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Posted

have you ever compared them to a real helmet for size and shape? they look very original.

 

I am seeing scale and shape differences.

 

very interesting work.

 

could you ship me one so I can measure it. then I'd return it.

 

I want to document it compared to AP and ATA and TM.  a photo line up, if you will.

 

can you add the chinstraps and foam liners... it's what makes them.

 

 

I can do that Vern...but I need to make a helmet for myself first.  I'm hoping in the next couple of weeks.

Posted

Wow... just read the entire thread. You should be very proud Jeff! Great work! Really cool to see the entire process end with a sweet bucket. Good for you dude! :smiley-sw013:

  • 2 months later...
  • 4 weeks later...
Posted

Finally got the vacuum former off the back patio and into my storage shed.  This spring I will be adding on to the shed so I can have a home for the vacuum former that will double as a work shop for this kind of stuff.  I plan on doing a few smoothing passes on the helmet...and I still haven't made one for myself yet.

  • 2 weeks later...
Posted

A little more work on the mold this weekend.  I'm going to extend the bell a little as well as the side tubes.  Based on some side by side comparisons with movie photos I want to make the tubes extend out a little more.  I've also smoothed the helmet a little more.  Here is pass #1.

 

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Posted

A few more pics.  I am also going to drop the bottom edge of the frown about a cm.    More to come.

 

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Posted

Looking good. Just a tip, while the bondo is going hard you can hit it with some course 36 grit sandpaper and get most of the shaping done before it fully dries ;)

  • 2 months later...
Posted

I finished the mold modifications this weekend.  Larger tubes and a little deeper bell shape on the back.  And of course I had to modify the ear buds to fit the changes.  I made them a little smaller as well.  Ready to pull some more helmets.

 

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16362316530_4bf96030de_z.jpg

 

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  • Like 1
Posted

Great additions!  can you take a measurement from the eyeline top

and note the distance from eye top, to top of frown  height of frown, to vocoder top.

 

this will give me vertical distances to compare.

Posted

I will do that Vern.  I have to add that I increased the frown size (made the teeth a little longer)  I took it off the bottom of the frown toward the vocoder.  Made a huge difference.  I also smoothed out the dome to get rid of the bumps.  It's very smooth now.  I ordered some HIPS to try out the new molds.  My only concern is the bell size and releasing the helmet from the mold without issue.  I may need to increase the return under the bell so that there is less surface to pull over the bell.

Posted (edited)

cut the plastic off the mold.  then using an angle tip on the compressor blow air into the lip.  don't remove plastic while hot. allow to completely cool.

Edited by TK Bondservnt 2392
Posted

Weekend update.  I got the face to pull with a small learning curve on the .093 HIPS I used this time around.  It was a chore to pull off the mold.  But the helmets did not fair as well.  Unfortunately I could not get the polystyrene to pull off the mold.  Because of the thicker HIPS and the deeper bell, and the reveal under the bell being too far back the HIPS would not come over the bell.  It was so locked on I had to rip the HIPS off the mold in pieces.  Bummer.  No big deal.  I will need to modify the mold just a hair to get that reveal to be a shorter distance from the bottom of the bell.  I know it will work.  Just need to be patient.

 

So for your measurement question Vern...  Here is what I have.

 

Top of eye line to top of frown ~2.5"

Top of frown (upper lip) to vocoder ~2 5/8"  

frown width at center top lip to bottom lip ~7/8"

eye height top of eye line to lowest point on eye ~1 3/8"

Posted

Been awhile since I checked on your progress, but awesome work, Jeff!!! Very impressive!!!

Posted

Thanks. I have a few more weeks before I'll have something to assemble. I am adding additional heat coils to the heating table to melt the plastic a little faster. Right now it takes about 10 minutes to heat the plastic. Longer if the ambient temperature is below 70 degrees. I need it to take about 4.

 

 

Sent from my iPhone using Tapatalk

Posted

The process for pre-heating the mold, also pre- oven tempering a low heat for a long period of time dries out the moisture

in HIPS and ABS.  ambient temp is avoided by pre- tempering your sheets of plastic, heating your mold and table surface

then bringing your plastic up to forming temp.

 

after the pull is settled on the mold and you've run your chopstick around the eye holes and pushed in the teeth with the stick.

 

allow the plastic to cool and cure completely.  then take a razor knife and score the plastic 1/8' away from your trim line.  peel your cut plastic away.

then using the air blower from inside the mold box, apply air pressure and work the cap n back from the brow around the rear undercut.

 

when pulling the face work the knife and pull from the forehead around the mold.

 

2 keys here

 

1 cool completely

2 cut near trimline in a score, (not completely though) use air and gentle pressure to help release the mold.

Posted

Vern has a few good points.....

 

HIPS won't actually absorb moisture from the air. Only ABS will you need to heat if it's been sitting for more than a couple of days. If you are storing it in a heated house it's not so much of a problem.

 

Heating the moulds a bit will help to a certain extent but if we are to get technical it's probably better to mention the rooms ambient temperature as that has a big play in your forming too. The main problem is when you apply the vacuum you also remove air from the room and move it about and this all affects the way plastic forms....To have a perfect forming room the air has to be controlled too.

 

Forming is a lot more complicated than it looks when you start to get into it......as for blowing off the mould you will need a compressor and high pressure blasts will help.....or a vacuum table that has a blowback system built in...... To remove the plastic it's best to do it when the plastic is still warm.... Cold will tend to make the plastic brittle....depending again on how hot you got the plastic to start with..... It's good to experiment on what timing you heat the plastic for.... a second or two can and will make a difference.

 

Another way is to have a mould that collapses... There are various ways to approach this... You can have a sliding mould where the pieces slide together and can be solid or you go for the plug method of silicone moulds that have a plug you pull from the inside and the outer mould then collapses and pulls out easily.... You can even reverse vacuum form by having a negative female mould and suck the plastic into rather than over....Mould making is an art form in itself......

  • Like 1
Posted

If i may..expand on what mark has shared with us....and it is shared becouse he has paid the price of learning it his self...

For some time i used a timmer to tell me when to pull..and i would ad more time till i burnt the plastic, then i would back down the time..and i woukd feel the sag also see how far the max it will go..ya know...experience the plastic...i now dont use a timmer and go by feel

1000% outside temp plays a part and indoors plays a part aswell..here in new England we have temps that drop to below 0 with no moisture in the air and rise to 45 in just a few hours...and that is a fun one to figure out

Mark???.what kind of silicone do you use on the plug??..private joke...he wont tell me

Also...HIPS yes i remove when warm to still hot

And again...mark thanks for sharing!

Posted

The room temperature is exactly what I have an issue with.  61 degrees outside working in a non heated space.  Eventually the space came up to temp with the oven and then everything worked great.  So I need to combat the problem with more heat....either that or just wait till we get some more 70 degree weather in a couple of weeks.   Not to mention I think I gassed myself out being in the space with the melted plastic fumes.  

 

Here is a shot of the new pull vs the old one.  The top is the new.

 

16012338124_67b3346b5d_z.jpg

Posted

it's just the camera angle. they look much different.

 

the before and after changes pulls are very much different

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