Spoiler alert - 996 aerokit front lip spoiler project

[Interference Fit]

Ok, a couple more steps closer today after the second pour.

But first, here is the first one that was cast last night, looking far less floppy.



A summary of upgrades to the second pour are:

Mould box set at 45 degrees to encourage gravity to assist flow through.​

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No silicone spray on the mould halves​

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Correct mixing ratio of black pigment, now down at 4%​

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Part A was mixed with the pigment then de-gassed, at least this gives me a fighting chance once mixed, if I'm careful​

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Part B degassed​

Both parts mixed carefully to try and minimise air entrapment​

The pour went pretty much the same way as the first one, there was only so much resin I could pour down the tunnel before it backed up and overflowed. It was at least entering the mould more consistently thanks to the absence of the funnel blocking the flow. This issue was that at the rate I am able to pour is slower than required to beat the pot life, and unless I can pour it at least 3 times faster, the same thing will continue to happen.

After 90 minutes, I lifted the lid. In the words of Jim Bowen from Bullseye - "This is what I could've won"...



About 20% more spoiler than last time. Not good.

However, attempt number two did show significant improvements in surface finish and lack of bubbles, thanks to the pre-mix de-gas and elimination of the silicone spray. The spoiler came out the mould just as easily with or without the spray, so I'll not bother with ti again. The data sheet for the silicone does state a release agenbt is not necessary but instinct got the better of me. As my Dad always says, "if in doubt, read the instructions!".

I cut the spoiled the spoilt spoiler a little more by cutting it into sections to better evaluate the various details.



This was the worst of the flashing, which is practically zero in moulding terms.



The flashing pretty much just wiped off with a cloth, leaving me with a finish I'm really pleased with.



The other side where flashing had potential to present was the hard front corner where the vertical element joins the mounting flange. I designed the mould so the two halves join at this very corner to minimise any evidence of flashing rectification and I'm chuffed with how this worked out. Also note the vastly improved mating face surface, free of any micro bubbles.



When I removed the lid it was effectively trapped due to the funnel contour I'd carved into the entry point. Knowing the spoiler was a dud, I just pulled it off the spoiler, which when still curing is easier to tear.

This is the profile of the entry tunnel.



This picture gives the game away regarding the flow rate challenge. The flow rate is ultimately governed by the cross sectional area of the spoiler, which with a flange thickness of 3mm means that even if I had a hole the same diameter as the width of the entire flange, the cross-sectional areas for the resin to flow through at the entry point is still slightly less than the cross sectional area of the tunnel. This means there is no point making the hole any bigger, it just won't flow any faster due to the viscosity of the resin. The 3mm cross sectional thickness further compounds the problem as due to the viscosity, laminar flow has a greater impact than it would in a cylindrical tube.

The bottom line is that I need a resin with a lower viscosity and preferably a longer pot life. If I can halve one and double the other, I'll be about right.

Disappointing, yes.

Progress in quality and understanding, yes.

I'll need to research resins for a while so this will be the last pour for a few days depending on what I can find and the postage times etc, but we march onward.

 

[kaizengruppe]

" sweating like Ted Stryker on final approach, I had little option but to continue." ...... Very funny, are there no end to your talents?

 

[Interference Fit]

" sweating like Ted Stryker on final approach, I had little option but to continue." ...... Very funny, are there no end to your talents?

I think any talents I may or may not have have rapidly run dry.

Over the last couple of weeks I've been searching for the lowest viscosity resin I can find and discovered one with a pot life of circa 15 minutes.

I ordered a kilo of it and have been preparing the mould over the last couple of evenings for another pour, tonight.

Frustratingly, I still cannot pour the resin quickly enough, despite it being muth thinner than the last resin I used. It definitely flowed more quickly and easily, but still had to be poured no faster than the equivalent flow rate of say, engine oil through a straw. Needless to say, it set in the pot and became too thick to pour before I had enough in to appear at the vent hole. I made a little more than I needed and only had about 80ml left in the mixing cup when disaster struck so I can't have been far away from a complete pour, but I won't know until I lift the lid tomorrow.

My guess is I have about 75% of the spoiler in there. We'll see.

It will at least allow me to assess this new material and how it moulds to see if it is suitable going forward. If so, my wild card is not to degass it prior to the pour, as this absorbed at least 3 mins of useful pot life that could make the difference on another pour if I'm close enough. Although this introduces great risk of air bubbles which we don't want.

Feels like I could almost touch the rear corner of the bus before it pulled away without me.

 

[Interference Fit]

Well that was a disaster.

The material is not fit for purpose and too brittle. It has a good amount of bend to it, but then snaps which is no good at all.

Aside from that, it carried all kinds of air blisters and voids and just doesn't look or feel quality at all.

Got closer this time....
















Irrespective of the above catastrophe, I'm not happy with the part number label - it just looks far too imprecise and amateurish so will need to be done a different way on the master.



Which will require a new mould to be constructed and cast as either way, I've not noticed that a divet has appeared in the silicone mould (highlighted below with a light shone from the side) that was definitely not there before and that I cannot fathom in any way how it has occured, but effectively renders the mould scrap.



Back to the drawing board I guess.

 

[plavix]

Why am I so fascinated by this thread

Keep up the good work. My only input would be as you now have the volume required, and a two piece mould, can you not pour evenly along the moulding, then clamp the pieces together?

 

[Interference Fit]

Why am I so fascinated by this thread

Keep up the good work. My only input would be as you now have the volume required, and a two piece mould, can you not pour evenly along the moulding, then clamp the pieces together?

Thanks, appreciate the kind words.

I tried this off camera before switching resin and trapped a heap of air bubbles, plus the squish of the excess prevented the two mould halves clamping together correctly, forcing them out of shape at the edges. It was such a mess I didn't even bother reporting on it, but as an idea, my mind went down the same road.

The issue however is that the mould now has a divet in it for some reason I can't work out, so is now no use. I'll need to make another one and use all the experience I've gained so far and lessons learned to make the second mould much better, more user friendly and easy to work with. I'll try to use the mounting hole areas for multiple fill points, thast way once drilled out, I won't need to worry about cleaning the surface up once I cut the fill and vent port witness marks.

I want to use the first resin as it really is a fabulous material and would deflect out the way if grounded out. I can bend it double on itself without any cracking or stressing and it returns to the original shape perfectly like a car rubber floor mat, only more rigid like a mud flap.

 

[Kersidan]

Multiple pour points? Maybe 3, one each end and one in the middle?

 

[Interference Fit]

Multiple pour points? Maybe 3, one each end and one in the middle?

Yes, something like that but with easier to use funnel points, square shape outer mold box for stability and handling, maybe even a pressure injection system to force it in (I tried vacuum but it collapsed the walls of the mould!).

I've just tried to 'drill' holes in the preferred rubberised material and it drills with the precision of gunshot wound (exit side, for the avoidance of doubt), so I'd definitely need to mould in the holes, or find a circle punch to neatly cut them out? Maybe I could cast the mould with an 'almost through' hole that leaves only a very thin rubber skin to pierce through? Dunno....

I'll get there - as I've said, this is a journey, the destination is a bonus.

 

[jerzybondov]

Yes, something like that but with easier to use funnel points, square shape outer mold box for stability and handling, maybe even a pressure injection system to force it in (I tried vacuum but it collapsed the walls of the mould!).

I've just tried to 'drill' holes in the preferred rubberised material and it drills with the precision of gunshot wound (exit side, for the avoidance of doubt), so I'd definitely need to mould in the holes, or find a circle punch to neatly cut them out? Maybe I could cast the mould with an 'almost through' hole that leaves only a very thin rubber skin to pierce through? Dunno....

I'll get there - as I've said, this is a journey, the destination is a bonus.

And when you do reach the destination, the reward is directly proportional to the difficulty of the journey!

 

[ryanwright91]

Just read this from start to finish. . . . . unbelievable work !! Looking forward to seeing the finished product hopefully have one off you when your ready

 

[Interference Fit]

Just read this from start to finish. . . . . unbelievable work !! Looking forward to seeing the finished product hopefully have one off you when your ready

Very kind of you, thanks.

Whilst doing all sorts of tidying and tinkering in the garage today, I removed the part number plate and filled the holes on one side as I prepare to refinish it. Again.

The prototype has seen more paint that the yellow submarine!

 

[ryanwright91]

Very kind of you, thanks.

Whilst doing all sorts of tidying and tinkering in the garage today, I removed the part number plate and filled the holes on one side as I prepare to refinish it. Again.

The prototype has seen more paint that the yellow submarine!

ill be keeping an eye out, Do you have any idea when you'd hope to have it finalised and what price will be yet?

 

[Interference Fit]

ill be keeping an eye out, Do you have any idea when you'd hope to have it finalised and what price will be yet

Time wise, I really don't know. Whilst I've got a prorotype still, I need to start again with a new mould. This is something I tinker with at the weekends for fun and interest, and with no idea of whether I'll be successful or not, it's difficult to say. If all goes well on the second mould, couple of months?

Price wise, this isn't a commercial venture so It's probably one I'd open to the floor and let people tell me what they think is fair. Not trying to be evasive, it's just that until I have something I can put in a box, it's difficult to quantify and objectively put a fair market value to. I appreciate your interest though, thank you.

 

[Interference Fit]

Just a small update to keep those even mildly interested up to speed.

Whilst I was 'mildly disappointed' that I've had to start again with a new mold and re-think the process for adding resin, I use every set back or failure as an opportunity to improve the outcome.

After experimenting with the failed first attempts, I have come to the following conclusions.

1) The first 'rubber' type resin is absolutely the way I want to go - having this level of flexibility and deformability is a real bonus for something that will likely ground out frequently. Much better that it deflects out the way rather than crack or wear down too quickly. Which leads to the next point...

2) It cannot be drilled for the mounting holes. It's like drilling silicone. Not happening, which means I either cast in the holes when moulding, or find another way to add them post mold.

3) Given I'll need multiple entry points for the resin, all of which will leave evidence when the spouts are removed (despite these being hidden on the mating surface when mounted) it makes sense to use the mounting hole areas as the multiple entry points, that way I can add the holes and eliminate the spouts at the same time.

4) I'll use a proprietary hole punch for leather and rubber to stamp the holes in - quick, precise and easier, using the Mk1 spoiler as a template jig for the hole positions.

After handling and spending some time with the first rubber trial runs, I realised what it was that was niggling me. The surface finish whilst very nice, when cast in resin/rubber leaves a unique semi-matte finish that unless perfectly uniform, leaves a finish that to my eyes, isn't quite where I want it to be. If I'm going for the OEM+ look, it needs to be better than the original plastic injection moulding.

So given I needed to refill the mounting holes completely and re-finish it (again), I've been experimenting with various textured finished to try and give a really nice, uniform, refined and 'quality finished product' look and feel.

Tonight I settled on one I'm happy with and trust you all approve?

I hope it looks as good when cast in the rubber/resin.



I'll hopefully start to assemble the new and improved mold this weekend.

 

[plavix]

That looks brilliant. Would paint up really nicely too