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Learning how to build Lotus Seven replicas...together!
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PostPosted: July 24, 2022, 7:54 pm 
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Location: New Zealand
Thanks Guys.

MV8 - Agreed, a clear coat to enhance the bling and as you say make it easier to clean and UV resistance, NZ sun is strong due to the ozone hole over Antarctica!

Chuck - got to pay the dues before you can sing the blues - is sanding molds the same thing? Next parts should be faster..... :BH:


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PostPosted: July 24, 2022, 8:22 pm 
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Would I be out of line saying you have a nice rearend? :mrgreen:

It’s looking fantastic!

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PostPosted: July 24, 2022, 8:32 pm 
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Ron, I would take that as a complement. I must confess I spent way too much time last night running my fingers along the lines :cheers:


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PostPosted: July 26, 2022, 8:56 pm 
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Congratulations. You've really stuck with the problem, and now you've solved it. It looks great.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: July 29, 2022, 8:54 pm 
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Thanks Lonnie, I see what you did there with my trigger word, very good!

CAD model for rear panel in fibreglass was estimated to be 17lbs, test panel weighs 9.5lbs raw. No paint, fasteners, tail lights or wiring included, but within target range so that is an encouraging result.


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PostPosted: August 14, 2022, 3:28 am 
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With a twin engine setup the separate clutch bite points might cause a behavior where the free engine could rev up under the "moving off" throttle setting, especially for a hill start. Learned the standard Speeduino launch control could be programmed in Tunerstudio to a low rpm setting to fake an "anti-stall", it only needs a clutch switch to feed a signal to the correct input pin. Will use the spare hall effect sensor to read the clutch position and an isolation switch on the control panel to turn the feature on or off on the fly - i.e. once the clutch pedal is pressed both engines will only rev to the set point regardless of throttle position, however once clutch pedal is released (or no voltage is supplied to the signal pin) normal throttle response continues. The first test drive will quickly establish if this feature is required, but will wire it into the ecu harnesses regardless.

Shown below is the wiki screen shot for the feature so would set launch rpm to something more like 2000 rpm

Attachment:
launch control.jpg


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PostPosted: August 14, 2022, 6:18 am 
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It seems a daisy chain throttle with #2TB following #1TB following the pedal would solve that and probably some other potential problems. #2TB could follow whether #2 was running or not. I assume a custom clutch master with twice the normal area teed to two accord slaves?

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360LA 442E: 134.5x46x15
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Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
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McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: August 14, 2022, 11:55 pm 
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Yup MV8, that's the plan. Each engine has it's own ECU which gets a signal from the appropriate throttle position sensor on the TB.

However in the cold light of day it is obvious that I have solved a problem I don't actually have! Majority of low speed running, commuting or city work will only be on one engine - 3.5L is plenty for those duties. Running both engines at full 7L noise will tend to be in open road conditions so gear changes will be lightning quick anyway. Sometimes I can't see the wood for the trees.....


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PostPosted: September 3, 2022, 1:42 am 
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The build has just had it's first anniversary...
Attachment:
1 year on.jpg


Happy with the tire to rear panel gap.
Attachment:
gap.jpg


Working on the drivers seat currently, really happy with the feel of the cardboard mockup so committing to making a plug for it, however the plug will be adjustable if required. Cutting the template out from 1/8" polypropylene sheet and attaching to a wooden buck, if the seat that the tool produces is not right can easily adjust it and remake tooling. Means I can avoid the sanding malarky that the rear panel encountered = faster results!
Attachment:
seat mockup.jpg

Attachment:
seat template.jpg


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PostPosted: September 17, 2022, 6:04 am 
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With a little help from a 2kw heat gun was able to coax the polypropylene sheet to fold where needed and retain on a MDF profile template. Will put filleting wax over the screw heads to give a flush surface before applying the tooling gelcoat, fibreglass and polyester resin. Once the seat tooling is made from this plug a polyester/glass seat shell will be made and shaped foam blocks added do the internal cavity to give a snug comfortable fit. Will make a carbon fibre seat for certification once long term comfort is tested.
Attachment:
seat plug.jpg


The plug fits nicely into place in the seating buck.
Attachment:
test fit.jpg


The curved sides are important for seatback stiffness but more importantly a space for passengers arms, while the cutout at the bottom of the seat matches the inwards angle of the structural spars either side of the driver, which allows for more space for passenger hips.
Attachment:
passenger elbow check.jpg


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PostPosted: September 17, 2022, 6:19 am 
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Looks good. You might also consider two part foam poured in a large trash bag you are sitting on, with a one inch foam board base underneath, then use this form to make your composite seat mold. Sit and wait about 30 minutes.

This is a two person job. Wear clothes that won't leave dents in the foam (i.e. buckles, belt loops, loose shirt, etc).

If there was not enough foam, you can do it again adding to the original pour.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: September 25, 2022, 9:41 pm 
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Good plan MV8, will do.

Sealed up all the screw heads and gaps with filleting wax
Attachment:
waxed.jpg


Gelcoat
Attachment:
gelcoat.jpg


Cheesey state of first stage of laminating resin was very easy to trim to the shape of the seat pattern.
Attachment:
seat mould first layers.jpg


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PostPosted: September 26, 2022, 1:01 am 
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Miatav8,MstrASE,A&P,F wrote:
Looks good. You might also consider two part foam poured in a large trash bag you are sitting on, with a one inch foam board base underneath, then use this form to make your composite seat mold. Sit and wait about 30 minutes...

I believe that it was Phil Hill who said when asked about this process, "You have to remember to place tape across any vulnerable orifices", or words to that effect.

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PostPosted: November 25, 2022, 9:52 pm 
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Sometimes a project reaches a stage where the fear of getting things wrong overpowers the confidence to progress. I have been wibbling for the last few weeks making minor changes to a cardboard & MDF mockup of the cabin to get everything goldilocked. However there comes a time when you have to commit to building the design, at which point it is merely a case of pouring in materials and labour. Other projects vie for attention and often serve as justifiable distractions.

Therefore under the "measure twice cut once" philosophy currently fitting the MDF templates over the "ideal interior" part to enable a fast and accurate plug construction phase (goal is to use minimal amounts of bog to save sanding time). The mold will be built over the plug and after cure the floor sections of the plug remove so that the mold is propped up directly. Hammer blows downwards onto plug extensions will shock the plug off the mold (as given the weight of the plug) gravity should assist release nicely. That's the plan anyway - more photos of stuck molds are possible however draft is generous this time.

Attachment:
interior plug.jpg


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PostPosted: November 26, 2022, 5:14 pm 
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If you use PVA, it's water soluble, so around the edges that are easy to initiate the separation, water can be introduced to help facilitate the separation when compressed air is blown in around the edges. This has worked for me on large molds.


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