[shirk007]

Getting closer.

Brian E Earle on Instagram: "So close, just one problem. Pulled out my CCDB Air CS that I intend to run on this frame put it in to cycle the suspension for the first few times and it got stuck down. Needs an air can service. That complicates finishing the bike for Friday night ride."

66 likes, 11 comments - earle.b on October 27, 2022: "So close, just one problem. Pulled out my CCDB Air CS that I intend to run on this frame put it in to cycle the suspension for the first few times and it got stuck down. Needs an air can service. That complicates finishing the bike for Friday...

www.instagram.com

Will do a full write up on this bastard child of a bike that started life pre-covid and it finally seeing dirt soon.

 

[shirk007]

This frame started life pre-covid as a completely different suspension design. It was originally going to be a split pivot fram with a shock layout like the original DaVinci Spartan.

The front end was build in the spring of 2020 and by the fall I had a front end tacked together.

Then the frame stalled out through most od 2021. I did a few more bit on it like the shock mount and rocker link mount. Late in 2021 I reused the chainstays off a previous frame to get the rear end started.

Spring of 2022 I got back on it to potentially have it up and running for the Pemberton Enduro end of April. I got some seatstays started and I was going to try and change it to flex stay instead of split pivot. I ran short of time and shelved that idea. Decided that flex stays would maybe not work with the travel I wanted without doing some real engineering.

This summer I started playing with Linkage again and this little scissor link design that Xprezzo used on a bike called the Ad Hoc. Decided I really like the leverage ratio it achieves and changed up my design. Some eyeballing and I removed the previous rocker mounts and put on news to change the layout.

Some time on the little benchtop mill and I had the links done. These are literally just flat plate with holes punched in them and bored to size to press in bearings. Simple as can be. Maybe I will draw up something fancy and farm out some CNC work to have nice ones made.

Finished it up Friday afternoon and did a quick 5 minute ride into the little kids trail we have at the end of our street. Bike felt good so then it was off for a real test ride later that night. First real ride was down some proper steep Seymour Darkside in the dark. Bike rides great.

I need to measure a few things to get the final geo. Highlights are tall front end, 145mm headtube, long at 1290mm, long rear center with chainstays at 455mm, bb sits about 345mm. Frame gets about 156mm travel (some eyeballing was done on the front shock mount, it might be a few more mm). Seat angle isn't mega steep, and reach isn't mega long. From my last frame I knew I wanted a touch less reach and a touch less steep sa and soon as I sat on this it felt just right. Will dig up those numbers but I was aiming for 74 at sag at full climbing height and about a 475mm reach.

 

[buckoW]

Looks great! I love how you used the old chain stay.
What is the next frame you were talking about making? The flex stay/split pivot design you almost made?

 

[shirk007]

Looks great! I love how you used the old chain stay.
What is the next frame you were talking about making? The flex stay/split pivot design you almost made?

Back in Sept I thought I would start fresh and just let this front triangle / chainstays hang in the garage rafters forever or cut it up as a big F U to shitty Covid induced procrastination and poor mental health. But I decided it could work with the new suspension layout so I buckled down and finished it. I don't know that I'll return to a flex stay / split pivot idea, I'd like to refine this compact little linkage.

Next frame has to be one for my spouse, she is LONG overdue for a new bike. It will be pretty much the same as this one above but in her fit numbers.

 

[lobsterCT]

Nice job @shirk007, I like your design! That linkage gives you a really clean way to get around the seat post tube (IE, easy to fit a dropper post), and it positions the shock in the front triangle very nicely.

I'm having to resort to a down tube tunnel on my non-linkage single pivot. This is not preferred in my world.

What % progressive is the build?

Edit: Also, excellent use of a boring head.

 

[sikocycles]

Welding practice today. It’s been a long time since I picked up the torch. Getting ready for frame #2

 

[Leafy]

Gotta work on your end of arcs. That second picture one is pretty bad, probably not going to be a structural issue unless this frame is going to be in the hairy edge. Take half a second to ease off the power while making half bead width diameter circles and you won’t get that crater with the inner nipple look.

 

[sikocycles]

Thanks for the input. I try to do that but not always as seen here. That’s why it’s practice. Trying an hour a day until I start my next frame.

 

[Leafy]

I’m there with you. Knowing what you’re supposed to do and what the welds is supposed to look like is only like 1/4 of the battle. My welds on alloy steel don’t really look any better than yours.

 

[sikocycles]

It takes alot of work with perfect lighting and mood. Its amazing how good, good welders are.

 

[lobsterCT]

Nice to see you working again sikocycles.


I started work on 2 front triangles. The bottom bracket shells took a lot of effort. I cut the basic shapes on the lathe. Then used the lathe with power unplugged to hold the shells in good alignment during hand tapping for bottom bracket threads.

confirmed threads are good

then made a backing plate to permit mounting a 4 jaw chuck on rotary table

then set up the rotary in vertical mode, with a tailstock on the milling maching. This was hard. The tail stock has to be exact height, perfectly level, and straight front to back all at the same time. Pretty fiddly to set up.

BB shells go in, and get milled for less weight.

The design idea is to make shoulders where side plates mount to the BB. This will make set up for welding easy, and since I will try to heat treat this build myself, hopefully they will make it strong in resisting movement during the welding and heat treating processes to help the frame end up straight.

Progress has been slow, but I very much enjoy learning machine shop skills as I go.

 

[buckoW]

Thanks for the input. I try to do that but not always as seen here. That’s why it’s practice. Trying an hour a day until I start my next frame.

What settings are you using out of curiosity?

 

[sikocycles]

93 amps
I need check the pulse rate. It’s a dial so I will take pictures of where it’s at.

 

[buckoW]

93 amps
I need check the pulse rate. It’s a dial so I will take pictures of where it’s at.

Building on what Leafy was saying about pimpled craters. Do you have a 2t and 4t option? 4t makes it easier on mine to ramp down and have a nicer end of the weld.

 

[sikocycles]

I do have the options. One is for finger other is for pedal. Welds last night were better. Let off the pedal a lot slower and swirled a little like welding tips and tricks says to do.
No inverted nipple this time.

 

[buckoW]

I started on a seat tube for a new front triangle yesterday. I’d like to lower the starting leverage ratio and steepen the head angle and add a cm more reach on this one.

I’m in no hurry to build it since the lifts opened for winter. So since I have the time I’d like to try and make it pretty. Hence the road bike style seat post clamp. I had to order some new reamers for the seattube. I destroyed 2 on my last frame somehow.

Here’s how far I got yesterday.

Anybody know where I can find some silicon bronze rod?

 

[shirk007]

Looks nice.

On my current frame I am just running a straight gauge 34.9 0.9mm tube and I made a thick shim from some siding flashing i had on hand. Ghetto but it works.

Listening to a recent conversation PVD had with Tyler from Firefly they use a fiberglass insert in their seat tubes instead of the welded insert like you have. They bond it in. Rockwest has a fiberglass tube that looks really close in dimensions I am going to try. Just cut a 4 inch long section and bond in. Lighter than the usual steel insert and no corrosion to worry about.

 

[buckoW]

I like the idea of a fiberglass insert! I’ll look into that. I have a shim in my wife’s bike and it works fine. A friend of mine just bonded a carbon tube in place of his seat tube. Now, I’m thinking about bonding tubes. I already have lots of structural epoxies from making snowboards. Maybe someday….

I’ve spent some time around the Atherton frames and those give me some ideas too.

There are new seat tubes from BFS with the butting built in so no need for an insert. I haven’t ordered any yet because I have tubing and inserts on hand.
https://www.bikefabsupply.com/seat-tubes/35mm-seat-tube-butted-for-316-seat-post-1659-x-600mm

I will order some of these when I’m out of what I have. Sometimes I make a new one just to try new techniques and welder settings. I’m intrigued by all of this!

Side note, I’m going to Nico’s place from Egerie Cycles this week to bend some tubing on his Toob Bender. He’s the one who built Paul Aston’s HP long boi. I think you saw it. He always has so much cool shit he made since the last time I was there. I love how he’s going for titanium now. He has no limits in his mind. It’s awesome!

 

[sikocycles]

New frame is starting

 

[shirk007]

I like the idea of a fiberglass insert! I’ll look into that. I have a shim in my wife’s bike and it works fine. A friend of mine just bonded a carbon tube in place of his seat tube. Now, I’m thinking about bonding tubes. I already have lots of structural epoxies from making snowboards. Maybe someday….

I’ve spent some time around the Atherton frames and those give me some ideas too.

There are new seat tubes from BFS with the butting built in so no need for an insert. I haven’t ordered any yet because I have tubing and inserts on hand.
https://www.bikefabsupply.com/seat-tubes/35mm-seat-tube-butted-for-316-seat-post-1659-x-600mm

I will order some of these when I’m out of what I have. Sometimes I make a new one just to try new techniques and welder settings. I’m intrigued by all of this!

Side note, I’m going to Nico’s place from Egerie Cycles this week to bend some tubing on his Toob Bender. He’s the one who built Paul Aston’s HP long boi. I think you saw it. He always has so much cool shit he made since the last time I was there. I love how he’s going for titanium now. He has no limits in his mind. It’s awesome!

For bonding most guys use 3M DP420 Scotch Weld, I think it would be easier to use than something like West 105 2 part epoxy like used on skis and snowboards. It appears to be thicker.

I think I am going to order one of the Velospec 44mm downtubes for the next build. Just priced out the 4130 straight gauge I have used from Aircraft Spruce for seat tubes and price is way up. It hurts on shipping and duty cost from the tube suppliers in the US, so if I can order from Aircraft Spruce here in Canada I tend to do that.

Yes I've followed Nico's build for Paul. I was messaging with Paul last week that he should rub down his patina raw frame with a oily rag to give it some shine. Mmmmm ti, always drool over ti. I went down a rabbit hole trying to find suitable straight gauge stainless tubing in an attempt for poor man's ti but can't find an industrial source for the sized needed. It exists just doesn't seem to be some online retailer where I can order small qty. Might just bite the bullet and order some KVA.

 

[shirk007]

New frame is startingView attachment 185549View attachment 185550

Mountain? Gravel? What you building?

 

[sikocycles]

Mountain? Gravel? What you building?

It is a mountain bike this time. EWR copy with modern geo.

Have you tried https://www.titaniumjoe.com/ I think he is in Canada.
I want to try Ti also but want at lease 10 steel frames done first.

 

[buckoW]

For bonding most guys use 3M DP420 Scotch Weld, I think it would be easier to use than something like West 105 2 part epoxy like used on skis and snowboards. It appears to be thicker.

I think I am going to order one of the Velospec 44mm downtubes for the next build. Just priced out the 4130 straight gauge I have used from Aircraft Spruce for seat tubes and price is way up. It hurts on shipping and duty cost from the tube suppliers in the US, so if I can order from Aircraft Spruce here in Canada I tend to do that.

Yes I've followed Nico's build for Paul. I was messaging with Paul last week that he should rub down his patina raw frame with a oily rag to give it some shine. Mmmmm ti, always drool over ti. I went down a rabbit hole trying to find suitable straight gauge stainless tubing in an attempt for poor man's ti but can't find an industrial source for the sized needed. It exists just doesn't seem to be some online retailer where I can order small qty. Might just bite the bullet and order some KVA.

I have some DP 420 and DP460. That’s what I was thinking of using for this.

44mm okay. Interesting. What headtube? That would have a lot of wrap on a 44mm headtube right? You could squeeze/ovalise it a little maybe? Horizontal at the bb and vertical at the ht?

There is a French framebuilder who uses 1.2mm wall thickness stainless tubes for his DH/FR frames. I can’t remember the name currently. I’ll ask Egerie Nico where his buddy gets the ss tubing. Although 1.2mm thick seems like overkill? I used 35x1.2 for the seat tubes on my last 2 DH frames.

@sikocycles These could be cool on your EWR?
https://www.pinkbike.com/news/boone-technologies-iconic-twist-cranks-now-come-in-a-titanium-version.html

 

[buckoW]

We need more pics.

 

[sikocycles]

@buckoW Yes they would be but that price! I will just use my XT for now.
I will post up more pictures while I am building

I have been using these hole saws. They cut really nice. Next time you need new ones pick some of these up.

Tools, Cutting

Return to TOOLS

metal-guru.com

 

[shirk007]

It is a mountain bike this time. EWR copy with modern geo.

Have you tried https://www.titaniumjoe.com/ I think he is in Canada.
I want to try Ti also but want at lease 10 steel frames done first.

EWR will be cool. I forgot you had that planned.

Ti

I have some DP 420 and DP460. That’s what I was thinking of using for this.

44mm okay. Interesting. What headtube? That would have a lot of wrap on a 44mm headtube right? You could squeeze/ovalise it a little maybe? Horizontal at the bb and vertical at the ht?

There is a French framebuilder who uses 1.2mm wall thickness stainless tubes for his DH/FR frames. I can’t remember the name currently. I’ll ask Egerie Nico where his buddy gets the ss tubing. Although 1.2mm thick seems like overkill? I used 35x1.2 for the seat tubes on my last 2 DH frames.

@sikocycles These could be cool on your EWR?
https://www.pinkbike.com/news/boone-technologies-iconic-twist-cranks-now-come-in-a-titanium-version.html

1.2 mm would be way overkill on stainless unless he is using weaker tubing like 316 or 304.

OD on the headtube for 44mm headset is 46mm so just enough without needing a squish.

I'd also like to make a part like Stanton did that they call the egg.

Land the DT and ST on this, I think it would also do away with needing a curved seat tube. I have a couple seat tubes I got from PVD that he had bent with a tighter radius bend that are now unobtanium. Need to work it out in CAD.

 

[buckoW]

@shirk007 Nice. Would you attempt that on the mini mill or have it machined?

The egg would work nice on my bike too but I’d be worried it comes out really heavy.

 

[Leafy]

@shirk007 Nice. Would you attempt that on the mini mill or have it machined?

The egg would work nice on my bike too but I’d be worried it comes out really heavy.

Desktop cnc? Sure. Manual mini mill? Ehhhhh. Right now that has 3d machining on it and I’m my head I can’t think of a good way to make it almost as light without it without spending more than a mini mill costs in custom ground form tools.

 

[buckoW]

Desktop cnc? Sure. Manual mini mill? Ehhhhh. Right now that has 3d machining on it and I’m my head I can’t think of a good way to make it almost as light without it without spending more than a mini mill costs in custom ground form tools.

Yeah, you would know more about that than me.
I think he has a manual mini mill at home so that’s why I was asking if he was going to try at home. I wasn’t thinking he would try and do an exact copy with those radii but his tooling would dictate that area.

Do desktop cnc’s handle steel well? I would think you would need an expensive one that is very stiff to do a steel part of that size? 3d printing seems like an option too. Tubes are always lighter than anything forged or machined so I like to do tubes on mine.

 

[Leafy]

If the mini mill cnc has ball screws it’ll be able to cut steel, just gotta whittle it away. I haven’t seen acme driven ones get acceptable surface finishes on steel. They can’t be that expensive if you can buy a whole free standing haas mini mill for like 35k (which they’ll let you finance on a 60 month note btw).

looking again, you could probably get away with doing that big radius with just a 1” ball mill and a rotary table. Then the next stopping block is the tube looking part of the bottom bracket, that a long length of cut and sickout for a bench top mill. If I really wanted to make that part in my garage I’d mill out the bracket piece and leave stock on to the pivot hole diameter and the width there, weld it to a bb shell, then pickup back on the bb shell and finish the important features together in the mill.

 

[shirk007]

I would farm that piece out. There is someone local to me that does CNC work that I would ask.

Trying to do that on my little manual bench top mill would be tough but probably doable. I'd have to watch every Joe Pi video on YouTube to get enough tricks and tips to figure it out.

Could also 3d print it then just clean up the bores on the mill.

 

[lobsterCT]

Have you guys looked at the MR-1 CNC? I forget if it came up in this thread. Not a Haas of course, but looks pretty cool for a lot, lot less money. Lots of youtubes on it.

MR-1 CNC Gantry Mill | Langmuir Systems

 

[Westy]

Have you guys looked at the MR-1 CNC? I forget if it came up in this thread. Not a Haas of course, but looks pretty cool for a lot, lot less money. Lots of youtubes on it.

MR-1 CNC Gantry Mill | Langmuir Systems

That doesn't look horrible. A key to a good machine is rigidity and it apears they have done a good job there for the price point. Z axis stroke and clearance will be a limiting factor but increasing it will reduce rigidity. I wonder if I can fit it down my basement stairs.

 

[lobsterCT]

you get it as a kit, and put it together yourself. Its designed to have concrete poured in the base for extra weight and rigidity. So, its likely to fit down your stairs!

 

[Leafy]

That looks like it’s an over built router. But if the videos are to be believed for performance and finish that’sa killer deal for a little under 6k, that’s hardly any more than you’ll pay for a decent Taiwanese Bridgeport new. I’d get the enclosure, just to get flood coolant and the tool and part probe combo. Can I dial in parts and touch off tools easily? Sure. Is $270 enough money to not have to? Absolutely.

from looking at it for 5 minutes, I’d consider it if I wanted a mill at home.

 

[Westy]

That looks like it’s an over built router. But if the videos are to be believed for performance and finish that’sa killer deal for a little under 6k, that’s hardly any more than you’ll pay for a decent Taiwanese Bridgeport new. I’d get the enclosure, just to get flood coolant and the tool and part probe combo. Can I dial in parts and touch off tools easily? Sure. Is $270 enough money to not have to? Absolutely.

from looking at it for 5 minutes, I’d consider it if I wanted a mill at home.

My eyeball online engineer analysis says that the wimpy little ball screws are going to be the weak point. They are going to windup under any real load. But the machine is probably capable enough to make new motor mounts and bearing blocks if you wanted to turn it into something more sufficient. Well that and the high speed low torque spindle motor. Your not exactly going to be able to chuck up a 5" face mill, just small tools spinning fast. It has feedback on the spindle motor, surprised it doesn't seem to support rigid taping, unless I am missing something.

 

[buckoW]

@lobsterCT That looks pretty sweet!

I ran out of Argon so I did another project I’ve been meaning to attempt for a while.

I made a linkage for my emoto yesterday. It’s my first time trying to make a linkage at home. I have had friends make them in the past for me. The stock link and shock used to top out AND bottom out while still being harsh. I tried reshimming an RC4 and an Ohlins shock with suboptimal results so I wanted to try a lower leverage ratio and less regression than the stock linkage.

Zero real engineering went into this and I just put the things where I thought they should go. Top link designs have problems and you can only choose where you want them, ime. I have worked with those in the past and have some experience with the limitations. The packaging will limit how much progression I can get and how low I can get the leverage ratio, I think.

A bike industry engineer friend came over last night and we figured out what I should do for v2. Here‘s some pics.

Here, I used the horizontal mill to drill the holes for the pivot points and square off the bandsaw cuts.

Boring head for bearing seats.

getting there.

I’ll make them look nicer when I like the curve. I’m thinking that in addition to a lower leverage linkage, I need to make a longer stroke shock with the body of a 10.5” rc4 and the 76mm fat shaft. I think that plus an extender and then lower leverage ratio linkage will get me in a useable range. That’s my theory anyways.

The bike felt so much better and it’s not topping out but it’s still a bit over leveraged, imo. I’d like to come down a bit so I’m not on such a heavy spring.

I also used a shock extender to try and shift the curve towards the progressive side and avoid that regressive end.

With an Ohlins cart in the fork and this shock and linkage it feels so much better. Hopefully the 2nd link will cure the last issues I have with the bike. And if not then I’m enjoying learning about this stuff.

Vague direction of the one I’d like to make this weekend. Not to scale, haha.

@shirk007 You inspired me with your links. I was going to get my friend to make these. Thanks man!

 

[shirk007]

Awesome. Yeah just cut em and run em. Especially when you aren't sure it's exactly the right thing. Maybe get something more refunded made after.

The MR1 had come up in my Google feed this week bit I didn't really look at it. Will need to have a closer look.

I spent some time this week re-working the little scissor link in my design. Basically flip it upside down from what I just built. The LR end up with a bit less end stroke ramp. With it flipped the part that mounts to the seat tube moves up and more of the link hides behind the upright from the rear triangle. Moving the mount should spread out the load. The links themselves get a bit smaller so lighter.

 

[lobsterCT]

Here is the MR-1 cutting steel. I'm trying to give Westy a case of new tool lust! We need to get him homebuilding a frame!

 

[lobsterCT]

It took a long time with covid supply train disruptions, but I finally got the heat treating furnace. I've been doing a lot of research on aluminum, and figuring out a recipe. This will not be easy!