Scale Soaring UK

I see what you mean Mark.
Although looking reasonable from a distance, my moulds look as if they need a good deal of attention upon close inspection.
I think I I’ll get John Hall to have a good look & advise when he calls by in a week or so.

This is a great effort! Having made epoxy one-offs for years I know just about everything that can go wrong! (and in my case still does!)
Just for info I enclose a pickie of a fuselage mould I recently made.
Without wishing to tread on toes the following may be of use:
I finish the pattern with two pack paint polished to a mirror, 7 coats of release wax, and then take an epoxy mould from this.
Never mix epoxy lay-ups with polyester ones. i.e. if you finish the pattern in epoxy or two-pack, don't try and take a polyester mould from it. It will invariably stick solid.
Make the mould symetrical: i.e: - one coat of gel (very thinly applied), an epoxy/microfibre fillet along all tight corners, one layer of 100gsm glass To prevent the weave showing through), 2 to 3 layers of 200gsm, one layer of 100gsm and another coat of gel. This should prevent the mould warping with age.
Put a fence around the whole lot - this too gives rigidity.
Use locating pegs - this can be done simply by drilling dimples into the first half of the mould, re-waxing and then make the second half.
Regarding the dividing plate: - I don't get too hung up about the initial fit of this (I use 9 mm MDF with a lower fence to hold this the correct height above the workbench to allow the plug to fit centrally). I taper the hole in which the plug fits and with everything firmly held, I apply a fillet of filler into this notch. Once set I remove the plug and sand this fillet flush with the surface of the dividing plate. The plug should now fit perfectly.
Hope this helps a bit.

Peter
Thanks for the explanation
But for someone that has only built woodies and would like to try to build a glass fuse, most of the paragraph above was gobbledygook. Maybe someone could start a new thread with step by step instructions on making moulds. Even small mould like control horn fairings.
Stu

Not able to find space to take the ASK21 mould to the Shrivenham aerotow, so a couple of pics to show current progress.
The excess mould flange material has been removed and the inner mould surface voids filled. Just needs a final surface polish now prior to making the first part.

I have decided to make an epoxy part (rather than polyester resin) as with a slow hardener this will give me a lot more time to get the various glass cloth & roving layers in properly before the resin gels.
The downside is that I will need to make both sides and then join them in one hit - using glass overlaps from each side to form the central joining bond. The upside is that I hopefully get a complete part in one go.

However, before all that, I will be having a practice on some much smaller moulds that John Hall has kindly lent me.

Superb work there Peter. I have always liked the K21, lovely lines for a 2 seat training glider.

Epoxy glass fuselage laid up last Saturday in a marathon 6hr stint.
After discussion with John Hall it had been decided to lay up each half with matching join line overlaps using slow cure epoxy resin. The 2 halves were put together whilst the resin was still wet & the overlaps smoothed down onto the other side to form the complete part in one sitting.
After the normal cure period, the part was post-cured for 8hrs or so at 30+. I finally managed to release it from the mould this afternoon after a bit of a struggle (as anticipated due to the less than perfect nature of the mould surfaces)
However, it is now out and should be useable after tidying up some surface blemishes.

I still have ply wing root & tail fin top to epoxy into place as these were left out at the lay up stage to reduce work.
An idea of the result is shown below.

Excellent work Peter. When does production start?

Thanks guys.
Still a long way to go to get a flying model, but at least I now have something to attach things to!

The mould needs some repairs & surface polishing before I can even think about re-use, and probably isn’t good enough for serious ‘production’ use - at least with my fibreglassing skill level. We will see where we go once the design is proven.

Once I have added the internal ply wing roots/tailplane mount and checked that my planned wheels will fit, I can progress the built-up wing and tailplane designs ready for part cutting.

Well done Peter. A lot of hard work I think I will keep with my lost foam method. But it is some great work you have done look forward to seeing how the rest of the model comes together. .Roo

Hi Peter, I have been watching this build and was wondering what weight of cloth you used in your epoxy glass fuselage, and how many layers? and did you use a gel coat or was this just layed up just using epoxy as the first layer?