anglia4 Posted July 10, 2021 Share Posted July 10, 2021 Dylan will the 4130 need pre-heating for tig welding? Quote Link to comment Share on other sites More sharing options...
ThePog Posted July 10, 2021 Share Posted July 10, 2021 30 minutes ago, anglia4 said: Dylan will the 4130 need pre-heating for tig welding? TBH I never bothered. I cant remember if that was the result of my research or laziness. I have a feeling that preheating allows more alloying elements to migrate away from the join than is desirable but I would need to look hard at the thing again to know, so dont take that as a given. I did spend a lot of time looking for the correct filler wire, my results told me that MIG wire (generally ER70s) is perfect for this sort of thing with 4130. Which tells me that a tidy Mig weld would be fine too. I don't know if anyone remembers the longbike, but that was MIG and stood up really well. 5 Quote Link to comment Share on other sites More sharing options...
ThePog Posted July 10, 2021 Share Posted July 10, 2021 Also while searching for that pic I found some inspiration for @Guypie 5 Quote Link to comment Share on other sites More sharing options...
ThePog Posted July 10, 2021 Share Posted July 10, 2021 5 Quote Link to comment Share on other sites More sharing options...
Guypie Posted July 10, 2021 Author Share Posted July 10, 2021 52 minutes ago, ThePog said: That is awesome! I will have to make one of those once I have finished on this bike Quote Link to comment Share on other sites More sharing options...
ThePog Posted July 10, 2021 Share Posted July 10, 2021 Here it is now after many years of hard use, proof that even shitty tig welds are entirely up to the task. 7 Quote Link to comment Share on other sites More sharing options...
Mr Vapour Posted July 16, 2021 Share Posted July 16, 2021 I've been looking at this a bit recently. Lots of youtubing etc. It's a future dream. But I will look with eager eyes. Steelcuts.co.nz have chromoly thin wall tubing. Websites not working ATM. But might be worth a look. Quote Link to comment Share on other sites More sharing options...
ThePog Posted July 16, 2021 Share Posted July 16, 2021 This is where I got most of my plain tubing; "Metal Archives - Aviation & Performance Parts Ltd" https://www.apparts.co.nz/product-category/aviation-parts/metal/ 1 Quote Link to comment Share on other sites More sharing options...
Mr Vapour Posted July 16, 2021 Share Posted July 16, 2021 13 minutes ago, ThePog said: This is where I got most of my plain tubing; "Metal Archives - Aviation & Performance Parts Ltd" https://www.apparts.co.nz/product-category/aviation-parts/metal/ What's the price like. Steelcuts is like 40 per meter. Quote Link to comment Share on other sites More sharing options...
ThePog Posted July 16, 2021 Share Posted July 16, 2021 No idea, it was a few years ago. Quote Link to comment Share on other sites More sharing options...
Guypie Posted July 16, 2021 Author Share Posted July 16, 2021 I had heard about the brake cleaner thing, pretty scary really. I figured out most of my problems with getting nice welds had more to do with sheilding. I'm pretty sure my torch body in just old and worn out. It has a gas tap on it that didn't have an o ring so I put one in, the wrapped it with electrical tape. I have borrowed a gas lens off a friend and that seems to help too and has brought down my gas flow requirement which is nice. I have a new torch body and gas lens setup on the way from aliexpress. After coping some of the tubes I had a couple of offcuts left so I had a little test on those with the gas lens setup: Happy with that. By this time I had already tacked the seat tube to the BB, so I just went ahead and welded that up. you can see it in the background of the above picture kind of, its not quite as good as my test weld as its a bit tricky with the BB being 3mm and the tube 0.9mm trying to get the heat to go where you want it. Heres a few shots of the tubes getting added to the jig: On the picture below you can see a little block that I 3d printed to get a level surface to reference so I could accurately clock the tube 90 degrees for the bottom bracket cope, also fresh deliverys from @ThePog thanks!: A few more pics to come in the next post... 8 Quote Link to comment Share on other sites More sharing options...
Popular Post Guypie Posted July 16, 2021 Author Popular Post Share Posted July 16, 2021 Some shots of the fitup: And tacked it in place. Current toll on the jig: 2 plastic parts melted haha. though they did their job, and 1 is still useable. As a single use jig I still think its pretty good. Probably should have gotten a bunch more done today, but ended up getting carried away on my morning bike ride and did 20km/700m vert up Pirongia mtb trails and was pretty tired after that! 17 Quote Link to comment Share on other sites More sharing options...
63Ragtop Posted July 20, 2021 Share Posted July 20, 2021 Fuck that's cool! Quote Link to comment Share on other sites More sharing options...
Popular Post Guypie Posted July 24, 2021 Author Popular Post Share Posted July 24, 2021 Front triangle is now fully welded, a few rough patches as you would expect for a noob but on the whole I am pretty happy and fairly confident that if will hold together fine I turned up some heatsinks out of scrap ali I had laying around to try minimise distortion: Some of the welds: The heatsinks probably helped, but the headtube has ovalised a bit. I will probably just give it a bit of a squeeze to get it close and see how it goes. 12 Quote Link to comment Share on other sites More sharing options...
Guypie Posted July 24, 2021 Author Share Posted July 24, 2021 More pics of welds: These are the uglier ones: I think the one sied of the BB wasn't clean or still had paint residue in the steel cause it was a bit fizzy and I couldnt really do much about it. I popped it on the scales to see how things are tracking: 1556g, not too bad. I think it will come out around 2.7kg mark, I have been making the "dropouts" (thru axle so they dont drop anything out) and they are going to be a bit heavy hahaha. I turned a reducer out of stainless on the lathe, which took a long time because my lathe is very worn out. A heck of a lot better than no lathe though! In the frame: This actually added 10% to the weight of the frame so far haha. I don't really care about the final weight that much, but I think it is worth considering while I am making bits and pieces for the frame. 4 Quote Link to comment Share on other sites More sharing options...
Guypie Posted July 24, 2021 Author Share Posted July 24, 2021 Aaaaaand welded in place: Will need to send a reamer down the tube as internally it has gone kind of hourglass shaped from welding it in place. I threw the frame back in the jig to see how far/close it was to original dimension, its pretty darn good! Using the height gauge it looks like in relation to the headtube the seat tube about 0.5mm off line. Which I don't think will be noticeable at all in the end product. I gave the lathe a cleanup at this point as the swarf overflow was starting to get sucked into the leadscrews which is generally a bad time This is my old lathe, its a selson probably from the 1920s. The headstock bearings are absolutely stuffed and it can only turn anything by virtue of being heavy. Too much cutting load and it starts to vibrate like crazy as the spindle "rolls in the slop" if that makes sense. I actually have another newer much better lathe on the other side fo the workshop, but it needs 3 phase that I don't currently have. To make the dropouts my plan was to turn some centres for the axle and weld them into a bit of tube, then cope the chain stays and seat stays to weld to the dropouts. kind of like this: but a bit more simplistic. So I got a chunk of stainless and started whittling it down... 4 Quote Link to comment Share on other sites More sharing options...
Guypie Posted July 24, 2021 Author Share Posted July 24, 2021 After a few hours of work (not even kidding, gotta go real gentle on the old girl!) I came out with these: I used a piece of stainless tubing I had to make the shroud part and tacked it on then remembered that stainless is poos and will go all sugary on the backside if it gets too hot as below. So I filed off the tacks for round 2 This time with 4130 tube: Then I welded it up... 2 Quote Link to comment Share on other sites More sharing options...
Guypie Posted July 24, 2021 Author Share Posted July 24, 2021 And it came out like this. fairly yuck after heaps of fileing/sanding/scotch bright it looked a bit like this: Its kind of ok, but I'm not really happy with it. So with about a days worth of work in it I decided to scrap it and start again. Today I spent most of the day turning these out of some mystery steel from my box of offcuts: They look a bit like oldschool skateboard wheels. Much more happy with the outcome, I need to cut the shroud parts down to the correct size so I will probably go get a nice new file tomorrow and just do it by hand. I had a little test run on the lathe putting it off centre with the 4 jaw chuck. It would work but it was mildly terrifying, not to mention if the jaws slipped on the workpiece it could turn it to scrap metal real quick 4 Quote Link to comment Share on other sites More sharing options...
Guypie Posted August 6, 2021 Author Share Posted August 6, 2021 I have managed to get a bit more done on this in the last couple of weeks. Here is a terrible picture of my BB to rear axle jig. I won't be using this again, for the next build I will make a proper jig. But it got the job done. I filed the bottom of the lip of the frame ends flush so that when you have the bike tipped upside down to pop the wheel in there's a ledge for them to rest on. The horrendous surface finish on the dummy hub in the jig is a bit weird. I have a bunch of lengths about 300mm long of some sort of medium tensile steel that was the offcuts of a CNC job from a friends workshop. I cannot figure out how to get a decent finish on it, it just always comes out with a very torn up looking surface. I have tried a few different tool geometries, different feeds and speeds, always comes out looking like balls. BB is centred on cones. The other reason I will be going with a new jig next time around is that there's barely any space in here for the 68mm BB shell. I only used that size because that's what the old marin had. Next time I think I will buy a new shell in 73mm. (or maybe 83mm...) Also those 2 holes from the old chainstays were a pain, I had to patch them as the new stays didn't line up with the holes. not sure if I took a photo but it looks a bit of a mess in there. fortunately that little nook is always just jammed full of mud anyways so as long as I don't clean the bike it should be well concealed. 3 Quote Link to comment Share on other sites More sharing options...
Guypie Posted August 6, 2021 Author Share Posted August 6, 2021 I started on the non drive side chain stay. It was a seat stay donated by the vintage marin (RIP) I gave it a little bit of a tappy tap with the hammer on the inside of the curve to tighten up the radius and tacked it in place I figured I should check for any clearance issues before going any further so I unbolted the rear axle and rotated it in the jig then threw the wheel in and gave it a spin: I forgot to take any pictures of the drive side stay before I tacked it in place. It is a chain stay from the marin which interestingly had 3/4" chain stays and seat stays, and I made a bridge to clear the chainring out of a piece of hardox 450 4mm plate. Hopefully the hardox works out well, 4130 plate is ludicrously expensive. the piece of wood in the middle is a very rough and ready tyre clearance gauge to make sure I don't make any silly mistakes while tacking it together 5 Quote Link to comment Share on other sites More sharing options...
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