Hi all! Embarking on my first frame build finally after years of waffling. SO excited! I will be using a propane/oxygen concentrator setup a/la Doug Fattic and many of y’all, with an 80/20 fixture I made. Tubes will be laser cut at PTL, and plate pieces will be cut and bent at Send Cut Send. I was hoping that the great fabricators and brains here would give me some feedback on some of the design decisions I’ve incorporated thus far (just to make sure IM not completely in the danger zone design wise!).
I’ll be doing a standard front triangle but then went a little funky with the rear end. Paragon sliders (because man I love their stuff!) and the standard slots and nickel silver for the dropouts to SS and CS. But then I designed up a yoke, and a little faux wishbone seatstay plate. And therein lies my questions ha ha. For connecting to the tubes I have it cut as slots for the tube to nest into, right now they are near net so they will fit very tight and require hand fitment. My real question is; Are there any underlying issues with this connection style? I know a lot of the older BMX frames and some of the plate style dropouts have this basic connection but its not two slots, just a single large one to connect the whole tube and no “tongue” of material that protrudes into the ID of the tube. And if there is no problem with this connection style, should I fab some plugs for the open tube sections so I dont have to fill them with a ton of brass? I really appreciate any input here. I admire all the works of art that form up in this forum and hope to contribute in the near future.
Good news you don’t need to worry about filling it with brass, because the Paragon dropouts are stainless so it will be silver! I just fill it with silver we are talking like 35 for a troy ounce and that’s like twice what you’ll need for the drop outs, bosses and mounts and if you do a fork.
You can fab a cap but there will need to be some mass to stabilize the connections.
thank you! any thoughts pro or con on the wishbone plate? i was thinking I’d need to make plugs for the 7/8 tube where it meets the plate but seems like I can fill it with brass and file it to match the fillet? same for the SS ends?
I am really excited about your project. PTL and Send Cut Send have the potential to change frame building, and your design shows it!
A few random comments and questions:
I really like the tabbed and slot seat stay design. I have yet to see someone do that before
Your design shows a seat tube topper. I recommend using a 35mm -31.6 seat tube. You won’t be able to laser cut it, but it the seat tube is a very easy miter, and the butted tube is much stronger.
A few things to consider with PTL:
PTL require 36in minimum + 6in extra for the machine to hold
– because of this, front triangles are not that cost effective (different diameters, shorter lengths). You end up ordering more material than you need. Plus, you won’t be able to use butted tubing.
– rear triangles, especially with all your slots are very cost effective and time saving
the sharp corners might have a “start and stop” as the machine changes direction. This creates a tiny hole on the corner. Adding a small fillet could prevent that, but I don’t know what size would be picked up by their CAM software.
Thank you so much Daniel! I love your work and appreciate the feedback! Unfortunately I already hit buy on the tubes set for PTL but I will definitely go with a butted ST next time! I plan on adding fillets by hand to all sharp corners because of the dwell in the corners with the laser. Very excited and will be going forward with the SCS order soon too to get the rest of the parts! Regarding the seat tube topper, any opinions on flowing nickel silver instead of brass for the wicking ability and capillary action there? Its what I was thinking to go for but just wondering if theres a general consensus on what to use. Thanks again!
Very clever! It hurts some of my more traditional bike building sensibilities but damn, very cool.
When I see things like this, I realized learning CAD would be a real benefit. Then I spend 10 hours in CAD to create a washer of unknown dimension and realize I could have nearly built a frame in that time!
@Okbikes just getting to the dropouts, theres a large gap around the inner diameter of the CS and SS to get to the dropout. Should I fab a plug for it to take up space for the silver to wick into? Or do you think that just silver brazing in the dropouts as is and either a) getting a small fillet between the tubing and dropout where they contact or b) trying to fill them up as much as possible will be strong enough? Im using safety silv 50N, but I also have G-72 NICKEL SILVER 3/32 to use. I would appreciate any pointers!
Depends on the size. I filled with silver but that was essentially just a fillet with the end of the CS and SS, but seeing PMW actually makes plugs I would go that way next time. I found silver build up to be harder than bronze.
Well figured I’d give a little update. First of all, thank you all for the input and inspiration. Already thinking of the next frame ha ha. And I havent even built this one up yet (waiting for the sealer to dry). Only real hiccups were the bigger learning curves pumping so much heat into the yoke and BB as well as the wishbone plate as well as an unfortunate dropout slip in fixture as I was tacking in the Right dropout, so theyre just a bit out of phase (thank god for sliders!). Silver is also a WHOLE different animal for heat control and that was a fun learning experience! Overall just so stoked about building a frame after years of waffling over it. I used Sculpt Nouveau Copper coating and Rainbow patina, masking off the frame for a little two tone action. Hit a few snags with that but its growing on me! Can’t thank y’all enough for fielding questions and openly sharing knowledge. Hoping to start frame number two soon, and as Daniel suggested I’ll retain the rear triangle build architecture but will be mitering the front triangle myself (still trying to figure out if it’ll be files or if I can find a lathe or mill or rigid drill press around me in the bay area). Cheers!
Thanks Bushtrucker! found the wishbone is a bit off and so the SS’s a off as well, which makes the whole rear end look uncentered from above ha ha. Rookie mistake of rushing and assuming infinite rigidity of a frame jig I’m sure. First ride hopefullly tomorrow! rides great around the block and seems like it will eat the downs.
