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A pair of Airfix Hawks in 1/72. Finished.


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Hope the tub mould is ok - as I don't have enough RTV left to make another one without restocking.

Just restocked myself, I can certainly recommend this stuff, been using for last few years without trouble. Cheapest I know too.

Success - or disaster?.......

Lets find out in the 20-25min demould time........

Edit :- always helps if you put the link in to what your refering to dun it.

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Ta for the linkie CT.

Results of first pour - mixed:

Tub was pretty good. Useable with only a few tiny bubbles at the odd corner - could easily be filled:

38A4AD84-9758-4E91-9B00-429EFD1A1873_zps

Confident now that I'll get a couple of decent tubs :)

Coamings less good:

F8BE2BB2-E874-4E5F-929E-ECABFF818BA5_zps

Resin didn't get to the extremities :(

Never mind. They only need a little of the resin mix and each attempt only takes a few moments.

BTW. I've cut the coaming moulds in two so that I can do each one separately. Look at those air bubbles! Looks like I was lucky that they didn;t spoil my moulds!

149F8787-9FCF-47FB-9BEA-2BDF22BD7BD8_zps

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the tub came out very well indeed. I kind of like the imperfections on the face of the coamings as it looks more like the 1:1 (i.e. not being 100% perfect) and I think that those natural type of defects always look way better than any designed in defect or flaw

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For the coamings I've had success by first manually getting resin into the extremity's with a cocktail stick dipped in resin before the pour. Even if you run out of time with the first batch of resin the pour can be completed with a second batch as it will bond with the first still being soft.

That cut RTV looks perfectly normal for undegassed RTV fortunately the bubbles don't normally break against the part and so retain a thin membrane between it and the part. So the cast remains true. ......most of the time.

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Just restocked myself, I can certainly recommend this stuff, been using for last few years without trouble. Cheapest I know too.

Thanks for the recommendation CT. Have had that stuff on my watch list for a while but not taken the plunge as had no idea what it was like. Shall get some when I use the last of my sylmasta stuff (bought at SMW 2013 & still usable...!!!)

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I like the tub too, very tidy work

As for getting into tight holes (OI!) I used a hypodermic needle to push down to the head box on my bang seat moulding and the airbrakes

I use the hypo tubes calibrations to get the right mix every time

If I pushed in the right direction it worked well

if I went wrong so did the workpiece :(

Usually not too hard to push thickened but not set resin out of the needle with a thin wire

usually :(

I need a new needle now, turned my back on it and it set down the hole DOHHHH!

I find the stiffening resin pushes out from the ejection port and back out to the world again when the plunger is withdrawn

Steve why not add a small stub to the mould to allow extra resin to get past the critical points, Airfiasetamya do it for the same reason, look at the extra stubs on some injection mould sprues

The end pool takes us down to the nitty G in there

edit

The hypo I use was part of a cheapo Inkjet Refill Kit, always saved one or two needles after use

I've got another one somewhere, wish I remembered where :(

Edited by perdu
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Nice work with the resin Steve.

Regarding the MDC if you etched it in thin copper you could use Ferric Chloride, which you can buy in Maplins for etching PCB's, not too sure where you could get the copper shim from though. On the full size machine are the MDC's flat or round? If they're are flat then etch would be the way to go. If rounded then you could probably give it a coat of thin superglue on one side, and the surface tension would give it a half round shape, leaving a flat to fix to the canopy.

Al

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New cottage industry stylee bits manufacturer arriving on the scene methinks....

"Man Friday's resin parts for the discerning Hawk modeller"

Woo,PP Aeroparts,they used to be the bog's dollox parts that everyone had BITD.

If you've the Flightpath set Steevo,they could well be originally PP bits,pretty sure

Mr Parkins snapped up some of the masters when Tim Perry shut up shop.

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The tubs look good. I really must try some of this casting myself, I am the sort of Muppet who will painstakingly scratch build the same part any number of times and then wonder why I am losing interest in what I am doing. :banghead:

Martin

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Well Fritag old chap, just back from the N Devon coast, meandered past RMB Chivenor, they're turning it into factory units! PM me with your details and I'll bubble wrap the etchie and give it to my boy with his cleft stick to deliver.

Regards

Stickers

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Thanks Stickers - I'll PM you.


As for getting into tight holes (OI!) I used a hypodermic needle to push down to the head box on my bang seat moulding and the airbrakes

......

I need a new needle now, turned my back on it and it set down the hole DOHHHH!

......

Steve why not add a small stub to the mould to allow extra resin to get past the critical points, Airfiasetamya do it for the same reason, look at the extra stubs on some injection mould sprues

Good Idea about adding a stub Blll. I think I'll try that in future.

For the present I've sort of solved the problem by making a new mould from RTV and ensuring that there is a really generous pouring lug - then when I pour in the resin (using a syringe but without the needle - thought I might end up cackhandedly piercing the mould) there is a generous reservoir of excess resin.

Then a judicious squeeze of the RTV in the right places gets the air out of the corners - and the bubbles slowly float to the top of the reservoir - and cos the reservoir is large enough when I release the pressure on the mould to suck back in the resin - the bubbles don't get sucked back down into the important part of the mould.



I kind of like the imperfections on the face of the coamings as it looks more like the 1:1 (i.e. not being 100% perfect) and I think that those natural type of defects always look way better than any designed in defect or flaw

Oh yes - I like that thinking hendie.....:)

Ok so - the resin casting is over for the present and I'm pretty pleased with the outcome.

Here's my kit of parts now (2 sets and 2 spares). I has a good success rate with the tubs - only had to discard one. The coamings had only about a 30% success rate with my original RTV moulds - but that improved to 50% + when I redid them with the more generous reservoir. Using CT's patented eye dropper method of measuring the 2 part resin mix it only took a few moments to do a coaming mould so it was easy enough to do several.

IMG_3623_zpstv5pblk2.jpg

The grey primed objects are the milliput masters from the old tooling Airfix 1/72 scale Hawk canopy. I prefer the shape of the old tooling canopy. The masters need a bt of filling and smoothing yet:

And here are a few piccies of the home brew resin tub and coamings test fitted:

IMG_3624_zpsfe6p3o0m.jpg

IMG_3625%202_zpsie4vcmtt.jpg

IMG_3629_zps1d6folg1.jpg

IMG_3628_zpslrs8rq3p.jpg

Hopefully all the measurements will work out and the flightpath etched instrument panels will fit........:)

On to the bang seats next.......

Edited by Fritag
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Like Martin, I have simply got to try this resin malarkey. There is so much expertise and/or hard-earned scarring around here. Standing on the shoulders of giants, and all that.

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This resin casting is awesome!! And I know I'll never be able to do that :weep::banghead: , but thank you so much for the detailed description!

Ciao

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My goodness - I go travelling and on return find that Fritag appears to be building a whole squadron (or two) of resin Hawks.

Now we all now know where to send any masters for resin casting - Excellent work as usual.

Your results look far better than some of the "professional" castings that I have seen for sale in the past. Looking forward to the next rabbit out-of-the-hat!

MD

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Very nice Steve, as with a few others here I really must have a go at this casting malarkey. Like Martin I tend to spend a lot of time scratch-building parts as well as masters and sending them off to others, including certain well known companies to cast when really I should be ar*&ed to learn to do it myself !.....trouble is I love hacking large pieces of resin and plastic into shape, do I have a serious OCD problem ? :shrug:

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Steve has obviously mastered it, but some might find the following applicator tip useful for attaching to syringes to get fluid resin into "difficult" corners of moulds prior to set:

Disposable%20Pre-Bent%20Dispenser%20Need

They can be purchased from EBay as "Disposable Pre-Bent Dispenser Needle Tips 20pcs 20G BLACK Luer Lock Slip Dental"

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Like Martin, I have simply got to try this resin malarkey.

Go on Crisp. You'd be pleasantly surprised how easy it is

Like Martin I tend to spend a lot of time scratch-building parts as well as masters and sending them off to others, including certain well known companies to cast when really I should be ar*&ed to learn to do it myself !.....

Typical. The General has a subordinate who gets his hands dirty and does the menial stuff ......:)

My goodness - I go travelling and on return find that Fritag appears to be building a whole squadron (or two) of resin Hawks.

Now you're back can we expect some progress on the Tucano then Nigel? :)

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Go on Crisp. You'd be pleasantly surprised how easy it is

Absolutely - I've been doing it for years, & you know the old saying, ''If I can do it, you, Martin & the General certainly can!!''

Certainly wouldn't claim my castings are always in the same league as Steve's though - those tubs/coamings look spot on...!!

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Go on Crisp. You'd be pleasantly surprised how easy it is

Typical. The General has a subordinate who gets his hands dirty and does the menial stuff ...... :)

Now you're back can we expect some progress on the Tucano then Nigel? :)

Ha! Ha! Life, hectic work, etc. got in the way - I hang my head in shame :weep:

However, now have some days off lined-up, so no excuses - Brushing the dust off the Tucano as I type (actually as we mere males cannot multitask - Apparently, I will be doing that next).

Carry-on the work on those two Hawks to inspire me - I have a 1/32 scale one waiting, but have promised myself not to touch it until the 1/72 scale stuff is done. Besides I'll let you do the research first.

Found this 1980's ad:

Scan_zpspqqxodw4.jpeg

In this RAF produced mag:

Scan%201_zpslhx4mitg.jpeg

And somehow thought of Fritag.

MD.

Edited by MolarDoc
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Found this 1980's ad:

Scan_zpspqqxodw4.jpeg

In this RAF produced mag:

Scan%201_zpslhx4mitg.jpeg

Nice Piccies MD :) Particularly like the Jag 4 ship. A beautiful shape in the skies........(sigh)

Actually there's also something of a tragic irony in those piccies..

The (then) student pilot quoted on the Hawk Ad went on the fly Jags - also flew the F117 Stealth Fighter on exchange with the USAF (before the rest of the world knew it existed) - become a test pilot with the RAF and later BAE and then tragically died displaying a Hawk for BAE - actually the single seat Hawk 200 - at an airshow in Slovakia in 1999. Quite a well known crash.

Edited by Fritag
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