How are resin masters made?

[Janissary]

What tools, materials, and techniques are used to make the masters for AM resin sets, like Wolfpack or Aires ejection seats, cockpits, pilots etc? Are they all hand made? The details and things like symmetry, straight lines etc. are usually done astonishingly well. Please exclude 3D printing at this time. 

 

The reason I ask is I'd like to scratch build a few details on 1/48 OOB ejection seats. Primarily seat cushions, belts, buckles etc. I just wanted to understand what it takes to make these details at a professional level so that I may learn a few tricks. I realize Aires uses PE sets for various details, but I am particularly interested in ejection seats where the belts and buckles are already a part of the resin piece, like this one:

 

Edited January 3, 2017 by Janissary

[Rex]

Wow, those are beautiful.

 

I don't know about seats, but, I was just told recently to make my masters in actual scale. Apparently resins have advanced so much that I don't need to make "1/71 or 1/70 scale" patterns for 1/72 finished parts. I know that is not much help with your carving,,,,but, what size to work in should be of some help.

 

Just avoid older, discounted resins when you get to the mold making and parts production phase.

[breadneck]

I`ve always wondered what type of tree produces resin. I mean we`ve all heard of the rubber tree right :)  

 

https://en.wikipedia.org/wiki/Resin

 

There`s just bound to be a lot of resin trees in the Czech republic ;-)  

[MoFo]

The short answer is, whatever it takes.  They can be carved from balsa, built from strip or sheet styrene, machined metal...  whatever the patternmaker likes, is experienced with, or feels will best create the required details.  The unfortunate truth now though, is that a large proportion of the top-tier resin products (AiRes, Wolfpack and the like) probably *are* 3D printed from digital files, using high-end SLA and DLP printers.

 

If we limit things to *just* old-school, hand made masters, however, and using your ejection seat as an example...

 

• The patternmaker will either start from a kit ejection seat, or will build the frame from sheet styrene.  If the latter, templates can be made from an existing seat, then trimmed out of the sheet stock and built up.
• Engraved rivet detail would be added with a pounce wheel.  Embossed rivets can be made on thin lead foil, which gets laminated to the plastic frame.
• Raised 'structural' details on the seat are added with strip and rod styrene.  The pieces are trimmed to shape and glued in place.
• Bottles, rockets and the like are made from styrene rod.  
• Wiring is added from either wire, solder, stretched sprue or epoxy putty 'snakes'.  Things like wound oxygen hoses would either be made with guitar string, or by wrapping wire around a core by hand.
• Dials, rings and other circular details get punched out of sheet styrene with a punch and die set.
• Seat pads are typically made from epoxy putty, sculpted to shape.  Detail can be added with various sculpting tools while the putty is soft, or carved in once cured.
• Seatbelts will typically be made from lead foil, or occasionally thin strips of epoxy putty.  Foil is easier to work with; epoxy lets you add texture.  Some might use tape, though it would likely need to be sealed before casting (you don't want the belts coming off in the mold)
• Buckles and hardware can be made from shaped wire, or styrene strip, or either custom- or commercially-available PE.
• Frequently used or repeated details may be re-cast in resin - rather than making a new O2 bottle or buckle latch every time, you just make one and use a resin copy on other seats.

Finally, to prep for casting, you'll need to fill any gaps or holes so you have one contiguous piece (you can't have a loop of seatbelt floating off the seat, for instance).  To do that, you either fill gaps with white glue, or brush on future, or apply some decal film (for holes that you want to stay holes) so the part will cast properly, and won't get trapped in the rubber.  Then you're into casting, which is whole 'nother art.

 

Basically though, the fundamental techniques and materials are pretty basic.  It's just a matter of practice and skill.  You can get a feeling for how one patternmaker does it by studying the in-progress shots of the various Black Box masters:

http://acc.kitreview.com/fa14cockpit32previewbg_1.htm

http://acc.kitreview.com/blackboxpreviewbg_6.htm

http://acc.kitreview.com/blackboxpreviewbg_5.htm

http://acc.kitreview.com/fa18c32previewbg_1.htm

http://acc.kitreview.com/blackboxpreviewbg_4.htm

 

Rato Marczak also does a lot of cockpit scratchbuilding, so it's worth checking out his articles as well: http://www.ratomodeling.com/index_finished.html

 

For ejection seats in particular, this is a much larger scale, but the principles are the same:http://www.aeroscale.co.uk/modules.php?op=modload&name=SquawkBox&file=index&req=viewtopic&topic_id=97776&page=1 

And this ridiculous scratchbuilt Viggen has an equally ridiculous scratchbuilt seat: http://forum.largescaleplanes.com/index.php?showtopic=45415&page=11

[MoFo]

1 hour ago, Rex said:

I don't know about seats, but, I was just told recently to make my masters in actual scale. Apparently resins have advanced so much that I don't need to make "1/71 or 1/70 scale" patterns for 1/72 finished parts.

 

FWIW, the masters I've done for actual production are usually scaled around 100.1% - 100.25% to account for shrinkage*.  It's a simple button-press for me, but yeah, I wouldn't worry about it on a handmade master - that's about the thickness of a piece of paper over the width of a 1/48 ejection seat.

 

(it's possible that other rubbers/resins will differ, so YMMV; I've found Eduard's Brassin parts often suffer from terrible shrinkage issues, for instance))

[KursadA]

The masters for almost everything from major companies (Brassin, Aires etc.) are 3D-printed as of 2016. 

 

I lived in the Washington DC area during 1999-2001 and spent a lot of time at the Meteor Productions headquarters, where Dave (Klaus) and Scotty (Battistoni) showed me many "old school" masters designed by Scotty for Cutting Edge line of resin cockpits and accessories. Most of the masters I had seen were painstakingly assembled from strip styrene, wire and lead foil; with balsa wood or epoxy putty used for some larger, bulky shapes.

[Janissary]

Thanks all for the pointers. I'm looking to pick up a few ideas for my own use, like the ejection seat of the Hase A-4F for my next project. So I have no intentions of mass producing anything. It's good to hear master making just takes the skill and common materials. I will give epoxy putty a try, the kit's seat is too plain. 

Edited January 3, 2017 by Janissary

[The Scaremonger]

On ‎03‎/‎01‎/‎2017 at 6:41 PM, KursadA said:

I lived in the Washington DC area during 1999-2001 and spent a lot of time at the Meteor Productions headquarters, where Dave (Klaus) and Scotty (Battistoni) showed me many "old school" masters designed by Scotty for Cutting Edge line of resin cockpits and accessories. Most of the masters I had seen were painstakingly assembled from strip styrene, wire and lead foil; with balsa wood or epoxy putty used for some larger, bulky shapes.

 

That's interesting! What was of all those Meteor Productions masters after the company went East, I wonder? Were them all destroyed or do they still dwell somewhere?

It'd be a blast if they were used once again.

[Janissary]

One more question about resin casting. I cannot see any parting lines on the few resin sets (cockpits and seats) I have, despite the presence of major undercuts in the master. For production sets like Aires, how are these cast? Single piece mould? There are some shapes I see wherein it would be very difficult to remove the master no matter how flexible the mould is. The apparent absence of any parting lines has caught my interest big time. 

 

I remember reading somewhere that these moulds don't last very long, maybe 30-40 casts and then their done (so unlikely that these are one-time use mould I suppose), but I would like to understand better what the general process is for 1/48 resin sets.

[MoFo]

That's really going to vary on a case-by-case basis.

 

The short version is: different rubbers suited to specific parts (softer rubbers for major undercuts; firmer rubbers for simpler parts).  Gang casting so you can get many parts out of a single mold (you cast 20 copies of your master, then make your mold from those 20 copies, so you can cast 20 parts at a time).  Carefully setting up your master so it will cast more easily.  And exploiting the properties of rubber - you can make small slits to help with extraction without having much visual impact on the part, for instance.  But most detail parts will be done in 1-part molds.

 

Also, FWIW but RTV molds will have much shorter lives than you'd think.  For a really detailed part with severe undercuts, it might be closer to 5 castings.  For simpler/smoother parts, 20 is probably on the high end.  Although that depends in part on what the caster feels is acceptable - one person might be okay with some detail loss; another may not.

 

http://www.detailscaleview.com/2015/12/eduard-novemberfest-2015.html has some interesting photos and videos of Eduard's resin casting process - you can see some moulds, and some video of how they do it.  Things will vary from manufacturer to manufacturer and set to set, but it should give a decent feel for some of the basics.  Also, these:

 

 

 

 

 

 

 

 

 

 

 

[Neil]

2 hours ago, MoFo said:

 

http://www.detailscaleview.com/2015/12/eduard-novemberfest-2015.html has some interesting photos and videos of Eduard's resin casting process - you can see some moulds, and some video of how they do it.  Things will vary from manufacturer to manufacturer and set to set, but it should give a decent feel for some of the basics.  Also, these:

 

 

Ah!!  Those videos bring back ALOT of memories, I remember all of that kind of thing oh-so-well ....  

 

 

[Janissary]

3 hours ago, MoFo said:

 

http://www.detailscaleview.com/2015/12/eduard-novemberfest-2015.html has some interesting photos and videos of Eduard's resin casting process - you can see some moulds, and some video of how they do it. 

 

Thank you! Just what i was looking for.

 

Btw, that gang casting was so dirty I switched to p**n when my wife walked in :)