either the pin or the tail will interfere and not allow a good fit.  putting a fillet or chamfer there can help.

guess 2-don't offset the sides of the tail as much (or maybe at all)

guess 3 don't offset the shoulder on either side.

guess 4- offset the head of the tail (where end grain would be if it were wood) a little more than anything else so it doesn't bottom out before the shoulders touch. (I have done dovetails in prints where I only offset this area, depends on the process)

[disneytoy]

I'm going to experiment.

i am thinking, I created the larger side of the dove tail (female) Then I offset inwards 0.1mm. I think that may have contracted the height of the dovetail (male) too much?

I think if I start with the Male side and offset out that would work better.

I've had excellent luck with rectangles and circles getting very precise fits. 0.1mm offset on a hole, example fitting a bearing in a 3D printed part makes a very accurate press fit.

Thanks

Max

[laughingcreek]

don't offset the female faces.  offset the male faces, making it smaller,  like @LeonardoBN shows in his post.

still no visual, so don't really know...

[disneytoy]

I am going to try both ways. Offset male and offset female. Print and see if this works. I will report back. This is a very useful process for 3D printing. If I can get it to work.

[disneytoy]

Haven't printed it yet.

But OFFSET inward (smaller side (MALE) looks better.

Dovetail Offset Inward