-

[dr_gn]

Bill, the release agent is for putting on the original canopy so that I can release the Milliput plug from it.

I'm going to try two methods:

1) Using a plug made directly from the inside of the canopy

and

2) Another made by a two stage process using the outside of the canopy.

I think some experimentation like this will be necessary to get the correct outer mould line dimension of the final canopy.

That looks like a nice unit, but I'm not planning on making anything other than a Tornado canopy using DIY vacform, so 'free' is better than 'cheap' in this case.

[dr_gn]

there you go

I have learnt something from you already

Vaseline release agent

Very very good idea (if you make sure there are no ridges of cream/vaseline to cause rippled surfaces)

I WILL try it for myself next time around

My vac box is made from strips of thin MDF I used for notices at an MG event I was one of the organisers (Funny thing is that Debs, Ascoteer in here, will certainly have seen some of them when she was there)

Then glued together with PVA and with the vacuum surface made of MDF with holes drilled all over

Your one will be better, because the vacuum will be more constant all over

I will just sit here with a tinny wtahcing a new master class you didnt even know about before

As I said, it's based on the link I posted on your other thread recently. I've added a huge cross-drilled wooden block to the underside so that I can clamp it in the vice, and I also added a small brace over the vacuum hole to stop the mesh getting pulled down into it.

I have no real idea what I'm doing here by the way.

I wonder if I held a heat gun vertically in a retort stand above the acetate it would work like the heater in Bill's picture?

Edited March 10, 2015 by dr_gn

[perdu]

When I use mine I have the box/unit/machine sat on the bonnet of my car

MG Midgets are not compulsory with this game

And have the acetate or plasticard in a frame made of two more pieces of MDF with a hole in them and Drawing pins pushed through to grip themselves and stop the drawn materiel pulling out

I heat the plastic (with the vacuum running plugged into the side port) and hold the boards up above the setup

Then I heat the whole caboodle with a propane blow lamp and when the materiel is right (you can tell by the sudden change across its sturface) I drop it to cover the vac bed

I have window insulation foam tape around the edges to retain the vacuum and when it drops in place it happens in a second or so

have fun

you may use it more often than you expect

[Navy Bird]

The heating element in my machine is an annular coil, not unlike what you see in an electric range. There is just one loop, though. What you want to achieve is even heating of the material. Heat guns put a lot of heat into a small area; I've never tried that but it may work.

I should shut up now and just watch the master engage in his art.

Cheers,

Bill

[dr_gn]

If I put the PET-G (or whatever it is I end up with) in a wooden frame, can I put it in the oven set to the middle of its working temp range? Apprently it's 120 - 190 deg. C, so set the oven to 170 and it's happy days presumably? If I cover the oven in molten plastic, less so. A bit like when I used the dishwasher as a gearbox casing degreaser.

Good idea about the window seal - I've got some spare.

Here's the article I've been looking at:

http://www.ipmsstockholm.org/magazine/2002/08/stuff_eng_tech_moulding_canopies.htm

[Navy Bird]

I believe the sheets I have are PET-G, their brand name is Vivak. I think they are 0.6mm thick, I remember getting the same thickness as Falcon uses (by measuring the non-formed part of a Falcon set).

You gonna heat that baby up tonight? I'll put off getting in my jammies if that's the case!

Cheers,

Bill

[perdu]

G the deciding factor with PETg or Acetate is time

Which is why I do the 'heat over the box then drop right down' scenario

Putting the PETg in the oven the onto the 'machine' is likely to engage the fail button more often than not

I do like PETg but find acetate easier to use, but acetate is what I used for centuries before this became a hopbby adjunct rather than a personal intention

Acetate was all over the place, missus's fripperies and chiristmas card boxes for instance

getting PETg is new science for me so I'm learning again

prediction

you will soon get the method sorted

We'll learn something (else) from you

[dr_gn]

I believe the sheets I have are PET-G, their brand name is Vivak. I think they are 0.6mm thick, I remember getting the same thickness as Falcon uses (by measuring the non-formed part of a Falcon set).

You gonna heat that baby up tonight? I'll put off getting in my jammies if that's the case!

Cheers,

Bill

Ha ha, no I'm off to bed it's 01:00 here! (Plus I've got no PET-G or canopy plugs yet). Thank You and goodnight.

G the deciding factor with PETg or Acetate is time

Which is why I do the 'heat over the box then drop right down' scenario

Putting the PETg in the oven the onto the 'machine' is likely to engage the fail button more often than not

I do like PETg but find acetate easier to use, but acetate is what I used for centuries before this became a hopbby adjunct rather than a personal intention

Acetate was all over the place, missus's fripperies and chiristmas card boxes for instance

getting PETg is new science for me so I'm learning again

prediction

you will soon get the method sorted

We'll learn something (else) from you

If I g-clamp the 'thing' on the oven door, it might work OK - not much heat lost?

[perdu]

Fingers crossed

It is constant heat all the way to the vacuum that matters, thus keeping the plastic floppy but unburnt

(mind your fingers)

[Giorgio N]

Just went through all the 17 pages of this thread, absolutely fantastic job !

Good luck with the vacform canopy ! If you haven't done this kind of things before, keep in mind that you'll need a few attempts but in the end getting a decent canipy is not too difficult. I use a similar "machine", with the only difference that the grill in my case is replaced by a hobby PCB base.

As you're now going to use a vacform canopy, have you considered the one made by Pavla ? I'm not sure if it's sized for the Revell or Hasegawa kit, but it's very cheap and easily available

[dr_gn]

Thanks Giorgio. The only vacform is for the Italeri kit IIRC. Ive got one, its far too big. Its one of the canopies in the line up I posted last night. The problem with the Tornado canopy will be the angled lower frames.

[Fritag]

Garth,

As I've been twiddling my thumbs before starting a Hawk build - and knowing you were thinking of vac forming a canopy if need be - I thought I'd have a play with something similar using milliput inside the Hawk canopy and see how it went. I plan to vac form new canopies so I knew the practise wouldn't be wasted.

I've got one the chinese dental vac machines identical to the one Bill posted above. I have to say it makes the job much easier. The heating element really does take the hassle away from the process.

I used a home built vac box for my chipmunk canopy and the chinese dental model for the JP5.

I used the sylmaster silicone mould release agent from my resin casting kit rather than vaseline - it's thinner so no risk of ridges.

Seeing as it was practice I did the canopies from both the revell and airfoil new and old boxings (the new boxing has the canopy as one piece):

It was easy to cut and sand the milliput to size and the silicone agent worked well in making it easy to release the master from the canopy.

However I didn't find that the surface of the milliput masters were very good. Each of them had little crease lines and pits of various shapes and sizes. I think it's because the milliput is quite dense and firm when mixed and resisted being pushed and squeezed into perfect contact with the canopy.

I'm not sure what the answer to that is.

Ignore the raised MDC in this photo and look closely at the side of the master - you can see the imperfections:

Just polishing the milliput master wasn't going to do the trick - and the surface is just a little too soft for comfort. So I brushed cyano all over it and let it dry for a bit but not fully harden:

That polished up reasonably easily and left a harder finish. I produced a reasonable test canopy from the master - but not perfect as I couldn't get the cyano surface perfectly polished - and every minute imperfection gets transferred to the vac form.

So I thought I'd try giving the masters a coat of Mr Surfacer 500 from a rattle can and see if that was durable enough to withstand the heat of vac forming. Of course it polished up a treat:

Oh - and I stuck some 1mm plastic strips on the bottom of the masters - just to hold them slightly above the deck of the vac machine and ensure the bottom of the canopy was moulded crisply.

I put some blue tack at either end of the main canopy master to make it easier to release from the mould. Here they are on the machine after some 0.75mm PETg has been heated and pulled.

The heating element makes it perfectly predictable. I know that if I set up the machine - raise the carriage with the 0.75mm PETg, turn on the heating element and monitor it until the PETg sags just to the bottom of the carriage frame - it's perfect for moulding.

Removing the blue tack then lets the master just drop out:

It's only practice - but doing two pulls on the trot produced some pretty bloomin good results:

And the Mr Surfacer did not deteriorate at all - which is excellent news:

0.75 PETg produces a pretty robust canopy - but if the original kit canopy was quite thick then the resulting vac form will be a bit slim such that I think you'd have to add the framing with plastic strip rather than paint.

Thicker PETg may be a better solution in those cases and I tried using some old 1mm PETg of indeterminate make - but for some reason it was very temperamental when heating - going quickly from sagging to bubbling before I could catch it:

Maybe a poor sheet of PETg or maybe poor techniques. Dunno yet.

Anyway - sorry for the large post/thread drift but hope it's useful.

Steve

[perdu]

That looks pretty good Steve

Already teaching me stuff, no doubt Garth will too

Mr Surfacer, looks the bizz

[Navy Bird]

The heating element makes it perfectly predictable. I know that if I set up the machine - raise the carriage with the 0.75mm PETg, turn on the heating element and monitor it until the PETg sags just to the bottom of the carriage frame - it's perfect for moulding.

+1

That's exactly what I've found.

Another thing I've found - when your modelling club members learn you've got a cool vacuform machine (of any kind) you suddenly have a lot of friends with favors to ask!

Cheers,

Bill

[dr_gn]

Garth,

As I've been twiddling my thumbs before starting a Hawk build - and knowing you were thinking of vac forming a canopy if need be - I thought I'd have a play with something similar using milliput inside the Hawk canopy and see how it went. I plan to vac form new canopies so I knew the practise wouldn't be wasted.

I've got one the chinese dental vac machines identical to the one Bill posted above. I have to say it makes the job much easier. The heating element really does take the hassle away from the process.

I used a home built vac box for my chipmunk canopy and the chinese dental model for the JP5.

I used the sylmaster silicone mould release agent from my resin casting kit rather than vaseline - it's thinner so no risk of ridges.

Seeing as it was practice I did the canopies from both the revell and airfoil new and old boxings (the new boxing has the canopy as one piece):

It was easy to cut and sand the milliput to size and the silicone agent worked well in making it easy to release the master from the canopy.

However I didn't find that the surface of the milliput masters were very good. Each of them had little crease lines and pits of various shapes and sizes. I think it's because the milliput is quite dense and firm when mixed and resisted being pushed and squeezed into perfect contact with the canopy.

I'm not sure what the answer to that is.

Ignore the raised MDC in this photo and look closely at the side of the master - you can see the imperfections:

Just polishing the milliput master wasn't going to do the trick - and the surface is just a little too soft for comfort. So I brushed cyano all over it and let it dry for a bit but not fully harden:

That polished up reasonably easily and left a harder finish. I produced a reasonable test canopy from the master - but not perfect as I couldn't get the cyano surface perfectly polished - and every minute imperfection gets transferred to the vac form.

So I thought I'd try giving the masters a coat of Mr Surfacer 500 from a rattle can and see if that was durable enough to withstand the heat of vac forming. Of course it polished up a treat:

Oh - and I stuck some 1mm plastic strips on the bottom of the masters - just to hold them slightly above the deck of the vac machine and ensure the bottom of the canopy was moulded crisply.

I put some blue tack at either end of the main canopy master to make it easier to release from the mould. Here they are on the machine after some 0.75mm PETg has been heated and pulled.

The heating element makes it perfectly predictable. I know that if I set up the machine - raise the carriage with the 0.75mm PETg, turn on the heating element and monitor it until the PETg sags just to the bottom of the carriage frame - it's perfect for moulding.

Removing the blue tack then lets the master just drop out:

It's only practice - but doing two pulls on the trot produced some pretty bloomin good results:

And the Mr Surfacer did not deteriorate at all - which is excellent news:

0.75 PETg produces a pretty robust canopy - but if the original kit canopy was quite thick then the resulting vac form will be a bit slim such that I think you'd have to add the framing with plastic strip rather than paint.

Thicker PETg may be a better solution in those cases and I tried using some old 1mm PETg of indeterminate make - but for some reason it was very temperamental when heating - going quickly from sagging to bubbling before I could catch it:

Maybe a poor sheet of PETg or maybe poor techniques. Dunno yet.

Anyway - sorry for the large post/thread drift but hope it's useful.

Steve

Thanks very much for that Steve - it will save a lot of trial and error. I've got some Surfacer 500, which I will brush on and flat back. I'll give it a few coats so that it will build up a few hundred microns to compensate for the thinner canopy plastic. i've also got some chemical release agent for carbon fibre moulding.

TBH I'm not that aprehensive about getting a decent 'bubble', its the bottom frames that will kill me. Their upper edges obviously need to be slightly proud of the 'glass'. This feature probably won't mould in to a high enough resolution to look any good, so I'll need to add plasticard strips over the flared bits of the transparency to form the lower framing. This will also extend back at the rear to form the hinge covers. I think doubling the thickness along these edges should result in enough extra stiffness to keep everything in place.

BTW whare did you get your good PET-G from?

Thanks!

[perdu]

If it's any use to you I use 0.5mm PETg from Hurlbatgames off ebay

5 sheets 0.5mm at £4.99, very good quality

Steve as ever providing a masterclass again

I was worried about the bottom frames on the Jag but it was silly easy to make the frames on the canopy in the end, you'd fly through it I'm sure

[dr_gn]

If it's any use to you I use 0.5mm PETg from Hurlbatgames off ebay

5 sheets 0.5mm at £4.99, very good quality

Steve as ever providing a masterclass again

I was worried about the bottom frames on the Jag but it was silly easy to make the frames on the canopy in the end, you'd fly through it I'm sure

Thanks, so what's the thinnest plasticard available for framing? And how best to glue it to the PET-G: Canopy glue?

[perdu]

I've got 5 and ten thou plasticard but I would probably use fifteen or twenty

thou depending on the real sill size you want

Did you see how I did it on the Jaguar's sill frames?

I moulded the bubble and cut it to size then dipped it in Johnson's Klear to protect it from cyano fuming

There is a certain amount of ripple-drying distortion across the bubble but I intend removing the coats of Klear with a pointy cocktail stick when it is to go on the model

The Klear lets me stick the sill rail with cyano safely though

When that set it has been easy to file and sand the rail to the correct section

here's the side rails in place glued at the angle to make the sill shape

And here's the rails sanded to shape, with the bit underneath that was clear of the moulding filled with a tad of milliput for strength then the outer frames were marked on two pieces of tamiya tape, cut out to suit and filler added to make the very shallow frame sections after rubbing it gently down to the thickness of the tape

One done here, one being done

Make and add the inner frame arches front and back, detail to taste

I know YOUR taste for detail

not really very difficult just slightly exacting, which you do as a matter of course

When you have had enough I will pull these off the thread if you like

They're just a simple guideline after all

Edited March 10, 2015 by perdu

[dr_gn]

Thanks a lot for that Perdu - no, leave all the posts here it will be another useful reference.

How about Tamiya tape? Ever tried that for framing? I've just run a riveting tool along some tape, stuck it to some acetate and dipped the lot in Klear. I'll spray it tomorrow and see if the rivet holes show up. The tape is about the same thickness as the original Revell frames by the look of it.

Next question - how about the tiny radii in the frame corners? Must be less than 1mm radius by the look of it. Whatever I use to cut these segments will probably work on thin plastic and/or tape, so any suggestions welcome. I'm currently thinking 2mm diameter brass tube with the end sharpened to a razor edge to use as a punch, then slice through the middle of the cut circle to form four external quadrants.

BTW I'm still hoping Spike's canopy will be a good 'un, but even that won't have the correct corner radii.

[perdu]

I've used Tamiya tape but these days I tend to use it to mask, leaving the thickness of the paint to replicate the framing

That was why I used it as the thickness gauge for the filler to make the frame with the slight additional thickness of the paint layer too

In the olden days I used Sellotape painted to frame canopies, I don't see any reason why Tamiya wouldn't do the trick

Radii.

I use my XO rotary stencil cutter for small rads, but I have used the tip of a Swann Morton number one blade gently following the curve

As a retired toolmaker the idea of using some sharpened tubing makes very good sense to me, relieving the curve where you dont want the cutting edge

Like all these things it has to be worth trying it

I hope Spike can solve the puzzle for you but this kind of extra stuff will please you when you do it, get successful and have a better model

b

[Fritag]

If it's any use to you I use 0.5mm PETg from Hurlbatgames off ebay

5 sheets 0.5mm at £4.99, very good quality

Thats were I got mine too. £6.49 for 5 of the 0.75mm A4 sheets. Manufacturer is Vivak - a name that's appeared on several posts

[Fritag]

BTW I'm still hoping Spike's canopy will be a good 'un....

BTW I'm sort of hoping that it ain't. I'd like to see your vac forming efforts. I have no doubt at all they'd be excellent and no doubt at all that I'd learn something useful by them.

...how about the tiny radii in the frame corners? Must be less than 1mm radius by the look of it. Whatever I use to cut these segments will probably work on thin plastic and/or tape, so any suggestions welcome. I'm currently thinking 2mm diameter brass tube with the end sharpened to a razor edge to use as a punch, then slice through the middle of the cut circle to form four external quadrants.

I agree. I would use my punch and die set with a similar object. Although I think it more likely that I'd punch several holes in card or strip and aim to get just one perfect corner out of each hole.

Steve as ever providing a masterclass again

Geroff. The milliput idea was yours in the scout build - and then Garth started talking about using the inside of the canopy as the mould for the master - and I was at a loose end so thought I'd have a go and learn a few of the pitfalls.

[dr_gn]

Thanks Fritag - irrespective of the new canopy, I'll try the vacforming 'thing' I built, just becasue I built it! I'll get some PET-G ordered this afternoon,and I'll make a start on the plugs this evening.

Where is the best place to buy a punch and die set? I've wanted one for while, but made do with modified leather punches so far.

[James G]

Hi dr_gn, this punch & die set is very good:

http://www.hannants.co.uk/product/WRP053

Not cheap by any means but great for making tiny details (I work mainly in 1:72 too). I'm fortunate my lovely wife-to-be got it for my last Christmas.

I use it with Tamiya pla-paper and it's very easy:

http://www.tamiya.com/english/products/70209pla_paper/index.htm

[dr_gn]

Hi dr_gn, this punch & die set is very good:

http://www.hannants.co.uk/product/WRP053

Not cheap by any means but great for making tiny details (I work mainly in 1:72 too). I'm fortunate my lovely wife-to-be got it for my last Christmas.

I use it with Tamiya pla-paper and it's very easy:

http://www.tamiya.com/english/products/70209pla_paper/index.htm

Thanks for that - I thought the punch set would be expensive! Luckily this is my "no saving month", so I think I'll get one ordered. The paper looks good too - have you use it for canopy frames?