[sikocycles]

I have the same saw and I do have it mounted to the same SWAG table.
I did just get my 2x72 kit yesterday and will be building it up. Some people miter their tubes with belt grinders.

 

[lobsterCT]

Right on BuckoW! We must have drunk from the same ground water back in AZ or something. There are a lot of funny parallels.

My wife and I have been doing a 10 year house renovation. We got one cheap, and lived there until we fixed it up, then made it a rental property, and got the house next door, and are living there and fixing it up. The house is on a steep hill, so I made (2) teracces with a small Kobota back hoe tractor to park boats, and turn them around for going up and down the driveway. Saltwater fishing is about 50-50 with bike stuff for me as a hobby.

I looked into electrical a while back and don't have a friend in the field to help me out. It was around $10,000 to get set up with what I would need just for the electrical. then the welder on top of that. So, I'm mildly content not to have my own welding stuff.

I understand the appeal of working with steel. A big factor for me would be not having to send the frame out for heat treating. That is a nice bonus. I guess my biggest factor for choosing working in aluminum, is that I'm trying to make all the pieces, and not buy any parts except rear axle and derailleur hanger. This is easier for me to pull off in aluminum than steel.

I use a JET 14" metal/wood band saw. It has a belt box on the back to change speeds depending on what you are trying to cut.

It has hardened steel guide blocks for the blade, and if I set them close for good support, during start up, the machine jumps, and the blade would dull itself on the guides.

I tried some ball bearing guides, and they were OK, but I ended up with simple carbon fiber block guides. I can set them close for good support while working, and they don't dull the blade when it jumps on start up.

I also added a few misc items: a simple fence, and hose attachment to vaccume while cutting. And inside the covers, brushes to brush dust and chips off the wheels, so they don't build up under the blade when it goes around the wheels.








I hope you guys had a good Christmas. As a gift, my wife signed us both up, to do a knife building class with a guy near us, that was on the show "Forged In Fire" twice. He won the first time, and came in 2nd, the 2nd time.

I'll get to try out a 2" grinder like you guys use. Looking forward to that!

 

[gonefirefightin]

I think I am going to dive down this rabbit hole and build a jig since I already have the other shop tools and skillz to build some frames. Looks fun.

 

[buckoW]

Yes @gonefirefightin! I think you would like it and already have plenty of experience. What style jig?

@lobsterCT Haha, the similarities continue! We just finished a rental property next door to our house too.

I looked into modifying my wood bandsaw to cut steel but then I saw a DoAll and a Mossner Rekord for sale used. One day I would like a big fat metal cutting bandsaw.

How about using 7000 series aluminum then you don’t need to heat treat in an oven?

 

[sikocycles]

I am on vacation this week so I am missing all the chat.
will start the seatstays soon

 

[lobsterCT]

@buckoW - that is pretty funny. Congrats on getting the rental squared away.

7050 and 7075 are not conventionally weldable alloys. 7005 is conventionally weldable, but I can't find a source of material for it.

I use 2" OD .125" wall, TT and DT, and .75" by 1" or .75 by 1.5", .125" wall box tube for rear triangle, then would need various solid rod and plate to make other parts.

I have seen pre-made 7005 parts, but typically, they are parts for road bikes rather than raw materials.

Regarding heat treating aluminum frames, it wasn't too hard to find heat treating businesses with the ovens, but it was hard to find one with the capability to drop quench aluminum parts, (at least ones that were willing to talk to me. . My non-expert understanding, is that to improve the welds, and not just the parent metal, the drop quench is required in the heat treating process.

I don't know if it would work, but I thought about as a building strategy in aluminum, if drop quench was not available, but ovens were, is if you could do the build with bigger than normal welds, and let the weld strength come from being mechanically larger, and then bake the frame in an oven to improve the parent metal.

 

[buckoW]

@lobsterCT Bike Fab Supply has some 7005 tubing but not the rest. I don’t know enough about it but I have a bunch of engineers around me that I can ask for you if you’d like.

I made a band saw table out of some scrap with inspiration from @bullcrew ’s double hitch mount moto racks on his Jeep builds. It can be stored directly below the workbench when not in use and is held together with two bolts so it’s easy to take the saw out there if needed. This thing eats through metal so much faster than my old one. Very happy with it! To the right are some new bits for my next build. That piece of 4130 tube for my main pivots was not easy to find and it just ate my 17mm drill bit…. Hard steel and a cheap soft drill bit…..

 

[bullcrew]

@lobsterCT Bike Fab Supply has some 7005 tubing but not the rest. I don’t know enough about it but I have a bunch of engineers around me that I can ask for you if you’d like.

I made a band saw table out of some scrap with inspiration from @bullcrew ’s double hitch mount moto racks on his Jeep builds. It can be stored directly below the workbench when not in use and is held together with two bolts so it’s easy to take the saw out there if needed. This thing eats through metal so much faster than my old one. Very happy with it! To the right are some new bits for my next build. That piece of 4130 tube for my main pivots was not easy to find and it just ate my 17mm drill bit…. Hard steel and a cheap soft drill bit…..

View attachment 169613

View attachment 169614

That's badass
Really love watching your progress and innovation...it's awesome to see someone else mechanically inclined and bring something to fruition...can't wait to see what else you make...

 

[lobsterCT]

Thanks @buckoW, that bike fab supply link has a lot of options. Its not exactly what I need but I appreciate the suggestion. Any knowledge your engineer friends can bring to the thread would be appreciated, if its not awkward to ask them.

I like your saw set up. Space is a big consideration in the garage here. I have to get my wife's subaru in the garage for hurricanes, hail, snow, etc. so I like the easily taken down aspect you built into it.

4130 is hard stuff. Might be more fun to make the bearing races if you bored it instead of drilled it?

I like AR Warner lathe tools. They have inserts like carbide cutters do, but are HSS instead of carbide. The HSS is more forgiving in small machines.

This is a kit that came with a left cutter, a right cutter, and a boring bar.

 

[buckoW]

@lobsterCT I ended up using a boring bar and then a hand reamer to finish. I was trying to save time by drilling up to size but cheap drill bits always suck. I ended up using a friend’s tailstock so I could use some nice SIP morse cone drill bits. 16.5mm is the biggest I have and I need a 17mm hole. Here are some pics of the parts I made yesterday.

Getting up close to size before hand reaming.

These SIP brill bits are so good but I only have half sizes. Interesting company with a lot of history. http://www.lathes.co.uk/sip/

My stash of boring bars.

Hand reamer works great and gives a perfect fit for the pivot axles.

These pivots are much thicker than what I used the last 2 times. Anyone have any idea on what wall thickness (4130) I should be using here? I’m thinking somewhere between 1.5mm to 3mm. Since it is welded to a .9mm thick tube I would think 3mm is overkill and 1.5 to 2 might be sufficient? Weight difference isn’t enough to be a factor. These are 2.5mm and my first ones were .9mm. Cotic frames are 1.5mm I think.

Here are some parts for the new frame. I haven’t decided which headtube I will use. Integrated bearing races aren’t my thing but I do like the looks. It’s funny how many compromises I’m considering for looks. Integrated bearing races and internal cable routing? Wtf?

I tried to harness my inner @AngryMetalsmith for the seattube insert and seatpost binder.

@sikocycles Thanks for the tip on the seat post inserts. That looks like a better way than what I was doing.

Insert on the left is how I got it and on the right is after some mods. I might try and hide the weld by using a bit too much filler and skimming/polishing it on the lathe after welding?

Happy with where this is going. Now I need to get some good filler rod and there aren’t anymore question marks, except my welding, haha. However, I have never laid such nice beads on my Mig welder before yesterday. All the Tig practice has made my Mig welding so much better. I couldn’t believe it actually!

 

[lobsterCT]

Looking good!

 

[sikocycles]

Wow. What progress.
I think this is my longest thread ever.
let’s keep it going.
Good tig rod. What a lot of frame builders use.

https://framebuildersupply.com/products/weld-mold-880-tig-rod-035-1lb

I am using ER70R2

 

[buckoW]

Thanks guys.

@sikocycles I just ordered 7lbs of that filler rod! Now, I don’t have any mystery steel or filler rod question marks. I have a much better idea of what I am trying to do and I’m going to try and make this one real nice. I think I will start this one this morning.

On the second frame, I wanted the increased bb height and more progression but I think I went too far on the progression. I might back off a bit on the next one. 35% is plenty and 40% has a too high starting point even if it feels good at the speeds I am currently going. 600lbs spring is going to be a bit much for the rebound circuit in my experience. It’s kind of outside of the useable range or else I can’t figure out a tune that works with such heavy springs. I usually prefer more damping and less spring but I wanted to try the extremes for bracketing testing techniques. It is theoretically too much but I want to feel it myself.

@lobsterCT Pretty cool video about Frank the Welder and Neko’s two frames. I used to do a lot of testing with Neko and always enjoyed his feedback. I bet you would like seeing all that sweet alu work! Frank’s shop is so cool.

 

[sikocycles]

FTW is a legend. I remember riding with him and Doc from BMW at Plattikill back in the day.
he is about 3 hours north of me and want to plan a visit.

 

[lobsterCT]

That frame is really pretty. I like the CNC work combined with the tube work. Beautiful stuff.

@buckoW , great timing. I would really love to see how you tweak the progressivity, and how you calculate the progressivity. I don't know how to do either of these yet. This would really help me for my next step of calculation.

For my build I would like to do a simple single pivot combined with an idler gear from my old Canfield Jedi.

I've been working on the math for my suspension design, and figured out A) where to place the shock and B) what the leverage ratio curve of the design looks like.

*Warning - Math content to follow!

I used the Arc Length formula S=R*Theta for my work. I also looked up the law of cosines, and the quadratic formula to make sure I remembered them correctly.

I arbitrarily used several parameters for the math, that won't necessarily be used for the build, I just needed something to work with to look at the math. I used 230 MM eye to eye rear shock. 65 MM stroke rear shock, 160 MM rear travel, single pivot, 450 MM from pivot to rear axle.

I wanted the shock at the end of travel, to be perpendicular to the line from the shock mount to the pivot. I reasoned that if 100% of the springs force would push against the compression at full travel, and less than 100% for all points prior to full travel, the leverage curve would be a strictly decreasing function, and the suspension would be progressive.

I'm not an engineer and not 100% sure of my work, so my plan is to reach out to AndreXTR on his website. He has it set up, where if you send him some Euros, he will do an in depth linkage analysis of your bike. This way, I'll be able to make sure the design, is not terrible before I go to all the work the make it.

Anyway, placing the rear shock boils down to the following problem:

Here is the solution:

Now I can place the rear shock in the frame, and locate it relative to the pivot point.

 

[lobsterCT]

The 2nd problem, to find a fuction for the leverage ratio curve, and graph it was harder for me.

Solution:

So there is the leverage ratio function. Here it is graphed on my graphing calculator:

I like the shape of it, being a strictly decreasing function. No wackyness. The leverage ratio is a max of about 2.539 and falls off to a min of about 2.462.

I'm not sure of the next step, to figure out how progressive it is.

 

[buckoW]

Without a link on the shock you couldn’t make it too progressive.

@lobsterCT You are way above me on the math part. I used Linkage or worked with engineers and could have things calculated for me. Saying that here’s my take.

2.53 to 2.46 is very linear. If you are starting at 2.5 then I would want to finish at 2. Below 2 can create a deep stroke rebound hang up.

If it were me, I would want a starting leverage ratio anywhere from 2.9 to 3.5 more or less and finishing around 2 to 2.5 more or less. This is for natural terrain DH stuff with a 75mm stroke shock, btw.

I would have troubles with your curve, I suspect with balancing traction and bottom out. I would want to have more rising rate to leave me some room for fine tuning. In my experience, 2.5 isn’t very supple off of the top if you have any compression going on and finishing at 2.4 isn’t enough of a change to prevent bottom out unless you are over sprung (or have a progressive spring extreme hbo circuit)and compromising on beginning stroke sensitivity. Unless you do a shock tunnel on the down tube then I can’t see you getting a lot of progression with out a linkage.

It would be impossible to make your frame too progressive due to the single pivot design so I would go as far as you can because packaging limits you. I think you couldn’t get above 10%. A shock with progressive damping and a nice bottom out bumper will compliment that design too. I’m thinking EXT and Ohlins could work. Maybe a trunion mounted shock could help get more progression because it is shorter i2i. Linkage is really easy for a single pivot.

 

[buckoW]

My seat post insert and binder are turning out real nice.

Before and after.

Once the seat tube is done the rest goes pretty quickly. I like how this one is turning out! Brazing would be cool to learn for theses kind of things or I guess I should get some Silicon Bronze tig rod for this stuff.

 

[sikocycles]

Really awesome job.

 

[lobsterCT]

Thanks @buckoW, that is really useful feedback. I appreciate your thoughts on the upper and lower end points of the leverage curve. Its great to get real world feedback from someone really knowledgeable.

How do relatively linear leverage curves work out with air shocks? It wouldn't be my favorite to use an air shock, but I'm not set on coil for sure.

I looked at the leverage curve of the GGDH 2011 in the Downhill forum thread. Looks like it starts around 2.85 and ends around 2.38 which seems more or less in agreement with your take on things.

Anyway, I'm motivated to try a couple of things, and see if I can figure out calculations. To start, I'll see how it looks with a 9.5 by 3 shock.

I'll get set up with the linkage program, and learn that eventually. I was hoping to wait until the next build to try to learn it, but maybe I will go for it sooner. Linkage seems pretty amazing to me. It looks like really smart people put a lot of effort into it. Based on looking at a simple single pivot here, the math built into the program must get very complicated for more complex designs.

EDIT:

I did a bit of experimenting, and see support for your reasoning regarding single pivots. Its easy to control y value of the end point of the curve, and you can incrementally control the y value of the starting point of the curve, but you can only push it so far.

These curves are for 9.5 by 3.0 (241.3 mm by 76.2 mm) shocks. I arbitrarily chose 2.35 to use for the y value of the end point of the leverage curve. I could push the black curve up to become the red curve, then the purple curve, then the blue curve, but after I pushed it too far, it became the green curve. The functions intersect around x=76.2 (end of rear shock stroke), y=2.35 (chosen value).

 

[Mave]

Hi guys, I enjoyed reading all 7 pages this evening, as I have the same ambition; make my own, steel frame. I just ordered the ideas2cycles fitting kit to start making a frame jig. Lots of learning still to do on tig-welding, but it's all about the journey, not the destination. I hope you don't mind if I drop in from time to time with stupid questions….
Anyway, do continue sharing your projects! It's much appreciate.

Marcel

 

[sikocycles]

No problem that why were are here. Aka away

 

[buckoW]

Hi guys, I enjoyed reading all 7 pages this evening, as I have the same ambition; make my own, steel frame. I just ordered the ideas2cycles fitting kit to start making a frame jig. Lots of learning still to do on tig-welding, but it's all about the journey, not the destination. I hope you don't mind if I drop in from time to time with stupid questions….
Anyway, do continue sharing your projects! It's much appreciate.

Marcel

Great! Go for it.

 

[sikocycles]

This is a collaboration of like minded rookies trying to stitch together frames. All are welcome.

 

[buckoW]

I got some reamers yesterday. Im just waiting on that sweet weld mold tig rod and then I’m off. I keep hearing of people using stainless steel tig rod for bike frames. I think BTR uses stainless? Anybody know the reasoning behind that or if it is a good idea? I have some stainless rod so I could start welding today rather than wait. Anyways, I am stoked on these Hauser cm2 drill bits and reamers.

 

[sikocycles]

I think Weld Mold is a stainless rod or a mix from what people say. If you watch Welding tips and tricks when he is welding a frame. Jody says it flows like stainless rod.

 

[buckoW]

I think Weld Mold is a stainless rod or a mix from what people say. If you watch Welding tips and tricks when he is welding a frame. Jody says it flows like stainless rod.

Jody does some nice videos! Thanks for that.

This is what I currently have.
I’ve been using the ER70SG3

Difference between ER70S-2、ER70S-3、ER70S-4、ER70S-6、ER70S-7

We all know class ER70S-2、ER70S-3、ER70S-4、ER70S-6、ER70S-7welding electrodes can be used for welding the carbon steel and the low alloy carbon steel with a strength less than 500Mpa, do you know what's the difference between them?

www.weldermetals.com

Almost ready for tacking.

 

[HardtailHack]

Without a link on the shock you couldn’t make it too progressive.

@lobsterCT You are way above me on the math part. I used Linkage or worked with engineers and could have things calculated for me. Saying that here’s my take.

2.53 to 2.46 is very linear. If you are starting at 2.5 then I would want to finish at 2. Below 2 can create a deep stroke rebound hang up.

If it were me, I would want a starting leverage ratio anywhere from 2.9 to 3.5 more or less and finishing around 2 to 2.5 more or less. This is for natural terrain DH stuff with a 75mm stroke shock, btw.

I would have troubles with your curve, I suspect with balancing traction and bottom out. I would want to have more rising rate to leave me some room for fine tuning. In my experience, 2.5 isn’t very supple off of the top if you have any compression going on and finishing at 2.4 isn’t enough of a change to prevent bottom out unless you are over sprung (or have a progressive spring extreme hbo circuit)and compromising on beginning stroke sensitivity. Unless you do a shock tunnel on the down tube then I can’t see you getting a lot of progression with out a linkage.

It would be impossible to make your frame too progressive due to the single pivot design so I would go as far as you can because packaging limits you. I think you couldn’t get above 10%. A shock with progressive damping and a nice bottom out bumper will compliment that design too. I’m thinking EXT and Ohlins could work. Maybe a trunion mounted shock could help get more progression because it is shorter i2i. Linkage is really easy for a single pivot.

I have sorta asked this before but I still don't really get how people cream their jeans over a coil sprung fork which has a linear spring rate but a SP bike with a linear rate at the back end is bad, why is that? Surely if you can control the front end well enough using HBO you should be able to do the same in the back, or does compressing the air inside a fork make it somewhat progressive?

Sorry for the slight derail.
I have only done a handful of hours on dual sus bikes so I have no real idea what makes a good or bad one.

 

[buckoW]

It’s hard to maintain suppleness off the top while avoiding bottom out with a coil rear shock without some progression. You compromise one for the other if you don’t have enough progression in the rear.

 

[sikocycles]

I am thinking of buying a GG chainstays and hardware kit. I already have Gnarvana seatstays and make a steel front GG frame. Don’t tell MTG

 

[Jm_]

I have sorta asked this before but I still don't really get how people cream their jeans over a coil sprung fork which has a linear spring rate but a SP bike with a linear rate at the back end is bad, why is that? Surely if you can control the front end well enough using HBO you should be able to do the same in the back, or does compressing the air inside a fork make it somewhat progressive?

Sorry for the slight derail.
I have only done a handful of hours on dual sus bikes so I have no real idea what makes a good or bad one.

One reason is that linear coil forks aren't really linear, there is still an air spring ramping up in there.

 

[buckoW]

I started tacking and welding yesterday. When I was tacking with the pedal and 38amps I felt like I had so much more control than the pulse. I could also see a lot better without the flashing from the pulse. The welds don’t look nicer but I feel like I am not as rushed. I think I can control the weld pool better with the pedal but maybe I just need more practice on the pulse settings. Whenever I do the recommended settings it seems real fast. Anyways, here’s what I got done yesterday.

Start of a seat tube assembly. I have an old Bianci road bike that is amazing so this is sort of themed after that I guess. Anybody heard of the Bianci Challenge?

 

[Mave]

Nice to see the progress! Also in the design.

I'm still waiting for the jig cones to arrive from Ideas2cycles, but I did receive this set of Stella Bianca files. Once the temperature in my shed get better I'll try mastering the art of coping.

I do have questions about the welding rods. I read that a lot of people use Weldmold 880, Er70s-2 and 312i. I live in the Netherlands and it doesn't look like these are readily available here. And the thinnest rods I can purchase are 1.6 mm, whereas I read most are using 0.035” (0,9 mm). Where do you guys get the “good stuff”? Buying from US gets expensive quite quickly due to shipping. I see buckoW also used different (and thicker) rods, but I'd like to take that compromise out of the equation and start with the correct (?) rods. Any pointers to suppliers in Europe are very welcome.

I will start practicing my welds with slightly thicker tubes and 1.6 rods first, so I'm not in a hurry getting the right ones, but would like to slowly gather all materials over the coming months.

 

[sikocycles]

Mitered my chainstays last week. Did not do any welding due to snow, school and Covid. Hope to finish up the bike this weekend. Will need to do a little more mitering.
Then onto the mountain bike frame.

 

[buckoW]

@sikocycles I love that setup! The jig, the vice and the Bridgeport! Very cool.

I ordered a big piece of 40x160 alu t-slot for the backbone of my jig yesterday. I hope it makes everything stiffer and straighter.

Nice to see the progress! Also in the design.

I'm still waiting for the jig cones to arrive from Ideas2cycles, but I did receive this set of Stella Bianca files. Once the temperature in my shed get better I'll try mastering the art of coping.

I do have questions about the welding rods. I read that a lot of people use Weldmold 880, Er70s-2 and 312i. I live in the Netherlands and it doesn't look like these are readily available here. And the thinnest rods I can purchase are 1.6 mm, whereas I read most are using 0.035” (0,9 mm). Where do you guys get the “good stuff”? Buying from US gets expensive quite quickly due to shipping. I see buckoW also used different (and thicker) rods, but I'd like to take that compromise out of the equation and start with the correct (?) rods. Any pointers to suppliers in Europe are very welcome.

I will start practicing my welds with slightly thicker tubes and 1.6 rods first, so I'm not in a hurry getting the right ones, but would like to slowly gather all materials over the coming months.

From what I understand, the tig rod that I am using is not as good as the ER70s-2 because I am not back purging the frame with Argon. It looks like it is a more stable rod regarding contamination and will have better quality welds without back purging. I think it makes it easier to get good welds without holes and contamination if I understood correctly. A framebuilding friend gave me two rods but I forgot to ask what they were. They seem to work nice but I don’t know what I am doing…. I wonder if Ceeway has anything?

Thanks! I’m hoping I can make it nicer looking and stronger due to better welds, thicker pivots and all 4130 steel. If I were to bend the 35mm tube down by the bb and main pivot then I could have one less weld and a stronger and nicer looking frame. I am so close to ordering that tubing bender from Cobra.….

I am trying to get this miter perfect rather than tack it in place while squeezing the fit. I am thinking that the least amount of tension will make for a straighter frame. Lots of filling then checking then filling then checking. After this stage there are only 4 miters left.

 

[Changleen]

I love this thread. Keep it up, guys!

 

[buckoW]

Seat tube assembly is done. I still need a lot more practice on the welder but this one is so much better than my last two.

 

[sikocycles]

Awesome

 

[buckoW]

A couple more pics of tacking and reaming while I still have access before the downtube goes in.

 

[buckoW]

I went to a friend’s place and he bent some down tubes and seat tubes for me. That Cobra bender is very nice. I want one!