|
I'd be really interested to see how you keep everything accurate within multiple planes on a big work surface. It's been more than a decade since I tried to take something from CAD to reality. I always look at tube frame cars in kind of amazement that someone can design something then take a pile of steel tubes and turn it into a race car. Meanwhile I struggle to turn a similar pile into a simulator cockpit when all I have to do is tack weld things onto an existing structure.
|
#
?
May 16, 2021 11:16
|
|
|
|
| # ? May 1, 2024 19:29 |
|
|
Well, the basic trick is that it's really mostly just 2 planes. The floor plane and the windowsill height plane can be done independently and fully finish welded and then there's just a bunch of vertical bits plus diagonal bracing connecting them. The safety structure with its bent tubes may take some fiddling to get right but if you think about it, done in the right order each tube starts defining where other stuff goes. Like with the top plane completed and welded to the verticals and diagonals connecting it to the bottom plane, the main hoop goes at this and that tube junction... its angle relative to the top plane is 90 degrees and that's further checked by the down tubes going backwards being the right length. Once I get to making guide sheets for myself I'll take pictures of how I have them marked up and this might get more clear.
|
|
#
?
May 16, 2021 15:13
|
|
|
My problem has always been tolerance stackup and warping from full welding sub-units before trying to put them all together. And I've never even attempted something that large.
|
|
#
?
May 16, 2021 15:58
|
|
|
My thinking is that I can keep the subunits under control because until they're fully welded, the chassis table they're clamped to is massively stiffer... for putting the top and bottom together, there's some triangulation that can be one of the first things finish welded that will help constrain everything properly. (I may be wrong and gently caress stuff up; I'll document that too if so.  )
|
|
#
?
May 16, 2021 16:53
|
|
|
The table will help but it won't prevent all warping. I would get 3 or 4 good solid tacks on and do any welds that will be annoying or impossible to do once it's complete and do the rest once it's fully assembled and tacked up, but... I'm certainly no pro.
|
|
#
?
May 16, 2021 19:49
|
|
|
I mean poo poo, my resume says "engineer" not "fabricator". Realistically I think I'm going to try doing the bottom plane first and see where it gets me. Nice thing is that I do have all the joint configurations designed in CAD so may just leave finish welding for stuff that's still accessible after tubes are added for later. There's also always "force the fucker into the right place with big levers and or clamps". Also also... suspension mount points are all added to the chassis last so there's opportunity to cheat.
|
|
#
?
May 16, 2021 20:17
|
|
|
 Crosstubes attached! Maybe stickwelding in a small space without ventilation isn't brilliant.  "Clever" argon hose routing - see you can see where the TIG box is hanging by its strap from a joist - that places it where I can get to what will now be my fab table, and also so I can get to the chassis table. But to avoid tripping over hoses I routed them along the joist. If the hose was a little longer I could make it look better but... 'cest la vie. Next step is some organizing so I can work without going crazy, modifying the tube notcher to work better and testing it out.
|
|
#
?
May 20, 2021 05:10
|
|
|
OK, notcher modified and mounted! Chinese clone of a JD2 Notch Master, with a SWAG Offroad Reacharound, bolted to the chassis table directly. Nice and beefy. Drill is an OLD Black and Decker that may be older than me but nice and full of torque. The reach around lets me use long hole saws and get to notches that are much closer to parallel to the tube than I'd be able to do otherwise.  Digital angle gauge from... god I don't know. Correlates to real stuff that I checked against. Is tenth of a degree excess accuracy for things? I don't know, maybe, whatever.  Shimmed the whole notchmaster to... pretty close to level. Why does that matter?  So that's a split 1.5" collar with flats on it. So some of the tubes have notches in more than one plane, or even if I want to notch both sides of a tube it's pretty nice to have a reference for rotation. The idea is that collar goes on, is zeroed relative to the notcher, then stays on until the tube is fully notched. Tonight I'm basically going to make a bunch of coupons notched to various angles and get my welding dialed in... it's been a while and I have no doubt that I could stand to get the rust off. I'll also take pictures of my solution to the fact that I'll be welding on evenings where it's Too loving Hot to be wearing proper gear.
|
|
#
?
May 26, 2021 23:56
|
|
|
Well, OK, so the temperature crashed and now I haven't needed to do the coolshirt stuff? Which is nice but weird. Made a bunch of test coupons mitered at various angles - notcher setup works to at least 20 degrees from parallel which is pretty cool. I'm going to TIG weld a bunch of stuff to get back in practice before I get to real stuff. Anyway, got to asking fellow competitors about LSD options for the quick change I have and... turns out that it's really marginal behind a 13B, to the point where the company got tired of supporting them because they kept breaking and won't sell them to rotary guys anymore. Ugh. So! The transmission I'm planning on using has drop gears so I can just change a pair of gears there for the same functionality... so that's OK... and it turns out that there's advantages to some aspects of the stock rear axle in the sense of available LSDs, relatively compact and ... it's not that bad, and it'll hold the power I'll be making. I mean, the housing is but the solution to that is well proven from Ford 9" stuff. Yes, I'm talking a fabricated Mazda rear axle housing. That combined with some stuff I'm working on getting from aussieland may actually end up a better solution. If a weird one.
|
|
#
?
May 28, 2021 16:13
|
|
|
How the hell do you make a diff that can't hold up to the  massive torque of a rotary? What's it for? An RC car? 
|
|
#
?
May 28, 2021 21:54
|
|
|
Don't they normally have big V8's in front of those axles? Or is it an LSD vs a spool strength thing?
|
|
#
?
May 28, 2021 22:00
|
|
|
Rotaries have some harmonics that make things a little harder on things here and there, and this specific axle series was intended for stuff like dwarf and midget cars - it's not one of the big ones for Outlaw cars or Late Models or whatever (much less drift guys) it has a similar ring and pinion size to the Mazda diff (about 7") but basically bevel vs the stronger hypoid. Safe design input seems to be about 200hp, and the 13Bs are well clear of that - and yes it's horsepower, because by the time you're to the pinion, you've geared it down a lot. It's not totally inadequate, it's just "this works but it's marginal, breaks if you're not careful, and is a maintenance hog" and that's not what I'm going for with this car. I think I already found a buyer so not so bad. https://msfracingcomponents.com.au/product/lightweight-diff-carrier/ "Totally unrelated"... 
|
|
#
?
May 28, 2021 22:24
|
|
|
Day one of working on getting back in practice at TIG... wow it works so much better when the battery in my autodarkening weld hood has a charge. Nothing I'm willing to show because it's ranging from "garbage" to "ohhh yeah, OK now next time I make more effort cleaning". Maybe tomorrow.
|
|
#
?
Jun 1, 2021 04:22
|
|
|
mekilljoydammit posted:I'll also take pictures of my solution to the fact that I'll be welding on evenings where it's Too loving Hot to be wearing proper gear. Could you go into detail on this? I cook myself every summer in my coveralls and I don't really have any solutions beyond "tuck an air gun in my pocket so I look like the michelin man" and "stand near a fan as much as I can get away with" Love the thread, it definitely looks like you know what you're doing!
|
|
#
?
Jun 1, 2021 22:09
|
|
|
 So drew up a fabricated style housing ala Ford 9", but for the Mazda diff carrier. Back plate not designed yet because I want to scan in a diff carrier with a ring gear but most of it's there. Might make the center section a bit wider but whatever. klezmer life yo posted:Could you go into detail on this? I cook myself every summer in my coveralls and I don't really have any solutions beyond "tuck an air gun in my pocket so I look like the michelin man" and "stand near a fan as much as I can get away with" I'll take pictures when I remember to but from racing, I have a coolshirt - like https://www.ebay.com/itm/142664863651 it's a shirt with tubing sewn into it and some quick disconnect ends - they're available for medical stuff to for probably cheaper, it's been a while. Anyway, you have a cooler full of icewater with a pump in it - 12V bilge pump for the race car, 110V submersible water fountain pump for the garage - and hoses going to and from the shirt. You just wear that under whatever gear (nomex fire suit, welding jacket, whatever) and it circulates ice water. It is so goddamn nice not overheating.
|
|
#
?
Jun 1, 2021 22:50
|
|
|
This thread is this week's community showcase!
|
|
#
?
Jun 4, 2021 11:41
|
|
|
So, minor lack of interesting progress just because of some job prospects stuff, and also I'm working on getting back in TIG practice still and practice coupons are boring and also I know what I'm doing wrong. And also the little bouncy castle we got for my kid showed up and I've been spending a lot of time playing with her... well slightly more. Bottom plane, which I'm going to start cutting and notching tubes out for tomorrow. The rear section will be revised because change of rear axle changes where the lateral locating stuff goes, but everything up to the rear bulkhead is staying the same so that's plenty to get busy. This is all a little bit concurrent development but also not in the sense of... stuff behind the rear bulkhead was always going to vary a bit with rear suspension specifics. I'll get it figured out by the time I need to cut steel for it.
|
|
#
?
Jun 4, 2021 17:09
|
|
|
OK, so how am I doing this without loving things up? Follow along! Very high tech drawing... snork. OK. Rather than make drawings in the CAD sense I just figured I'd mark stuff up with dimensions that made sense to me. So take tube #1; 43" at the narrowest point, IE at the crotch of both notches.  Tube sticking out of my steel rack with 2 piece collar as guide.  And where I cut it to. 1.5" extra to accommodate the notches and stuff.  Split collar with flats and angle cube to make sure stuff is staying in plane - IE once I put tubes against the notches on both ends, those tubes will be parallel.  Split collar aligned 43.0" outside edge to crotch of other notch. Cutting first notch not photographed because screw it, I forgot.  And butted up against the hole saw. End result, the cut was within a couple hundredths of an inch; I'll work to do better once I get used to hole saw tolerances.
|
|
#
?
Jun 6, 2021 04:58
|
|
|
Is there supposed to be an end result photo? Thanks for detailing your setup.
|
|
#
?
Jun 6, 2021 08:21
|
|
|
I skipped the end result because... well, the end result is a tube with notches at both end. The intermediate steps I was using though, I haven't seen before.
|
|
#
?
Jun 6, 2021 15:30
|
|
|
  Well what have we here... why... it looks like a magnesium differential housing.
|
|
#
?
Jun 14, 2021 20:36
|
|
|
That is beautiful. I really like your collar idea for aligning the tube notcher.
|
|
#
?
Jun 14, 2021 20:43
|
|
|
I have a theory on all of my fabrication methodology - I'm sort of looking at everything from the point of view of "what can I do so I only have to measure this once?" So I can measure the distance with everything free and no pressure to be lining it up at the same time, and keeping the cant correct, and working around the notcher. Because, let's be honest, once you start trying to do a lot of things at once, it's easy to miss things like "oops the tape slipped or is on the wrong place" or alignment or whatever... maybe only once in a while but that's irritating as hell if you don't catch it right away. If I set out a methodology where I can take my time with each measurement I'm less likely to screw it up when I'm tired and hot, which happens a lot with when I'm working. edit: too bad this thing doesn't have the front nubbins that the S2000 one does or they could sell it to more people
|
|
#
?
Jun 14, 2021 20:55
|
|
|
What's the weight difference on the diff housing?
|
|
#
?
Jun 16, 2021 07:21
|
|
|
 Progress! Could be going faster but other stuff has been taking up time.
|
|
#
?
Jun 22, 2021 05:34
|
|
|
More progress! But first a demonstration of a not so hypothetical scenario... see I'm getting better at getting miter lengths exactly right now that I figured out what I was doing wrong, but it's humid out, I'm sweating like a pig, and sometimes I mess up. So first, keep in mind the split collar with the wrench flats and the angle finder - that stays on the tube until the fitup is as good as it's going to get. So I can always put it back into the notcher and preserve angles. So slide it all the way to the holesaw like so:  And there's a reference for where it's cut to now. Which is in this case about a quarter inch too long.  So I grab my handy dandy 0.251" pin gauge... (what's a thou between friends?) (OK really I'm using a holesaw, I don't need this precision but it's sitting right there)  ... and use it to set a split collar standing off from that side of the notcher the thickness of that pin gauge. Just slide it forwards that bit, voila, 0.251" (ish, lol) more notch depth.  Where I left off for the night. Most welds are at best tacked, a bunch of joints are just held together by clamps or tension, but you get the idea. Obviously there's an order it has to get finish welded in.
|
|
#
?
Jun 28, 2021 04:58
|
|
|
mekilljoydammit posted:More progress! But first a demonstration of a not so hypothetical scenario... see I'm getting better at getting miter lengths exactly right now that I figured out what I was doing wrong, but it's humid out, I'm sweating like a pig, and sometimes I mess up. So first, keep in mind the split collar with the wrench flats and the angle finder - that stays on the tube until the fitup is as good as it's going to get. So I can always put it back into the notcher and preserve angles. So slide it all the way to the holesaw like so: Out of curiosity and maybe you have said already. But what are welding the tubing with? That looks like a huge amount of tig welding and I’m not sure that would even be needed. I think a lot of the race shops tig weld chassis because they have the time and the money.
|
|
#
?
Jul 1, 2021 23:54
|
|
|
Valt posted:Out of curiosity and maybe you have said already. But what are welding the tubing with? That looks like a huge amount of tig welding and I’m not sure that would even be needed. I think a lot of the race shops tig weld chassis because they have the time and the money. I'm TIGing it - not out of any need, but because TIG welding is more fun to me than MIG. MIG would be totally fine, but hell, if I was doing this as anything other than a labor of love, there's a lot of things I'd do differently.
|
|
#
?
Jul 2, 2021 01:32
|
|
|
mekilljoydammit posted:I'm TIGing it - not out of any need, but because TIG welding is more fun to me than MIG. MIG would be totally fine, but hell, if I was doing this as anything other than a labor of love, there's a lot of things I'd do differently. It’s definitely a great practice session. What are using as far as cup size? Are you using a gas lens or just a regular gas jet setup?
|
|
#
?
Jul 2, 2021 02:09
|
|
|
I'm sure you don't need yet another project expense - but a wireless TIG pedal was a game changer for me. On the flip side, the much cheaper pressure (how hard you press with your thumb) amp control was just as amazing.
|
|
#
?
Jul 2, 2021 02:23
|
|
|
Valt posted:It’s definitely a great practice session. What are using as far as cup size? Are you using a gas lens or just a regular gas jet setup? I moved to gas lenses because I kinda felt like it, changed over from straight WP17 to Stubby at the same time... just #5, purple 3/32 tungstens (oh man did I mention the cheap diamond lapidary wheel for sharpening? Holy crap that's a gamechanger) and 1/16th ER70S2 (because I have it). Nothing special. the spyder posted:I'm sure you don't need yet another project expense - but a wireless TIG pedal was a game changer for me. On the flip side, the much cheaper pressure (how hard you press with your thumb) amp control was just as amazing. Kinda funny, I'd been using thumbwheel amperage control for the longest time and just moved to wired pedal instead. I like it, but I'm kind of used to heat control by changing torch motion rather than by changing amperage because of the thumbwheel for so long. It's all good enough for now; I can't do luxury project expenses right now, and besides, I'm dragging the torch and welder (IE me) coolant hoses across the shop, what's a pedal cable too?
|
|
#
?
Jul 2, 2021 02:41
|
|
|
Wtf is a diamond lapidary wheel? Quick google seems to point at gem cutting. On the gas lens front I bought a cheeeeaaap pyrex kit off Amazon and holy poo poo that works really well. See through cups are amazing for tight corner cage work.
|
|
#
?
Jul 2, 2021 03:23
|
|
|
honda whisperer posted:Wtf is a diamond lapidary wheel? Quick google seems to point at gem cutting. https://www.amazon.com/gp/product/B07NRL8VB9 So I got this in 240 grit because whatever, chucked it into the bench grinder with mandrel bushings. One of those "diamond dust surface abrasives" like some knife sharpeners and stuff, but the crux of the whole thing is that it sharpens tungsten a lot faster than aluminum oxide wheels, and without leaving a mark on the wheel. Will update if I manage to do anything to it over time, but since I have a dedicated tungsten grinding wheel anyway, why not go whole hog? edit: Oh, and I'm just using plain ceramic ones because I'm poor right now and I'm used to it... I like the idea of the pyrex stuff but enh, for now NBD.
|
|
#
?
Jul 2, 2021 03:33
|
|
|
I'll have to try the wheel since having a grooved out dedicated wheel sucks. https://www.amazon.com/RX-WELD-28pc...rex+tig&sr=8-10 The pyrex stuff I got was something like this. Was from Rx weld but I can't find the actual kit I ordered. It's way better than $25 has any right to be but not perfect.
|
|
#
?
Jul 2, 2021 04:06
|
|
|
Stuff ticking along... have a quote for a bunch of plasma cut pieces for the axle which I'm waiting to get done... and went poking around and have a hypothesis about an alternative to routing bodywork molds from MDF. I still think polystyrene foam would melt or soften or something at 250F but then I poked around and it's well within the range of polyisocyanurate. Much faster to cut than MDF and while it's about 50% more than polystyrene, it's about a third the price of MDF. Will have to get some to test.
|
|
#
?
Jul 22, 2021 23:16
|
|
|
It's been a while, any updates?
|
|
#
?
Sep 25, 2021 02:18
|
|
|
Short answer is I got a job, wife is student teaching, and my kid started daycare so... have money to tackle a few boring things and waiting for stuff to settle a little before I get back to work. Like, for example, had money for lumber and stuff to get new barn doors... which I badly need... and if I can get done before snowfall, will help keep snow out of the barn. Also saving up for the big ticket items like a trans. Arguably I should be paying down debt faster but enh, that's boring.
|
|
#
?
Sep 25, 2021 03:54
|
|
|
Time for projects, money for projects, energy for projects. Pick 2. Congrats on the job.
|
|
#
?
Sep 25, 2021 13:22
|
|
|
honda whisperer posted:Time for projects, money for projects, energy for projects. Pick 2. God, this is such truth.
|
|
#
?
Sep 27, 2021 20:29
|
|
|
|
| # ? May 1, 2024 19:29 |
|
|
It's not quite that bad... just that there was a bunch of maintenance debt on house and barn stuff I was ignoring because I didn't have money for it. Once that's caught up on a bit, I can get back to sparky sparky fun time.
|
|
#
?
Sep 27, 2021 22:32
|
|