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TURK
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Group: Forum Members
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Hi guys, I realise it's been a while since my last update, but I feel some members may wonder how things are coming along. And how I'm getting on with EC products and materials. The ABS parts I'm able to vacuum form using these products are superb, better than I had hoped actually  These are still prototypes, and as I'm planning on making three different versions of the quad headlights, I made a few spares >>  The parts look fine and I managed to get very good definition. 3mm thick ABS is surprisingly strong when vacuum formed >>  Then you have to trim and profile the parts, machining all those varying holes is the hardest bit! >>  But once the Hella headlight units are installed, it makes the entire project worth while >>  So now I'm having to make the actual headlight covers. Currently I just have my clear PETG prototype covers that I made last year >>  These are my new and improved headlight covers ( plugs ), for creating my moulds. A few coats of Pattern-Coat-Primer' and lots of sanding >>  While I'm working at that, I'm also thinking about the next stage. What process will I be using to create moulds from these plugs ? While checking out YouTube, and in particular 'Easy Composites' YouTube channel ( as I'm subscribed ), I came across this older video clip > So, it all boils down to this question ..................... Is that material ( paste ) he's using in the tutorial video, the same as the 'EMP60 Epoxy Moulding Paste' that can be found on your website? My plan is to make a 'negative' mould of this plug ( the plug in the images above ), to create a vacuum forming tooling plug ( positive ). So I would need the paste for the inside of the cover basically . TURK
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Hi all, Quad headlight tooling plugs for vacuum forming now complete  just got to drill a few vent holes in them and then I can begin vacuum forming hundreds of parts !
I got to say, I am very impressed and very happy with the CS25 RTV silicone rubber, I did have de-moulding issues because it tends to 'grip' the resin but I think that's more down to the size and shape of my plug.But it's tear strength is absolutely amazing ....... you can tug, pull, spread and stretch it all you like and it will not break ! >>
 I would recommend spraying soapy water into your mould while trying to demould, makes life so much easier. Got another perfect resin tooling plug as well >>  Now I have two - NearSide and OffSide headlight tooling plugs for vacuum forming headlight parts >>  These tooling plugs will be subjected to a lot of heat for at least a couple of minutes ( about 120°C ), but with the Vac-Cast Epoxy casting Resin with it's aluminium content, that shouldn't be an issue. The plugs feel very solid, pretty much like a solid block of alloy, and very very smooth ........ I estimate I could feasibly make a couple hundred vacuum formed parts, before I need to make some more tooling plugs. TURK
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Just received my order Warren
Ordered Wednesday the 8th ....... as I live in the boondocks in the middle of nowhere in central France, I think that's absolutely superb !
Excellent service mate 
Now I can make a start on the OffSide headlight tooling plug. |
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Hi guys ....... ( and girls if there are any on this forum ) ! it seems to me that this is more of a male dominated world ......... so ladies, introduce yourselves !
This is going to be a lengthy post, because I'm simply going to cut n paste from my original forum group. So bare with me, my intention for doing so is to see if any of you clever guys can put me straight. Even though it worked, I got great results ......... but where can I make life easier for myself, and is it possible to get better results in a quicker time.
Anyway, onto my quad headlight project ........... In the last update I left you all with this. Two perfectly formed silicone moulds for casting aluminium resin tooling plugs for vacuum forming. The thing is, you couldn't simply poor ( cast ) resin in those as you would end up with a solid block of resin. Because of the intricate shape of the tooling plug itself, there must be vent holes coming from underneath the plug >>  There aren't too many ways of accomplishing this task, making a hollow tooling plug. One way the industry do it is to use sheets of a special hard wax, an A4 size sheet of wax cost £19 ! and the thickest they do is only 5mm. That's no way thick enough for the walls of a vacuum tooling plug, as mine have to be at the very least 20mm thick as they have to be able to withstand at least 20 pounds of pressure per square inch or the plugs would simply crack under pressure, so I would need dozens of sheets of wax. Making that particular method ridiculously over priced. Spending over £200 in wax on a mould that already costs in the region of £400 is not a cost effective method of producing hollow moulds. There is another method however, known as 'blocking-out'. Some people simply use blocks of wood ........ but I've had problems in the past using solid materials against one another in mould construction. Another method I believe would work would be the use of plasticine, but I haven't got enough of it in stock, so I came up with this .......... >>  I began by cutting out some templates indicating the area to be 'blocked-out', leaving me with about a 20mm gap as a side wall >>  I then transferred all those dimensions to a sheet of 5mm PVC foam, and cut them to shape >>  And then assembled the 'skeleton' with the aid of a glue gun ........ I now have my basic shape >>  You then have to block-out the gaps using a polyurethane foam, to create a solid structure >>  The reason why it's a good idea to use PVC foam for the ribs and PU foam for the blocks is, when you move onto the sanding stage, the sanding is so much easier as the PU foam is very soft and the PVC ribs are a little firmer, it's easy to see how far you have to sand ....... once you hit the 'green stuff', stop sanding ! >>  And you should end up with this ........ the inside of what will be your cast resin mould ....... minus 2cm all the way round >>  Then you apply a skim of body filler to harden the whole thing, and sand that down. but it doesn't end there ........ you now have your 'block-out' mould, but you have to be able to release it from your resin cast afterwards >>  I then turned my attention to working out how much resin I would need for casting. So I filled the silicone mould with dry rice to find out the volume >>  As it's so important to remove the 'block-out' mould from my resin cast afterwards, without damaging the resin tooling plug, I decided to use a flexible material as a 'glove' as sorts. People 'blocking-out' using wooden blocks in their resin casts, would have to chip out the wood with a chisel as resin sticks to wood like sh!t to a blanket, I chose a different method. I simply used the remainder of that OOMMOO 30 silicone rubber I had from the last fiasco, and just painted a few millimetres of it onto my foam plugs. I also found two tupperware containers about the same size as my 'block-out' mould and deducted them from my silicone mould volume >>  Now that I know the actual amount of resin I'll be needing to fill my mould, I still need to workout what that is as weight as the rice thing is it's volume ( the amount of space the resin will take up inside the mould ). You can't workout how much catalyst you need just by volume, you need it's weight. It so happens that the volume of the rice was equal to 2000ml on my measuring container. As I'll be doing the casting in two pours, I put an equal amount of dry rice ( 1000ml ) in each mixing container, then weighed that. So we get the weight of the rice which is 947 grams, but lets not forget the density of the resin ....... this particular resin because it has aluminium in it weighs almost twice as much as the rice ........ that is to say 1.80 grams per cubic centimetres 947 g X 1.80 ( g/cc ) = 1704.60 grams of resin And as the resin/catalyst mix is a 100:6 mix ratio ( for every 100 grams of resin you need 6 grams of catalyst )So the sum is 1704 x 0.06 -------- 102.24 grams of hardener required for mixture -------- Now it's just a case of prepping everything, you must give the resin a though mix before use, as the aluminium would of sunk to the bottom >>  As I'm doing this in two pours, I prepared both the resin and the catalyst, you don't want to be mucking about with weighing scales midway through casting resin >>  The two pour technique is to minimise on air entrapment, so I used Archimedes' principle on 'fluid Dynamics', where any object submerged in a body of water displaces it's own volume of said fluid. Same if you were to fill your bath tub up to an inch from the top, then stepped into your bath it would overflow. So I poured the first container into the silicone mould >>  I then positioned the 'block-out' mould very carefully into the resin being careful not to trap air underneath. An air pocket trapped under the mould would most certainly destroy my completed resin cast >>  I then poured the rest of the resin from the second container to fill the silicone mould, after securing the block-out mould in place. You'll also notice on this close-up that there's a millimetre gap between the silicone mould and the wooden side of the mould box ........ that's not good ! ........ that's due to shrinkage, most materials will shrink after they have had time to cure. The drawback with this is, the mould could end up a millimetre too small !  Now I just got to wait for it to cure .......... curing time is 12 hours >>  A couple of hours later I went back into the workshop to check on the progress, and saw this ! ........ that's not good As careful as I was, there had been an air pocket trapped under the block-out mould :eek: it caused the resin under the mould to escape thus causing this bubble burst ! ......... nothing I can do about it now, I just have to pray and hope ! The interesting thing is, notice the tape has come unstuck ....... that's down to the amount of heat that the curing process produces. The 'exothermic' reaction caused even the wood to heat up to a point where is was as hot as a cup of coffee, and even dried the adhesive on the tape ! >>  Moment of truth .......... I stayed up like a little kid at Christmas eagerly awaiting Father Christmas with my presents :confused: So at 4 AM it was time to demould, the foam block-out plugs ( or 'Bucks' Gaz ) are simply a temporary measure and will not be used agian, so I can simply break them apart. >>  Well, that worked out a treat ! after releasing the tension, the rest of the 'buck' just peeled away. The cavity isn't pretty to look at, but who cares ......... I've got a hollow mould. And it doesn't look like the air pocket did any damage to the inside of the resin cast. Actually, I think it was completely expelled, leaving that bump of cured resin on the sidewall >>  I struggled for almost 2 hours trying to demould this cast as the resin was stuck to the silicone mould ......... then I hit upon an idea, so I squirted some soapy water into the silicone mould. This is where I cut my fingers to shreds, trying to force my entire hand in between the cast and the silicone mould to break the 'seal', those edges are like razor blades ! It's amazing just how strong and flexible this RTV silicone is, it's tear strength is amazing. At one point I had both my hands up to my wrists inside that mould and it still didn't split ! And this is the result .......... an absolutely flawless resin cast ! T: >>  I am well happy with that not a single blemish on the resins surface, nice solid 20mm walls, should be strong enough to produce many vacuum formed parts. I've just got to tidy up the base a little, sand off that resin bump and smooth out the edges which are really like a knife edge >>  Was all this really worth the effort ? ........ you bet ya ! From a PU foam plug covered in Pattern-Coat resin to a silicone mould to a foam buck to a cast aluminium resin tooling plug ........ a lengthy process and an expensive one >>  I've learned a great deal from this entire process and had a lot of fun doing it, and now I'm pretty sure I can create just about any shape, that will lead to producing just about anything .......... I'll only be restricted by the size of my vacuum forming machine. Just look at the surface finish of that ........ flawless :db >>  And just one last shot of my first attempt at making a tooling plug. This thing is so heavy that it actually feels just like a solid block of aluminium >>  Next up will be to drill some vent holes in it, in order to allow the vacuum to form the shape required for the part. I'll have to work out where the holes will be positioned, as it's not just a case of drilling anywhere. And I also have to make another one ! Yes folks ....... the drawbacks of designing and fabricating headlights, every process is done in two's. I didn't have enough Vac-cast Epoxy resin left to start the other one, but it's already been ordered and it's already on it's way. I know that most if not all of you lot are well past this amateurish stage, but there's always a novice newbie out there ......... hopefully it will also help others out. Hope you enjoyed the update peeps ........ plenty more to come
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Thanks for the tips guys ........ I was totally aware of the maximum piercing of the bung as the warning is actually printed on the gauge itself. I used a map pin to pierce the bung that's only 5mm long and didn't go all the way. But that' a good tip Richie, removing the bung first and then piercing it. Many thanks Warren for the replacement Gauge. No doubt you've already found my details on my account for my address. Regarding the scales 'Auto Shut-Off' ...... It would be fine if the auto shut off wouldn't go OFF while in use ! to conserve battery life after the scales have been dormant for a few minutes would make a good sense, but not when you're halfway through weighing something ! 2 minutes while trying to pour silicone accurately is not long enough, the auto shut off should be longer. I did make a note of the bucket weight ( always do ), then' tarred' the scales so no issues there. The problem came up when I re-weighed .......... I got three different results ! TURK
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Hanaldo
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Group: Forum Members
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Regarding the scales auto-off function, this is why I always take note of the weight of the container I am pouring the stuff into. Before you start, tare the scales and measure the container, write it down. Then zero the scales including the container and start pouring. If it flicks off on you while you are pouring, simply weigh what you have and subtract the weight of the container. As Warren said, most battery scales will have an auto-off function. I used to have one set that didn't have it, and trust me it is a LOT more frustrating having to replace batteries all the time because you were too focussed on the pot-life of what you were mixing and forgot to turn the scales off!
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Rich (Staff)
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Just to add to Warren's last post - you could actually remove the bung from the gauge to pierce it before replacing it to make absolutely sure.
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Warren (Staff)
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Group: Administrators
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Hi Turk,
You will find most battery scales will have an auto shut off to protect battery life. It is a bit frustrating if you need to leave the scales for a while mid measuring!
In terms of the silicone pulling from the wall of the box, I would not worry about it as in practice, the weight of the resin you pour into the mould will force it back against the box anyway so in practice there should be no problems.
I have a replacement vacuum gauge here which I will dispatch to you today so that should solve your problem. Only thing to note is be careful how deep you pierce the bung to equalise pressure. The max on the gauge is 4mm. Some people have gone a fair bit deeper then hit the mechanism so be careful how deep you go.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Hi guys, Thanks for those kind words guys ........ yeah, really happy with the way it turned out, resulting in two immaculate silicone moulds
After only having one attempt at mixing and pouring RTV silicone prior to these ( the outdated OOMOO 30 fiasco ), preparing and mixing just over 4Kg of silicone can be a stressful experience for a novice such as myself. What calms the situation is the knowledge that the CS25 has a pot life of around 60 minutes, so there's no need to panic as you would probably would do with other silicones with shorter pot lifes. Things did almost go pear-shaped immediately though ....... the scales I bought from EC, really aren't up to the job I don't think. Not EC's fault as they didn't design them, who in his right mind would design a product like that, that are an 'Auto Shut-OFF' system !? I was midway through pouring the silicone into my weighing bucket when the scales turned themselves OFF ! then when I tried to re-weigh again, to the point where the scales shut down, I got different readings ! everytime I re-weighed, I got different weights !
I have bought myself some decent postal scales made by Steinberg accurate to 0.5 of a gram, but I won't be receiving them from Germany till the end of February ! and they're mains powered
I happened to mention that ideally I would of liked a silicone with a higher Shore A rating, purely because of the situation that can be observed in the picture below. The cured silicone mould on the left was the one I had just completed ........ the completed silicone mould on the right however, is the one I had made the previous day. Already you can see that the mould' wall is moving away from the mould set up box under it's own weight. I think because the silicone is quite flexible, thus soft, it's 'falling' inward. A firmer silicone would undoubtedly be able to support itself. It's not a major disaster, and I think the only remedy would be to tape the side of the silicone to the mould set up box wall to give more support >>
Thanks Warren for the info ...... I've come to the conclusion that the gauge could be faulty also. I understood that by piercing the bung would in effect 'set' the gauge to the atmospheric pressure that I was working at ( on average 450m above sea level where I am ). But even after a couple of days it still hadn't set itself to zero, so then I removed the rubber bung for an entire day ........ nothing really happened so I replaced the bung. Now that I've used the system about a dozen times, it's still doing the same. After about 3 minutes of the vacuum degassing process, the needle goes way past the -30 Hg mark ! As for the air bubble in the gauge itself, it's the entire top third of the gauge ......... I'm by no means an expert with these things, but I suspect that' there's something wrong here 
As with anything in life, particularly work related, we all develop our own styles of doing things, I'm still felling my way around this business, learning the processes and the different materials. I don't leave things to chance I research everything ...... Am I dissatisfied with CS25 ? ...... no, not all, I'm very happy with it and believe I will continue using it on this project. I did look at the AS40 Addition Cure silicone originally, and will undoubtedly be trying it out in the future, as I now have the correct equipment. But for the time being I'm very happy using CS25 on my headlight project.
Next up ............ casting 'Vac-Cast Epoxy Resin' |
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Warren (Staff)
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Group: Administrators
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Hi Turk,
Glad the moulds came out ok. With densities and volume, you will find in most cases, the densities are listed as a range of figures rather than one set figure to account for batch variation. Also remember that the relationship between volume and density is effected by temperature which could account for you being slightly under in quantity.
CS25 is quite a soft silicone and for most people this is ideal, although often for far more complicated shapes than you are doing where the flexibility is great to get the parts out. Our AS40 Addition cure is a fair bit firmer at Shore A 40, but is also a bit more expensive. Realistically for a simple casting I think you will be fine.
What altitude are you at? sometimes that can effect the gauges a little. If you're not especially high, then it sounds like your gauge has had a heavy knock to be off centre like that. If that is the case, contact me or any of our staff and we will happily replace the defective gauge.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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