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So occassionally I see that people make their own carbon fibre parts, which appears to be cutting out a shape. I have a few questions as I've been looking at the TA07 carbon conversions which appear to be 2 plates, the main chassis and top deck, or VTD if you go for the TA07MS style. I've seen carbon fibre sheets for arpund $20 which would make the whole thing and probably have offcuts for shock towers too!

I assume that carbon fibre sheets aren't all created equal - how do you know if a sheet is good or not? Would a sheet off Banggood be any good?

Do you need any equipment or will a steady hand and a dremel do the job? I have a dremel, not so sure about a steady hand...but I do have a friend with a milling machine and propensity to do dumb stuff with me.

Is it a case of measuring the current chassis, making a shape that seems about right and cutting it out? Then drilling holes? Surely there must be more to it?! I could also look at pictures and basically copy one that is available given I know how far apart holes are from my TA07 chassis.

This all seems too easy, what am I missing? Surely someone has tried and can tell me I need $5,000 worth of equipment to save $150 on a chassis conversion kit?

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It's not so much cutting out the shape that's the difficult or even important part.....it's the perfect alignment of all the screw holes.  Any misalignment, especially will cause the suspension/gearbox/bulkheads to be crooked.  But even worse is any misalignment between the top & bottom decks will cause the entire chassis to be twisted (typically refereed to as tweak).

But to get to your questions....the 1st most important part about the material is that you use the right thickness.  Tamiya typically uses 3mm 2.5mm and 2mm thick plates.  At the very least you want to match the ones you are trying to copy.  Upper deck, lower deck, and shock towers are usually different thicknesses.

If memory serves me correctly, the ideal tool for the job would be a scroll saw with a permagrit blade.  You absolutely can use a dremel (That's what I do).  Typically you make your cuts outside the lines and use sanding blocks to knock down and finish the edges.

Please be aware carbon dust is extremely bad for your lungs (carcinogenic). You definitely need a mask.

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In engineered applications you'll find carbon fiber material defined with a number of parameters such as weave pattern, number of layers, surrounding resin, overall thickness, etc.  The weave patterns and layers define bending and torsional properties, so while you can buy a $20 sheet of material and cut it in the shape of a chassis, you may or may not see the properties you're after.

The other thing to keep in mind is safety while working with the material.  You don't want to breathe in any of the released fibers from milling or cutting.  Good masks, ventilation, intentional air flow, or even wet processing will help you.

Personally I would use an existing chassis as a drill guide for the holes first, then trace the old chassis shape for reference and define a new shape from there.

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22 minutes ago, 94eg! said:

It's not so much cutting out the shape that's the difficult or even important part.....it's the perfect alignment of all the screw holes.  Any misalignment, especially will cause the suspension/gearbox/bulkheads to be crooked.  But even worse is any misalignment between the top & bottom decks will cause the entire chassis to be twisted (typically refereed to as tweak).

But to get to your questions....the 1st most important part about the material is that you use the right thickness.  Tamiya typically uses 3mm 2.5mm and 2mm thick plates.  At the very least you want to match the ones you are trying to copy.  Upper deck, lower deck, and shock towers are usually different thicknesses.

If memory serves me correctly, the ideal tool for the job would be a scroll saw with a permagrit blade.  You absolutely can use a dremel (That's what I do).  Typically you make your cuts outside the lines and use sanding blocks to knock down and finish the edges.

Please be aware carbon dust is extremely bad for your lungs (carcinogenic). You definitely need a mask.

Thanks, I was thining along the lines of cut it out with a margin to be sanded down later, and then use the milling machine to drill the holes as you can make tiny adjustments and get that exact.

I've done a heap of research (by searching banggood once so pretty much none) and it comes in a range of thicknesses in .5mm increments. I've seen aftermarket kits with 2.25mm and 3mm, with the most common being 2.25mm

18 minutes ago, speedy_w_beans said:

In engineered applications you'll find carbon fiber material defined with a number of parameters such as weave pattern, number of layers, surrounding resin, overall thickness, etc.  The weave patterns and layers define bending and torsional properties, so while you can buy a $20 sheet of material and cut it in the shape of a chassis, you may or may not see the properties you're after.

The other thing to keep in mind is safety while working with the material.  You don't want to breathe in any of the released fibers from milling or cutting.  Good masks, ventilation, intentional air flow, or even wet processing will help you.

Personally I would use an existing chassis as a drill guide for the holes first, then trace the old chassis shape for reference and define a new shape from there.

This is my major concern - how do I know what properties I need and that the sheet i'm buying has them. Can you suggest and websites I could read? Its cheap enough to buy and try, but would be good to know what I'm looking for.

 

And always safety first (when my son went to preschool in dress up he had real earmuffs, safety glasses and gloves cos thats alk we had) and i would be looking into the right mask. That may make it cheaper to order the exotek kit!

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The safety gear you should buy, particularly when it comes to the mask, will most likely exceed the cost of buying a pre made carbon chassis.

That being said once you own the safety equipment and all the other gear you’ll need you can knock out heaps of parts and eventually earn that money back. 

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5 minutes ago, Juls1 said:

The safety gear you should buy, particularly when it comes to the mask, will most likely exceed the cost of buying a pre made carbon chassis.

That being said once you own the safety equipment and all the other gear you’ll need you can knock out heaps of parts and eventually earn that money back. 

And it comes out of a different budget!

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Whilst all of the above is true in terms of performance and manipulation of properties, I genuinely don't think that level of though and development is applied to RC cars. When I order my custom parts from fibre lyte I don't get to specify fibre orientations and the like, just material thickness. This says to me that they use one layup for everything which will be a simple 90/90/45/45 Cross ply which gives roughly isotropic (all the same in any direction like metal) and the carbon boards off the Internet will be the same I would guess. I also wouldn't worry too much about quality either. Its not going to be top notch but it's not awful either. In my day job we prototyped a rear swingarm out of carbon prepreg off the Internet just to prove a concept. We had control of the layup, but the material we just had to make some assumptions. Finally, even at 2.5mm thick rc cars need material for stiffness way in excess of their requirement for strength. The prototype swingarm I mentioned was thinner than that in plenty of areas and worked as a structural part of a mountain bike. 

Long story short, buy the plate off bang good or aliexpress and take a lot of care with breath masks when cutting, and have a go.

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45 minutes ago, ThunderDragonCy said:

Whilst all of the above is true in terms of performance and manipulation of properties, I genuinely don't think that level of though and development is applied to RC cars. When I order my custom parts from fibre lyte I don't get to specify fibre orientations and the like, just material thickness. This says to me that they use one layup for everything which will be a simple 90/90/45/45 Cross ply which gives roughly isotropic (all the same in any direction like metal) and the carbon boards off the Internet will be the same I would guess. I also wouldn't worry too much about quality either. Its not going to be top notch but it's not awful either. In my day job we prototyped a rear swingarm out of carbon prepreg off the Internet just to prove a concept. We had control of the layup, but the material we just had to make some assumptions. Finally, even at 2.5mm thick rc cars need material for stiffness way in excess of their requirement for strength. The prototype swingarm I mentioned was thinner than that in plenty of areas and worked as a structural part of a mountain bike. 

Long story short, buy the plate off bang good or aliexpress and take a lot of care with breath masks when cutting, and have a go.

Thats really interesting about the quality and properties of the carbon fibre, and how you can't really specify it anyway.

Does anyone know if theres anything I shoukd be looking for - either to buy ir avoid? I have seen 3k, high hardness etc which sound like properties, then matte, glossy, weave etc which i assume are just the look?

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2 hours ago, Jonathon Gillham said:

Thats really interesting about the quality and properties of the carbon fibre, and how you can't really specify it anyway.

Does anyone know if theres anything I shoukd be looking for - either to buy ir avoid? I have seen 3k, high hardness etc which sound like properties, then matte, glossy, weave etc which i assume are just the look?

3k is a type of fibre but its a pretty widely used structural spec ply. Hardness will be resin, but hardness usually equals brittleness so that's not super important in my opinion. Everything else is finish options, you are correct. 

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Does raise an interesting question as companies seem to be going back to aluminium lower decks, that carbon hasn't been looked into that hard. It would not be difficult with a layup of lots of unidirectional fibres along the length of the car with a smaller proportion of fibres at around +-20 to give a deck that would be very stiff in bending, but quite soft in torsion for grip. 

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In the volume RC cars are produced that would potentially benefit from carbon chassis and which don't already have them it's not viable or necessary compared to frp / alu.

Flat CF chassis plates for pro racing series cars (not just Tamiya) makes sense and are indeed used but then these cars are expensive and will only sell in 10s per country. The chassis/suspension plates are also very simple in design so cut from sheet not individual layup. 

For everything else frp or alu is cheaper, easier to mould into a formed shape and weight isn't a concern. Alu is more robust for off road where cuts and scratches would compromise CF. 

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Most offroad cars are aluminium but there are still some carbon fibre around. The HB D413 was one of the most robust cars around and that was carbon fibre. From what I have seen in onroad cars is that aluminium is offered as a tuning option and used for very high grip surfaces.

I did some reading last night and the opinions on DIY carbon fibrecparts ranged from 'its simple and safe, do it outside if you're worried' to 'its easy enough but you will die in 30 years just like asbestos'. Also saw an interesting take on asbestos removal - firms were using older staff as it takes 25 years or so to manifest so theres a good chancectheybwoukd be dead anyway. A bit grim

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@Jonathon Gillham, this seems like a good resource to understand carbon fiber better:  link

You can read about different precursor materials, fiber characteristics, weave patterns, different tow sizes (1k, 3k, 6k, etc.), weave densities and the impact on strength, resin materials, material properties, etc.  Her pages also include links to external resources and videos; some of them are pretty interesting.

The mostly likely situation is you're going to find a ton of sheet material out there using epoxy as the resin, 3k material, basic 0/90 and 45/45 weave layers, and various thicknesses just as @ThunderDragonCy says.  While carbon itself is supposed to be biologically inert, I think the issue is fibers lodging themselves in lungs (like asbestos) and causing growths 25 years later.  So grab some 2.25 mm for the lower deck and damper stays, and some 2.00 mm for the upper deck, and have some fun (safely).

I guess I dwell on the question of material properties because it comes back to a question of what you're trying to achieve.  For example, if you wanted more flex you could always consider G10/FR4 material instead of carbon fiber -- it's used widely in printed circuit boards.  Aluminum is another option as well -- some of the touring cars are providing it these days.  Some guys have suggested the aluminum chassis is great because it adds more weight very low vs. sticking weights on top of carbon fiber.  Some have also suggested aluminum has some different responsiveness characteristics, making a car less twitchy than one with carbon fiber (on certain surfaces).  The downside is aluminum bends and it's nearly impossible to straighten perfectly.  Maybe there are some noticeable damping characteristics in these materials.  So to me there there are some tradeoffs to play with, including weight, flex, inherent damping, and especially cost.

It's all just one big rabbit hole, isn't it?

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While the questions of the OP have been answered, I'd just like to share some thoughts.

I bought 2mm, 3mm and 5mm sheets of CF boards and did my own custom parts for chassis modification. Cutting can be tricky especially on the inner curves. I use Dremel for doing such but takes a lot of template measuring before doing the cutting on the CF. Although I only did this on not so big parts. Cutting the CF board manually to create lower/upper decks or anything big is impossible to do with precision. 

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Thanks for all the replies. Of course the chassis plate is over 300mm long which means the costs go up. I have asked a couple of suppliers on alibaba for quotes on small orders - with the saving it will probably still work out a similar cost its just I will have a heap of carbon fibre left. This could get interesting as there are a bunch of things I could use it for, assuming I can work out a good way to do it in the first place.

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Great thread !

Whats going to be really interesting is how quickly consumer 3D printing catches up with current industry printing in space / defence / aero.

It’s where most of what we now take for granted started ... and (for me) the pace of consumer conversion is accelerating - due largely to commercialising space and the hugely reduced transfer cost ?

If that’s true, there are already stronger, lighter and more flexible composites / polymers in both segments that humble  carbon fibre mats.

So - like everything - they’ll flow through to the 3D printed mainstream ... and if I were you guys I’d only look at investing time / cash in carbon fibre if it were a cheap stop gap !

Or maybe as an investment in a material that will quickly become obsolete / collectable :) 

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6 hours ago, SuperChamp82 said:

Great thread !

Whats going to be really interesting is how quickly consumer 3D printing catches up with current industry printing in space / defence / aero.

It’s where most of what we now take for granted started ... and (for me) the pace of consumer conversion is accelerating - due largely to commercialising space and the hugely reduced transfer cost ?

If that’s true, there are already stronger, lighter and more flexible composites / polymers in both segments that humble  carbon fibre mats.

So - like everything - they’ll flow through to the 3D printed mainstream ... and if I were you guys I’d only look at investing time / cash in carbon fibre if it were a cheap stop gap !

Or maybe as an investment in a material that will quickly become obsolete / collectable :) 

Funny you mention that today. I was just reading about the SR72 which Lockheed's skunkworks have apparently been working on. The spokesperson was saying that a lot of what they are doing they couldn't have done even 5 years ago but the development of 3d printing has made it possible. They specifically referred to parts for the scramjet engine. Also rocketlab, the NZ based company putting small satellites into space, use a lot of 3d printing in their rocket engines. So yes, there are a lot of technologies out there which will become available to consumers relatively quickly.

Thats not going to stop me giving this a go though, its pretty cheap and will be a fun project

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11 hours ago, SuperChamp82 said:

Great thread !

Whats going to be really interesting is how quickly consumer 3D printing catches up with current industry printing in space / defence / aero.

It’s where most of what we now take for granted started ... and (for me) the pace of consumer conversion is accelerating - due largely to commercialising space and the hugely reduced transfer cost ?

If that’s true, there are already stronger, lighter and more flexible composites / polymers in both segments that humble  carbon fibre mats.

So - like everything - they’ll flow through to the 3D printed mainstream ... and if I were you guys I’d only look at investing time / cash in carbon fibre if it were a cheap stop gap !

Or maybe as an investment in a material that will quickly become obsolete / collectable :) 

I have just been offered a pilot scheme for 3D printed carbon fibre from shapeways. It's coming. 

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3D printed carbon fibre is not the same as carbon fibre pre-preg sheets such as those that many RC parts are milled out of. Infusing short fibres randomly into the plastic makes it stronger than plain plastic but it does not achieve anywhere near the strength as parts where woven carbon fibre with long unbroken strands has been impregnated into the part.

All consumer grade 3D printers are fairly poor in terms of mechanical strength of the parts produced. It's inherent to the fact that when you dispense hot plastic on to cool plastic the resulting bond is relatively weak. So your 3D parts are either going to be more fragile or excessively heavy/bulky compared to factory injection moulded parts.

If you are serious about making custom RC parts i'd look into a 3-axis milling machine and cutting parts out of carbon fibre sheet and aluminium. Probably have to invest at least $2k for something decent and at that point you ask yourself if it's cheaper to just buy premade hopups and pick a chassis that has decent aftermarket support. Either that or just spend hours making parts by hand with a dremel/files/drill/etc

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I would agree on most of those points, but the halfway house of ordering from providers like Shapeways gives you access to much higher quality parts. The SLS nylon parts I have made can easily match the strength of ABS with careful design as they are pretty much homogenous. The carbon reinforcement just makes it viable for more parts like suspension arms. Hopefully the price isn't too high. 

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