I have printed PLA Molds (~50% infill+at least 5-8 layers full layers on top) and cured a carbon fibre frame at 43°C with 0,85bar below base pressure. the molds held up with no deformation and I was very satisfied with the result. The molds were made from x parts, screwed to a wooden plank.
Was this bagged pre-preg or and infusion?
I did my Engineering Thesis on Resin transfer Moulding with 3D printed molds. It entirely doable. we used ABS molds that went through a consolidation/polishing process with Acetone vapor then using water-based sealers and release agent. the idea was to get genuine 2 A-grade sides direct from mold and dimensional stability without doing a heap of mold re-work Its doable. Getting decent in-mold pressure is a real struggle. and a mold that will last for more than 2 or 3 parts is near impossible particularly with complex geometry with limited draft
With the availability of decent DIY/Hobby grade home CNC routers A Fiberglass or Carbon (depending on what's required for thermal stability) mold off a MDF or Epoxy plug. is probably faster easier and more durable, it's easy to find a fiberglass guy who had prepped 100s of MDF plugs and pulled molds off them that the process is well understood
I have printed PLA Molds (~50% infill+at least 5-8 layers full layers on top) and cured a carbon fibre frame at 43°C with 0,85bar below base pressure. the molds held up with no deformation and I was very satisfied with the result. The molds were made from x parts, screwed to a wooden plank.
Was this bagged pre-preg or and infusion?
I did my Engineering Thesis on Resin transfer Moulding with 3D printed molds. It entirely doable. we used ABS molds that went through a consolidation/polishing process with Acetone vapor then using water-based sealers and release agent. the idea was to get genuine 2 A-grade sides direct from mold and dimensional stability without doing a heap of mold re-work Its doable. Getting decent in-mold pressure is a real struggle. and a mold that will last for more than 2 or 3 parts is near impossible particularly with complex geometry with limited draft
With the availability of decent DIY/Hobby grade home CNC routers A Fiberglass or Carbon (depending on what's required for thermal stability) mold off a MDF or Epoxy plug. is probably faster easier and more durable, it's easy to find a fiberglass guy who had prepped 100s of MDF plugs and pulled molds off them that the process is well understood
In my experience printed PLA moulds work great for 1 offs in processes with room temperature cure (infusion, compression moulding or to make a plug for a mould).
At elevated temperatures or when there are other forces than isostatic pressure from a vacuum bag are involved it get's more tricky and frankly even carbon moulds can be rather limiting for processes like bladder inflation moulding.
One way to get around some of the limitations, and what I'm doing with all the inserts that go inside the negative mould (shock tunnel and other undercuts), are printed inserts from a high temperature filament with gyroid infill pattern and 0 bottom layers. After printing you can then fill the inside of the print with a high temperature resin and aluminum powder as filler (increase heat transfer rate and less expensive than the resin). The gyroid pattern is great as there is only a single volume to be filled and resin can flow everywhere, which will result in a lower void content. We will see how it holds up to an autoclave process, so far I've only used it for compression moulding at elevated temperatures and for smaller parts.
Loads of knowledge in here, always great to read all of your comments guys!
I have printed PLA Molds (~50% infill+at least 5-8 layers full layers on top) and cured a carbon fibre frame at 43°C with 0,85bar below base pressure. the molds held up with no deformation and I was very satisfied with the result. The molds were made from x parts, screwed to a wooden plank.
Was this bagged pre-preg or and infusion?
I did my Engineering Thesis on Resin transfer Moulding with 3D printed molds. It entirely doable. we used ABS molds that went through a consolidation/polishing process with Acetone vapor then using water-based sealers and release agent. the idea was to get genuine 2 A-grade sides direct from mold and dimensional stability without doing a heap of mold re-work Its doable. Getting decent in-mold pressure is a real struggle. and a mold that will last for more than 2 or 3 parts is near impossible particularly with complex geometry with limited draft
With the availability of decent DIY/Hobby grade home CNC routers A Fiberglass or Carbon (depending on what's required for thermal stability) mold off a MDF or Epoxy plug. is probably faster easier and more durable, it's easy to find a fiberglass guy who had prepped 100s of MDF plugs and pulled molds off them that the process is well understood
In my experience printed PLA moulds work great for 1 offs in processes with room temperature cure (infusion, compression moulding or to make a plug for a mould).
At elevated temperatures or when there are other forces than isostatic pressure from a vacuum bag are involved it get's more tricky and frankly even carbon moulds can be rather limiting for processes like bladder inflation moulding.
One way to get around some of the limitations, and what I'm doing with all the inserts that go inside the negative mould (shock tunnel and other undercuts), are printed inserts from a high temperature filament with gyroid infill pattern and 0 bottom layers. After printing you can then fill the inside of the print with a high temperature resin and aluminum powder as filler (increase heat transfer rate and less expensive than the resin). The gyroid pattern is great as there is only a single volume to be filled and resin can flow everywhere, which will result in a lower void content. We will see how it holds up to an autoclave process, so far I've only used it for compression moulding at elevated temperatures and for smaller parts.
Loads of knowledge in here, always great to read all of your comments guys!
Filling empty prints with resin and aluminium powder sound like a good plan! I was thinking about somenthing similiar for future frames. Also would like to try poraver (Poraver® expanded glass granulate is an ideal lightweight filler for model, mould production due to the easy and costeffective way of building moulds. https://www.youtube.com/watch?v=-5Hgcymq3qU&ab_channel=R%26GFaserverbundwerkstoffe
Filling empty prints with resin and aluminium powder sound like a good plan! I was thinking about somenthing similiar for future frames. Also would like to try poraver (Poraver® expanded glass granulate is an ideal lightweight filler for model, mould production due to the easy and costeffective way of building moulds. https://www.youtube.com/watch?v=-5Hgcymq3qU&ab_channel=R%26GFaserverbundwerkstoffe
I would stay away from anything foamed. In my opinion the lack of stiffness defeats the purpose a little, but mostly coefficient of thermal expansion will be huge which might result in all kinds of troubles with post machining.
All you guys doing home made carbon stuff just blow my mind. That cyclocross bike is just gorgeous, outstanding job!
My junk is back in the jig getting the rear triangle done more better-er. I think I'm finally at now-now, video wise. Hopefully the next episode will be shit I'm filming now, like now-now. Anyway.
Hey everyone, I am currently working on a project and thinking about the tubing I would want to use. How do you decide what tube diameter will be strong enough(for the down tube, top tube, chainstays etc.) ? any standard dimensions which work well?
Hey everyone, I am currently working on a project and thinking about the tubing I would want to use. How do you decide what tube diameter will be strong enough(for the down tube, top tube, chainstays etc.) ? any standard dimensions which work well?
Hard to go wrong with the following, assuming that high-quality tubing is used.
Down tube – 34.9mm (1-3/8") or 38.1mm (1-1/2") or in some cases, even larger diameters can be used up to +40mm or so, but getting hold of tubing with appropriate specs (length, wall thickness, not to mention butt profile) can be challenging.
Top tube – 31.75mm (1-1/4") or the previously listed (34.9mm (1-3/8"). In lightweight applications, 28.6mm (1-1/8") might be a good choice.
Seat tube – Whatever allows you to run the seat post size desired.
Hey everyone, I am currently working on a project and thinking about the tubing I would want to use. How do you decide what tube diameter will be strong enough(for the down tube, top tube, chainstays etc.) ? any standard dimensions which work well?
Hard to go wrong with the following, assuming that high-quality tubing is used.
Down tube – 34.9mm (1-3/8") or 38.1mm (1-1/2") or in some cases, even larger diameters can be used up to +40mm or so, but getting hold of tubing with appropriate specs (length, wall thickness, not to mention butt profile) can be challenging.
Top tube – 31.75mm (1-1/4") or the previously listed (34.9mm (1-3/8"). In lightweight applications, 28.6mm (1-1/8") might be a good choice.
Seat tube – Whatever allows you to run the seat post size desired.
New year, new rear. Hope everybody has a good one!
It's not quite as terrible as it looks in the pictures. Chain stays are 5/8" .058" and the seat stays are 1/2" .058" from the local race car store. It's too thick, but it was in stock and I was impatient. It's also pie cut (kinda) and welded, so it's wrong in a bunch of ways but I like it so much more than the actual bike tubes.
Hey all, thought this would be the right place to ask with the weird Frankenstein I’m thinking about building this year. But has anyone messed round much with a hardtail mullet set up for 26/27.5? Thinking of having a plus size tyre for the rear when I’m hitting trails and normal DJ tyre for dirt jumps and skate park. Probably having two different forks so I can run 26 on the front if the 27.5 proves too big. Haven’t finalised geo yet but going to be something like an aggressive long dirt jumper that I could use for playing round with on trails as well, without it feeling skittish. got an idea with using custom dropouts to compensate for the different types of riding too. I know it sounds dopey and will probably be horrid to ride but just wanting to make something to mess round with and experiment. Using a heap of 3D printing for the jig and trialing fitment of the weird stuff I’m trying out so will try post some updates soon
This forum is my holy grail! What softwares do you guys use to model frames and kinematics? I’m planing on diving head first and designing a full squish frame. I’ve got a lot of experience with fabrication, welding, and overall metalworking. Any tips you guys would be willing to share?
I'd recommend linkage for (surprise) the kinematics, and fusion 360, onshape or a educational Solidworks licence for 3d modeling. Really depends how complex your design will be, the 3d modeling might be absolutely required or completely overkill tho, and it will take a big junk of time even if you have experience.
Love this thread, helped me so much on the way to my first frame! Just started framebuilding 2 years ago and want to build a Trailhardtail (around 140 mm fork) as my fourth project after 3 gravelbikes for me and friends.
So one question: Like to take the Reynolds 853 BX3038XL as downtube. There are two butted sides on the tube: One long with 0.9 to middle section (0.6) and the other side 1.15 to 0.9 to middle 0.6. Which one would you prefer for BB and which for HT?
To be precise, the lenghts are 38.1x1.1/0.9/0.6/0.9x850 butt lengths 40.20.60.50.350.50.280
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