CORONA / Need Help For German Police
Hello friends,
I'm a german police officer and (just like everybody else) we are running out of masks / filters.
I try to design a reusable filter for our gas-masks but I have trouble with the thread. I started 3D-modelling / printing for private use some weeks too late, so I am not fit enough to help myself.
Could anybody help me please? I think, I just need an XML-file for my thread, but didn't find anything... Of course I would publish the result for free use for all again!
If you have any ideas, please write me! I will check mail and messages as often as I can, but I'm doing this between my watches, so I can't read all the time, but I will answer every message!
Thank you very much!
Chris
Accepted answer
Model attached. Give it a try. The OD is created exactly at 40mm which is the maximum tolerance for the profile, but a quick rub with sand paper will knock it back if the fit is too tight (better than too loose).
Don't force the fit if the face piece is plastic, if the threads in the mask fail the whole mask is lost.
This model is based on dimensions shown in Table 1 - Thread Limits from BS EN 148-1:1999. It says the European standard EN 148-1:1999 has the status of a British Standard. The thread designation is Rd 40 x 1/7
Let me know if it works, or if changes are needed. Post some pictures of what you make, or share the design. No doubt a lot of countries are using this same standard on their respirators and masks.
2 Other answers
The thread is probably based on some standard (such as DIN), but what standard?
Or you could try measuring the thread on the filter, and they try modeling it. You need measurements on the outside diameter, pitch, root diameter, thread profile, etc.
DIN EN 148-1 40mm dia. is a thread which seems to be in standard use for screw on filters for respirator masks DIN being the standards in common use in Germany. I had in my tool kit a respirator that had this type of fitting to attach the filters. I have not used it for many years so I may not still have it but I will look through my tools to see if I can find it.
https://www.techstreet.com/standards/din-en-148-1?product_id=2043273 is a link to a place that this standard can be downloaded from but is not free and has to be purchased. This standards document will give the dimensions to model this thread.
You are looking at making a 3D printed respirator filters with standard 40mm thread the same as the replaceable filters. If I had details of what you require, along with the specifications for this DIN EN 148-1, making a model of this which would be output as an STL file, the format from which the G code required by most 3D printers is generated would probably be a quick and simple task. You can use GrabCad mail to send to me details of what you want and I may be able to produce the required model of help you to do it yourself
