"Building a welding JIG first" - design process and thoughts

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Hi Ratrodders,

I know I have a lot of projects running... but still thinking about the ability for producing custom frames, or in other words, 'more professionalisation' of this functional artform. And since learning probably never ends, I am currently exploring another from scratch build.


So I need some tools in my shop to really start with simple frame building:
  • Frame welding JIG, to keep the alignment in check.
  • Tubing roller.
  • A tube notcher makes it easier, but I currently work with patience, hacksaw and file.
  • I have acces to a welding machine in our vehicular hobby shop.
I can expand my tools when needed. I tend to take my time and enjoy the process.

So I wanna keep you posted on the designs and thoughts. I will start with a few chapters:
  • GEOMETRY
  • INSPIRATION
  • REQUIREMENTS
  • EARLY CONCEPT SKETCHES
GEOMETRY

The last few years I built some great riding bikes. My current commuter is "Pope Roger". And I am very happy with that big bike. The position and riding feels really good.
Build link:
https://ratrodbikes.com/threads/pope-roger-bike-build.111479/page-4
20230226_143243.jpg


Some time later, I built a bike with a "Ruff Cycles Porucho" frame. This bike is very comfortable! But has in my opinion some serious drawbacks to be able to ride it every day. The biggest downsides were the VERY low bottom bracket and the VERY forward placed bottom bracket. The bottom bracket position gives a lot of room for a low seat, which looks simply great. I had to ride this bike with 155mm cranks and still pay attention to pedal strikes when cornering.
Build link and picture:
https://ratrodbikes.com/threads/boardtracker-antique-motorcycle-style-bicycle-build.114712/page-7
20220801_205342.jpg



Before I had an account on the Ratrodbikes forum, I rode an "Project 346 Basman". One of the most beautiful modern production frames I believe. Yet the low frame made sidewalk crossing impossible.
0ff8800ae0d25d663dc4bd758480de65.jpg



So you'll probably guess where I am heading...

I am looking to combine the best features of all above mentioned bikes. The basic starting geometry of the Pope Roger crossframe bike, but with the seat and bottom bracket relocated a bit to get closer to the Basman or Porucho bike. But with a more practical bottom bracket location.

The current production cruisers which are easier to attain, have relatively small frames, thus a seat with long seatpost for my size...

*I like big bikes and I can not lie*


INSPIRATION

In relation to looks I got quite a lot of inspiration from this forum.

Following pictures are not mine.

d2e6c877705a53eb7e6e3c2ca14c3fb5.jpg

Classic look.

2e4e784b3023bf8f2de6d30ddb62cd1c.jpg

Huffman Lafrance.

20230803_071950.jpg

My Electra Ratrod. Love many features of the design, just wish the frame was slightly bigger. The combination of straight and curved tubes is what I really like.

155044-30-min.jpg

This bike is incredible. I love the straight line underbelly!

230206-Ratty-elgin-twin-20-2-2-.jpg

From @Reallybigtim


181258-IMG-20211218-183155.jpg

From Graffix1972.

All these bikes have features I absolutely love:
  • The open frames from the Elgin Twin and Graffix1972 his work.
  • The straight underbelly of the blue Ratrodbikes buildoff (#8 I believe) bike.
  • The antique rugged looks of the top cruiser.
  • Combination of straight and curved tubes.
  • I like small diameter tubing, but need to keep stiffness in check.
So I started with a geometry and sketches... but first some requirements.

REQUIREMENTS
  • Steel frame. CroMo, HiTen or construction steel.
  • Intended use: Commutes, maybe even light bikepacking.
  • The frame must be stiff enough, but is not the first aim here.
  • 26x3.0" or 29x3.0" Wheels. 26" wheels have more tires options for cruisers.
  • USA bottom bracket for one piece cranks. 68mm wide.
  • Horizontal dropouts. 130mm wide.
  • Bracket for coasterbrake attachment.
  • 170 - 175mm cranks.
  • Bottom Bracket height from ground: Minimum of 280mm. Depending on wheel size.
  • Wheelies are not required.

CONCEPT SKETCHES

Most sketches have low rear rack tubing drawn. I am certainly aiming this take this bike for commutes and possibly multiple-day holiday trips.

The sketches are based on geometry models with lines on paper.

20230803_214715.jpg

Geometry first sketch. Checkout the letters at the measurements.

Fiets Geometrie Waarden.png

Side note: The Wheelbase of the Electra Ratrod is incorrect! I measured in the dark and did not have enough space.I think it is 1200mm actually.

20230804_211801.jpg

20230804_211808.jpg

20230804_211832.jpg

20230804_211851.jpg

Tried something here. In hindsight it was a bit silly.

20230804_211900.jpg

20230804_211936.jpg

20230805_171755.jpg

20230805_171802.jpg



Some fun sketches:

20230513_095317.jpg

20230731_075917.jpg

I felt inspired by @handyandy1100 regarding the exhaust pipes. Thanks for that Andy!

20230803_214725.jpg



In the end, I'm not looking to create the most extreme bicycle design. More functional, utilitarian art 😉

Thanks for having a look ya'll!
 
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So a few months back I made an 3D model of an idea. A friend (who builds trike and quad frames), hooked me up to some contact for CNC bending.

Frame sketch4.png

Concept2.png

Concept4.png


Every side is a single CNC bent tube.
The price to bend a single frame shocked me (thousands ** not my budget!) and I immediately decided to bend my own frames in the future.
 
View attachment 245008

Incredible

1.125 head tube for modern clean fork and stem options?
Thanks captain!

Don't know just yet. I have the intention of designing and fabricating the fork too.
Personally I have more of a weak spot for the look of older 1" stems. So I'm already biased ;)
 
Thats a pretty in depth start to a project!, I found the better you can fabricate those joints to fit snuggly the easier the welding is, any gaps can be a real pain!
I just use an angle grinder to knotch all my stuff, its fiddly as anything but gets the job done, the better I can make those the better my welds are!
 
Thats a pretty in depth start to a project!, I found the better you can fabricate those joints to fit snuggly the easier the welding is, any gaps can be a real pain!
I just use an angle grinder to knotch all my stuff, its fiddly as anything but gets the job done, the better I can make those the better my welds are!
Agreed! Snug joints do not need filling by the welding machine ;)

I can't always use an angle grinder, because most of the time I can do fab work the kids are sleeping. A file is much quieter :bigsmile: And I really like the meditative work with a file.

I will post some concept drawings of the welding/alignment JIG soon. One of the more used JIGS is the "ARCTOS" JIG I found on the internet.

Instructions I found on a welding JIG *click here*

Great JIG on that instructable, but there are a few things I would love to do differently.

I will first explore working with the "extruded aluminium" pieces.

Thanks for reading guys!
 
So the most fun parts are first yeah?

First models, work in progress. Changed a few measurements! And the seat + chainstay take some time due to the multiple directions the tubes go in relation to these tubes in the pictures.

I built the model around an axis skeleton so if I change geometry, the tubes and notches just go along.

Enjoy!

WIP1.png

WIP2.png

WIP3.png

WIP4_BB_to_ST.png

Seat tube height.

WIP5_TT_EFF.png

Top tube effective length.

The model has room to play with geometry.
-Wheelbase is 1400mm.
-BB drop is 100mm. So pedals are about 100mm from the ground. That is (according to the internet) in line with most manufacturers.
 
Update.
Changed a few things in the skeleton of the geometry, like fork offset.

Next is the gussets and dropouts.
I really like the "Electra Ratrod" gussets, but they are not the best for strength in comparison to gussets on each end of the tube. (Let me know if you want me to elaborate on that).

So I'll start with what I like best and do a strength analysis later on.

This is the dropout I had in mind, where the seat stay goes all the way down:

20230805_205948.jpg

Man I love this sketch!

20230810_094717.jpg


WIP7.png

WIP8.png

Checkout that dirty chair in the background... the way I like my workshops :grin:

WIP9.png

WIP10.png


Let me know what you think!
 
only coz I been going this way as of late..maybe bring that down tube to follow the front tire profile and then run it back to the BB, sort of like a racing bike fairing!
like this.
View attachment 245384
Very nice!! I'll keep that in mind.
For now I'm not aiming to go as low and long as this one, but it definitely looks great. Thanks!

Made the dropouts after my vision this evening:

WIP11_DROPOUT_SKETCH.png

Quick and dirty sketch. The white dots are constraints. I directly sketched in the assembly.

WIP12_DROPOUT_DESIGN.png

Result with some rounds included. The back eyelet is for carriers and fender mounts.

WIP13.png

Friggin' cool!

Like you mentioned @Son of Kradus I can lower the headtube a bit. In regards to the downtube.
 
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So the best part is obviously building/designing, assembling and riding our bikes.
But I need to focus now.

So I am selling some bikes for space (probably two this weekend) and hang some on the wall.

The largest thing I need to get a bit more professional is the JIG. Alignment is important.

I don't mind the JIG being heavy and harder to move. One person and some trolleys/wheels need to get the job done.

The most important alignment points are:
Seat tube - Bottom bracket - headtube- and rear shaft.

And a JIG needs space to tack the tubes in between.

I need a long base since I would also love to build stretch/burrito bikes in the future. Or bikes with slack head angles.

I also consider leaving the "ARCTOS" JIG: ARCTOS JIG link
And build an solid "low beam" steel JIG.
Early concept sketch:

20230825_093547.jpg



Feel free to share thoughts, experience or critique!
 
nice one bart, I too need this If im to become serious about building bikes, so far after a year now im still just standing back and useing the eyeometer, a tape measure has made appearances in the last couple bikes but seriously....cmon... I too need a jig,
Watching with intrest here!
I must say you computer design skills are 2nd to none:cool:
 
Very cool project Bart! I'll be watching this with interest. I have some frame building aspirations for the future and that's the jig I'll probably build someday as well. For now I'll be using the old 'eyeometer' ala SoK. Great stuff so far!
 
So the best part is obviously building/designing, assembling and riding our bikes.
But I need to focus now.

So I am selling some bikes for space (probably two this weekend) and hang some on the wall.

The largest thing I need to get a bit more professional is the JIG. Alignment is important.

I don't mind the JIG being heavy and harder to move. One person and some trolleys/wheels need to get the job done.

The most important alignment points are:
Seat tube - Bottom bracket - headtube- and rear shaft.

And a JIG needs space to tack the tubes in between.

I need a long base since I would also love to build stretch/burrito bikes in the future. Or bikes with slack head angles.

I also consider leaving the "ARCTOS" JIG: ARCTOS JIG link
And build an solid "low beam" steel JIG.
Early concept sketch:

View attachment 246334


Feel free to share thoughts, experience or critique!
Very similar to the Chopsource design I was going to modify for bicycles

IMG_1895.jpeg
 
nice one bart, I too need this If im to become serious about building bikes, so far after a year now im still just standing back and useing the eyeometer, a tape measure has made appearances in the last couple bikes but seriously....cmon... I too need a jig,
Watching with intrest here!
I must say you computer design skills are 2nd to none:cool:
Thanks a lot! I will openly and happily share the process.
And working with 3D cad is not hard, I always have a hard time staying awake at the courses, so I'll learn by doing it. I'm sure anyone can learn this. Much appreciated!

Very cool project Bart! I'll be watching this with interest. I have some frame building aspirations for the future and that's the jig I'll probably build someday as well. For now I'll be using the old 'eyeometer' ala SoK. Great stuff so far!
Good ol' eyeometer haha. Thanks!

Very similar to the Chopsource design I was going to modify for bicycles

View attachment 246344
I looked at it on the interwebs and I see its used for choppers and motorcycles, very nice! Thanks Cap!

That Chopsource JIG looks good, but I do think I will change a few things:
-Use a single 'enclosed' beam for the torsion-over-length stiffness.
-Use as little parts and contact surfaces as possible, since tolerances add up.

The beam I'll use will probably in line with the following standard:
EN10210-1/2

I can build a CAD model and share it here if people are interested.
 
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Thanks a lot! I will openly and happily share the process.
And working with 3D cad is not hard, I always have a hard time staying awake at the courses, so I'll learn by doing it. I'm sure anyone can learn this. Much appreciated!


Good ol' eyeometer haha. Thanks!


I looked it on the interwebs and I see its used for choppers and motorcycles, very nice! Thanks Cap!

That Chopsource JIG looks good, but I do think I will change a few things:
-Use a single 'enclosed' beam for the torsion-over-length stiffness.
-Use as little parts and contact surfaces as possible, since tolerances add up.

The beam I'll use will probably in line with the following standard:
EN10210-1/2

I can build a CAD model and share it here if people are interested.
What about using 8020? Thinking out loud
 
What about using 8020? Thinking out loud
Assuming that you mean the 'aluminum extruded profile': Certainly a possibility and they are very handy in regards to adaptability.

Its perfect that you can slide nuts in there and clamp stuff down.

I still have my fork JIG at home:
34eeb250f0b922b1f44631fc225b52e3.jpeg
 
Looking like good planning and you’ve done your research. I used the extrusion to build my jig, though a different design, I’m considering modding it to an Arctos type. Earlier in life, I made a version of the Chopsouce and it worked well enough.

Love your ideas for full-sized cruisers that don’t scape the ground or require a pogo-stick seat tube.

I need to learn a 3D cad software, not just Cardboard Aided Design!
Keep it up, I’ll be watching. 😎
 
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