HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Oct 21, 2014, 08:38 AM
Registered User
meerkat13's Avatar
United Kingdom, Birmingham
Joined Jan 2013
417 Posts
The most important thing is don't skimp on your quantities, and that you are going wast at least half of your mix. I'm using about 23.5 grams of mixed resin to produce a 10 gram wing skin.

With those very early moulds, I actual included 1mm vent holes to let the air escape but allow some pressure to build.

With the wing moulds the parting plate do that job as they are not a perfect seal. I think this is why the parts failed on the lower density UP foams - no seal equals no back pressure and therefore the foam doesn't pack as tightly, giving me a poor surface finish.

I'm definitely going to do some more testing with the lighter foams as there is some weight to be saved if I can get it to work. Then again if I have to beef up the structure because it becomes too weak then we are back to square one .
meerkat13 is offline Find More Posts by meerkat13
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 21, 2014, 02:04 PM
Registered User
Denver, CO
Joined Dec 2005
6,315 Posts
With traditional wet layup molds, we often reinforce the mold with layers of fiberglass on the back of the mold. If the mold is not rigid enough reinforcement might be possible.
Roto Rob is online now Find More Posts by Roto Rob
Reply With Quote
Old Oct 22, 2014, 04:24 AM
Registered User
meerkat13's Avatar
United Kingdom, Birmingham
Joined Jan 2013
417 Posts
Quote:
Originally Posted by Roto Rob View Post
With traditional wet layup molds, we often reinforce the mold with layers of fiberglass on the back of the mold. If the mold is not rigid enough reinforcement might be possible.
Yes defiantly. You will see in the casting videos that one of the cores is quite a lot weaker then the others. I've had to repair in a couple of times, particularly around where the alignment pin are... more of an inconvenience then anything else.

I will be looking at different methods at filling the mould cavities when I do the fuselage or any other big moulds.

Cheers, Steve
meerkat13 is offline Find More Posts by meerkat13
Reply With Quote
Old Oct 22, 2014, 07:29 AM
Registered User
meerkat13's Avatar
United Kingdom, Birmingham
Joined Jan 2013
417 Posts
3D Printed ABS for Mould Making – PART 17

Topics covered in PART 17

--- Release Agent Overview
--- Ease Release 2831
--- Applying Ease Release 2831

Thanks for Watching!

3D Printed ABS for Mould Making – PART 17 (18 min 2 sec)
meerkat13 is offline Find More Posts by meerkat13
Reply With Quote
Old Yesterday, 05:20 AM
Registered User
meerkat13's Avatar
United Kingdom, Birmingham
Joined Jan 2013
417 Posts
3D Printed ABS for Mould Making – PART 18

Topics covered in PART 18

--- Mould Alignment
--- Print Time vs Quality & Strength
--- What happens when you force things (warning includes some cursing)

3D Printed ABS for Mould Making – PART 18 (12 min 52 sec)
meerkat13 is offline Find More Posts by meerkat13
Reply With Quote
Old Yesterday, 06:08 PM
Breaker of Things
elbowdonkey's Avatar
United States, OR, Portland
Joined Dec 2011
253 Posts
Quote:
Originally Posted by meerkat13 View Post
(warning includes some cursing)
Funny, I could use those "curse" words all day long and no one would notice.

Regarding the pegs - it seems like you should align the mold halves prior to drilling, and drill one hole at a time, putting a pin in after each hole. There's a lot of room for introducing misalignment if you do each half separately.

I think you'd probably really benefit from a layer of fiberglass/epoxy on the flat, non-mold side of the mold halves. It'd drastically reduce the chance of splitting, which printed ABS seems to want to do when given the chance.

I might also model the holes to be as much as 2mm larger than they should be. Then, as you're glassing the back of the molds, simply fill the pin holes with resin. Once cured, then you drill them out to your actual pin diameter. You'd get some perfectly sized and very strong holes that way.

Final though: with fiberglass backing (and maybe even on the sides of the mold), you might be able to reduce the number of printed shells too.
elbowdonkey is offline Find More Posts by elbowdonkey
Reply With Quote
Old Today, 03:58 AM
Registered User
meerkat13's Avatar
United Kingdom, Birmingham
Joined Jan 2013
417 Posts
3D Printed ABS for Mould Making – PART 19

Topics covered in PART 19

--- Foam-it 8 Overview
--- Mixing & Ratios
--- Tools & Equipment
--- It’s All about Preparation
--- Pouring Sequence & Clamping Overview

3D Printed ABS for Mould Making – PART 19 (18 min 5 sec)
meerkat13 is offline Find More Posts by meerkat13
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log 1/7 Aermacchi M-346 / Yak-130 / T-100 2x90mm Composite Scratch Build ysolomon Scratchbuilt EDFs 111 Jun 04, 2014 04:16 PM
Build Log Hawker Hunter Scratch Build Sandracer17 Scale Kit/Scratch Built 51 Feb 02, 2014 11:49 AM
New Product F-117 Stealth Fighter 70mm EDF jet. Scratch build crispy1074 Parkflyers 0 Jan 08, 2014 05:05 AM
Build Log Hawker Hunter- First Scratch Build rhinophoto Foamies (Scratchbuilt) 12 Jun 19, 2008 09:48 PM
Video Scratch Built 24" span Hawker Hunter EDF rcminiman Electric Plane Talk 2 Aug 08, 2007 01:55 AM