Making Foam Seats - UPDATE

[ECR]

If you want to get the best ratio mix then pour some of the liquid into a measuring cup and then pour it out against a stopwatch. This will leave a residue in the cup (just as it will when your do the actual mix). Tare (zero the scales with)the wet cup before you add the correct weight of component for the actual mix What you are doing here is pre wetting the cup. It's more essential if you are making small amounts of foam as the quantity you leave in the cup is a greater percentage of the mix. With larger mixes it's not quite so important.

A piece of 4mm (approx) dia wire bent into an offset L shape and used in your drill is a good mixer as it scrapes the liquid from the sides of your mixing vessel. If you are using a drill to mix WEAR GOGGLES and stop the drill before you remove it from the mix.

As stated, temperature of the mix is important ......

[Richard Price]

I have bought survival bags for pouring the mixture into

Jez,

I think survival bags may be a bit too tough, so the foam may not flow that well into all the corners.

I've used wheely bin liners. They're tough enough, and flexible enough.

[Z3MCJez]

Thanks ECR / Richard.

 

I will get some wheely bin liners and compare. My biggest worry with anything is that I'll get all of the foaming stuff into the bottom of it, and it won't make an even seat (I.e. there'll be too much under my legs / around there, and not enough around my 🙆🏻)

 

Still, might be fun trying

 

Jez

 

Build Photos

[jchasey]

The trick is choosing just the right moment to 'sit' in the seat as the foam is setting.

 

Too early and its still to liquid and you sit on the floor with a wafer thin foam layer, too late and its too hard to mould to your 🙆🏻.

 

The first one I did on my car went perfectly, and we thought it was easy and then managed to bugger up the next three attempts on the passenger side

 

The great thing though is if it all goes wrong you can just mix up another batch and try again.

[Z3MCJez]

So, any tips as to what the timing is?

 

As I'm tall, I'd rather it was too thin that too thick. Or is that going to be horribly uncomfortable? Oh, what fun I'm going to have tomorrow! 😬

 

Jez

 

Build Photos

[jchasey]

After you have poured the mix into the bag, just keep prodding it with your finger (through the bag) to check the consistency, and be ready to jump in once it seems be be thickening.

[Jay 28]

Jez, making a seat aint as hard as you think, i did mine a few weeks ago, and believe me you will do a better job than caterham. i imagined the mix would start foaming as soon as it was mixed but it wont, you have planty of time to mix and pour. Once the mix is in the bag leave it about 1 to 1 1/2 minutes till you start to see it lifting the bag, then gently lower yourself down into your driving position, dont worry if your sat on the ali floor you can sort this out later. You will feel the foam under you and you can massage the foam round your legs and into any position you want, remember left foot on clitch! afetr about 20 minutes get out, if you find your sat on the ali floor, you will find you can peel the bag off the foam upto a point and re-fill the base (where your arse is) and get a thin base and good lumber support, dont worry the two foam mixes will stick together as one. Again sit for a good 20 mins. I would suggest you then leave it for a good hour before you try to take it out. Beware, it took me longer to get the base out in one piece than it did to make the base, you may not think it but it will come out eventually! Then just trim, and tape, easy! The back is done in exactly the same way, remember you can always top the foam up if you aren't getting support in a particular area.

I used a paint pot on scales then added 250g of A and 250g of B then mix for the base, and about 300g for the second pour for arse base and lumber support. rinse and repeat for the back.

 

Hope this helps and i will be inspecting your efforts on Wednesdy at Combe!

 

Edit to add i used 1kg for the first pour not 500g

Jay

 

Edited by - Jay 28 on 4 Apr 2009 08:15:11

[Z3MCJez]

Well, I followed all of the information as best I could.

 

1) Survival bags too big. Impossible to get rid of the crumples

2) Mix it way more than you think! The second and third pours produced better foam with a much more even formula - the first pour has honeycombed a bit ...

3) The 2kg pack from Demon Tweeks is barely enough to make a whole seat / back.

4) Putting the tape on nearly takes *AGES*

 

As I will make a passenger seat in due course, does anyone know where I can get the mix in bigger quantities than 2l at a time, at the sort of rates that look like they used to be available - the company mentioned earlier in this thread don't seem to be selling it anymore ...

 

Jez

 

PS No canoe moments 😬

[Roger Ford]

CFS Fibreglass Supplies. I usually buy the 5kg pack - allows for a few cockups/retries.

 

[Myles]

So lunchtime research found me this thread...

 

The jury stills seems to be out with regard to using a survival bag or just rubble sacks.

 

One thing I'm still unclear about (that may make the survival-bag option more attractive) is whether the seat back is created as an independent part - or as a a second pour into the seat base. I.e., do you end up with a two-piece seat, or one?

 

A survival bag would seem to lend itself to a single piece seat, but I can see that it might be a trickier build....?

 

What's the recommended method for a temporary back support while the base is curing, by the way?

 

I will need to be somewhat reclined but don't think I can sit for 20 minutes at an able with no support...

[Z3MCJez]

I've made a second one since the one referenced above. It isn't that hard. I wouldn't try to make a one piece seat though. I think that will be very difficult. As Richard Pirce says, wheely bin bags are good.

 

I'd make a base (use cushions behind you) and then a back later.

 

For a whisk, I used a metal coat hanger shaped to a whisk shape and then put into an electric drill. Empty paint pots or 6pt milk jugs are good as mixing pots. Ambient temp and a little bit of "restrictive pressure" are the variables that are most difficult to control, but carefully measure volumes give you a good chance of success.

 

And if your first effort doesn't quite work, use the failed effort as a start point for the next one rather than starting from scratch.

 

Jez

[Richard Price]

Quoting Z3MCJez: 

I think that will be very difficult. As Richard Pirce says, wheely bin bags are good.

 

Who 🤔

 

Quoting Myles: 

One thing I'm still unclear about (that may make the survival-bag option more attractive) is whether the seat back is created as an independent part - or as a a second pour into the seat base. I.e., do you end up with a two-piece seat, or one?

 

Definitely go for two separate parts. If you make it as one, you'll never get it in and out.

I'd also remove the harness lap and crotch straps before trying to make a seat. It's easier if they are not in the way. You then cut slots to suit them once you've sorted the seating position.

Quoting Myles: 

 

I will need to be somewhat reclined but don't think I can sit for 20 minutes at an able with no support...

 

It's not that bad. You do actually have quite a bit of support from the foam it's self.

It swells and fills the gaps around you.

[Myles]

Thanks. I was definitely going to remove the belts - must remember to keep my legs a suitable distance apart though!

 

Getting the ambient temp up could be a challenge - might have to pinch the conservatory heater...

[Myles]

Drove home tonight - caught the headset band a couple of times particularly when turning right.

 

Sat in the pax cockpit (no seat) when I got home - loads of clearance.

 

Foam ordered 😬

[RS2000]

Post some pictures please when you've created your masterpiece!

[Myles]

Oh, I will! Probably set up something to record video or timelapse as I don't want that stuff anywhere near my camera kit and I suspect the first attempt(s) may be somewhat fraught!

[andy bell]

just make sure you cover the entire cockpit in something in case it spills and wear something that if you had to bin wouldnt make you sad ;) I bought way more than I needed for tests and stuff which helped too.

[Myles]

Yep - I've already taken that on board. One blog (LoCost Builder?) said something along the lines of "the car, the driver and the helper should be retained - everything else should be treated as expendable"

[andy bell]

Quoting Myles: 

Yep - I've already taken that on board. One blog (LoCost Builder?) said something along the lines of "the car, the driver and the helper should be retained - everything else should be treated as expendable"

 

i had a friend to help make it and we only had some small escape as the bags were probably smaller than we should have used. It is absolutely horrendous when it gets on anything as its heating up. Bag selection seems key.

[Myles]

Thanks. In the first instance, I think I'll look out for the wheelie-bin liners. I'm sorely-tempted by the survival bag option - partly as I already have one kicking around and it would obviously be one of the longest bags available. It is heavy plastic though.

[Myles]

Ok, not that I'm planning to try this for at least two weekends (I'm off driving the other 7), I've just picked up Tesco wheelie bin liners when I was out getting some grub this morning.

 

They are described as heavy-duty (with an official caveat that this is in relation to their Value range.... ).

 

I'll double-bag them, but are they likely to be up to the job, or should I source something not-as-heavy-as-survival-bags, but maybe closer to rubble/garden refuse sacks?

[nickh7]

if you double bag wont they slide on each other ?

[Myles]

I guess so, but all I'm trying to achieve is containment of the goop - I'm worried that a single bag might get torn or burst some other way....?

[oldbutnotslow]

OK its simples!

you cut the bottom off one bag so that it becomes a tube. you then stick this on the OUTSIDE of the other bag with something like Tessa tape and you have solved the problem

 

I've made a couple of dozen over the years and the method on the first page works well and gives consistent results. The trick is to stick thin cardboard over the seatbelt mounting in the sideskin. This allows the seat base to be removed. Something like a cornflake box cardboard is really good. Make an L shaped upstand and stick this to the floor in order to restrict the foam/bag from growing too far forward

Wear something old and get a friend to pour the foam into the base first. You can then jump in without fear of the foam starting to go off. Put your foot under the clutch to simulate what your leg is like when you are actually depressing the clutch.

Most importantly get your friend to restrict the foam from growing too far up your back. Much better results are obtained by restricting the foam as opposed to just allowing it to expand as much as it likes.

Let this set and then clean up the top edge behind your back with a tenon saw. The back will then fit nicely to the base shape when you pour this.

[Bob L]

Does anyone have a video of doing this (successfully)?

 

Mind you failures would still be good viewing 😬