Locost: Dry Sump, Part 1/2

I have been considering building a dry sump for a long time, in fact, ever since I started building the the car. However they are a fairly complicated piece of kit, and I have therefore shied away from them until now. Fortunately I changed my mind due to the data I collected at Snetterton and having access to a decent Turret Mill at my new job. Lets get into this.

What is a Dry Sump?

Up until now I have run a Wet Sump on the Locost. In a Wet Sump system oil passes down into the oil pan under gravity and is fed back into the oil pump via a static pickup. Under longitudinal and lateral acceleration this pickup can become uncovered, leading to oil starvation and heartbreak.

A Dry Sump deals with this problem by running an extra pump attached to the engine; a Vacuum Pump. This moves oil from the sump pan to an external tank, which is tall and thin, and much less susceptible to oil starvation. An external oil pump, or the original internal pump, is then fed from this tank; supplying oil to the engines bearings and moving parts.

Although I have built a complicated baffled and gated Wet Sump the car still experiences a slow drop off in oil pressure in long right hand corners. I felt it was finally time to take the leap and fix this once and for all with a Dry Sump System.

If you still have no idea what I am on about, my previous post covering the build of my Wet Sump is a good place to start  (link).

What are the Benefits?

  • Depending on the oil tank used, it allows constant cornering at a lateral acceleration of up to 5g.
  • Instead of the crank case being under positive pressure, due to combustion blow by, it can be designed to be under constant vacuum. This helps to…
    • Reduce Windage, increasing engine efficiency at high speeds.
    • Improve the in-cylinder octane level, as less oil passes by the rings into the combustion chamber.

The Build

As a Design Engineer I’m trying to do more… Design, when it comes to the Locost. So instead of jumping straight in and cutting metal on day #1, I drew up what the system was going to look like and got an idea of the layout. Packaging in the Locost is TIGHT, so this wasn’t ever going to be easy.

This is the space I had to work with. The ignition trigger wheel was already there and potentially in the way, and there wasn’t enough room to fit a pump on the passenger side of the bay (the alternator was in the way!) and the pump needed to be positioned to avoid the chassis rail and steering column. Oh, and retain a place for the ignition trigger sensor…
This was my initial design. I already had a Pace CD2000 Pump that I had bought many moons ago for such an occasion and I modified it into a two-stage vacuum pump, with no pressure stage. I then used some calipers to measure and get it into cad. This allowed me put a drive gear on the front of the “engine” (well sump flange and front pulley) and work out the beginnings of the new oil pan.

After many evenings and iterations it looked something like above. I had decided to use silicone hose for the oil routing between the sump and pump, as it gave many more options in terms of packaging. This mean’t I had to run steel tubing out of the pan.

I then finalised the design of the drive-hub and gear. It indexes onto the lower cam-drive and is driven through the five M6 bolts that hold onto the front pulley.

With the component designs sorted I could finally start cutting steel. I had a spare standard sump on one of my engines, so I used that as a donor flange. When I built the baffled sump I made my own flange and… it wasn’t as good as the pressed Suzuki item. All the small details really help to seal the gasket to the block and I was happy to carry them over. I marked the sump 25mm down from the flange and attacked it with the grinder.

At this point I got my own lathe to help move the project along; achieving a massive life goal in the process! Its only a little Sieg SC3, but it is super useful for making little top hats and smallish components. The drive hub for example.

I was able to go from bar-stock to component in one afternoon. I had made my own digital read out for the top slide which made boring accurate depths super easy.

The final features were then machined on the mill. A slot to clear the crank keyway, the five M6 bolt holes and the five M4 gear mounting threads.

This was what I thought would be the hardest part of the project, but once I used the right equipment to make the components it was actually really straightforward.

At this point I could properly place the vacuum pump in the real world, choose a belt length, and finish the oil-pan.

What I don’t have is pictures of the countless hours I spent trying to seal the sump for leaks. I used water and air to find pin-holes and just kept welding, grinding, checking and repeating.  Side note: I need to get a TIG welder…

I also added some bolt-in mesh within the sump to protect the outlets. You’ll noticed that I ended up moving one of the oil outlets relative to the CAD. It actually ended up far tighter and better packaged in real life.

Having made the oil-pan, pump-mount and drive, there were a few small components that needed to be made before I could install the pan. One of these was a bung for the original oil pickup in the engine. This was essentially a large top hat, bolted in place, allowing the use of the original pickup seal.

Following this I could finally install the whole lot in the car.

In the final part I will cover the installation of the oil tank and oil lines, and then find out if it actually works!

Locost: The Six Week Dash

It been a while since I last posted on OgilvieRacing. Life has been pretty hectic for the family since the end of February, and sadly there has not been a whole lot of time for toy cars. In fact the rest of this year is likely to be a quiet one, as I will be changing jobs and location.

I would like to do a track day at Castle Combe before the end of the year, and I will be sure to fill you in on that and the reliability upgrades I have planned for the Locost. However, I promised a run down of the build up to Snetterton, and that’s what your going to get.

Here are some of the many mini-projects that got completed in a time period I like to call: The Six Week Dash.

Rear Arches and Lighting

Having molded two rear light pods out of fibreglass (see here for details), I made cutting templates from the cad drawings and made the required holes in the rear arches. The pods’ were then clamped in place and fibreglassed from the back, which would then allow me to blend them in from the front.

Given that the rear lights were now positioned correctly I could run the loom from the centre console back to the lights. I 3D Printed a little switch panel which mounted to the tunnel and gave me quick access to my light controls without cluttering my vision while driving. It was very satisfying to have the brake lights come on when pressing the brake pedal and seeing the dashboard light-up when the side lights were on.

At this point, approximately a week and half into the ‘Dash, the rear arches were put aside. I had really hoped I would have the time to clean them up a little before Snetterton, and the process of adding epoxy-filler to blend in the light pods would make them far stronger and less likely to break.

I decided to dig deep in the final two weeks, staying up late and popping home in my lunch breaks to get these blended in and painted in primer. It was worth it because they ended up taking a hammering around the track.

 

Front Arch Brackets

Most trackdays do not allow “Open Wheelers”. This is to stop people bringing single seaters and full on race cars to what is mean’t to be a fun day out. Subsequently you must run some form of wheel arches on all four wheels; so getting the front arches mounted to the car was super-high-priority.

These turned out to be deceptively complicated components to create. I started by making brackets that mounted to the front upright caliper bolts and tie-rod bolt, to give somewhere to weld tubes too. This required a little artistic flair.

The left and right versions of these were made. I then positioned the arches on the wheels, with their own bracket-strips already attached and cut and shaped tubes to join the two together.

There was a lot that could go wrong , and positioning the arches laterally and radially on the wheels was difficult; nothing wanted to stay still! In hindsight I probably should have made some form of quick-wooden jig for this, but ultimately the final mounts turned out straight enough. I even think they look good. I cut away a lot of unneeded material and ended up using only two mounting points; the top caliper bolt and the tie-rod bolt.

These pictures still don’t do justice to just how much work these mounts took to make…

The Bane Of My Life Sump

I’m trying to remember how many times this sump went in and out of the car, but due to some form of post-traumatic stress (or my terrible memory) I can’t recall. It was at-least three times. I really struggled to get this to seal to the block correctly and after leaving it for a while and having a proper think, the problem was obvious.

I placed the sump on the relatively flat floor of the workshop and it was clear that it was bowed. If the front of the sump was going to seal, the rear wouldn’t, and vice versa. The rear flange was especially bad. At some point I must have welded it without bolting it down block (doh!).

So, as time was starting to get tight (week four of six) I decided I would do the correct thing and hammer the hell out of it until it was flat. I cut, ground, re-welded, added gussets, and did whatever was required to get this to keep its shape. In the end it was good enough for use with a cork gasket and hasn’t leaked since.

I’m very proud of this piece of kit and it performed well on track, however I think I will eventually install a dry sump for total peace of mind.

Data Logger

This has probably been one of the most enjoyable projects I have ever undertaken. I worked as an Analysis Engineer for two years and have really grown to appreciate data, sensors and processing; so to take that experience and apply it to the Locost was greatly enjoyable.

In my previous Snetterton post I referred to the data log for each of my runs on track. It gave me a another level of understanding of what the car was doing and how the engine was performing. As I add more sensors and systems to the car this is going to become invaluable.

The logger was probably not super high priority, but I snuck in an hour here and there throughout the ‘Dash to make sure I got this on the car; I just enjoyed building it so much. As you can see, this required some Micro-Controller Programming, 3D Printing and Electronic Design; pure engineering bliss.

Tyres

I made sure I got a new set of tyres for the Locost, as the Yokohama A539s were getting on a bit and were as hard as glass. Also having just blasted them with a ton of UV when welding the Front Arch Brackets they weren’t in a good way.

I ordered a set of Nankang NS2R’s and had them fitted by a local tyre shop. Again, this required lots of running around in lunch breaks and burning the candle at both ends.

Thermostat

Having only ever driven the car in short sprint-like events it had no real need for a thermostat. Now that it was going to be doing far higher speeds, for longer periods of time, it needed much better thermal management; so it was important to make sure one was installed.

I installed an in-line thermostat in the top hose leading to the radiator; which was probably the easiest job on this list. I like the look of it, however I will eventually weld it into the top rail to get rid of one of the flexi-hoses and clean up the installation. Oh, and I will match the clamps, blergh!

Rear Cover

With only two days to go until Snetterton, it was getting rather tight to get the car finished. My brother had arrived and was working on installing the passenger seat, which thankfully gave me the time and space to focus on cutting and installing the rear panel. This turned out to be no small job.

I had budgeted the Saturday to cut the three carbon panels to shape, bolt them in place and add the quarter turn fasteners to the centre. However the carbon fibre blank had tapered sides, so absolutely nothing lined up with the car. Once the two sides were done it took a substantial amount of measuring and fettling to get the centre section correct.

Also fitting this around the seat belts and fuel filler, in a neat and tight fashion, was time consuming. In the end it took me a day and a half, leaving us just enough time to load up the car and get some sleep.

 

Conclusion

I was fairly broken after doing all of the above, and I have appreciated a short break from the workshop. The Locost has come a long way in the last twelve months and I’m proud of what I have achieved so far. In-fact, almost exactly a year ago I rolled it out into the sun in full light-weight AutoSolo trim, to get the engine up to temperature and give it one last blip before pulling it apart.

Locost: Snetterton Damage Report

We made it to Snetterton; its official. I’m going to leave it until later to give you a run down of what it took to make my little red car trackday-ready. However, its fair to say the six weeks leading up to Snetterton left me feeling both physically and mentally achy.

Having just performed a two day fabrication marathon on Saturday and Sunday (Feburary the 11th/12th; for posterity), the car was sat on the trailer ready to go at 7pm. After a quick batch of takeaway pizza and beer we were ready for bed; we had a 5am start the next day to get to the track. “We” was myself and my younger brother Alex, who is now the official truckie for OgilvieRacingTM and second mechanic (he fit the passenger seat in the car the day before).

The two hour drive to Snetterton went without a hitch and we rolled in at about 7:40am, giving us 50 minutes to unload and sound check the car.

Sound Check

Every circuit has a different static noise level which your car must pass to be allowed on track. Snetterton’s static noise level sits at a deafening 105dB, which mean’t I was quietly confident the car would sneak in under the volume radar. While sitting in the cue waiting to be tested we both got quite giddy, as it dawned on us we were actually at a race track track and it was really happening. Hence the following terrifying selfie.

We were surrounded by Sevens of many shapes and sizes, Subarus, RGBs, Hatchbacks and a multitude of MX5s. The atmosphere was quietly buzzing as everyone was excited to be there and not taking themselves too seriously.

When our turn came around the operator asked us what type of engine we were running, I said “A 1300”, and he explained that we should bring the car up to 5000rpm and hold it there for the test. This was based on the car being at ~3/4 of its peak RPM, which was a fair guess as I was  planning to shift between 6500 and  7000rpm. Fortunately we breezed through with a reading of 100dB; even though I was running a weedy little motorbike exhaust can. This was our first achievement of the day.

Run 0 – Sighting Run
Data: None

Following the drivers briefing we were required to perform three sighting laps in a group of approximately 20 cars, to get a feel for the layout of circuit and any slippery bits. Given that it had snowed all weekend the track was very greasy and gave me a few surprises even at low speed. I was following a Porsche 911 , which was both gorgeous and  incredibly hard to keep up with at full chat! I took these laps to get used to the gearbox and pedal layout, having never driven the car for this period of time before. That said, it took to the track rather well and had a lot of front end grip.

Having completed my three laps I returned to the pits,.

Run 1 – A trip in the mud
Data: LOG022.TXT

Feeling confident, my brother and I jumped in and went for the first official
drive of the Locost at Snetterton; this didn’t last long. We did a slow out lap to
get a feel for the grip level and then started to push a little. The car felt good,
the gauges looked happy.

Coming into T6 (Oggies) on our first flying lap I over cooked it on the brakes, expecting
there to be a lot more grip than there was; doh! With a little steering angle the
rear would start to step out, and with less steering angle the front would plow on, giving me two options. Go off front-first, or off rear-first. I chose front.

Fortunately the car kept turning as it went into the mud and we were almost back on
track once we came to a stop. I slowly got the car back to the pits, thankfully without having to be rescued, and we were surprised to find that the car was not damaged at all. Just slightly sad looking. With an old towel in hand we were able to clean the car to an acceptable level and get ready for another crack at it.

About thirty seconds after we got into the garage my far-more-trackday-experienced-friend Dan rolled in covered in mud. He had also gone off at Oggies, which made me feel a lot better about my driving!

Run 2 – Before Lunch
Data: LOG023.TXT

Given how slippy the track was I made some setup adjustments before heading out again. I raised the Front Ride Height by 3mm at the front dampers (1.5 Turns, ~1.6 Wheel/Damper Motion Ratio giving +4.8mm Front Ride Height), which also happened to reduce the Front Static Camber (due to the camber change in bump) and raise the Front Roll Centre; each of these helping to stabilise the car. I also increased the front damping by two clicks to slow down the initial turn in response. The car was a little two reactive for me at this time of the day.

The car felt great following the changes I had made and gave just a touch of understeer, with on throttle rotation on exit thanks to the open differential.

I only managed four laps, including my in and out laps, as I could see a big drop in oil pressure on the gauge in T7 going onto the back straight and I wanted to make sure the car was okay. That said, I drove the car as fast as I could while I was on track; it appears all mechanical sympathy goes out of the window once your at speed!

Having checked the data over lunch it appeared that the engine temperatures were safe and the oil pressure never dropped below 20psi. That said the oil pressure was dropping off in right hand corners, from 40/50psi to 20psi, but never going to zero.

It was likely the engine was sucking some slightly thinner aerated oil in these corners. To be safe we topped up the sump to the maximum amount I’d designed for. In fast right hand corners the oil pressure stayed rock solid; Turn 3 (Palmer), Turn 4 (Hamilton) and Turn 8 (Brundle).

Run 3 – PM Brake Bias Forward
Data: LOG024.TXT

Before lunch I was struggling to trail braking into the T2 hairpin (Montreal) without some rear inside locking; especially as I released the clutch. I decided to move the brake bias 2% forward to help with this, which was ~2mm at the balance bar.

I went out again with Alex in the passenger seat, so setup wise it wasn’t going to be too representative, but it is plenty of fun with a passenger on board.

Unfortunately I had forgotten to put my helmet strap on! Being smart I did an Out/In lap and fixed my helmet in the pit-lane. This coincided with a red flag on track so we ended up sitting in the pit lane for a little while looking at a red flag (the data suggests almost 6 minutes). We noticed the engine getting properly hot at this point, and blowing a little steam, so we took it back into the garage to cool down.

I didn’t notice it at this point in the day, as I already had enough to think about , but the fan had failed; maybe even when we towed the car to the track on the trailer. The data showed very high pit lane engine temperatures all day, however the car had not sat still for long enough for this to be an issue; until this red flag.

Run 4/5 – Overheating!
Data: LOG025.TXT / LOG026.TXT

We went out for two short runs (two timed laps, three timed laps) but clearly the car wasn’t running right. Once we brought it back in and it was finally clear to me that it was overheating.

Once it had cooled down I opened the water cap and topped up the system, a lot; too much . Following the pit-lane incident in Run 3 the engine had spilled a lot of its water onto the pavement (I have no expansion tank) and was now running sub-optimally. There was still water in the head but the top pipe and the top of the radiator were completely empty. Flow across the thermostat would have been very slow indeed.

Fortunately I had dodged a bullet. The water was running clean and the oil was also clean; so no blown head gasket.

These runs did show an improvement in oil pressure in right hand corners, which was a relief. Topping up the sump had at least made a measurable difference.

Run 6 – Short Lived Glory
Data: LOG027.TXT

With the track having fully dried out, and my car back in tip top health, I went out for what would be my final run of the day; riding solo and at race weight with a little less than half a tank of fuel.

This fifteen minutes was what the day was all about. The track had gripped up nicely and the car was running the best it had all day. I kept pushing the braking points until I was starting to under rotate the front inside wheel and felt I had quickly found my limit.

The Nankang NS2R’s actually came in quite quickly, which was a surprise for a Medium compound tyre, and gave really good feedback. My lines were pretty lame and I was only pushing the kerbs on corner exit, but I was having a lot of fun and going faster each time around.

Coming into T4 (Agostini) on my fifth lap I felt a large front end vibration which suddenly disappeared. This was accompanied by some mid-corner understeer/weirdness and a general feeling of confusion. Once I limped around to T10 (Bomb Hole) I was flagged by the marshals to return to the pits. Upon my arrival the man in orange explained to me that I had broken my front splitter and it was waggling all over the place; fair enough!

At this point I parked the car and basked in my own smugness. I had experienced a small glimpse of all the fun that could be had doing track days and was relieved that I had made it this far. Of all things to break the splitter was the easiest to fix, but it would have to wait until the car was at home. This felt like the right time to pack up and call it a victory.

Final Thoughts

On paper, we didn’t have a hugely successful day. The car didn’t turn that many laps and suffered a few engine teething problems along way. However, that was never what this was about. The Locost has been the accumulation of almost ten years work, and started life in my young teenage mind going on fifteen years ago.

On Monday the 13th of February 2017 I achieved a life goal: I built and trackdayed my own little racecar; and I’m still buzzing about it! I have definitely caught the trackday bug it. A car like this, driven in a track environment  is a massive endorphin hit.

What really surprised me was how well the chassis handled on track. In the tight car park events that I am used too, it lacks rotation at a high steering angles and tends to plow on if you push it too hard. On track it eats up kerbs, rotates on demand on corner entry and, if your willing enough to use it, has great peak grip in the mid-corner. The small adjustments I made at the beginning of the day gave me a measurable change in handling, and the engineering knowledge I had learn’t in motorsport was both applicable and effective.

The Locost has always held a special place in my heart. Uncountable hours have been poured into it, however it hasn’t always been that usable. Now that I can drive it on track, I think I have fallen in love with it all over again.

Time for more trackdays, lots of development, and endless fun. Success.

 

Engineering Notes

Just a few bullet points about the car, which I will likely elaborate on in the future:

  • The engine was definitely down on power compared to where it could have been and is in need of a dyno session in the very near future. This was also reflected in poor drivability out of corners.
  • I am getting spikes in RPM from the ECU which suggests the ignition system needs more filtering/shielding. This tended to happen at the same engine speed each time, supporting my electrical noise theory. These could be felt as flat spots while driving and were obvious in the data.
  • The fan is dead, long live the fan; replace the fan.
  • The splitter needs supports back to the chassis at the forward edge; clearly.
  • Having to add so much front ride height to balance the car suggests the mechanical balance is too far rearward, and I need to get softer rear springs, stiffer front springs OR add a front anti-roll bar.
  • The GPS was broken on my datalogger all day and it needs to be torn down and investigated. This was also the case when I drove the car in the week, but I didn’t have time to fix it. It has been tested and known to work, so it was rather odd.
  • The car needs a water expansion tank. Badly.

Locost: Desperate Trackday Preperation

Life has got the better of me over the last few months and progress on the Locost has been slow. I had hoped to be doing a Trackday this December, but the car simply wasn’t ready, and there weren’t enough hours in the day to make it so. Subsequently, when my mate Dan messaged me about a Trackday he was organizing at Snetterton in February I was all ears. This is just far enough away to give me enough time to get the car prepared, but at a push. Fortunately, I work well under pressure.

So for my benefit, here is my Locost-work-list that needs to be completed before February the 13th:

  • Fibreglass Rear Arches – By now you have read my article about the Locosts rear light pods. These are still being fettled into the arches so the lights can be fitted. I’m hoping to get these into primer over the Christmas break and bolted to the car.
  • Finish Lighting Loom – With the arches in place I can finish the loom for the rear indicators and brake lights. I ordered connectors for this job, and have built an unfinished rear-end loom, so this should be fairly straightforward.
  • Mount Front Arches – This is one of the more complicated tasks. I have some M8 threaded standoffs that I can weld to the front uprights to make mounting easier, but really I need to bend some 3/4inch tube to make the frames for these. If I can measure these up before I head back home for Christmas I should be able to get this done.
  • Finish Mounting Drivers Seat – This is a straightforward task as it is already bolted in place, the 8mm holes simply needed to be taken out to 9mm. I would also like to re-paint the floor pans while the seat is out; just in case it rains.
  • Fix Leaky Sump – Remember that awesome wet sump I made? Yeah it leaks. I’ve been struggling to get it to seal to the block. I always used to use the standard Suzuki cork gasket but this time have been trying to go purely Silicone; this is clearly a terrible idea. The sump needs to come off one more time and get sealed properly. I have a spare gasket so all I need is time.
  • Mount Rear Panel – I have a sneaking feeling that I need have a rear panel to cover the fuel tank for Trackdays. It would make sense that the driver would not be allowed straight line of sight to a flammable tank of gasoline. So for my safety I need to sort this out. I have a carbon rear panel molding, so I just need to get measuring and cutting before Snetterton.
  • Shakedown – I need time to drive the car and check it has no issues. It has been dried stored for over twelve months now, so with a little luck it should be fine.
  • New Tyres – My old Yokohama A539s are almost as old as the car and have seen far better days. While they have heaps of tread on and I’m tempted to give them a final send off, they need to go. Given I’m not going to be racing anyone I may just get a fresh set of A539s or the Toyo equivalent. Cheapish tyres, but at-least new tyres.

Optional:

  • Paint Front/Rear Arches – It would be nice for the car to look good while on track, but my priority is actually being there. However, if I get the time it would be nice make things pretty.
  • Wire In Datalogger – This is a project I am yet to write up, however over the last couple of months of dark evening I have created a datalogger for the Locost. I would quite like to run this at Snetterton as the data will tell me a lot about the car and help me progress my driving. This is almost not optional in my eyes, but I guess its low priority.
  • Cover Gearbox Opening – I ran a pneumatic paddleshift system for a while, which is now on the back burner until I can track the car. This required opening  up the tunnel around the gear-stick to fit. With the normal gear-stick mounted now the driver has line of sight to the engine bay. For safety reasons this is bad, and although I don’t think it will cause any issues, when I get the time I hope to cover this up.

What do you think? I don’t have anywhere near as much free time as I used to and could do with some spending some time with friends over the Christmas break. So realistically, other than the rear arches, everything has to get done in six Sundays. Fingers crossed.

(Featured imagine taken from here)

Fabrication: From CAD, to 3D Print, to Fibreglass

To trackday a car it needs a reasonable level of illumination, to communicate your intensions and make yourself more visible in low light conditions. Indicating left, pass me on the right. Hazards flashing, I’ve had a bad day. This is something the Locost has not needed until now, as it has only ever been driven on closed courses with only one car competing at a time.

I already own a set of rear light clusters that I bought almost six years ago when I was initially stockpiling parts. I decided to go with these “hamburger” style rear lights as they mirror the round headlights at the front of the car, that I am also yet to install, and also I could get them with clear LED’s which would keep the car aesthetically pleasing. It also helps that they weren’t cut-off-your-left-leg-and-right-arm expensive.

The easiest and quickest place to mount rear lights on a seven is directly to the rear bodywork. While this could have been done on a Saturday afternoon, with time for a few cups of tea in-between, it would have been almost irreversible and completely illegal for road use if I ever felt like going that way (lights must be a maximum of 100mm from the outer most bodywork). So this left me with only one option which was to mount them on the rear wings. Never one to turn away the opportunity to do something the hardway I decided this would be a great opportunity to make my own light pods, in my own asthetic style- fire up the 3d printer!

CAD

First of all, my printers build volume is a measly 150*150*150mm, and would have never been able to print an entire light pod in one go. Also, PLA plastic would have never been a good choice for components like this, given that they will sit in the sun for extended periods of time (damn you 60degC glass transition temperature). These would have had to have been printed in ABS. Printing thin walled ABS shapes is pretty much a no-go without some major warping, so this left me with only one option… a 3d printed mould.

I grew up around fibreglass in all its forms. Quick shabby make-a-mould-out-of-Tupperware fibreglass, and top quality a-thousand-layers-of-wax-and-lots-of-polish fibreglass; this was going to be something in the middle. Because of my limited build volume I opted to design the mould to split into four separate parts. This also meant that releasing the strangely shaped light pod would be relatively straightforward as long as everything was unbolted and persuaded a little; so it was win/win.

After measuring the curvature of the rear arches and the geometry of the lights I frew the mould itself and split it in the X and Y axis. This is a female representation of the lightpod, with the reverse being the actual “male” final piece. Getting a clean striation-free mould surfce was going to be unlikely, and comes with the territory when 3d printing, so I knew I was going to have to sand and polish the final mouldings after they were produced.

Light Pod Mould

3D Print

I believe these components took between 16 and 19 hours each to print in PLA, which goes to show how awesome my Printrbot Simple Metal is. I’m very happy with my printer setup at the moment, as it’s hugely reliable over a long period of time. Hold on, where’s your RepRap gone Josh? That’s a story for enough time…

Light Pod Complete Mould

The mould was sanded with 200 grit sand paper and given 5 layers of wax. The wax helped to fill in the crevasses between the separate mould pieces and massively helped the release after moulding. In short, this stuff rocks.

simonizwax

Fibreglass Mouldings

Once the mould itself was ready to use the mouldings were made in a fairly simple way. Firstly a layer of White Gel Coat was applied to the mould with a brush. Gel Coat is essentially resin with pigment in, which gives the moulding an outer layer which can be sanded and painted to achieve a nice finish. If the mould is of a high quality the Gel Coat can simply be left as is. I would eventually be painting these moulds so I wasn’t too bothered about the initial surface finish.

Light Pod Gel Coat

Once this had adequately hardened polyester resin was brushed into the back of the Gel Coat and 450gram fibreglass rolled into that (I gave it approximately 4 hours at 10degC, with a 3% mass fraction of catalyst to kick things into gear). The rolling process is important as it helps to remove air bubbles from the structural fibreglass and improves the strength of the composite. It also helps reduce the amount of resin you have to use, as the fibres are pushed tight against the Gel Coat and the resin soaked through. If the whole lot was just brushed on then it would have likely had a higher resin content and been heavier.

Light Pod Laid Up

This was left for two days to harden and then extracted from the mould. I’m very happy with the final product and its far lighter than I expected it to be. The ‘pods will be glued into the back of the arches and then faired in with filler. The whole lot will then be smoothed and painted; probably glossy battleship grey.

Light Pod A

Light Pod B

Light Pod C

Have you ever tried any Fibreglass work? If not, give it a go! Its actually ver y rewarding and if you take your time with each step you can achieve great results.