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TURK
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Hi folks, Just a quick explanation of my current project. And a chance for me practice my skills at uploading pictures 
This is what I'm trying to make. The rough shape of the quad headlight cover was vacuum formed using my DIY vacuum former.
 I'm still a long way away from creating the final product, I know. But a lot of things have changed since then. Namely the mounting brackets. The new design is a modular system, these plugs are made of MDF, I've had to use body filler to shape the draft angles, as I'll be using my newly acquired Formech 508DT vacuum forming machine. Here are my MDF plugs for the headlight brackets >>  My first question to you guys would be, now that I've purchased some 'Pattern-Coat Primer' to cover the plugs with, is how to measure out ( or weigh ) how much pattern-coat primer I need the cover the plugs ? Would I calculate the volume of the plug ? say, L x W x H ........ then what ? |
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Dravis
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You need to work out / roughly calculate the surface area you want to cover with the primer. Then work it out from the amounts in the info on the EC pattern Coat primer ..
I think you will need about 1 kg of it pr. roughly 0,7 sq metre .. But that is not taking into account of sanding down, flattening and applying multiple coats.
Depending on the amount of catalyst you put in and your workshop temperature, be aware that it "sets" very abruptly- My advise is to work fast and stop brushing as soon as you notice it thickening.
Good Luck!
"Sapere Aude"... Dare to KNOW!
The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...
103% of all people do not understand statistics...
Do not adjust our mind, theres a fault in reality :-)
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TURK
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Group: Forum Members
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Many thanks Dravis, My MDF plugs are ready, all flatted, sanded, just ready for the Pattern-Coat Primer. They're basically box shaped. (L)150mm x (W)140mm x (H)70mm
So I have to workout the volume of said part.V=L x W x H ( V=15x14x7 ) to get the volume area in cm3the total is 1470 cubic centimetres
I then converted that volume into weight and got 52 fl.oz ( imperial )
That's an awful lot of resin just for a small plug, that's over 2 pints per plug !
This is what I'm covering with one layer of resin >>
There's two in the picture, but in all I have four as they're modular construction. But I'll be doing them individually.I'll apply more coats of resin if required. |
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Dravis
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Group: Forum Members
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No -No no -- You do NOT need the VOLUME -- You need the SURFACE area ..
Cut out some soft cloth or tissue cover the "plug" and cut the tissue so it just covers the surface of the "headlamp bracket" then measure the AREA in Square meters of the sheet.
This method is plenty accurate enough ..
"Sapere Aude"... Dare to KNOW!
The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...
103% of all people do not understand statistics...
Do not adjust our mind, theres a fault in reality :-)
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Dravis
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Just some comments on your Bracket "Plugs" I assume that, since you are going to "pattern" coat them, you are making the "pattern" or "plug" to make the Mold from?
To my eye, you have a lot of very sharp corners on those plugs ... I would put a bit more of a "radius" on all those sharp corners .. I personally only use smaller radius than 5 mm on very small parts, using very light weight CF weaves.
You may be able to make a usable mold from such a sharp edged "pattern" but it will be VERY difficult to avoid the final Carbon-fibre bridging in the corners and you may get corners that are only resin, with no fibres in there.. This will make the corners brittle, and compromise the strength of the bracket.
"Sapere Aude"... Dare to KNOW!
The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...
103% of all people do not understand statistics...
Do not adjust our mind, theres a fault in reality :-)
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Dravis (24/09/2015)
No -No no -- You do NOT need the VOLUME -- You need the SURFACE area ..
Cut out some soft cloth or tissue cover the "plug" and cut the tissue so it just covers the surface of the "headlamp bracket" then measure the AREA in Square meters of the sheet.
This method is plenty accurate enough .. Hi Dravis, I really appreciate the help. I just realised my mistake  I was just reading one of those BBC Bit Size math tutorials for dummies, and relised I was measuring the interior of the 'box contents ! ( volume )
Your analogy of the cloth covering is spot on. Only my cloth would be centimetres in size. The only guidance on the Pattern_Coat Prime expresses it's coverage in 1kg=1 sqr metre.
Those plugs will have radius'ed corners when I get my combination sanding machine later today. |
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Dravis
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Group: Forum Members
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1 square cm = 0,0001 square meter .. 
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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TURK
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Group: Forum Members
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Hi all, OK, I've worked out all the dimensions of all six sides. W=14cm x L=15cm x H=7cm all x2 are there opposing sides. Give me = 826 square centimetres Now that I know how much surface I have to cover ......... how do I work out how many grams of resin I need ? Sorry about all the questions, you pros would of been newbies years ago, how did you solve the problem ?
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Rich (Staff)
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Hi Turk, 826cm2 equates to 0.0826m2 - so you'll be looking at around 80-90g (0.862 x 1kg) of pattern coat to cover at a thickness just shy of a mm. You'll be sanding and fairing back through this so your final thickness per layer is likely to be a lot less than this. Generally though, it will use as much as it requires, the first coat especially may draw into the MDF if it is unsealed and it is likely that you'll need to apply a few applications to achieve a flawless finish and there may still need to be some filling with body-filler between stages to ensure that you have a smooth transition between sections of MDF.
Remember that, as with all resins, temperature can have a big effect on the cure speed so if it is particularly warm where you're working, you may want to use a slightly lower catalyst ratio to slow down the reaction and to give you more working time.
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TURK
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Group: Forum Members
Posts: 101,
Visits: 662
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Hi Richie, And many thanks for taking the time to respond 
Your math must be spot on as it's close to what I have found out.
Originally I was going about it totally the wrong way, I began looking at the online conversion tables and calculators on various suppliers websites ( should be one on here as well I think ). Unfortunately all of those are for wet laying glassfibre so that's taken into account.
The answer is really in the usage guide of the product, but for newbies it's not understood. What I did in the end was to half the information given. so ...... 1Kg of 'Pattern-Coat Primer' per 1m² which is 10,000 cm² 500g of resin - covers 5,000 cm² 250g of resin - covers 2,500 cm² 125g of resin - covers 1,250 cm² So on and so forth ....... may be not the conventional way to do it, but then I'm not a conventional sort of guy ! 
Also, Catalyst ...... 2% @ 250g = 5 grams ? My intentions are to build up the layers of resin, and sand back till I've got the required dimensions. My final coat will be 'Pattern-Coat High-Gloss'. My workshop is currently 21°C but can be warmed up if necessary. Many thanks for your help TURK
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