MIRO 2

[Rod]

Pretty straight forward build. Weight 22gms for both, a little heavy but strong.

[Rod]

Finally making headway here. Decided on stab adjusters afterall. Am using Tufnol again but with hindsight I think a softer plastic is better as the tapped holes shrink slightly and grab the grub screws. With Tufnol they will need loctite to stay in which is OK too I suppose. Have used my usual manual CNC system

[brusty]

Hi Rod, You certainly are an ingenious fellow. Early in this post we spoke about release systems, I have just had an experience with taking another spinner model out of the mould for my Raven. I am using this Freecoat system, so just applied a further three coats of release (I have already had two spinners out) and laid up in carbon and epoxy. This morning on trying to open the mould, it was stuck solid and I had to use brute force to pry it apart, with the resulting damage shown in the attached picture. The spinner is recoverable as I need to true it up on its backplate in the lathe. I have just paid a visit to my Fibreglass guru, and the conclusion is that Epoxy and cloth or carbon is an aggressive glue. For the first two spinners , I prepainted the mould with an acryllic undercoat and he thinks this formed a barrier, just as a tooling gel, or a polyester gelcoat does in their layups, and thus I got away with it. This time because I was going to retrue the spinner, I thought painting it was a waste of time, and hence I have paid the price!! All my other moulding released perfectly, but they were all pre-painted, but interestuing that I took a small partial mould out of the fuz mould (unpainted) to form the root rib covers for the wing, and was surprised then when they were rather hard to pry loose. Lesson learned, albeit a little late.
The advice this morning is to continue using the freecoat system when building moulds, because I am using tooling gel , but with the models, he suggests I use the mould cleaner and mould sealer systems, but then wax the mould as I have done in the past and continue to paint the mould before laying up. Previously, even with the waxing regime, I did feel that painting the mould helped with the release, but also lessened the dreaded pinhols forming.
I would be interested to hear your or any other's experiences.
Regards, Barrie. R.

[Rod]

Hi Barrie
Very frustrating, I highly recommend the Zytec system from Fibreglass Supplies. The fuselage I did with the Zytec finish is so slippery it is difficult to hold. See my earlier posts on this thread. PVA release works OK if you put plenty on. I like to do my finishing after molding as I think I can get a lighter product that way. To be honest if I get pinholes I know I have a light part, and I have an easy and light system do deal with them. However if I want a real glassy carbon finish I struggle with micro bubbles on the surface.

[alec taylor]

well barrie the edge fuse is ready to paint. another 3 weeks before i get the sheeting for the wings. special order. whats best glue for edge joining of sheets as the cabbots varnish shows up some glue lines. never had any luck sending photos on this site. shes in a camera club so should know what to do. i will get 1 can on the phone and he can talk her through it. the last sht. of foam i got weighed 14 lbs. size 8x4 ft x 6inch thick. anything better ? alex

[brusty]

Hi Alec, Sounds like excuses on those photos !! That foam I think is about 15kg by my calcs. I used 12kg foam on Mike Briggs' recommendation, it was great, and I got it from Styrobeck plastics in Auckland who will make it to order at your required density.. I don't know whether there is a local manufacturer down in that island you live on ? The freight is costly.

I usually edge join the balsa sheets with cellotape to get a good tight fit, and then run a thin bead of aliphatic down the folded back edge, lay the skin flat and close the joints, and run a chisel on the surface over the join to remove the excess glue. Then stack the four skins with greaseproof between each and leave them overnight under a piece of weighted mdf. I find the aliphatic sands well without leaving a ridge.

It will be interesting to hear what Rod advises, he is by far the most experienced in these matters.

Cheers, B.

[Rod]

Yes Barrie I do it that way too. I have detailed my system on this thread. Balsa cement can be used as well but is probably harder to apply. Some just tape the sheets and leave it on while guing to the foam and let the glue seep into the joins. The down side to this in my mind is hard epoxy or PU in the joints.

[alec taylor]

hi barrie , i get my shts down freight free. got a scam going. some use gorila glue to join sheets. others just tape and the glue comes through when under compression. i wouldnt trust that.

[Rod]

Hi Alec Styrobeck is a really good company. Their foam is virgin bead and they have 4 or 5 densities. I use SL grade (super light) for wings and hard for making patterns.

[Rod]

Sorry I havn,t posted much on the new Miro build. I managed to put the stab on 28mm forward of where it was supposed to be so I have cut out the tube and have nearly finished redoing it.

[brusty]

	Quote: Originally Posted by Rod
	Sorry I havn,t posted much on the new Miro build. I managed to put the stab on 28mm forward of where it was supposed to be so I have cut out the tube and have nearly finished redoing it.

Rod, I'm so pleased to hear you are human !! I've cleaned my Sukhoi moulds and applied four coats of sealer today. Tomorrow will apply the Zyvax #4 release coats.
most impressed with the sealer, it is easy to apply and already very slippery.

cheers, Barrie.

[alec taylor]

hi rod. after some hints from barrie i sent him some photos last nigh. alex