Hard Shell Basic Mask by ksihota

Last crawled date: 4 years, 1 month ago

Update31/03/2020 (2)
I have uploaded a few new picts of the latest design.
I do not recommend printing the bottom section (part with threads) in TPU as the threads will tend to bind more readily than with PLA to PLA. It may work fine if the whole section can be printed in TPU but if its just the end, the TPU and PLA may separate under the pressure of threading in the filter. The TPU gasket is loose at the threads so this doesn't have the same issue. It could also be an issue of my print being done quickly and at a low resolution.
So far my silicone sealant gluing appears to be working okay. I tried using a cyanoacrylate based glue which works but is rigid. After the materials flex for some time the bond weakens. I am hoping the flexible silicone sealant won't have this issue.
31/03/2020
I have added a new version of the PLA/TPU combo mask (V3) The new design fits my wife and me pretty well.
It does need to be shifted on the face to allow it to seal properly.
I left off the upper bead as it makes the TPU less flexible. I have also added an inner (thickening) band that allows the joint (PLA//TPU) to be wider. Hopefully this will result in a stronger bond.
I have also adjusted the nose bridge area as well as the angle of the filter so the mask can be printed with a larger TPU section. It can be printed in a single piece by printing the PLA up to the top of the fastener ridge and then the remaining upper section in TPU.
I printed a the complete mask (no filter parts) in just under 2 hrs. I used 0.3 layer height but this does result in a courser thread and not as nice a finish. I would recommend a smaller layer height and/or using adaptive layers.
I do not recommend printing the bottom section (part with threads) in TPU as the threads will tend to bind more readily than with PLA to PLA. It may work fine if the whole section can be printed in TPU but if its just the end, the TPU and PLA may separate under the pressure of threading in the filter. The TPU gasket is loose at the threads so this doesn't have the same issue.
I have also included the same design split into two pieces in case you want to try and print the TPU and PLA parts separately and then try and glue them together. I am currently experimenting with using silicone sealant as a bonding agent.
30/03/2020
I have uploaded a slightly different style shell, meant to be printed in mixed materials (hard for shell and flexible edge.)
I used PLA for the shell and TPU for the flex edge. I did a 3mm initial TPU part instead of having to print a gasket then the main shell in PLA and the final upper edge in TPU. The transition heights were 3mm and 46mm.
I have not done extensive tests of the bond between PLA and TPU. The join is only 1.2mm wide but on my prints it appears to be holding up so far.
The new design has a different strap fastener and the nose (bridge) shape is slightly different. It still does not fit me well but it fits my wife perfectly.
29/03/2020
I did a test print of the mask in TPU. I had to stop after the nozzle portion, as it was definitely going to fail. Instead of wasting the print I decided to experiment with a mixed PLA/TPU print, so I swapped filament to PLA and continued printing till it got past the strap holes. I then swapped filament back to TPU. The pictures are uploaded so you can see how it did.
The bond appears strong enough. I may have to try and redesign the top edge so it is a little thicker and move the strap holes a little so I can get more TPU at the edge.
28/03/2020 (2)
For anyone who would like a slightly larger tool so its easier to turn, I have just uploaded a Filter Tool Tall.
28/03/2020 (1)
Updated a new full mask seal that is not as large as the seal previously posted.
The new seal needs to be printed in TPU and will add a little softer surface where the mask touches the face.
An alternative, to printing a TPU seal, is to take a length of small diameter silicone (or similar) tubing and cut a slit lengthwise and then place the tubing around the mask edge.
27/03/2020 (2)
Just realized I forgot to upload the filter gasket. Its now in the file list.
27/03/2020 (1)
I just uploaded an upper seal that can be printed with TPU. The mask can be moulded slightly by heating the shell with hot water or hot air and bending the edges carefully. The TPU seal can be used to fill some of the extra gap for those with smaller noses and lower bridges than mine. It can also be sliced or trimmed to help fit better.
Let me know if there are other alterations that would make it fit better.
Not sure why the STLs are not displaying. Hopefully Thingiverse will get the bugs worked out soon.
Summary
Here is my latest hard shell mask design. This is designed to be printed without any supports using PLA or other similar filaments. I did not have any success printing it with TPU but I have only just started playing with flexible filaments so it may just be me.
There are 3 parts to the mask that can be printed in PLA. These consist of the main shell body, the filter cartridge and the cartridge cap. There is also a cartridge tool that you can print that makes assembling the cartridge a little easier.
Note: the nose pad and copper filter are not included in the parts. They are only for visual demonstration purposes.
I just used some of my wife's make-up remover pads as the filter material.
The filter material gets inserted into the cartridge and the cartridge cap is screwed in to hold the material in place. The whole cartridge assembly is then screwed into the front of the mask. Use some TPU filament or other material as the straps to hold it on.
The shell is only 1.2 mm thick so it can be softened and reformed a little if necessary.
It fits my face but the nose bridge is quite high so it may need some foam or other padding around the upper edges. There are different types of material such as self adhesive weather stripping or soft, flexible medical tape that could be used depending on the thickness needed.
I am looking at ways to print a TPU upper seal and will update it if I come up with a simple solution.
Note: This is a dust mask and is not meant as a medical equipment replacement.
If you do succeed in printing it in TPU please let me know.