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I expected: "There is the difficult cheap way, and an easy expensive way. And my way, which is both difficult and expensive"

Hey Matt, hopefully this doesn't get too lost in the sea of comments, but back when I was working on the aero department of my FSAE team we had excellent results using foam molds with spray-on gelcoat on top. Makes for a really nice surface finish and (potentially critically) a really durable mold so should the unfortunate happen and you crack a fiberglass part you don't have a damaged mold from the first part and can just lay up another part. Plus it's really easy to get a nice full coverage of the foam so it sands nice and even. A real tip is to use different colors for each coat so when you're sanding you have a visual indicator of when you're getting too close to the foam underneath. Lastly, it might be worth looking into some basic metrology, once you're done with the first part, it may be a good idea to 3D scan it and compare it with what you were intending to make. Mold making is a real pain and it's easy for tolerance stacking to cause some real aero headaches that feel impossible to diagnose - ask me how I know. Anyhow, really dig the content. Godspeed on the build, and I'd be more than happy to give any other advice on composites/aero if you're coming up against a particularly annoying hurdle.

"...the front needs to be done well. So I am starting at the back..." SuperfastMatt is my spirit animal.

Man, I’m glad you added Barby vomit extraction before that top radiator got fully clogged and your spindle explosively divorced your CNC

At 1:15, I like how the "engine explodes" and "250mph" statement encompasses both the optimism and pessimism of racing.

No ham sandwiches were harmed in the making of this video

I used to work for a small aerospace engineering company and we built stuff the exact same way. Some of it even made it into space.... on purpose.

The fast cheap good triangle strikes again!

I recently rewatched some old videos of ThisOldTony. Notably his 3D Printing video, where he built a 3d printer on a surface plate, leveling it out with shim stock to get all the rails square and parallel. Quite the contrast to Matt who runs his CNC router off a piece of wood, fastened to the wall and supported by a single post. Love it!

Many years ago I ran the department, no, I was the department making expanded polyurethane caskets. No respiratory protection. Washed my hands with Methyline chloride to remove the sticky crap at the end of the day. I'm 68 and amazed I'm alive and don't have cancer or emphysema. And thrilled to see the nifty stuff a cool mind like yours makes with modern technology. And humour. Thank you for what you give to society man.

hey Matt, the eats-away-foam or doesnt-eat-away-foam comes from the solvents in the paint/coating. the trick we use is to spray from further away so the solvent flashes off by the time the paint gets to the foam. also, light coats so it flashes off on the surface, not soaks into the material. hope you read this and i hope it helps.

If you are a broke Industrial Design student, you can form pink foam with surform tools. It's less dusty than sanding. Static will still turn you into a pink snow monster.

“As long as everything works the first time” - Oh, foreshadowing!

11:33 "Respectfully, may I ask if you are on the spectrum" I spit out my coffee.

11:34 - "Respectfully, may I ask if you're on the spectrum?" lmao

Matt, you are an inspiration. Not because of your racing, or your videography. You are an inspiration because of your transparency and your troubleshooting abilities. Your troubleshooting abilities might actually be in the god-damned-hero category. The transparency is in the everyone-should-do-this-but-humans-suck-and-therefore-dont category. I appreciate that you are extremely honest about your mistakes and show us the whole process because that is honest and real.

I worked with a R+D composite fabricator who started each of our projects with a trip to Home Depot for insulating foam. No degree no formal education, just smart. Of course they laid him off when money got tight…He obviously landed on his feet.

Painted a lot of this foam in architecture school. You can paint it with anything, but you have to hold the can at least 6-8” away from the foam. This allows the solvent in the paint to evaporate before hitting the foam and melting it. Takes more paint, but it is the way to do it.

Barbenhiemer. Your CNC has become the destroyer of foam. You're just Matt.

Always a good day when there's a superfast Matt video

0:46 As soon as I saw the lead screw being covered in foam dust I immediately knew that this is going to be difficult AND expensive

I think people stress too much when making a 'buck' for a form: 1) they can be made out of anything, esp in the center if not just hollow(and by 'anything' I mean even bags of trash inside) the materials used and colors don't matter, as long as just the very surface is good; and it doesn't have to last long, cue the ham sandwich for this if anything 2) while the final shape here is important to accurately match your design, not all pieces have to be cut from solid full blocks(you could rough out most of the shapes in glued together scraps, and of course leave voids that aren't near the surface) think about all the material you needlessly wasted by just grinding it into so much dust - and once you have the tricky bits cut that must be right and define the shape, just slap boring mostly flat or smoothly curved(bent) thinner sheets on by eye to fill in-between(like the sides or top) and shape by hand with saw/files/sander 3) no need to have all the foam sheets stacked all in one orientation, if one area needs to be mostly flat just use a flat sheet going that way instead of trying to make a flat area from so many edges of stacked sheets, which would be much harder and the worse way to make and finish a flat from many different levels of edges and glue seams 4) caned spray foam is 'great stuff' to fill gaps and stick things together - to get around the mess use plastic sheet in-between the project and yourself/floor, and because the foam when cured doesn't stick to the plastic you can cover the growing foam with it and shape it nearly exactly how you want(vs out of control blobs) even adding layers of thinly spread foam squishing it around(thru the plastic) with your hands and small cardboard to get it totally smooth; this would be the "additive" method of sculpting vs only removing material and can fix any area where you removed too much 5) you aren't going to keep this part! this buck will either be a 'use once' as a positive mold and destroyed(or just left in), or used to make a negative mold to make multi parts from that - so no need to go nuts on the structure and strength, that only makes it harder to break apart and trash

The day we all wanted but never expected: the making of the body. Rejoice!

"Moldless construction." I built an entire carbon fiber Porsche Boxster body this way but I didn't know that's what it was called. Thanks for the new term! Love your channel, BTW.

To make a fiberglass body for a racecar, you first need a mold..." ("And NOT the kind growing in my vertical stabilizer.") -Matt, probably

Well I have an engineering class rn but I guess I'll watch this instead, surely I will learn a similar amount

It is nice to know that I am not the only one who ends up trying to do something a cheap and easy way and ends up spending more money and more time and energy than I would have doing basically anything else. Best way to look at that in my opinion, is to just know there would be unforseen problems with whatever route you took. Some people have lots of luck and everything works out for them every time. Some other people, you can put ten times the time and effort into something and have it all fall apart. It used to bother me, but I got used to it.

Hey Matt when your done..paint it gray, add a few flippers and tail, and sell it as a scale dolphin or whale model.. recoup your losses!!!!!

Matt, if you check with roofing companies in the area they might have left over foam from projects that they'd let to cheap. Come of the pieces can be really big, and are usually high density.

Nice of you to share the foam with the neighbors

Looking good! Latex paint should work well and then you can work with the cheaper poly or vinylester resin. You can drill a couple of holes for compressed air (put a pipe/straw in there) to help pop out the shell, plug them with wax or play-doh before you laminate. Any additional advantage is good. Use multiple thin layers of fiberglass rather than thick ones, easier to laminate with a roller. Sand the shell before popping it out by hand with a long flexible ply board with handles, hot glue or staple the sand papers. Sand systematically with long passes along the part, should be quite quick if you have the correct grit. Another way is to sand the whole body when all parts are installed, then you can do even longer passes with the sanding board tool. And in case you make a mold from a plug, careful with removal agents and gelcoat, the agent can cause spider web like defects, I prefer to use only wax. Spray-on removal agents are safer then brushing, but in any case don't use much. With only wax you can get a bit of a suction-cup effect, depends on the part.

You could strengthen your router tube by running a wire down the center and tension it . If the wire is forced down at the centre point (slug of ally with an offset hole) it will add some upthrust. You can calibrate it with the amount of tension you put it under. 😊

Matt. You need to get a four axis laser alignment tool. They are now quite inexpensive, at least the Korean ones like I have. After wasting man months or even year of times with rulers tape measures and carpenters squares, one of my subcontractors gave me one when he upgraded. It is brilliant. Self leveling, use just the axis you need, or as many as required, lock it and rotate to handle non-square alignments, etc., etc. If you do, get a green laser, not a red one. The green is more visible in normal daylight, even outdoors, but not in bright sunlight. I think you'd need a military grade one for that. 😇

I just signed up for Ground News, based on a single recommendation from some guy on the internet. I'm also an engineer and watch your videos because they are the quintessential combination of engineering skepticism, sarcasm, and persistence. One of my favorite sayings, that I made up is: My momma taught me that persistence pays off. The thing she forgot to tell me and I didn't know to ask was how damned slowly it pays off. Carry on!

You can also machine the foam under size, slather it in filler, then machine again at the correct size to get a hard shell.

I love this channel, it allows me to have realistic expectations in my projects

My favourite channel, perfect blend of engineering, automotive and entertainment.

Spray your fome down with polycrylic before you use the wood filler. I got a $17 spray gun from Harbor Freight, and I use straight polycrylic. It takes two or three coats to get a decent hardness on the surface, but it only takes about 10 minutes to dry between coats in warm, dry air. Then you get a uniform sanding surface

going to steal that vacuum hold-down system. looks perfect for me.

So much foam!!! That's one of those projects you remember 10 years from now when you find a pile of foam dust inside a box that was slightly cracked open. 😆🤙

Matt, the internet told me that I am dumb, because I spent a lot of money on a Shopsabre CNC and a proper dust collector. They said I should have bought a onefinity machine and a harbor freight dust collector and saved tons of money. So thanks for validating my decision to buy the real thing!

@14:55: aaaaand thats the reason tooling foam exists :P It can also be coated with Automotive paint filler and sanded extra smooth, ....

I end up going down this same path on 90% of my projects. Start with the least important part cus you know you're doing something you have no business trying. Fail, learn, fail, learn, finally make it good enough. Can be a challenge to keep the spirits up sometimes haha.

Matt, I just LOVE your channel. As an ex-salt racer in caars and bikes, I'm really enjoying your streamliner build.

When you've been assembling the mill, i've been thinking "how does he square the rails?" And when the pieces were misaligned it hit me, you didn't :) I'm glad you've been able to find the root of this problem

Man, I have never seen someone who needs a 3 car garage more than Matt.

When tasked with the choice between the easy but expensive option and the cheap but hard one I tend to chose the hard and expensive one.

Years ago at my work our films department used a ton of that pink foam to make a fake log cabin set for a live stream event that was going to happen. They used a miter saw to make all the big cuts. 6 months later we were still finding pink dust everywhere on that floor.

neat stuff. Been watching my school's FSAE aero team do pretty much this for the last two months so this is an interesting alternate viewpoint. (Yes, we are behind.)

10 seconds in I was expecting a joke about a ham sandwich sitting in the back of the garage for way too long.

9:36 rctestflight has a bunch of nice videos on printed cyclone separators, he used it for "exploded barbie foam" aswell but his design was quite a bit wider

Always a good day when a 'SuperfastMatt' video pops up.

Your solution serves as both inspiration, and an illustration of things to consider.

no ham sandwich? can i at least get a taco in there instead

I've been using that same HF shop vac for years (including for dust collection) and I agree, those bags make life SO much easier.

Conventional milling has more tear-out, not climb. You're clearly using climb milling (in some of the shots, although now I'm seeing conventional in others) so I'm sure you know that, just wanted to clarify in case someone watching wants to learn a bit about cnc, which they definitely should. Climb milling is heavily discouraged on hand routers as it is inherently more dangerous, however a CNC does not care because it is a robot, so it is generally preferable to climb mill in most situations. Conventional milling is like trying to paddle a canoe as it is moving backwards through the water, the medium fights you the entire way. Climb milling is like paddling a canoe that is heading forward.

I use a shellac primer to seal the foam before pulling a part from it. It leaves a really hard candy shell that you can wax for mold release. Looking good tho!

No ham sandwiches... Dang Matt... What about turkey..? It's more Aerodynamic 🤣🤣🦃🤣🤣

the best way to make a mold is to go to Missouri in the summer, buy a loaf of fresh made bread from the bakery and put the loaf of bread in your cupboard. wait about 15 seconds, and you will have a nice loaf of mold.

The vacuum trick for holding the foam is super neat...! Something about the way Matt talks makes the videos enjoyable to watch. Straight to the point and funny

Need to create a opposing charge on the foam or groud it all.

definitely should invest some time in a metal table for that cnc machine 😂

Those separators don’t do well with sawdust either. My solution was a 32 gallon trash can, with the inlet as the separator, the outlet of the separator taped over, and a new outlet cut into the trash can lid. With that the dust has to make a 90 turn to leave the can, and at least for sawdust, most ends up at the bottom of the can. For the foam dust, I’d try covering the outlet hole with a piece of screen or a layer of paper/fabric from one of those vacuum trash bags. If this works the added benefit is 32 gallons of dust in a cheap plastic trash bag instead of 9-10 gallons in expensive vacuum trash bags.

kudos for publishing your struggles with CNC trueness and squareness. i'm about to get one, and i'm sure it'll save me a bunch of headache down the line.

Love seeing the exact same materials get used by miniature diorama KZfaqrs and landspeed record KZfaqrs.

I made lots of parts like this and we used epoxy after machining to use as a harder surface for sanding. Though that might be more expensive for you, we could buy it in rather large batches, but worked great!

I've got a production car with a fiberglass body and started using resin and matting for small repairs to it. Since then I've used it for adding a durable, contoured surface to various objects or for adding a strengthening backing or reinforcement to all kinds of things. I don't use a mold, as you should for a smooth finish. I paint some resin on to the surface, lay dry matting on then apply more resin onto it all. This avoids resin soaked matting from disintegrating when handling it. I then build up a few layers repeating the process and spray paint it once cured. I know it's not the recommended way of using the stuff to get maximum strength out of the material, but it has allowed me to repair plenty of things where gluing it wouldn't last and where a textured surface finish isn't essential.

I love your videos, they remind me that no matter how much practicum there is, experience is the real teacher.

top tip for spray painting foam, use more distance, its actually dissolving in the propellant gas not the paint (unless its solvent based paint which would surprise me a little, a lot of those rattle cans are water based these days...)

Pretty AWESOME STUFF. My friend in the SF Bay Area Bob Wirth builds lots of SCTA Bonneville motors including bikes. His R&D shop is amazing and he told me the tale of a few years back about the "CnC Routing Method" to shaping the modern streemliners....I'm pretty sure the case he described was from a "bottomless checkbook" racer involved tens of thousands of $$$ in the design & shaping of the body. Your skills & innovations are amazing! Job well done! I'm sure you have a great handle on things but, if you ever start struggling with your powerplant....Bob is the MAN! His services and skills were employed during the AckAttack's record setting venture....Bob didn't build or design that machine, he was just brought in when they were struggling and made the best with what was there to work with. You can see bits of his AMAZING SHOP when they did "Dyno Testing" in the documentry that aired on the Discovery Channel.

One 24"/ 50 micron bag is like 15 bucks on ebay. My dust collector cost that, plus one ratchet strap to hold it to the base of an old shop vac with that diameter as the ring betweenthe bag and the fan. The rest was free stuff so milage varies. Its the fan that gets ya. My inline 6 with a 24" diameter came from a scaredy cat's clandestine greenhouse and probably cost 500 or more new.

Hey Matt - you might want to try light weight topping compound instead of regular drywall mud. It's noticeably softer and easier to sand.

There was a time that some random guy on the Internet told me to 'hail the algorithm', so I did... he was right... it totally worked! All Hail the Algorithm!

Nice one Freddy. If you could rotate the CNC head in two directions, then you could fit a hot knife in place of the router and save on all that foam dust/chips. Ofcourse, that means possibly new CNC software with more dimensions of freedom, wiring, motors and a 2D rotation assembly mounted in place of the router (I guess this would look like a universal joint?)

such an inspiration. thank you for going through the challenges so much of doing this work you do.

Use vinyl on your mould for a nicer surface finish and release!

I fine tune the squareness on my machine by making a cut down the Y axis then across the X axis, measure the squateness of the actual cut, if adjustments are needed i turn the slave axis off momentarily(Y2), move Y1 up or down towards the direction of square, repeat the process until fully square.

I do a lot of miniature modeling with XPS. The best route for painting would be to make a wash with Modge Podge, water and paint color of your choice. You can apply with a roller, or brush as it self levels pretty well. After that has dried, you can also now spray paint it for more even coverage and the solvents will not eat the away at it. I haven't made a 20 foot object before so there maybe some scaling in the procedure I haven't thought of.

There is an easy, expensive way and a hard, cheap way. My way is both hard and expensive 💁‍♀

What I have found that works well with finishing the foam bucks or make molds is to coat with epoxy once you have the basic shape. I usually have really old stuff around that I don’t want to use for finished parts anyway. Then I use either 30 or 45 minute mud (the stuff in bags) which dries pretty fast and sands easy. When “done”, another coat of epoxy gets the finish close and and makes ti less likely to deform.

Latex house paint can be used to "prime" the foam...flat cieling paint works great and goes with the drywall filler well. After the latex has curef, you can use some spray paints on top. I tested that rustoleum 2x and some rubberized auto undercoating on a scrap piece about 6 months ago and no bubbling or lifting has occured. I also tested several types of silicone caulk and adhesives which melt foam and the latex paint primer worked there as well.

Extend your garage.... genius. The permits and supplies will be cheaper in the long run.. BTW I love your videos. Keep it up

Thank you for the heads up on ground news. I'm always looking for the truth. I will definitely give them a shot.

my highschool used this same foam for prototyping in our engineering class, we had pretty good luck with the oneida dust deputy dust separator to keep the chips out of the vacuum. we were producing smaller chips though so that may be factor

I learn so much from your mistakes. Thanks Matt. This is a fun adventure.

I was about to say buy a cyclone but not the small one as the air velocity would be too fast to separate the foam from the air. But you did. Oh well. If you go out and buy a second cyclone, add it to a second bin, and adapt the vacuum duct so you split it into two before the cyclones, you'll likely be able to separate to your heart's content. There are duct calculations for this (I know, it's my job) but - without the hassle - if you can slow the suction enough to separate but still extract from the workpiece you'll have success.

im the aero lead for my schools sae team and we've been using 3m grey multipurpose duct tape as mold reliese. It works great for west systems 105 epoxy and ducttape is SOOO much cheaper than release films and teflon tape!!

I don't do cars other than my 98 xj... but I do woodworking, and its nice to see someone else try to track down problems and fix them... there are always problems...

Also...I spent good money playing with this foam and different adhesives...and I found Gorilla Glue type 2 water resistance the best for the price. A gallon is about $30 and it has held up to a full Canadian winter in the elements with zero lifting or ill effects. I used it to bond all the foam, and as the base adhesive for the poor man's fiberglass lamination process. I tested tightbond type 2, foam spray adhesive, several caulk gun tube adhesives and the cheap Gorilla glue worked as good as anything for far less $$$.

this was the method i used to make my wing. It works fine, just time consuming. eating away the foam while sanding is definitely a pain. I ended up doing a thin fiberglass layer (3oz plain weave i think) with epoxy (as polyester will eat the foam) to give me a solid base for further coating and sanding to smooth the surface. Extremely time consuming but I did the drywall filler too and it works fine.

I tried almost exactly your process 9 months ago. Same 2” foam. Onefinity. Ballnose EM. I did get special foam glue. I think the rear of my “race car” had about 40 parts. The joint compound sanding was a chore.. I’m looking forward to see how that goes.

On any coat/fairing compound, always check the thinning and hardening agents. These are the ones reacting with your bulk medium. You can also add the barbie dust to an epoxy and apply that for harder edge, which can be later on faired with regular bondo. The epoxy goop has similar consistency as the bondo, so these two can be sanded to a smooth finish. Much more important bit is how you are going to 1. Attach this Speeldo to your existing structure so that it holds on both runs? Panel gluing bandages with threads sticking through is common, also this makes the skin flap in the breeze like used raincoat. It needs some sort of structure to stiffen it, and this needs to be designed into the mold. You can panel glue the inner structure to the outer skin, in fact this semi elastic bond edge holds best of all the options, but you still need the mating surface to be exact. 2. How are you going to attach these outer skin parts to each other? You need to machine every seam into the mold. Yes it's possible to hand craft these over lays afterwards, if you have 25 years of experience in hand carving precise mating surfaces. But after seeing your skill set, I whole heartedly suggest you design the mating surfaces of these pieces into your CAD, before you cut them out. Again, if you had simply pulled the car apart, added the attachment points to your frame, wrapped the frame in plastic/cardboard and sprayed two boxes of spray insulation on top of that, sanded, added some epoxy to the dust and plastered the mix back on, sanded again, another round of epoxy dust goop, sand, bondo, sand, latex, fiber glass, sand, bondo, sand, paint and done. Maybe a week. Real, successful land speed racers are all done by hand. This CAD/CNC nonsense is just a waste of time. When the effort is lost in spinning a virtual model around inside incomplete program, the essence of land speed racing is lost, and the end result will never be anywhere near the goal.

For task lighting take a look at the Westek Citro LED modules at Menards. They are inexpensive but very good quality, and come in three sizes. They can be linked directly or with an included short jumper, and are direct plug-in, so no transformer.

I only started watching your videos a little bit ago but I think your channel came at me right when I needed it. I’ve been sitting unmotivated to work on the project car. Today I marathoned a bunch of your videos starting from the bottom. Another thing I did today was paint the shift linkage on my project car. The thing I’ve been dreading (and I don’t know why) is putting the cables back on the A/C controls on the dash the same way they came back in. But hey, the shift linkage is painted so I’m basically almost done!

3M Marine Acryl-White Glazing Putty. The stuff is amazing. Since you're using XPS the pore size is small enough that you won't use a ton of it, which is good since it's like $2/oz. But it sands like a really good dream. Definitely use it between the fiberglass body and the sanding primer before painting.

As weight isn't an issue trying Toupret Joint skim and fill to smooth the foam mould. It's sands super easy and is a very fine finish. Cheap too.

You can "slightly" cut and snap XPS foam just like drywall, so no hot wire needed. Also...dont let the CNC do all the work. If your shape involves hogging out half of the material than roughly trim off that material with a knife beforehand. May not necessarily save time, but it will save on the pink fluff.

I watched a youtube foam model maker test glues for foam a few years ago and the best was Gorilla Glue Construction Adhesive (it comes in a caulk tube). It is strong and the hot wire cuts right through it. I use it to make molds for fiberglass airplane parts. It works great.

Put the suck and blow sides of the vac into the tent. Keeps air moving and clears things fast. Add a little exhaust bypass to outside to keep the tent slightly negative pressure.