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Jigging and Mitering the rear triangle ... thoughts on chainstay-fixture

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Jigging and Mitering the rear triangle ... thoughts on chainstay-fixture

Old 04-19-21, 03:56 AM
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apollodriver
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Jigging and Mitering the rear triangle ... thoughts on chainstay-fixture

dear Community,

Jigging and Mitering the rear triangle ... - seems to be a nice challenge.

well i think constructing the rear half of a bike frame poses many more challenges than the front half.
Besides the tubing choices we ve got questions about techniques for jigging these assemblies - and in aiming so to create some nice framebuilding tools that help here:
Well - in order to assemble the chainstays as accurately as possible, i plan am to build

1. firstly a jig-mitering tool that mimics the final positioning in the finished frame
2. going to elaborate this a bit more.

Doing so: this hope that i can finalize the miter on the seatstays: I have had a quick view on the mitering-tools and chainstays that are out there:

recently i saw the chainstay fixture - here - at the instagram account of Kristofer Henry ( https://www.44bikes.com/ ) - Well - i like this it looks very impressive. (see the chainstay-fixture at his page ( or at the instagram account. )

see this - it looks so awesome - created by Kristofer Henry -


one question - does this tool need (and afford) a bending process of the tubes that takes place a bit earlier - i.e. right before they were put into the fixture. And besides this - the question for all of you. Which chain-stay-fixture and mitering-tool do you use.

By the way: afaik the tubes tubes (of the chain-stay) for a street-bike are straight - with no windings - so iguess that they are bended seldom - isn t it so!?

Well - this chain-stay - jig is very nice designed and i like it very much.


on a side note: Steve from Pithybikes has created some Phase-Blocks. - can we use the Phase Blocks (from Steve at Pithybikes) - for creating something … that goes into that direction of such a nice tool

cf; Steves pages - pithybikes.; with lots of useful stuff, videos and more... - here very interesting the Phase-Blocks ..:
https://www.pithybikes.com
https://www.pithybikes.com/pithy-bikes-jig-copy-1

cf: Phase Blocks for 1-1/4"(31.75mm), 3/4"(19.05mm).

Will take screws: 10-24nc or M5. Holes are near size but will need drill chasing and tap.
Recommend print with PET. 50% Infill seems to work well. Not meant to hold work for miter cuts.
But if you're daring, maybe 100% infill can hold work? ​Pithy Bikes Phase Blocks are free for use but not for re-sale.
The question is - are the Phase-Blocks that Steve offers - are they useful in the task of creating a chain-stay-fixture and mitering tool?

and yes: the question for all of you. Which chain-stay-fixture and mitering-tool do you use.


look forward to hear from you

your apollo,



see more Tools i have seen on the net:

Chainstay mitering |

chainstay-fixture - a extensive discussion - with many pictures
https://www.mtbr.com/threads/chainst...re-diy.680352/

Varcocycles Stay-Mitering Fixture:
https://varcocycles.com/2020/02/25/s...ering-fixture/

Chainstay mitering jig
a collection of images - collected from Schnubbi • actualized in January 2021
29 Pins - 29 images - have a closer look:
https://www.pinterest.de/helbigdanie...-mitering-jig/

Chain Stay Mitering Fixture - see image collection
Explore Anvil Bikes' photos on Flickr. Anvil Bikes has uploaded 1482 photos to Flickr.
https://flickr.com/photos/anvilbikes...57623563680959

The Miters Touch - For Chainstays
https://farrframeworks.com/farr-tool...-miter-fixture

Behold: Method to miter oval chain stays using free-ware mitering templates - a discussion
https://www.mtbr.com/threads/behold-...plates.990335/


And as a additional info some links to Kristofer Henry: This is the current Flickr link for 44 Bikes https://www.flickr.com/photos/44bikes

This is the chain stay mitering jig you probably should reference: https://www.flickr.com/photos/44bikes/51104776470

There’s more detail shots starting here: https://www.flickr.com/photos/44bikes/26646331965

The other tool to miter chain stays by the dropout end is here: https://www.flickr.com/photos/44bikes/51099818819/in/dateposted-public/

And a chain stay sub-assembly jig here: https://www.flickr.com/photos/44bikes/50669106503

Current Attachments Valid file extensions: bmp doc jpe jpeg jpg pdf png psd txt zip


and besides - see more stuff here:
https://www.instagram.com/explore/tags/framejig/
https://www.instagram.com/explore/ta...buildingtools/


another approach: Well the plan is to create a simple/cheap chainstay mitering fixture.- i want to have accessories that can be added to standard 80/20;
That said - i want to require as little machining as possible in order to keep the cost down.

i found interesting approach - see this basic setup.

see here some interesting overall photos:
https://www.pinkbike.com/photo/14367112/
https://www.pinkbike.com/photo/14367111/
https://www.pinkbike.com/photo/14367109/

Last edited by apollodriver; 05-05-21 at 06:38 AM.
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Old 04-19-21, 07:47 AM
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unterhausen
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You can grab a link from a post on Instagram.

I have always just hand mitered my chainstays. No templates. I'm building a fixture because I want to check clearances ahead of time.

Paragon has tubing blocks. They said all of the sizes will be back in stock this week. Alex Meade has tubing blocks with oval cutouts for fork blades. I haven't seen tubing blocks for oval chainstays. Vee blocks work fairly well since there are a number of different chainstay sections.

Last edited by unterhausen; 04-19-21 at 07:52 AM.
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Old 04-19-21, 08:07 AM
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unterhausen
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Here is the 44 bikes fixture

The second round bar on that design doesn't add anything.


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Old 04-19-21, 08:20 AM
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hello dear untershausen

first of all - many many thanks for the quick reply - glad to hear from you


well - thank you for the comment. - i have seen dozens of chain-stay-mitering jigs - but this seems to be the most elaborate and sophisticated i have seen in this whole year.




btw: are those tubes - /(which look like very interesting -(note: they are not straight but look like winded while being bended with special tools:
in other words.- Do they fit especially for Mountain bikes - but not so much for a street-(racing) bike!?


and besides this: the both blocks which are marked - (with a red marker) - they look very very sophisticated and complex.


Look forward to hear from you

apollo

update: btw: this is another part - from Kristopher Henry - see here: https://flickr.com/photos/blackcapst...7718964022612/
designed in 2011
- it looks also very outstanding - and seems to be (at least it seems to me ) a predessor of the new chain-stay - mitering tool - which we see on the instagram image in the threadstart - (which is [at least to me] brandnew designed )?!

Last edited by apollodriver; 04-19-21 at 08:24 AM.
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Old 04-19-21, 09:20 AM
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unterhausen
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Yes, he said that the fixture in the insta that I linked replaced his older one. I'm not sure it's significantly more sophisticated than other fixtures I have seen. It's nice though. The blocks at the front are cut away for clearance. Otherwise they are just vee blocks.

The tubes are chainstays. They look to be something that is commercially available, but maybe he added some bend. The interesting thing to me is that they are mitered off-center. I'm not sure that was intentional to add a little more clearance. I assume they are for a bike with big tires. Some people use s-bend chainstays for road bikes, but these have more bend than would be required for that. These appear to be for an all-road or mountain bike.
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Old 04-19-21, 09:38 AM
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hello dear Unterhausen,

great to hear from you again !

Originally Posted by unterhausen View Post
The tubes are chainstays. They look to be something that is commercially available, but maybe he added some bend. The interesting thing to me is that they are mitered off-center. I'm not sure that was intentional to add a little more clearance. I assume they are for a bike with big tires. Some people use s-bend chainstays for road bikes, but these have more bend than would be required for that. These appear to be for an all-road or mountain bike.
i also guess that the chain-stay is for a big with bigger tires. To me it looks exactly this way. I get the same impression as you do!

the question for me is - do we need to bend the tubes in the chain-stay.

for some kind of bikes - it seems to be obvious or mandantory - (eg for bikes with bigger tires perhaps) but if we take street-bikes - i guess that the tubes are very often just straight - aren t they!?


i can second your statement: "These appear to be for an all-road or mountain bike"

i have the same impression!

greetings
Apollo
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Old 04-19-21, 09:52 AM
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Originally Posted by unterhausen View Post
Yes, he said that the fixture in the insta that I linked replaced his older one. I'm not sure it's significantly more sophisticated than other fixtures I have seen. It's nice though. The blocks at the front are cut away for clearance. Otherwise they are just vee blocks.

The tubes are chainstays. They look to be something that is commercially available, but maybe he added some bend. The interesting thing to me is that they are mitered off-center. I'm not sure that was intentional to add a little more clearance. I assume they are for a bike with big tires. Some people use s-bend chainstays for road bikes, but these have more bend than would be required for that. These appear to be for an all-road or mountain bike.
Kris makes his own stays from round tubes. His Flickr feed shows the process that he uses to bend and smash them for clearance. The stays are offset mitered to attach lower on the bottom bracket, which I have found to be very helpful in allowing better torch access for welding around the stays and the rear of the seat tube/bottom bracket joint. It can get very tight in there with a zero offset miter on the chainstays, as the stays are often touching the seat tube.
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Old 04-19-21, 12:31 PM
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I also mitre by hand. It's not a difficult mitre. Most important is that the chainstays are exactly the same length, or the back wheel won't sit right. You can only do this if you can fixture it right. I attach the CS before the front triangle as it makes it easier with fixturing.

I weld the ST to the BB first, then add the CS after that, before the front triangle.

I have a bit of square tube with two nuts welded onto it about 80mm apart. This is clamped to the edge of my table. A piece of threaded rod goes through the two nuts, is locked in place with two more, and two more pairs of nuts (locked against each other) define the rear spacing (usually 130mm or 135mm). The dropouts are then put in place and held down with two more nuts.

Knowing the height of the rear axle off the table I use math to work out how far away the BB shell should be and what angle the ST should be at. Then I clamp a piece of angle iron across the table for the BB to rest against. I check everything for level and square with a laser level box. Then check it again.

This gives a pretty accurate jig that doesn't move around so I can now mitre the CS (by hand, using templates). They are tacked at the dropouts first and then at the BB shell. Then with a couple of tacks on it I take it all out and put a true rear wheel in to check, trying it both ways round just in case.

Then I weld it all out. Things will move around a bit but that can easily be corrected. This way things are fundamentally the right length and will be back in the right place once bent back.
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Old 04-19-21, 02:25 PM
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I made a version of the setup pictured above using Alex Meade's tubing blocks for small oval tubing.



chainstay mitering setup

It wasn't the easiest thing to use but the results were good. If I had a drill press, I could have clamped this to the table and done it that way. Since I don't, I used a hand file.

I then joined the chainstays to the bottom bracket using a similarly rudimentary setup.




The real disadvantage of this kind of setup is that you have to check everything very carefully - there are 100 ways it can go out of alignment, out of plane, crooked, etc.
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Old 04-19-21, 08:41 PM
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I now use an Anvil mitering fixture. But I hand did a number before and agree with the ease of slight offness in stay lengths. That's one reason to build with BB shells that have sockets Even with the Anvil I follow up with a small bit of hand file strokes to fine tune the miters. This is where a tacking jig (different then the mitering fixture) is a nice thing. It is better at consistent stay placement and aids the ability to check minor miter tuning far better then what I had before.

While not the initial topic of this thread here's a unicrown mitering fixture I made for the first (and so far only) MtB fork I've made. The tube blocks are Alex Meade's. The rest is either specific bought or bits I had in the scrap bin. The blades still needed some hand tuning after the hole saw did the bulk of the work. With some creative thinking and fairly simple fab work a reasonable mitering fixture isn't hard to make. maybe not quickly though.
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Old 04-20-21, 10:06 AM
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hello dear dsaul, hello unterhausen, guy153, jimn, Andrew R Stewart, good day

many thanks for your replies,

dsaul ... yes fully agreed - this is Kris Flickr-Feed: https://www.flickr.com/photos/44bikes/

Kris makes his own stays from round tubes. His Flickr feed shows the process that he uses to bend and smash them for clearance. The stays are offset mitered to attach lower on the bottom bracket, which I have found to be very helpful in allowing better torch access for welding around the stays and the rear of the seat tube/bottom bracket joint. It can get very tight in there with a zero offset miter on
the chainstays, as the stays are often touching the seat tube.
i also like this way kris goes this way - "offset mitered to attach lower on the bottom bracket" -


btw. this is a view on the chainstay from the top - very actual: https://www.flickr.com/photos/44bike...kRTgoG-2kQHbm2
cf. Kristofer Henry - Jeremy's Sub-Assembly :: xwww.44bikes.com

guy153 - you mitre by hand - as i am currently working on the finish of the fixture according tanner w (cf. https://www.instructables.com/Bicycl...-Building-Jig/ ) i like your idea. Several weeks ago i found Kristofer Henrys chainstain mitering fixture - now i am musing on working out such a nices solution too.

but i like your ideas of the mitre-process by hand. Your detailed description of doing this is great and very helpful.

I also mitre by hand. It's not a difficult mitre. Most important is that the chainstays are exactly the same length, or the back wheel won't sit right. You can only do this if you can fixture it right. I attach the CS before the front triangle as it makes it easier with fixturing.I weld the ST to the BB first, then add the CS after that, before the front triangle. I have a bit of square tube with two nuts welded onto it about 80mm apart. This is clamped to the edge of my table. A piece of threaded rod goes through the two nuts, is locked in place with two more, and two more pairs of nuts (locked against each other) define the rear spacing (usually 130mm or 135mm). The dropouts are then put in place and held down with two more nuts. Knowing the height of the rear axle off the table I use math to work out how far away the BB shell should be and what angle the ST should be at. Then I clamp a piece of angle iron across the table for the BB to rest against. I check everything for level and square with a laser level box. Then check it again. This gives a pretty accurate jig that doesn't move around so I can now mitre the CS (by hand, using templates). They are tacked at the dropouts first and then at the BB shell. Then with a couple of tacks on it I take it all out and put a true rear wheel in to check, trying it both ways round just in case. Then I weld it all out. Things will move around a bit but that can easily be corrected. This way things are fundamentally
the right length and will be back in the right place once bent back.
very helpful - and instructive. Thanks!

I have a bit of square tube with two nuts welded onto it about 80mm apart. This is clamped to the edge of my table. A piece of threaded rod goes through the two nuts, is locked in place with two more, and two more pairs of nuts (locked against each other) define the rear spacing (usually 130mm or 135mm). The dropouts are then put in place and held down with two more nuts.
Jimn, thanks for sharing your ideas and your setup!

I made a version of the setup pictured above using Alex Meade's tubing blocks for small oval tubing.
agreed with this comment
The real disadvantage of this kind of setup is that you have to check everything very carefully - there are 100 ways it can go out of alignment, out of plane, crooked, etc.
Andrew R Stewart, thank you for sharing your experience and thoughts; the Anvil Mitering i did not know before.
Thank you for the ideas - and for showing the unicrown mitering fixture that you made for a MtB.

Many thanks for this very fruitful discussion

Apollo


update: as for some additional support of the threadstart that is a image that kris mentioned in a recent posting (i am in a mail conversation since two days) cf. Kris Flickr-Feed: https://www.flickr.com/photos/44bikes/


cf -kristofer at flickr: https://www.flickr.com/photos/44bike...kRTgoG-2kQHbm2



picture taken this month...


by the way and on a sidenote: if we compare the both view of the chainstay-jig - we see intersting things



note: - here we have another bar on that design - whereas Unterhausen said: this doesn't add anything...!?
But anyway - it looks pretty sophisticated... Here is the 44 bikes fixture


note: - here we have another bar on that design - whereas Unterhausen said: this doesn't add anything...!?
But anyway - it looks pretty sophisticated...

Last edited by apollodriver; 04-20-21 at 12:34 PM.
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