Body buck making techniqiues, preferences?
Discussion
I'm about to undertake the construction of a body buck from which I, or ideally a grp specialist, will take moulds for the production of bodies for a kit manufactuiring project.
This will be for a kit car of relatively low cost, so I'm not necessarily looking for absolute perfection, nice though that would be. Mnny of the areas will be flat, and most of the curves will be single plane. I'm ok on the shaping side of things, having done a fair bit of that kind of thing in the past, though mostly with hard surfaces such as wood.
I've been making a study of this recently, and it seems that there are a number of methods available for producing the finished surface over an approximately shaped armature. Professionals appear mostly to use modelling clay of the Plasticene variety, which they shape by hand and with scraping tools. I quite like the idea of that, especially as there is no dust, and no waiting for materials to harden. However I have no experience of that type of thing, and the materials are quite expensive.
Alternatively I could use plaster, which is comparatively cheap, or car body filler.
Anybody have any thoughts on this subject, or anecdotal information they would like to share?
This will be for a kit car of relatively low cost, so I'm not necessarily looking for absolute perfection, nice though that would be. Mnny of the areas will be flat, and most of the curves will be single plane. I'm ok on the shaping side of things, having done a fair bit of that kind of thing in the past, though mostly with hard surfaces such as wood.
I've been making a study of this recently, and it seems that there are a number of methods available for producing the finished surface over an approximately shaped armature. Professionals appear mostly to use modelling clay of the Plasticene variety, which they shape by hand and with scraping tools. I quite like the idea of that, especially as there is no dust, and no waiting for materials to harden. However I have no experience of that type of thing, and the materials are quite expensive.
Alternatively I could use plaster, which is comparatively cheap, or car body filler.
Anybody have any thoughts on this subject, or anecdotal information they would like to share?
Well, technically "professionals" would design the body in some form of CAD software (or now more commonly Alias) and then probably have the mould CNCed from foam (to then convert it into a fibreglass mould perhaps). The CNC step can be replaced by a hybrid wood/ply & foam buck, by having the wood taken as sections of the body shape and filling in the gap with foam.
The above would give you the best results if you have a body planned out in CAD (or other design software).
If you are just going by eye, then personally I think body filler (over a rough shape made out of almost anything) is the cheapest and easiest way to go.
The above would give you the best results if you have a body planned out in CAD (or other design software).
If you are just going by eye, then personally I think body filler (over a rough shape made out of almost anything) is the cheapest and easiest way to go.
rypt said:
Well, technically "professionals" would design the body in some form of CAD software (or now more commonly Alias) and then probably have the mould CNCed from foam (to then convert it into a fibreglass mould perhaps). The CNC step can be replaced by a hybrid wood/ply & foam buck, by having the wood taken as sections of the body shape and filling in the gap with foam.
The above would give you the best results if you have a body planned out in CAD (or other design software).
If you are just going by eye, then personally I think body filler (over a rough shape made out of almost anything) is the cheapest and easiest way to go.
I knew about the cnc stuff, just thought it was a bit out of context here. In fact Kolb, the original and largest makers of plasticene, also make a complete cnc system for machining foam/clay bucks.The above would give you the best results if you have a body planned out in CAD (or other design software).
If you are just going by eye, then personally I think body filler (over a rough shape made out of almost anything) is the cheapest and easiest way to go.
Anyway, do you think body filler would be cheaper than plaster? It's obviously easier to shape, but I would have thought it a good deal more expensive than finishing plaster? And, of course, car body filler would preclude the use of polystyrene foam I guess.
I'd use what you're comfortable with and there's no reason whilst the buck can't be a hybrid in terms of material as long as you end up with the shape you want. Unless you intend to do this on a regular / frequent basis, use what's appropriate to the project in question: if it's a simple shape in terms of planes and curves, would it not be possible to fabricate it in wood and metal with a little filler as necessary?
Clay & Plasticene are suitable for more complex forms, plasticene gives about 60-80% of the usefulness of clay, it doesn't hold form anything like as well but is a lot less hassle and I believe you can make it yourself. Modelling clay ain't cheap in the quantities you'll need, has to be warmed in an oven (rendering it useless for anything else, unless you like the taste of clay...) is hard on the hands when you apply and then takes some skill to work effectively using a set of tools that you will have to buy or make, and flat surfaces are one of more demanding things in this material. Frankly, in many regards it's awful stuff.
Italo might comment about plaster as I think he's mentioned using it, as regards bodyfiller - whilst it's good for small areas it's less appropriate for larger areas for anything other than final finish, and even then it's messy to work with. It is possible to skim a styrofoam buck with bodyfiller, but this can result in a fragile shell susceptible to damage in the mould-making process.
Clay & Plasticene are suitable for more complex forms, plasticene gives about 60-80% of the usefulness of clay, it doesn't hold form anything like as well but is a lot less hassle and I believe you can make it yourself. Modelling clay ain't cheap in the quantities you'll need, has to be warmed in an oven (rendering it useless for anything else, unless you like the taste of clay...) is hard on the hands when you apply and then takes some skill to work effectively using a set of tools that you will have to buy or make, and flat surfaces are one of more demanding things in this material. Frankly, in many regards it's awful stuff.
Italo might comment about plaster as I think he's mentioned using it, as regards bodyfiller - whilst it's good for small areas it's less appropriate for larger areas for anything other than final finish, and even then it's messy to work with. It is possible to skim a styrofoam buck with bodyfiller, but this can result in a fragile shell susceptible to damage in the mould-making process.
seansverige said:
It is possible to skim a styrofoam buck with bodyfiller, but this can result in a fragile shell susceptible to damage in the mould-making process.
Some kind of barrier would be needed, though, as polystyrene foam disolves in the presence of polyester based car body filler, does it not?singlecoil said:
car body filler would preclude the use of polystyrene foam I guess.
Not necessarily - you skim it with a fine layer of filler to get a controlled reaction and that's a stable barrier to take more bodyfiller; question is whether it's worth the hassle - and to be honest we only ever used the technique on quarter scale - probably not appropriate for full size buck. There are also other fillers out there that don't react - there used to be one we nicknamed mars bar, but I'm guessing even more expensive than body filler.Have you seen the thread on locost about the guy in SA making a T70 body - might be some useful info there.
Edit: Here you go - http://www.locostbuilders.co.uk/viewthread.php?tid...
Again, with a simple form might be a sledgehammer to crack a walnut...
Edited by seansverige on Sunday 15th November 18:45
Joe T said:
Mmm I would have loved to have a go with foam, but if I had to produce something large I would make make a wooden stucture, skin it with thin ply that bends etc and skim it with body filler.
Whichever way you choose I suspect it will require the same amount of patience.
Harder to achieve complex curves that way though, compared to using 1" wood/ply cut to the correct shape for the section and then 5" of foam between this and the next wood/ply section (foam can easily be cut to follow the contour of the wood by using some copper wire connected to say a car battery)Whichever way you choose I suspect it will require the same amount of patience.
seansverige said:
singlecoil said:
Many of the areas will be flat, and most of the curves will be single plane
rypt said:
Harder to achieve complex curves that way though)
Doesn't look like it'll be relevant...Using a frame and "flex ply" (6mm with all the grain the same way) may get you around a reasonbly complex shape. Getting it symetrical is always going to be important. A skin of body filler is tough but I always brush on 2 coats of 2 pack primer and then sand down to 1200 grit b4 waxing. Reckon the heat build up of the GRP mould will cause probs on plater. Getting the plug right always saves tons of time on mould pefection. Using a uniform material helps for when your sanding it in to shape.
I also use jelutong, it's quite expensive but it great to work with on the awkward parts such as corners with lights recessed in.
Hope this helps. Stiggy
I also use jelutong, it's quite expensive but it great to work with on the awkward parts such as corners with lights recessed in.
Hope this helps. Stiggy
My technique is to get as near as you can in the ply, sanded etc
I then give it a couple of coats of watered down PVA glue mix to seal it,
The skim with filler and sand back,
I did try a primer coat and sand back before taking a mould but for whatever reason found it liked sticking to the mould, so now just prefer to wax the bare filler.
I would suggest some experimentation to find your preferred medium.
I then give it a couple of coats of watered down PVA glue mix to seal it,
The skim with filler and sand back,
I did try a primer coat and sand back before taking a mould but for whatever reason found it liked sticking to the mould, so now just prefer to wax the bare filler.
I would suggest some experimentation to find your preferred medium.
stig mills said:
I always brush on 2 coats of 2 pack primer and then sand down to 1200 grit b4 waxing.
That's interesting, Stig. I know about the two pack primer, but didn't know it could be brushed on successfully. Any particular make/type?seansverige said:
singlecoil said:
car body filler would preclude the use of polystyrene foam I guess.
Not necessarily - you skim it with a fine layer of filler to get a controlled reaction and that's a stable barrier to take more bodyfillerEdited by singlecoil on Sunday 15th November 19:57
I made all my bucks using aluminium, fibreglass & filler. I then primed & painted in 2k black so that any faults would be obvious & could be corrected b4 getting as far as making the mould, I then had all the first panels made in black & polished to a high gloss. If it looks ok in black you know your panels can be made in any colour & look good & ripple free.
My personal opinion is that a few extra hours spent on the buck pay dividends in the long term.
My personal opinion is that a few extra hours spent on the buck pay dividends in the long term.
Joe T said:
Mmm I would have loved to have a go with foam, but if I had to produce something large I would make make a wooden stucture, skin it with thin ply that bends etc and skim it with body filler.
Whichever way you choose I suspect it will require the same amount of patience.
Body filler on wood is a bad idea, its what I have done and basically the filler distorts as it dries and the shape is constanty changing.Whichever way you choose I suspect it will require the same amount of patience.
try to use something that doesnt shrink as it cures.
I would suggest something along the lines of a mdf frame finished with some low density modelling board, then epoxy painted & polished. And make sure your buck is really well finished, especially if you are looking to take bare gelcoat panels from your tool.
Another thing worth considering is that adding crown and compound curvature will make for much nicer parts - shame you are not going down the cnc route as I think it is well worth it in the long run.
Another thing worth considering is that adding crown and compound curvature will make for much nicer parts - shame you are not going down the cnc route as I think it is well worth it in the long run.
egomeister said:
shame you are not going down the cnc route as I think it is well worth it in the long run.
Indeed, absolutely! I would love to design the whole thing on a computer and machine the buck with a 5 axis cnc router, but unfortunately don't have access to the necessary skills and equipment, or the financial resources to buy those things in.Has anyone costed the CNC route?
For most the possibility of modelling the car in CAD is a non starter but a body buck can be measured by laser or probe and converted into the cad model albeit just as an outline.
The advantage is that only one side of the buck needs to be sculpted as the resultant digital image just needs to be mirrored.
Only having to produce half a buck may make the required savings.
Steve
For most the possibility of modelling the car in CAD is a non starter but a body buck can be measured by laser or probe and converted into the cad model albeit just as an outline.
The advantage is that only one side of the buck needs to be sculpted as the resultant digital image just needs to be mirrored.
Only having to produce half a buck may make the required savings.
Steve
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