DỤNG CỤ NONG NÓN (HAT STRETCHER)

This  model is suitable for a Prusa Mini, and prints easily with no supports and (almost) no infill.  Printing details are at the end of this description but first:   

SIZE

Two models are attached in Small Size (EU size 54 and up), and Large (EU 57 and up), and both of these are more than adequate to cover the full range of standard hat sizes.

Using the smaller size stretcher to expand to the largest hat size will work, and will result in a narrower oval shape - this may or may not be preferable depending on your head size and shape.  You can easily check your preferred fit by printing the size check template (in two parts for the Prusa Mini).

If you wish to customise the size a little for whatever reason, they can be enlarged or reduced in your slicer but PLEASE remember to use the same percentage in every axis and for every part or nothing will fit!

Measurement in Inches

Hat Size

European Size

21 1/8

6 3/4 - S

54

21 1/2

6 7/8 - S

55

21 7/8

7 - M

56

22 1/4

7 1/8 - M

57

22 5/8

7 1/4 - L

58

23

7 3/8 - L

59

23 1/2

7 1/2 - XL

60

23 7/8

7 5/8 - XL

61

24 1/4

7 3/4 - XXL

62

DESIGN

While the device may look bulky - it's not.  It's actually printed (almost) entirely hollow thanks to the miracle of Lightning Infill, and has been designed effectively as a box beam structure, making it more than strong enough for the purpose.

ASSEMBLY

Note that the two screws are opposite handed, one left thread, one right.   There's no need to glue them together but it's a lot easier in use if you do - just a tiny drop of super/crazy glue on the mating surfaces of the screws is enough - use the “x” shaped  key to ensure a nice alignment.    From there, you just have to make sure you mate the right stretcher part with the right screw and everything will be fine. 

USE

I prefer to slightly dampen leather bands if they are to be stretched, but once the hat fits, simply popping it onto the stretcher after use will prevent it from shrinking as it dries over time.    (I have hats including a panama with a leather band, a woven wool cap and a beret that I keep on these forms to preserve their shape)

PRINTING

This is the really fun part!  Of course printing with traditional infill is fine, and I recommend 15% Gyroid infill for the screws, no supports are necessary.

For the stretchers I use 15% Lightning infill and no supports are necessary.   

Use 0.2mm layer heights, the standard two perimeters and a 0.4mm nozzle for a very light, strong model.

For simple printing orient as follows: