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Ford GT LM
#1

Hello gents, this thread contains a series of articles I've posted on several other fora, This was the first post on me and my team's "Road to Le Mans" , well at least to the 1/32nd version of it, the DiSCA 24hrs Le Mans race at Henley in Arden, April 2019. To support Slotracer online I though it might be good to repost it here as well. 

With kind regards
Tamar



The Ford GT LM (3rd Gen) 1/1
Ford returned to Le Mans in 2016 as a factory team  in a blaze of glory, its modern GT winning the GTE LM class exactly 50 years after the original GT40's 1-2-3 in 1966.
Although it was always intended to take its place among the world’s most desirable ultra-high performance sports cars,
make no mistake, the third generation Ford GT was conceived, designed and built with one priority in mind:
Win the 24 Hours of Le Mans on the 50th anniversary of Ford’s fabled victory at le Sarthe in 1966. So for that one..mission accomplished.


[Image: LM2016_finish.jpg]

Some may say that the Ford GT LM is a masterpiece in design, echoing the iconic shape of the Ford GT40 that Bruce McLaren and Chris Amon piloted to victory in the “ronde infernal”,while taking every possible advantage of the Fédération Internationale de l’Automobile’s regulations to create another Le Mans winner.
With a miniscule frontal area and dramatic “flying buttresses” the Ford GT cuts through the air on the Mulsanne Straightaway like the proverbial knife through butter
with plenty of of help from a 3.6 liter, twin turbo Ecoboost V6 engine producing 530 horsepower and 494 ft-lb torque.

Some may say that by doing so Ford has moved the goal post in GT "beyond" what was intended by the "spirit of the rules". That it is a prototype clad in GT bodywork.
In any case the combination delivered a dramatic Le Mans win in the car’s inaugural campaign, along with several other victories in World Endurance Cup and IMSA competition, indelibly stamping the Ford GT as worthy successor to its legendary namesake...and that of other goal post movers like the (mid engined) Porsche 911 evo and Toyota TS020 GT-One of two decades ago.

The Ford GT LM (3rd Gen) 1/32
With such a new Icon on the racetracks it didn't take long before both the major players in the slot, Carrera and Scalextric announced that they would do the GT LM.
As did the small volume 3DP manufacturers The Area 71 and Arrow slot. With both of them acquiring and entry for the 2017 Oxygen LM 24hrs it was the latter that was to give the Ford GT its debut in DiSCA competition (TA71 withdrew its entry two months for the race). Alas no copy of a debut victory like its big brother. 
The Arrow slot Ford faired well, the 3D printed body and chassis finishing second in class and 5th overall, but major succes came a year later when Spanish team Ditslot i3D entered a development 3DP chassis with simple slot.it pod and a similar 3DP body. They not only took first in class but also 1st place overall.


Does this make the Ford GT LM an absolute winner in the slots as well? Well it definitely has potential, its low, wide and has a long wheelbase. With slotcars in general running with the same engines and weights that's definitely an advantage. But Ditslot i3D did not claim its victory by having a much fast(er) car.
By times our Corvette C7R was faster and by a large margin Rockingham's Toyota LMP1 had the legs on the Ford GT.. at least over a single lap. 
The true merit of the Iberian team was its incredible consistency, punching out fast times lap after lap (with a slight punch left right and center), staying on track all the time and only pitting half a dozen times to change tires. It was an impressive Team result, not specifically down to the fast pace of the Ford itself.
 
[Image: post-769-0-21691900-1522061135.jpg]


The Road to Le Mans, [b]1/32[/b]
As I post this its just 9 weeks till the 8th edition of the DiSCA Le Mans 24hrs, some of you that have read my other post will know that for the past six months "my road" to Le Mans was heading in a totally different direction, or should I say a totally different car. Although good progress has been made on the BMW M8 GTE  project, the M6 GT LM test car winning its class and 3rd overall @ the Suzuka 6hrs, we've got some the delays on the M8 that will curtail the R&D program to such an extent that we decided to switch to plan B. And Plan B is to stick the #18 on the #68 Ford GT-LM and run that car @ the Le Mans 24hrs.

Here's an "artist impression" on what's going to be the #18 Ford Monkeytown Team NL Ford GT-LM.
[Image: 18-Ford-GT_monkeytown_01.jpg]
 
 
#18 Ford MonkeyTown Team NL, Ford GT LM GTE
Part of the reasoning behind this late switch to another car is that we're not totally starting from scratch. The Ford GT has been on the workbench next to the BMW M6 for some weeks now a

[Image: IMG_0226.jpg]

Via this topic I hope to keep you updated on what work will be done to get our Ford which will be based on the Scalex RTR car..with a Prospeed chassis in the following 9 weeks on our road to Le Mans 1/32



To be continued
with kind regards
Tamar
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#2

Posted 13 February 2019 - 08:53 PM

The Road to Le Mans 1/32: 8 weeks and counting
Finally have a short moment to post an update, its been a busy week and a half, spend most of my free time in the "workshop" getting the Ford ready for its first shakedown.
That clock just keeps on ticking.

Most of last weeks work was focussed on categorizing and analyzing what body and chassis modifications needed to be done to fit the chosen race set-up and then implementing them on the first Prototype chassis
For a race like the DiSCA Le Mans 24hrs that means a set-up that has been tried and tested, evolution instead of revolution, experience gained the hard way [Image: wink.png]
So it won't be much of a surprise for most of you to see the first pics of the Mark I chassis with a slot.it sidewinder pod.
I'll be building on the experience gained in the last two editions w
ith the DiSCA Proton Porsche and the SRFH Corvette C7R.
 
Taking stock...
So the first thing I always do when I start a new project is to open a new excel sheet and take stock, I've got one for every car I've build in the last 4 years.
Each data sheet contains all the parts used for the car during the build & testing and the race(s). It list part nr, dimensions and most important their weight.
With most of the specs for the running gear pretty much at a constant, the sheet allows me to calculate what consequences a specific a set-up will have on the weight of the car.
But for each car the chassis and certainly the body can be very different.
So here I usually start with noting down the values for the Stock parts (if there is a stock base car) in the first column and set target values in the last.
During the build a new column is added for each test so I can keep track what progress (if any) has been made.
 
[Image: taking-stock_weights.jpg]
From left to right: Complete Stock body, rear Wing support & wing, Rear wing, Stock Windows, Interior & motor detail, Detail parts, Bare Inner body, Bare outer body

...and making plans
Taking stock also helps with making plans as it becomes pretty obvious where the biggest gains can be made. With a target weight of 16 gr (need 3gr for lights) the Ford is pretty good to begin with.
Ditching the rear wing support section for something lighter and a vacformed interior and we're a good way towards our target. 
But because the Ford has such a small and low body I won't be able to make such serious weight gains as I did with the Carrera M6. 
So like very other car I've build to DiSCA spec..every 10th of a gram will matter.

Besides making masters for Vacformed parts, modifying the body to make room for the SW configuration will also needed to be done.
In my "S- can conversion" post I mentioned that little or no body mods would het been required for Scalextric to have fitted their regular S-can.
And that even a SW configuration would have been possible...for a Stock chassis. But for a DiSCA spec car with offset pods and 1 -1,5 mm suspension travel..its a different story.
 
Suspens(ion)
One one of the reasons why the Ford became our plan B was that besides a Scalex base car I also had a ProSpeed 3DP chassis.
Although its designed to be compatible with slot.it pods it did not have any pick up points for the Evo-6 springs.
But like with the M6, Stefan was willing to incorporate any changes I would need in new chassis versions.
I would modify the first chassis to my desire and use that as a prototype to test the changes, evaluate and after Stefan added them to the design have a Mark II version printed. Within the 8 weeks window that would give us possibly 3 development cycles, way to go ProSpeed. [Image: thumbsup.gif] 
So the first thing I did was add another layer of on top of the rear of the chassis, covering the general area where I thought the suspension and body adjust screws could be placed. Using 1,5 mm thick plasticard this would give me enough "depth" to countersunk the suspension screws.
I've always been a fan of side suspension when running on Ninco, and the wider I can spread my suspension points the better.
So the good news with the Ford was that (unlike most other GT's) the wide Evo spring arms do fit under the body.
The bad news was that there's no room to mount any spring on top. So I went through my spares box and dug up varies springs and suspension bits and pieces.
The shape of the body and the pod more or less dictated where I would be able to mount the springs.
 
[Image: suspension_proto.jpg]
I had some parts on order, but did not want to wait till they arrived, and I had cut off the evo 6 mounts on all the SW pods we prepped for the Porsche and C7R. The only pod left was a 0,5mm offset..for a prototype it would have to do. Besides having Side suspension I also wanted to be able to adjust the spring screws without having to open the body..so some kind of top nut retainer was needed. Turned out the Thunderslot top nuts with Scaleauto screws was the only combination with plenty of travel but still low enough to fit under the body...well almost [Image: lmfao.gif] 

[Image: suspension_mounts_0,5mm-offset.jpg]
 
So here are the suspension adaptors I fabricated from 1mm GRP, just thick enough to cut a thread in so I could mount them with grub-screws (lighter then normal screws cause they have no head) to the OEM slot.it mounts.
And just thin evenough to slide between the chassis and the suspension arms. Must say easier said than done.
Although officially you could call these adaptors Mark I, I must have fabricated, and oops dropped on the floor and lost for ever..half a dozen of these tiny parts. 

Inner body
A very interesting feature of the Scalex Ford GT is that they've conveniently designed their casting, separating the body in an outer and inner body shell.
Conveniently as it was very helpful to just be able to use the inner body shell dismounting it a zillion times to see if it fits, and if not..where it rubs.
An oh boy did it rub. On the workbench all looks fine with plenty of clearance, but on the track with all the body float and pod travel everything would start to foil and hinder free movement.
 
[Image: IMG_0553.jpg]
No matter what I tried, I could not get the radiators to clear the top suspension nuts, so they had to move, or more accurately they had to rotate a bit.
Below you can see how I cut them of the inner shell and remounted them at an slight upward angle. Now I had room enough for the suspension mounts with their top nuts to move freely.
 
[Image: IMG_0546.jpg]
 
Ok that's it for now, got more work planned for 2 night, got a master for the interior to finish, mould and cast.
As a preview of post to come.....see pic below..cause yes...I did manage to finish the Ford GTLM Mark 1 for last Sunday's roll out and shakedown.
The results were promissing...

to be continued
with kind regards
Tamar

 
[Image: first_roll-out.jpg]
Ford GT LM Mark 1 leaving the Pits @ Suzuka for its first Shakedown
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#3

Posted 15 February 2019 - 10:26 AM

The Road to Le Mans 1/32: 7 weeks and counting
Hello guys, just seven weeks till the start fo free practice, time for a quick update, as mentioned in my last post this week's work focussed on getting the masters for the vacformed parts ready for silicone casting.
No completely finished yet, still have more work on the cockpit and driver seat, but the motor compartment is finished

 
 
 
[Image: IMG_0216.jpg]
Stock Scalex interior tray, already with serious chunks dremmeled away, Scalex Motor detail and half of driver seriously lacking.
 
 
 
 
[Image: interior_01.jpg]


 
 
On the left Stock Scalex driver now with legs and new tray for motor compartment, on the right with new seat and all Motor detail added.
 
 
 
[Image: interior_02.jpg]
On the left , right side view of interior , on the right interior split up in parts to be vacformed separately. First and probably last time anyone will see the scratch build intake manifold, but at least I'll know its there.
 
 
 
 
[Image: motor_detail01.jpg]

 

Motor compartment with a coat of Vallejo plastic primer added, this to seal and close any gaps between the glued parts on the master (and looks much better too)

More words to follow, gotta work
 
with kind regards
Tamar
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#4

Posted 25 February 2019 - 04:02 AM

The Road to Le Mans 1/32: 6 weeks and counting
 
Another week has flown by, work on the Ford is making good progress, but I'm running seriously behind with my post updates.
Last week I finished the master of the cockpit, vacformed the first prototype and ran a second test in Best, checking the modified body for any clearance issues with the modified chassis. But let's pick up where I left with my last post.

In the driving seat 

As I mentioned before, the stock Scalex interior was lacking a bit of detail..and half of the driver ..not to mention the rudimentary driver seat.
On almost all slot cars the driver and his position in the car are hideously incorrect and when they make a vacformed version of the stock interior most of them will look like shapeless..blobs. Seems like if you want to save a bit of weight you should not care on how it looks...well.... I do.

With all the space you need for the chassis bits (not to mention the Oxygen Chip) there's no way to replicate the depth of the interior in true scale, so its more about creating a suggestion of depth and detail.
Doesn't take much to do so, a few rectangles of styrene, some wires here and there. I'd collected tons of reference images..but in the end you just have to wing it.
It does help that on contemporary Sportscars the seats are thick and well padded. And with the HANS devices the helmet and driver have got a vacformable shape.
A bit of putty here and there to properly "seat" the driver, used some thin foam I had in my bin box for the padding.

Created a bit of extra room for an Anglewinder Flat-6 in the passenger compartment so the interior would fit both SW and AW configurations, at least so I hope [Image: wink.png]
 
[Image: interior_03.jpg]
 
Going pear shaped
Below the various steps I made to make casts of the masters. Your never to old to play with Lego, excellent stuff to make cast boxes, yeh they will leak a bit, but nothing too bad. More important when you make vacformed masters is to keep in mind they have to be pear shaped, or beter pyramide shaped. They have to be wider at the bottom than at the top..otherwise you won't be able to get the master out of the vacformed PET. 
A trick to help you go pear shaped when obviously your master is not...is to mount the master at an angle in the Cast box. Lean the interior backwards to capture the most of the dash and driver detail. Same goes for the Motor compartment, Slightly tilted backward so I can vacform both sides of the firewall.
[Image: interior_casting.jpg]
 
 
Negative mold to cast positive master.
So here's a picture of the "negative" silicone mold and the positive resin cast, looks nice and clean, but its actually a messy business. Unfortunately my resin was way over date so I needed to add more harder for it so set which meant more air captured in the cast and several cast to get a few decent ones. But for the first test it would do.
A lot of holes were drilled in the"deep" parts of the resin cast to allow the vacform machine to suck the Pet into the cavities
[Image: interior_casting02.jpg]

Here's a shot of one of the first vacformed cockpits..with just a light shot of satin black and some dabs of Vallejo white primer. Cut back stock roll cage fits like a glove.
A lot of work considering how much detail you'll actually see when he's mounted in the car...but at least it gives the impression of a proper race driver...in the driving seat [Image: wink.png]
[Image: interior_vacformed.jpg]


To be continued

With kind regards
Tamar
 
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#5

Posted 26 February 2019 - 01:42 PM

This is a copy of an answer I gave in an other Slotracing & Tuning topic.
The question was what method slotters preferred to insert their lead wires into the guid: Eyelets or grubscrews?
 
With al the (endurance) testing for the DISCA LM 24hrs I have come to the following best procedure (I.m.o) a combination of both.
I prefer the bigger M 2,5 grub screws to secure the braids and leadwires, but will use brass eyelets to protect the lead wires from being cut.
For easy fitment I crimp the eyelets flat on the lead wires, it also keeps them from falling of while changing braids [Image: wink.png]

Pitcured below is a modified Scaleauto guide with self drilled and threaded holes for the M 2,5 grubs.
With the eyelets crimped you gain the rigidity of material for the grub screw to press on, but keep the full flexibility of the lead wire.
With tinned lead wire ends it is hard to control how far the tinn gets sucked into the lead wire, which can create a rigid and thus break point in the wire.
 
M2 grubs, specially those with a pointed tip are more likely to split, cut of even miss the lead wire all together during a quick pit stop than the broader (flat) tip of a M2,5 grub. But yes you do need to drill the hole and thread it carefully, but when done well no splitting of the guide... that is unless you over tighten the grubscrew.
 
 
With kind regards
Tamar

[Image: Guide_eyelets.jpg]
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#6

Posted 26 February 2019 - 02:13 PM

And while we're at it..the guide I mean....before you guys start asking questions about the guide nut....
Here's an other repost from older topics:
....The way I treat my guides is a crossover from the world of 1/24 racing where you use guides with a threaded stem and a guide nut.
Ok what you're looking at is a Scaleauto guide with a 6mm grubb screw and a M2 aluminium locknut.
You can get these from Conrad in aluminium or anodised red and blue.

The reasoning behind me using this system is that with the regular 1/32 guide screws you have no way to lock the screw in its position.
Its eather tight or not, if you want to give your guide a bit of guide float you have to use a longer screw.
Screwing them in, in excatly the same way and perfectly straight every time is very hard to do.
By inserting a grub screw in the guide stem you only need to get it right once.
I use a m2 thread cutter to thread the hole of the guide stem, and as the cutter has a long handle its easy to get that perfectly straight and aligned.
With the metric thread you get a much finer adjustability and the nut serves a dual purpose.
As the bottom of the nut is perfectly flat it acts as a flange and stabilizes the position and angle of the guide in the guide holder,
even when the guide holder is a bit wider than the guide stem.
And as its a lock nut its position remains fixed, no matter how much guide float I set.

As this is applicable to all cars, and not just the Ford GT.
 
With kind regards
Tamar
[Image: IMG_6616.jpg]
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#7

Posted 28 February 2019 - 05:22 PM

The Road to Le Mans 1/32: 5 weeks and counting
Just 35 days and we should be on the ferry to Le Mans, yep starting to count days now instead of weeks. As I needed to prep a motor pod for the MK2 chassis for the Ford,
I took some pictures during the process so I could finally make good on a promise I made Dave Maddock some time ago..so here it goes a post on:

 
How to modify a Slot.it SW pod for ballbearings and multiple gear & pinion combinations.
Light, compact and offering great handling, these are the main characteristics why running a Sidewinder motor has become the popular choice for DiSCA spec GT's.
They have but two minor disadvantages that with a bit of handy work are easily to overcome. 
1: You can run but two gear/pinion combinations: 6,5mmø pinion with 18mmø gears or 5,5mmø pinion with 19mmø gears.
With stock gears the lowest gear ratio you can run is 2.38 which means that on the longer straights of some of the DiCSA events your Vmax will be limited as well
2: Due to the close proximity of the rear axle to the motor magnets there is some magnetic drag on the rear axle. 


I'll start with the 2nd issue first:
There are two stock options in the slot.it range that will reduce the magnetic drag, the first being Slot.it's sipa01-54r "reduced centre" axle, which as the picture below shows has
a reduced diameter centre section which provides  more clearance between your motor and the axle. But with it being "just' 54mm wide it can be a bit short.
[Image: motorpod_ch115&sipa01-54r.jpg]
If you need a wider rear axle your other option would be to use a 55mm Titanium rear axle as available from Scaleauto and Slotingplus.
The advantage (besides them being of a non magnetic alloy) is that they are light, the disadvantage is that they are a bit softer than the hardened steel axles.
Meaning you would prefer to run them in ballbearings rather than the regular slot.it olites. 
For which Slot.it has the ch115 Evo-6 1mm offset motor-pod, which is compatible with their CH105 ballbearings (not included in the kit)

But what if you want to run an other offset? Well then its time you got yourself a set of good drill bits.. a range that starts @ 3,3 mmø going up by 0,10mm to 4,8mmø
 
[Image: motorpod_mods01.jpg]
The procedure is actually very simple: Start with the 3,3mm drill, use the slowest speed setting on your drill and let the drill bit "guide" itself through the rear axle hole towards
the one on the other side. As you repeat this process several times using a 0,1mm bigger drill every time..it does help to switch sides every two or three passes.
[Image: motorpod_mods02.jpg]
 If you're into fine precision tools, you can replace your drill for a reamer to enlarge the openings for the last 2/10th to 4,8mmø (the CH105 ballbearings are a 4,75mmø,
 and if you source them from other brands..that's the diameter you'll be looking for) The next step is to grind away the outer part of the olite holders.
You can grind them perfectly flat with the rest of the pod but I prefer to keep 0,1mm as it will be easier to align the ballbearings later on.
Clean up any burr's left on the pod with the reamer or a sharp knife.
 
 
Room to move..and improve on fixed diameter gear ratios
As I mentioned before, the lowest gear ratio with stock gears is 2.38 which means that on the longer straights of some of the DiCSA events your Vmax will be limited.
If you want to run a lower ratio you'll be looking at different gears & pinions with different dimensions.
So here's a number you should keep in mind: 24,5mm (6,5mmø pinion + 18,0mmø gear)
This is not an exact value of the distance between the pinion and the gear (as there's an overlap etc etc) but its a good value to compare possible other pinion and gear combinations.
For example the Slot.it 14t 7,0mmø Ergal pinion in combination with a Nylon Scaleauto 31t 17,5mmø Sw gear also adds up to 24,5mm. But with a lower ratio (2.24)
If you want to go lower, then you could use the 17,5mmø NSR gears, although you will have to ream these to fit on the titanium axles. But you'll have ratios going down to 2.0 with a 28t gear.

Big pinions, small gears
With a 2.0 ratio you are approaching the limits on what a MX16 small can can accelerate and decelerate on a 72-78gr Slotcar.
But for the long Mulsanne straight a bit of extra top speed might give you that little edge.
For my cars I prefer to use bigger nylon pinions (less weight and better mesh) but even when the sizes of your mixed brand pinion & gear combinations do match, your mesh might still be a bit off.
So below are some images that can show you how you can give your pinion that little bit of wiggle room needed to adjust your mesh.
[Image: motorpod_mods03.jpg]
So what you'll be looking for is grinding tool with a 6,0mmø, what you'll be needing to do is to enlarge the opening in the pod for the Motor bearing by 0,5mm forward and backwards.
Again use the slowest speed possible on your power tool to keep good control of where you're grinding material away.
The next step is to enlarge the openings for the motor screws by the same amount. You can use a power tool, but a plain old fashioned rat-tail file will do the trick just as well (just takes longer) 
As you can see below I also grind away some material of the top of the pod, this is done to make it easier to snap the motor in the pod..and reduces the amount you'll deform the pod by doing so.
[Image: motorpod_mods04.jpg]
I usually wait with aligning the ballbearings till after I've mounted the motor (as this will deform the pod a tiny bit) I use 2 short motor screws to secure the motor.
Best procedure is to use the front screw to adjust the mesh (with axle and gear in place). Tighten it and then remove the gear to be able to insert and tighten the rear screw.
The reason why I prefer to use Torqx screws should be obvious..they don't fall off your screwdriver that easily.

So there you have it, with these mods you'll have an adjustable pod that accepts pinion/gear combinations within a 24 - 25mm range.

With kind regards
Tamar
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#8

Posted 01 March 2019 - 02:06 PM
Setting Gear mesh and axle play....for Dummies
Sometimes when I re-read my posts I notice that I have omitted some of the basic steps in a described procedure...because...

...well, I assumed they were part of all slotter's basic steps. But that does not always seem to be the case. So...
To finish off my previous post on how to modify a Slot.it SW pod...here's one on an idiot proof way to set a proper gear mesh and axle play.

 
 
[Image: gear_mesh&play.jpg]
 
From left to right: 
  • With motor, pinion, axle and gear mounted. Insert a piece of paper or a plastic zip bag between the pinion and gear.
  • Push the motor tight towards the rear axle/gear and tighten the front motor screw. Not fully, just enough to fix the motor position.
  • Remove gear and insert and tighten the rear motor screw (not pictured) and then the front motor screw
  • Get your axle play adjuster tool (the H-shaped parts) from the PA47 or PA52 slot.it axle spacer set.
  • Remount gear and insert tool between gear and spacer
  • Squeeze/press gear tight on axle to eliminate any axle play.
  • Tighten gear grubscrew. If you use 2 grub screws tighten one side lightly to fix position of gear, rotate gear 180˚ tighten 2nd grub lightly, rotate gear 180˚ tighten 1st grub  more, etc etc.
  • Remove axle play tool

So there you have it, an idiot proof procedure to set the same and correct amount of axle play and have a perfect gear mesh, any time, every time.
As usual the most simple ideas can be the most ingenious ones, and by adding the axle play tool to the PE spacer set a Slot.it PA47 and/or PA52 is really one of the best buys you can make.

with kind regards
Tamar
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#9

Posted 06 March 2019 - 02:14 PM

The Road to Le Mans 1/32: 4 weeks and counting
Just 30 days before the start of the first practice session in Henley in Arden. With the MK2 Sidewinder chassis now on the bench, work in the last week was focussed on prepping the MK2 chassis and converting the MK1 chassis to a AW configuration. We've got a test session planned this Saturday where the goal is to give both chassis a thorough endurance test and compare both configurations.
 
 

From prototype to production
With all the post on detail bits and pieces of the Ford, I thought it would be a good idea to post an overview  of the chassis "development" from the original ProSpeed chassis via the prototype Mk1 to the now almost ready for testing MK2 chassis. 3 images representing a lot off work done in the past 3 weeks.
On the left the original ProSpeed design which more or less had the same shape as the Scalex Ford with the side skirts and diffuser attached to the chassis.
In the middle the Mk1 prototype where I'd cut of the side skirts and diffuser and fabricated mounting points for the body support grubscrews and the side suspension.
This is how we ran the Ford in the first two test runs. 
On the right the assembled MK2 chassis the with all the lessons learned and changes that were made "manually" to the MK1 now incorporated in the 3DP design.
The main difference being the addition of some reinforcement ribs on the chassis to prevent the chassis from bottoming out in the middle, a different shape for the Flex slots in the chassis with the forward grub screws moved..forward. This was to make more room for the O2 chip. 
 
[Image: chassis_prospeed_mk1-mk2.jpg]
 
The differences between the MK1 and MK2 are more visible from below. As you can see the MK2 chassis is a dedicated SW chassis, wrapped tight around the the Slot.it pod. 
Besides the shape of the pod surround you'll also notice that the rear of the chassis has now been beefed up and now has a U-profile in which we can glue a kevlar strand for even more rigidity and crash resistance. Just behind the front axle is the mount for the front suspension bracket (which I still need to fabricate) that will turn the quad point slot.it pod in to a tripod.
Last but not least, the guide has been moved forward by 1mm and the guide recess in the chassis has been enlarged so we can fit the Thunderslot guide with its wider and longer guide saddle.
 
[Image: chassis_prospeed_mk1-mk2-bottom.jpg]
 
2nd time around
With the 2nd chassis almost ready to run it was time to start prepping a 2nd center body section. Wasn't to happy with the first one anyway, removed too much material and the modifications were a bit crude. But you learn from your mistakes so I.m.o. the MK2 center body is much neater and cleaner.
Although we could in theory run the modified plastic parts....I do hope there will be time enough to cast the MK2 body centre section in silicone and laminate at least one GRP version.
[Image: body-mods_mk1-mk2.jpg]

Spend a good  few hours to get the motor wires, the ferrite man and the connector to the O2 chip in a position that works for both SW as AW configuration..without interferring with the body. Here's a look "under the hood" as you can see it all fits, but its a tight fit [Image: wink.png]
[Image: Bodymods_sw-aw.jpg]
 
 
Pet project
Last but not least, a bit of scale detail. I needed to make a 2nd set of front wheels for the MK2 chassis, had a good look at the stock scalex front wheels and they are actually pretty good.
A quick trueing on the hudy and they were as good as the Delrin Sloting plus wheels I usually use. But with one difference...
...the Scalex wheel has scale spokes, no hub and insert.  
Modified some Black arrow brake disc which even when "lightly' coated with paint are not totally opaque and slid them over the wheel hub.
All we need to do now to create one of my long desired  pet projects...is to stick a red smd led in the hub and we could have glowing brake disks. [Image: wink.png]
 
[Image: wheels_scalex_mod.jpg]
 
 
Testing 1,2,3
So there you have it, both Ford GT's side by side. Although the MK2 is a good step forward (at least that's what I hope saturday's test will confirm) we'll most likely be racing a MK3 version in Henley with some minor detail changes and some extra 3DP bits & pieces.
[Image: 2xFord_AW-SW.jpg]
 
to be continued...
 
with kind regards
Tamar
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#10

Posted 13 March 2019 - 03:39 AM

The Road to Le Mans 1/32: 3 weeks and counting
Just 24 days before the start of the first practice session in Henley in Arden. Looks like we're going to play catch up with Garage 27 for car prep.
We've had a good test session last weekend in which we managed to do a lot of work and testing, not everything I had hoped we could do, but it was a very, very constructive day.

First and foremost, we've now got a good base set up for the new MK2 chassis, that may look easy, but with a new chassis you basically start from scratch for 50%.
And one those test days..time fliesBut I'm getting ahead of the story, more on that part in a later post, because before we could go testing I first had to finish some parts.
 
 
Bussy Bees and Lego time..again
Marc was going to bring the Dental Vacform machine to Best (thx Eric) so we could pull some lightweight windows, meaning that I had to prep the masters.
So here I go, its lego time again. Besides great for building the walls of your cast box, the little Lego pieces can also be used to support and fixate the position of the part you want to copy.
Most important when they're fragile breakable parts like windows, even more important when those windows need to be fitted from the inside of the body..to maintain the correct shape and fit.
On the left image you can see how I used some Lego blocks to build up a base. In the centre image you can see how I then applied the Modeling bees wax around the Lego base. (sorry, a bit out of focus)
You can actually see the top of the Lego sticking out of the bee wax.   
The Bee wax can be shaped cut and moulded with a knife, a spatula and even with your fingers. Its great stuff.
It gets softer when warm and can be dissolved (as in when you need to clean the master again) with cleaning petrol.
When building up the bee wax you need to pay attention to three things:
 
1 that you seal your master completely, because even with the tiniest  small gap between the master and the wax...the silicone will creep in between.
2 that you keep the master as pyramid shaped as possible.
3 that you maintain a clear definition on where your master ends, if needed you may need to go against the pyramid rule here, as long as the overhang is minimal.
 
After bee waxing its time to build the cast box, and the to clean your master, and I mean clean, polish and remove every flint or dust particle that you can find.
Because the silicone will copy anything, even the tiniest surface details like lettering on the window streamer or the tiny raised window frames that Scalex tamponed on the glass...
...which in this case isn't such a bad thing... but that too is for a later post.

[Image: vacform_master.jpg]


Casting bubbles and how to get rid of them
I've covered casting the silicone before so I'll skip that part and head straight to the resin casting. Here (also due to time restraints) I used a very fast setting PU resin. 
Handy when you want to pour several casts in a couple of hours, but the down side of the fast stuff is... you've got a two minute window in which to mix the stuff and pour it into the silicone.
As with silicone casting the main thing to avoid here are air bubbles, they are unavoidable (well with out a vacuum pot they are) but there is a (quick) work around to get them out of the important parts...
.. and those would be detail parts like the thumbs and fingers of your driver or some delicate motor detail that took you hours to create on your master, or the bottom (and thus in the mould the top side) of your air intake.

[Image: vacform_casting.jpg]

So before you start mixing your resin, have you silicone moulds laid out in sequence of casting, have a fair amount of kitchen towels ready for the Oooops! [Image: wacko.png] moments.
A spatula to wipe off the excess resin and most important..a couple of tooth picks. 
Now you can mix your resin, make sure you mix the minimal amount, as the more resin you mix in the cup the shorter your cast window will be. Don't worry about mixing too little for these type of masters.
Resin sticks to resin like....well that would automatically be corrected here on SF, but believe me it bonds very well. So even when your mould isn't filled to the edge, just mix a bit more and complete the casting.
So..about the work around to get the worst bubbles out...well its simple, as you can see in the pics above I use the tooth pick to pry them out of the deep parts in the mould.
Just stick it in the cast resin while its setting and wobble it around... sounds simple doesn't it ?...

[Image: vacform_casting02.jpg]

...well off course it isn't that simple and it will take you several casts before you get it right as can be seen in the picture above right.
Took me several pours to get one air intake without some air bubble caught in the mould. But the windows and headlight lenses came out perfectly.
Ready for some Saturday afternoon vacforming.
 
Front suspension from quad pod to tripod
There was one more item that I had to fabricate for the MK2 chassis and that was a bracket to mate the Slot.it SW pod to the central front suspension mount we'd incorporated in the MK2 design.
We'd used a similar design last year with the C7R for which Stefan Kievit designed a nice 3DP part, but although it worked very well, that bracket needed to be dis mounted from the motor pod if you wanted to change the O2 chip.
For the Ford I wanted too keep it more simple, stronger and lighter. So I rumbled through my supply of GRP and cut this small (and if I may say elegant) bracket from a 1mm thick sheet.
A Big head tall Slot.it suspension screw, some spacers and a 2mm bushing, a short Scaleauto spring and a Thunderslot top nut.
The Slot.it SW motor mount had now been modified from a quad pod to a tripod with just on screw to set the front pod float, which can be done without taking the body off.
Now we were ready for some serious test runs. 

[Image: suspension_mount_front.jpg]
 
 

To be continued

with kind regards
Tamar
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