Helmet Sizing question

[Dead3ye 2]

When sizing a helmet for a person's head, is the measurement taken from the largest part of inside the helmet's diameter (like just above where your ears would sit when the helmet is on) or is it measured at the largest diameter of the head opening?

Edited March 14 by Dead3ye

[Dustin 160]

Moved this topic to a better section.

[Starman37121 1]

1 hour ago, Dead3ye said:

When sizing a helmet for a person's head, is the measurement taken from the largest part of inside the helmet's diameter (like just above where your ears would sit when the helmet is on) or is it measured at the largest diameter of the head opening?

  ..by sizing, could you also mean "Scaling" or making a part larger in one or more directions.

In my experience, most "softwares" scale or resize from a reference point such as X-0, Y-0, or Z-0.

AND/OR some will expand or reduce from the center of the object.  In either case,  UltimakerCura allows you to expand or contract your part Spherically or like a balloon. 

"Clicking" the part, which "pops-up" a window and allows you to select an icon on the left.  the second one down is scale, picking that will give you options by size or percent, snap scaling and/or uniform scaling.

If you wish to alter in one direction only, you must "UN-check" the box for Uniform scaling".  Now, in the case of your Helmet,  It most likely would expand it at the largest diameter.  Complication:  It will expand it as if you had a Basketball and scaled only the X-axis,  You could end up with something like the American Foot-ball.   OR, if the area below the Ears is much smaller than the area AT the ears, (going to extremes) You may not be able to put it on or take it off.

So, Yes.  If  where the Ears are is the largest size it will scale from there, BUT, if the head opening is larger, it scales from there.   Clear as MUD?  Think, Ball or Block. If you scale a ball in only one direction it will stretch it into a Football.

If you scale a square block in only one direction it becomes a rectangle.

[GregValiant 1,342]

Hat size in English units is "circumference / PI()".  Metric may be the same sort of thing.

 

Take a piece of common 1/8" solder.

Wrap it around the persons head at the level that the hat will sit.  Tape the ends so they don't move and be gentle with the "form" so it doesn't change shape.

Lay it gently on the floor with a ruler next to it.

Take a photograph.

Load the photograph into the CAD software of your choice.

Scale the photo until the ruler in the photo is the correct length.

 

Some heads are round, some are oval, and some are apple shaped.  This one is mine.

(If anyone makes a comment about the fact that it's empty I WILL FIND OUT!)

When I have this scaled so that a spline on the shape is 23.18" in length then I know this will fit my 7 3/8 head.

 

When you get done, you can make a helmet.  This is my personal helmet.  160 LED's 3 LED PCB's, a PCB for the siren and a PCB for the bell, and a PCB for the MP3 Player, and 2 speakers.  It is powered by 6 AAA batteries.  It weighs about 2lbs.  It contains no printed parts.

I figure it's about a $5000 hat.  Yes, that is a molotov cocktail on the shield.  "Richards Wild Irish Rose" bottles made the best.

 

And if that isn't enough, here is the one I built for my Scottish brother-in-law.

He fishes, he golfs, he hunts.  He requested that it play bagpipes.  I got to pick the song.

 

Edited March 14 by GregValiant

[Slashee_the_Cow 409]

I'll start with the mandated, bold disclaimer:

You didn't say what type of helmet you're working on. If you are considering making a helmet to be used as protective equipment (a bicycle helmet or workplace safety helmet for example) then you should NOT be printing one, or modifying one with printed parts. You should buy one which meets the appropriate safety standards for the activity for which you will be using it.

 

5 hours ago, GregValiant said:

Some heads are round, some are oval, and some are apple shaped.  This one is mine.

(If anyone makes a comment about the fact that it's empty I WILL FIND OUT!)

It's not empty. But it seems to be filled with some boring, repetitive pattern.

 

5 hours ago, GregValiant said:

Hat size in English units is "circumference / PI()".  Metric may be the same sort of thing.

So by circumference ÷ π you mean diameter?

[Dead3ye 2]

1 hour ago, Slashee_the_Cow said:

I'll start with the mandated, bold disclaimer:

You didn't say what type of helmet you're working on. If you are considering making a helmet to be used as protective equipment (a bicycle helmet or workplace safety helmet for example) then you should NOT be printing one, or modifying one with printed parts. You should buy one which meets the appropriate safety standards for the activity for which you will be using it.

 

It's not empty. But it seems to be filled with some boring, repetitive pattern.

 

So by circumference ÷ π you mean diameter?

It's a one-piece helmet RED HOOD from Batman. It's smaller at the initial opening than when your head actually gets in there. My thoughts were to make the opening fit my dimensions which would leave more room inside the shell to pad and wire and light and so forth. But if there's a rule of thumb when it comes to helmet making, I'd like to know.

[GregValiant 1,342]

9 hours ago, Slashee_the_Cow said:

So by circumference ÷ π you mean diameter?

 

Because heads are rarely "round", it isn't really the diameter.  I suppose hat size would be an "equivalent diameter".

[Slashee_the_Cow 409]

9 hours ago, Dead3ye said:

It's a one-piece helmet RED HOOD from Batman

Just had to get the obligatory (and by that I mean my OCD won't let them go unsaid) warnings out of the way. Sounds pretty cool though.

 

9 hours ago, Dead3ye said:

But if there's a rule of thumb when it comes to helmet making, I'd like to know.

The rule of thumb is that the best way to do it is to make a plaster cast of your noggin and work from that, but since I don't think you're a movie's costume department, I don't think that's a realistic option. If you had a 3D scanner that would be a more realistic option, although your options for 3D scanners these days tend to be "ones you can't afford" and "ones which don't have great quality" (I have the latter).

 

Honestly, my advice would be... measure everything... much easier if you have someone who can help you do it. But you can use that to make a basic model of your head in <insert 3D modelling program of choice> and then design around that.

 

And remember: small scale testing is your friend. In this case, I don't expect you to make a miniature helmet (unless your superpower is being able to shrink yourself) but instead of printing the whole thing at once, print it in multiple sections, testing each one as you go. Then when you have a complete set of sections that fit, tape them together and see if the whole thing fits. Much quicker, easier and less filament waste than printing the whole thing each time you need to make a small change.

[Dead3ye 2]

On 3/15/2024 at 7:23 AM, Slashee_the_Cow said:

print it in multiple sections, testing each one as you go.

My powers on shrinking are limited to cold water but I decided on splitting the helmet top to bottom (face side and back of the skull) and set the inside of the helmet to the specs of my head. I'm just going to magnet it (after laughing about how I'd just glue it and forever live in it) and see if it pulls off or if it could use any altering. I appreciate the advice. 

[Dead3ye 2]

On 3/15/2024 at 5:08 AM, GregValiant said:

I suppose hat size would be an "equivalent diameter".

This is what ended up doing to get my specs. Turns out I solely sleep flat on my back because my head is flat in the back lol