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The garage frame building journey

sikocycles

Turbo Monkey
Feb 14, 2002
1,509
712
CT
Only the first steel one is hanging up because the welds are sketchy.

The rest are built up and being ridden by my wife, brother and I. We live in a huge bike park and the 3 of us work part time for most of the year, so there’s plenty of opportunities to ride them. I know It’s completely crazy to have so many bikes but I like to tinker and chin scratch. My life has revolved around bikes since maybe 2001.
Monkeyfest 2023 at your place next year?
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
EA39C831-579F-41FC-A5F5-A50F7C7D39F2.jpeg


I haven’t been reaming and facing my head tubes up until now. This should allow me to weld right behind the bearing seat where as before I was trying to keep the heat away from the important parts.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
I am trying to find a place that sells the Cyclus seat tube reamer with the reamers I need
I got this headtube one from Peter at Ceeway. I just emailed him because I couldn’t find the 44mm insert anywhere.

The seattube reamer I found on a random Dutch website. A longer tapered hand reamer would probably be better than the Cyclus one just because it’s short and hard to get started straight.
 
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shirk007

Monkey
Apr 14, 2009
433
285
I use an adjustable reamer on the seat tube. Much cheaper than finding the proper seat tube reamer.

For headtube I have the same 44mm Cyclus. Back when I got mine Cyclus only made a low depth ZS 44 cutters, luckily found some other frame builder that made a little adapter to set the reamer further off the facer so it would cut deeper for proper EC headsets.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
I use a seat tube reamer from these guys.
https://www.tracytools.com/index.php?route=product/search&keyword=Reamer&page=4


I got an NOS cross slide for my lathe last week. It has no play and is a lot more precise than the one I was using. Flipping parts in the chuck took a lot of care and I had a hard time doing it consistently. This one is so much easier to flip parts with less setup time. No backlash too!

It’s also a rare long travel version. I’m stoked on it and started making the pivots for a new frame. My brother wants to keep my last black frame after riding it a few times so I guess I’ll make another one.

CE6476A3-64FE-4159-A146-D84856E5057F.jpeg
 
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buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
I’ve been really enjoying the ride on the shortest one lately. It was a little unstable so I’m running the rear end kinda long compared to what I normally ride at 450mm CS. I have 3 different seat stays for these from the DH race team so I can get a bunch of different feels.

It’s fun to play around with geo and ride from home as the bike park season winds down. I’m still up for DH laps with people faster than me but the little bikes are a hoot when I’m not trying to go my fastest.
3B2ED2B3-3D1D-43FB-A796-31B1E863323A.jpeg


The Switchgrade seat angle adjuster is so cool for a little bike like this. Feels like a little FR bike but then pedals real comfy.
7DDA6465-43E5-4C18-8F6D-78E898F022BF.jpeg


On the building side, I borrowed an 8 jaw chuck with soft jaws from a friend last week. It is the perfect headset lathe chuck for modifying a zs49 down to a zs44. I have loads of zs49 cups laying around so, I can repurpose them into a useful size for the steel headtubes I have. I’ll take some pics of it later today.

@sikocycles and @shirk007 How’s the building coming along? I hope y’all aren’t holding out on me here…. Any pics of cool shit?
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
I borrowed an internal and external one of these soft-jawed chucks. They are super easy to get setup with no runout that I can measure.

85595BED-6C1A-44C7-98B3-5A9AB1D24C53.jpeg


5D4BE3FE-4557-4849-9B92-C4F7088B31A9.jpeg


Just playing around with a top cap. I’d like to make a headset from scratch.
AD31808D-DE9E-44B3-9147-EAC8C4056345.jpeg
 

sikocycles

Turbo Monkey
Feb 14, 2002
1,509
712
CT
I have not built anything lately. I am getting my BPT running and a few other things.
BPT should be running next week and I will start.
 

shirk007

Monkey
Apr 14, 2009
433
285
I've been fiddling away in Linkage finally motivated to build something.

I started a frame just before Covid that was supposed to be a split pivot Cotic/Canyon Spectral/original Devinci Spartan. The front end got built then it was shelved. In the passing time...I've lost motivation for the specific suspension layout, worked at maybe doing it with flex stays...then just resurrected my previous frame for it's 3rd-4th-5th time.

Late summer got the urge to get back in the shop, have now worked out the next frame in linkage and roughed out in CAD.



Back to single pivot with a shock linkage. The shock linkage is unique in I've only seen it done once before by Xprezzo on their AdHoc. I had an Xpresso Super D traditional single pivot and really liked it. Why this linkage? I love the look of shock in the center of the main triangle...vain yes. But then I dug deeper in the leverage ratio I could get with this little scissor link.



After much fiddling I got progressive - linear - progressive in a nice clean progression with an amount of total progression that I'd like. It should handle air or coil well, had great mid stroke support, and nice little ramp in the end.




Anti-squat and anti-rise are both a change from what I've done the last couple frames. The main pivot is further forward in the frame giving it less progression in anti-squat but also less anti-rise. It should hold speed well pumping the trail, we'll see how that higher anti-squat late in the stroke affects things.

On the shop side I've pulled my ghetto jig back out of the corner and set it up in the garage. Couple small bits have been turned on the lathe and I have cut the bb out of a previous frame to recycle it into this one.

Finally excited to get back at it on a new rig.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
Nice one! I like the small and discrete packaging on that link. What do you use for a jig?

Lately, I’ve been thinking about making a single pivot. Did you see the one Egerie/Nico made for Paul Aston? I think I’d like to build one one like that but with a shorter rear end. And maybe a trunion shock (because i have them on hand) for more shock angle/progression.
4AA5030A-94D4-4432-90B9-BD34C35EF1E7.jpeg


Paul’s has a 500mm CS
569AE837-63B6-4683-9249-5D852F492B9E.jpeg


Here’s Nico’s personal one.
7E91500C-FEEE-4B3A-93AB-49E407B0463E.jpeg
 

shirk007

Monkey
Apr 14, 2009
433
285
My jig is a cold rolled steel bar stock a copy of one I saw Blacksheep using. Guys at Reeb also used one line this early on.

I need to get some better pictures of it in use.

Looks like this.



Yes I have been following Paul's build and Nico. Singlepivot has far fewer downsides these days in a 1x world especially if you ad in a compact link to drive the shock.

I had been thinking of doing an elevated chainstay trussed swingarm on this build kinda like this one.


But in the end I think it ends up heavier and last night settled on a more traditional rear triangle.

Order some more steel for some custom dropouts, going to do a UDH hanger on it.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
My jig is a cold rolled steel bar stock a copy of one I saw Blacksheep using. Guys at Reeb also used one line this early on.

I need to get some better pictures of it in use.

Looks like this.



Yes I have been following Paul's build and Nico. Singlepivot has far fewer downsides these days in a 1x world especially if you ad in a compact link to drive the shock.

I had been thinking of doing an elevated chainstay trussed swingarm on this build kinda like this one.


But in the end I think it ends up heavier and last night settled on a more traditional rear triangle.

Order some more steel for some custom dropouts, going to do a UDH hanger on it.
Oh nice. I haven’t seen a jig like that. I like how the Seat tube can be held at any angle. I have seen a similar design with with square tubing but not bar stock. I keep meaning to make a better jig but each time i end up make another frame instead.

Yeah, the only down side I see is high-ish antirise. Which isn’t a huge issue unless you like panic braking like I do.

That trussed rear end looks sweet! I would like to make a trussed front triangle one day to hold a battery for an emoto.

What steel do you use for dropouts? The 4130 plate I got is expensive and I was thinking about stainless for that? Seems like a lot of builders use stainless for dropouts?
 

shirk007

Monkey
Apr 14, 2009
433
285
I ordered 4130 from Aircraft Spruce. It is speedy for the flat plate. I think some use 1018. In stainless maybe 17-4?

The cold rolled bar stock is dimensionally accurate enough and simple to work with.
 

jstuhlman

bagpipe wanker
Dec 3, 2009
15,151
10,481
Cackalacka du Nord
I’ve been really enjoying the ride on the shortest one lately. It was a little unstable so I’m running the rear end kinda long compared to what I normally ride at 450mm CS. I have 3 different seat stays for these from the DH race team so I can get a bunch of different feels.

It’s fun to play around with geo and ride from home as the bike park season winds down. I’m still up for DH laps with people faster than me but the little bikes are a hoot when I’m not trying to go my fastest.
View attachment 181981

The Switchgrade seat angle adjuster is so cool for a little bike like this. Feels like a little FR bike but then pedals real comfy.
View attachment 181982

On the building side, I borrowed an 8 jaw chuck with soft jaws from a friend last week. It is the perfect headset lathe chuck for modifying a zs49 down to a zs44. I have loads of zs49 cups laying around so, I can repurpose them into a useful size for the steel headtubes I have. I’ll take some pics of it later today.

@sikocycles and @shirk007 How’s the building coming along? I hope y’all aren’t holding out on me here…. Any pics of cool shit?
the seat angle adjustor thing still makes me laugh. this is actually how i prefer my seat for climbing (this is at the top of a 3200' climb-to be fair the front end is a touch high in the pic)...lol. to each their own! bikes are the funnest!

 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
the seat angle adjustor thing still makes me laugh. this is actually how i prefer my seat for climbing (this is at the top of a 3200' climb-to be fair the front end is a touch high in the pic)...lol. to each their own! bikes are the funnest!

You will have a lot of things to laugh at if you come! I have all kinds of quirky shit.

Hats off to you! I wouldn’t voluntarily climb 3200’ on any seat angle these days, if I’m honest. There are so many lift accessed options round these parts so I’m still in DH/FR mode.

I wouldn’t be able to feel my junk after riding that seat angle uphill. It’s probably because I have 4 compressed discs in my lower back (L2 to S1) and don’t have the hip flexibility anymore. I have to be real careful or else I need a week of no walking/activity to recover. Shits moldy.

All my bikes are designed around my ideal freeride bike that I’ve always dreamed of. Basically my DH bike with a steeper seat angle and a really long dropper post. I think I’m extra nerdy about bike design so my logic might not sound logical. Come do some single track laps on a train shuttle in Bex with me once to get the idea. I think you’d like it.
 
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buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
New frame started. My brother is trying to get my last DH frame off of me so I’ll make a new one so we can all have one.

Cleaning up the seat tube insert. Since I’m using 1.2mm thick tubing on the seat tube the insert part doesn’t fit so it’s just a butt weld which I’ll need to tie in with a gusset. I need to bend some .9mm thick seat tubes in the future so the insert part works.

9979EA79-7B7A-4FF2-91E1-6BE601DC7C3A.jpeg


Nice and clean. Ready for welding.
87E90A31-3736-4619-8906-2955F92FA9E4.jpeg


I was truckin along and then I was stuck. My seat tube reamer is already fucked and the cutters are rounded over. Think I can somehow ground them down to good cutting surface again? I’m going to try to put it on the lathe and make some sort of a tool post grinder to get some more life out of this thing. It was cheap but still….
B49917E4-06A1-4319-8367-EAD3C2CF2102.jpeg


This one was a 31.6 and the new one I ordered is a 31.8. Why do you guys think there are 2 so close to each other? I was happy with 31.6 and ordered the 31.8 on accident. Probably close enough?
 

lobsterCT

Monkey
Jun 23, 2015
249
339
Buckow - Have you measured the ID of tube you are reaming with a bore gauge and your calipers or micrometer? If you are killing reamers fast, you could be taking too deep of a cut. (assuming you are not turning the reamer backwards, which will kill it right away)

You can look it up on the interwebs, and get several types of advice, of how much of a cut to take with a reamer. One that came up a few times for hand reaming around 30mm diameter is 1% of the diameter or less. (.316 MM, 0.0124")

If you measure and confirm that too deep a cut is not the problem,

then maybe try reaming 2x? Do it the first time on the lathe, using the chuck to hold the tube, and using the tail stock to push the reamer (possibly with a 31.4 reamer), and turning the reamer with a hand wrench; then do it a second time with your handle tool after the frame is all welded up?

I used a 1.25" reamer on my GGDH front triangle (31.75" mm). The seat post fits a little loose in the frame, so I use an aluminum shim. It works good enough for a rigid post, but i don't think I would like it for a dropper.

You can grind down reamers to re sharpen them, but the diameter gets smaller. You could grind your 31.8 to 31.6, and your ruined 31.6 to a 31.4 and have a useful set.
 
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buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
Buckow - Have you measured the ID of tube you are reaming with a bore gauge and your calipers or micrometer? If you are killing reamers fast, you could be taking too deep of a cut. (assuming you are not turning the reamer backwards, which will kill it right away)

You can look it up on the interwebs, and get several types of advice, of how much of a cut to take with a reamer. One that came up a few times for hand reaming around 30mm diameter is 1% of the diameter or less. (.316 MM, 0.0124")

If you measure and confirm that too deep a cut is not the problem,

then maybe try reaming 2x? Do it the first time on the lathe, using the chuck to hold the tube, and using the tail stock to push the reamer (possibly with a 31.4 reamer), and turning the reamer with a hand wrench; then do it a second time with your handle tool after the frame is all welded up?

I used a 1.25" reamer on my GGDH front triangle (31.75" mm). The seat post fits a little loose in the frame, so I use an aluminum shim. It works good enough for a rigid post, but i don't think I would like it for a dropper.

You can grind down reamers to re sharpen them, but the diameter gets smaller. You could grind your 31.8 to 31.6, and your ruined 31.6 to a 31.4 and have a useful set.
Thanks for the tips! It’s probably a mix of what you are saying here. I hadn’t informed myself about proper depth of cut and was feeling it out. Pro not a good idea but hey.

I don’t think I could do anything on the lathe because of the bends in the tubes. I might be able to mount the reamer in the horizontal mill and hold the tube in my hands? Sounds sketchy but I see other people doing stuff like that. I’ll figure it out.

I think I’m probably trying to take out too much like you say in addition to the welds seem to be very hard metal too. Much harder to cut through with the bandsaw and reamers than the tubing. It was a butt weld and I had a little too much heat so the weld is protruding more than I’ve ever had before.

It’s the angled portion of the reamer that has been abused. So I wouldn’t change the diameter but give it a fresh leading edge if that makes sense. I think the welds are making very hard metal and chip teeth off of the bandsaw for example when I cut through a weld. I use Weldmold 880 I think it’s called. Some sort of stainless rod.

My other reamers are tapered and I think they work a lot better than this Cyclus one. It’s very short and doesn’t seem as nice as the ones I bought from a tool store.
 

lobsterCT

Monkey
Jun 23, 2015
249
339
I've been fiddling away in Linkage finally motivated to build something.

I started a frame just before Covid that was supposed to be a split pivot Cotic/Canyon Spectral/original Devinci Spartan. The front end got built then it was shelved. In the passing time...I've lost motivation for the specific suspension layout, worked at maybe doing it with flex stays...then just resurrected my previous frame for it's 3rd-4th-5th time.

Late summer got the urge to get back in the shop, have now worked out the next frame in linkage and roughed out in CAD.



Back to single pivot with a shock linkage. The shock linkage is unique in I've only seen it done once before by Xprezzo on their AdHoc. I had an Xpresso Super D traditional single pivot and really liked it. Why this linkage? I love the look of shock in the center of the main triangle...vain yes. But then I dug deeper in the leverage ratio I could get with this little scissor link.



After much fiddling I got progressive - linear - progressive in a nice clean progression with an amount of total progression that I'd like. It should handle air or coil well, had great mid stroke support, and nice little ramp in the end.




Anti-squat and anti-rise are both a change from what I've done the last couple frames. The main pivot is further forward in the frame giving it less progression in anti-squat but also less anti-rise. It should hold speed well pumping the trail, we'll see how that higher anti-squat late in the stroke affects things.

On the shop side I've pulled my ghetto jig back out of the corner and set it up in the garage. Couple small bits have been turned on the lathe and I have cut the bb out of a previous frame to recycle it into this one.

Finally excited to get back at it on a new rig.
:thumb:

I like that your leverage ratio function is a strictly decreasing function on the interval. Your linkage is giving a nice spread to the starting and ending values, looks around 2.525 to about 2.975.

Messing around with my single pivot project, with no linkage, it seems like if I spread the values further than something like 2.40 to 2.51, then I lose the "strictly decreasing" aspect of the function.

Using a progressive spring to try to help out the situation.
 

HardtailHack

used an iron once
Jan 20, 2009
4,984
3,059
New frame started. My brother is trying to get my last DH frame off of me so I’ll make a new one so we can all have one.

Cleaning up the seat tube insert. Since I’m using 1.2mm thick tubing on the seat tube the insert part doesn’t fit so it’s just a butt weld which I’ll need to tie in with a gusset. I need to bend some .9mm thick seat tubes in the future so the insert part works.

View attachment 182148

Nice and clean. Ready for welding.
View attachment 182149

I was truckin along and then I was stuck. My seat tube reamer is already fucked and the cutters are rounded over. Think I can somehow ground them down to good cutting surface again? I’m going to try to put it on the lathe and make some sort of a tool post grinder to get some more life out of this thing. It was cheap but still….
View attachment 182150

This one was a 31.6 and the new one I ordered is a 31.8. Why do you guys think there are 2 so close to each other? I was happy with 31.6 and ordered the 31.8 on accident. Probably close enough?
Are they lead soft jaws?
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
Couple more things done yesterday.

Making the upper pivot. I’d like to find some 4130 tube closer to my final dimensions. I have to go from a 12 mm hole up to 17mm. For now I’m getting better at sharpening drill bits, haha. One of those carbide insert type drill bits could be useful here maybe. I see them come up used around here but never saw the need. Does carbide cut 4130 better than hss or am I just way off with the feeds and speeds? I am learning by feel here and the speeds n feeds isn’t my strong point. Accidental work hardening could be though.

E91CC49A-E70D-46E1-8835-6ACBCD064CFE.jpeg


Welded in the main pivot and BB. I tried some pulse settings on the bb and lower pivot. It went well but I still had a shaky hand.
D7AE5B61-FB11-46FB-9649-2DF2D800C5F2.jpeg


I finished these parts yesterday and they are in the jig ready to tack. Then on to the down tube mitering.
209D5703-5606-43AD-BF0D-2F9CE6CB00F3.jpeg



D63017E1-1C93-4E3F-9AF7-2F9721C195A1.jpeg
 
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buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
I got some more done on this one yesterday. I’m sharing all these pics hoping that you guys are gonna share some frame building pics with me, haha.

Using a live center from the lathe to find the center of the tube before mitering.
8A5333F0-0344-4117-A18D-AA19E4DD62CE.jpeg


setting up the angle
0EEBA365-6B40-47AE-BE8E-575C41E84E72.jpeg


Working my way up to final size. I don’t know how to get the final tube cut length without taking a little off bit by bit.
9712283F-837D-4A2C-93D7-4B7D586883E8.jpeg


One down and one more to go.
26C674A9-9F9C-458C-9904-57D589F6A816.jpeg


All ready for tack welds.
837E85A5-B6BA-4DEC-9B60-70F67F540052.jpeg


This the first one where I only used the pulse settings on the welder so I was learning a lot here. I normally used the pedal but want to get better at different settings and techniques. It was a lot easier however the welds don’t look better. I figure if I keep at it it will come eventually.

951AFFC0-B7D5-4AA9-8EAE-41C69279F2C9.jpeg


.
 

letsgethurt

Chimp
Sep 15, 2022
2
10
The Scott Gambler is already one of the nicest looking DH bikes around and those steel front triangles with the straight top tube compliment them very nicely. The continuous line through the seatstays and tt looks super clean. Big fan of your projects @buckoW !

Here's my attempt at rebulding a front triangle. My buddy crashed his Nukeproof Mega nose first into a platform and was lucky enough to walk out without getting too seriously hurt, but the frame was toast. The swingarm and rocker were still serviceable though, and he gave me the remains of the frame to build something fun/stupid out of it. Apart from a two-day framebuilding class I'm mostly self-taught and had only built two frames before this, so it was definitely a big challenge, but somehow I dunning-krugered my way through and did the 2021 park season on this bike.

fa268b9d93c15427cb74b3b32fb043e03429c270.jpeg


I'm lucky to share a workshop with a couple of friends. We've got a second hand jig built of aluminum extrusion and while it's originally designed with rigid bikes in mind, it's easy to extend it ad-hoc with off-cuts and whatever we've got handy, like I'm doing here with the pivot points. Luckily the original frame was only damaged on the front so I could still use it as a template to locate the pivots. Just put it on the jig by the bb and seat tube, tighten everything on the pivot jig, lift the frame and insert new tubes. The shock mount on the original frame had buckled in from the crash so I had to do some guesswork with Linkage to approximate it's location.

0988dfb8a27060690dd40285c5e082d5e55eba60.jpeg


Building the main pivot was the most challenging task for me. The original 2017 Mega still had the capability to run a front derailleur so they made the main pivot offset to the nds. The offset is a good few mms and I figured squashing the seat tube would have left it's cross section too thin for gravity riding. I took some inspiration from Nicolai and offset the seat tube forward away from the pivot and build a box-type support for the pivot using a square tube off-cut (S355 structural steel) I got for cheap at the local steel supplier who are friendly enough to sell to hobbyists without ridiculous MOQs. The wall thickness was pretty substantial so I shaved it down a bit on the milling machine.
9caff2a7eb2f8aa9e81ff97749d7daedc73946c8.jpeg




I have to say I was pretty proud of getting all the mitering done without scrapping the part, even if it's looking a bit fishy!
375f0aeeaf7c154a32de22d90d414cf1ddd4a20d.jpeg


Looking back the whole contraption could be simplified quite a lot, but sometimes you have to go through with your design to be able to see what could be improved.
f2c68c884a10fbc37aa61e139fe4a4e50a45030b.jpeg


The finished frame with the swingarm attached as soon as the last fillet had cooled down enough to allow handling the frame. Took me almost three months to reach this point. After rinsing off the flux I just clearcoated it with some rattle can 2k. The original swingarm actually cracked on the brake tab weld on my first uplift day, but luckily a buddy who knows how to weld aluminum repaired it!
16e6244c1eabc82dc5fd3146c200f4407ea29051.jpeg


I ran the bike as a single speed park rig. 26" wheel on the rear, 27.5" front. The most suspension I had been riding at that time was my 135r/150f trail bike and was amazed at what I could do with 160mm rear paired with a 180mm Boxxer. It's definitely an exciting feeling of accomplishment and fear of death when riding jumps bigger than I've ever done before while being my own crash test dummy at the same time! The picture was taken at the end of the season so there's already a bit of patina going on.
5afb0e7df3134065147f8910ae43c7715695b4b7.jpeg


Gussets. Nothing gets people on framebuilding forums more riled up than gussets. People say a badly designed gusset can become a can opener and now I know why. I was doing some spring cleaning on the bike to get it freshened up for 2022 and found a crack right at the tip of the downtube gusset. Naturally I was a bit bummed but also very relieved to have found it before the frame would fail under me, or worse, someone else getting injured. I could have rebuilt the main frame but decided not to push my luck with the swingarm any further. Anyway, I was happy that no one died and I got to spec a new frame! Went with a off the shelf option this time but maybe I'll build another full squisher later if I have time on the off-season. Already got some ideas about better materials, better jigging, getting more stuff laser cut to save time rather than fabricating stuff on the go and so on!
75d341e5a41d8cd0fe23ed3963f1d4c36f26f176.jpeg
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
@letsgethurt - Funny you mention gussets! I was just considering leaving them off of my last frame. I’ve been getting away with no seat tube gusset on a few frames and I don’t want to create any stress risers with a bad gusset design or a bad weld.

How thick is that gusset on your downtube? I’ve been trying to keep wall thickness down and the welds on the sides of the DT. I also finish the gusset in a thinner point so it isn’t as stiff at the end and can hopefully distribute the load better.

Awesome! Nice work. I like your main pivot box. Thanks for sharing!
I’d like to learn to braze one of these days.
 
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letsgethurt

Chimp
Sep 15, 2022
2
10
@letsgethurt - Funny you mention gussets! I was just considering leaving them off of my last frame. I’ve been getting away with no seat tube gusset on a few frames and I don’t want to create any stress risers with a bad gusset design or a bad weld.

How thick is that gusset on your downtube? I’ve been trying to keep wall thickness down and the welds on the sides of the DT. I also finish the gusset in a thinner point so it isn’t as stiff at the end and can hopefully distribute the load better.
I really should measure it for a proper post-mortem but off the top of my head the wall thickness of the square tube is a hair over 1mm. I agree that it would be better to make the gusset geometry a lot less rigid and join it at the sides of the tube to avoid concentrating stress like I'm doing here. Live and learn I guess!
 

buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
I really should measure it for a proper post-mortem but off the top of my head the wall thickness of the square tube is a hair over 1mm. I agree that it would be better to make the gusset geometry a lot less rigid and join it at the sides of the tube to avoid concentrating stress like I'm doing here. Live and learn I guess!
Yeah, learning by doing! I hope my top side DT gusset works out and isn’t another learning experience.
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Leafy

Monkey
Sep 13, 2019
309
217
Are you getting your 4130 as annealed, normalized, or pre-hard? All options are going to be softer than the HSS tools but normalized and pre-hard are going to impact tool life for sure on HSS. How many parts are you getting with HSS? Should still get dozens if the tools are decent and you're using cutting fluid.

Carbide will last longer than HSS if your machine is decently rigid and you can run enough RPM to get the surface footage that carbide wants to run, like you're going to need to be able to spin at least 1000 rpm to run a 1/2" carbide drill in steel and at least 2400 to run a 1/4" drill. You'll know if you're not rigid enough if the tools are chipping out after only a few dozen parts. What is nice about carbide in the home shop is that making carbide tools is difficult enough that the Chinese haven't figured out how to do it shitty yet so the cheapest aliexpress carbide tools are decent, where you've got to at least get US, Europe, Japan, or Tiwan manufactured to get halfway decent HSS stuff. Even if you cant run fast enough for carbide, it'll still last longer than cheap HSS.
 

sikocycles

Turbo Monkey
Feb 14, 2002
1,509
712
CT
I am in CAli for business and since PMW is 30 minutes away I went there for a tour. Mark and Coco were very nice, Great to see where the parts come from. An amazing shop and I was happy I was able to go.

See you all in Philly bike expo if your going
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buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
Are you getting your 4130 as annealed, normalized, or pre-hard? All options are going to be softer than the HSS tools but normalized and pre-hard are going to impact tool life for sure on HSS. How many parts are you getting with HSS? Should still get dozens if the tools are decent and you're using cutting fluid.

Carbide will last longer than HSS if your machine is decently rigid and you can run enough RPM to get the surface footage that carbide wants to run, like you're going to need to be able to spin at least 1000 rpm to run a 1/2" carbide drill in steel and at least 2400 to run a 1/4" drill. You'll know if you're not rigid enough if the tools are chipping out after only a few dozen parts. What is nice about carbide in the home shop is that making carbide tools is difficult enough that the Chinese haven't figured out how to do it shitty yet so the cheapest aliexpress carbide tools are decent, where you've got to at least get US, Europe, Japan, or Tiwan manufactured to get halfway decent HSS stuff. Even if you cant run fast enough for carbide, it'll still last longer than cheap HSS.
Ok! Thanks Leafy. I‘ll try some of this. I noticed the nice HSS cuts a million times better than mystery HSS.

Started building up my last frame yesterday. This thing makes my headsets go in much nicer!

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buckoW

Turbo Monkey
Mar 1, 2007
3,354
3,761
Champery, Switzerland
I got her all built up yesterday and the tram in town is open everyday. I’ll put on a 25mm setback seat post on but other than that this thing is ready. The raw steel ones don’t like riding in the wet so I had to paint this one. The others are getting some nice patina that I’d like to lock in with some clear coat soon.

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A couple days ago.
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This edit of Vinny T riding Champery shows a lot of the main track.