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Your approach should work, I've done similar before. You might want something other than styrofoam for the plug due to temps, but there are tooling foams that might be a little more costly but stand up to multiple parts. If you're doing it in slices I'd recommend adding locating features for the slices and leaving ~0.010" for hand finishing for good transitions before you gel coat. The biggest potential issue is probably going to be mold life for multiple parts and getting good consolidation for multiple plies - vac bagging that shape is gonna be a pain and doing bladder molding can be a headache to get good pressure.
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Apr 1, 2021 21:45
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| # ¿ May 15, 2024 20:29 |
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I think insulation/styrofoam is gonna max out around 175, basic tooling foam (high density machining foam, renshape, etc) will get you to 250 I think without needing to go to high temp options. You can also do a positive master and cast plaster molds for each part if you don't want to make a glass negative, but that's gonna be way more work than your current plan, it just gets you around the temp requirements. Other option is wet layup but that's its own beast and I've only done pre-preg or resin transfer moulding so no experience there.
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Apr 1, 2021 23:03
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Yeah I feel ya on the not doing a flat square and mdf is probably going to be your cheapest option tbh. Getting a good vac seal is totally doable, I think your main challenge is going to be patterns for your vac bags so you don't get wrinkling or bridging, you're gonna have to do some weird cone sorta jawn but 100% doable - paper pattern templates will be your friend here.
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Apr 2, 2021 00:04
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You're definitely going to want to keep either a physical or digital archive of patterns as you go along, you can even do pattern development digitally for tweaking as you get down the line and you start making smaller changes. Even without the drag knife printing templates and spray mounting to light cardstock before cutting with a razor knife works pretty good. No idea what your experience level is with this stuff, but vacuum sealing putty (we called it monkey poo poo) is going to be your best friend for weird vacuum bag shapes and an ultrasonic leak detector can save you endless frustration trying to get it to loving seal. And don't be afraid to give in and just bag your whole tool in an envelope bag if you're getting vac loss through the mold or it won't seal to the mold surface. I don't know poo poo about cars but I've been enjoying the thread so it's cool to be able to give some (hopefully helpful) input.
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Apr 2, 2021 00:39
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If you're doing surface work in solidworks make sure to take advantage of the zebra tool or export and import into an actual surfacing program, their representation of surfaces is poor enough it will hide a lot of screwyness with wavy or rippled surfaces you won't see until you make molds, it's bitten me before.
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Apr 14, 2021 23:43
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When you say DOM mild steel, do you mean something like 1018 for grade? I'm getting ready for a welding project of my own and chasing grade and manufacturing process with suppliers has been a bit confusing for me. I'm assuming the cages can be thinner with 4130 because with higher UTS at similar stiffness you get more energy absorbed before the material fails? I've not done a tone of preheat welding (or much welding at all tbh) but I've had good luck with annealing hardened steel parts with a normal hot plate, cast iron skillet filled with sand and a thermocouple in it to monitor temp. It's not closed loop but pretty easy setup for keeping parts at elevated temp for a long time at a low cost. You might have mentioned this but youre gonna tig the frame? I was struggling with not burning through tubes unless fitup was near perfect so I didn't have to fill any gaps, but again I'm a pretty amateur welder. E: are you using SW FEA tools for checking stiffness? Do you have targets for flex at load or just doing relative comparisons between designs to decide on bracing strategies? Still enjoying following along and enjoying watching the progress.
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Oct 13, 2021 19:43
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Yeah I'm struggling to separate out manufacture specs from grade of steel from shorthand names. I'm planning on using square and rectangular tubing instead of round which adds another layer. I think I want a513 mechanical tubing, but that seems to cover multiple steel grades and when it's a513 round its considered DOM but manufacturing method isn't listed for square or rectangular tubes so I'm confused.
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Oct 13, 2021 20:52
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Thanks for the info, I'll probably also go a513 and just see what it looks like. Sucks that our local steel yard here got purchased by standard steel a year or two ago and their online catalog disappeared so you either have to call or fill out a quote request with exactly what you want so its not great for browsing to help decide what you want haha. And yeah I'd take the same approach with frame and cage design, unless you have the tools to prove out something is better you might as well go with the spec or standard for the class. I've done the closed loop controller thing for some stuff and yeah that works, I can't remember who made it but I have a controller at work that plugs into the wall and has a thermocouple port and a 3-prong port, dial the temp and it PIDs the output to hold it there. Super convenient and maybe cheap? I've also run an old oven via PID but that was with an omega panel mount PID controller running a relay that switched the hot line, worked good enough for some carbon fiber stuff without building a full-on autoclave/oven jobber. Half the reason I'm doing square and rectangular tubing is to simplify the cutting, I've got a cold saw I can use that'll do brilliant cuts as long as it doesnt need to match a round tube. If I was gonna do round tube I was thinking of doing something kinda like what you are with the collars but using a toolroom lathe to spin the hole saw and attaching the tube to the toolpost but I realized I wasnt getting much from round tube as everything it was mounting to was flat.
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Oct 14, 2021 01:48
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Why do you see round tube as the easier option? I guess with compound miter joints its harder to do the cuts than round tube with your system, and tbh that's a concern I have. I have a couple of compound cuts to make and tbh I'm not sure how I'm gonna do them, I don't think my cold saw has a compound miter adjustment. I guess if thats correct, what's the perceived benefit of square tube? Most automotive stuff I see is round tube so I figured it was standard. SW weldment tool is so close to ideal, I just wish you could choose to align profiles at both ends of a line segment instead of one. On my design I have one plane of the structure that needs to fit inside of something so I'm using the sketch to define the outside of the profile and the other plane has something that needs to go into it, so the sketch marks the inside. Theres no clean way to get the connection pieces to fit correctly that I've found, I've had to draw up a separate sketch that goes from the two tube sets centerlines to get it to all line up. I was gonna turn a solid extender shaft that would hold the holesaw out from the jaws to clear. I had an annular insert cutter that was like .002 undersized on one of my tube ODs and would make snap fit joints, it was magical. Are you shopping out the milled and turned parts in the suspension or doing yourself?
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Oct 14, 2021 03:26
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Excited to see the updates!
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Oct 26, 2022 19:43
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| # ¿ May 15, 2024 20:29 |
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I cant tell how much clearance you have from the photos but any concern with wheel flexing under impact causing contact?
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Dec 15, 2022 04:32
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