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Making a frame thread


Blake

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Well, this thread was going to be started by me sooner or later, so it might as well be sooner.

It is coming up to the second year of my BTEC Engineering level 3 diploma, and as part of the second year you have a main project where you make anything of your choice.

Of course being the avid trials rider I am, I have decided to take on the challenge of making a steel trials bike frame. We have all the equipment available at college and I believe I am passionate enough to finish the job, which is why I have taken it up.

However, I also know that if I do this without the help of the forum, I will regret and do it wrong, so I am asking for your help even in the designing process.

Due to the lack of a jig the geo is not going to be completely spot on, so I am going to simply aim for short CS, high bb and long WB. with a 116 rear end and 4 bolt mounts.

I am making this to ask for help on dimensions for tubing, I am going to need the following tubes:

2 x tubes for CS

2 x tubes for SS

1x tube for BB shell

1 x tube for Headtube

1x for the Top tube

1 x for the downtube

1 x for the seatstay

I am going to ask for much longer tubes than I require, for example 600mm tubes for the CS just so I have room to cut them down to the specific length. I am going to go for tubes with a material thickness of 0.8mm thick all round, as I think this will make a good weight/strength compromise.

However one think I am stuck on, is the outer diameter of the tubes. I could measure my frame but because that is Alu I would not get the results I need for steel tubing.

Can I have some assistance on what I require for CS, SS, Top tube, Down tube and Seat tube, someone who is familiar with working with steel/frame development would be most helpful, but anyone who thinks that they can help are more than welcome to join in with the conversation.

Please, feel free to comment on this thread with views, opinions, critisims or praise, everything will be read and considered.

I hope everyone looks forward to the next year as much as I am and enjoys looking at the progress of this project.

Thank you

George :) xx

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i´d take at least a 34.9 for the top tube,a 38 for the downtube,for the cs and ss its common to use something between 12 and 21 mm(edit:or even tapered,better for the rear dropout join to fit those thingies of the dropouts that sit in the stays tubes),so youre pretty free in choice there.you could use higher diameter ones for the cs and ovalize them at the bb to gain space for the sprocket and tyre,and at the dropouts to,well to weld them on without having no welding surface at all.seat tubes hmmm,a 25,4 inner would be 26 outer dia,so its a thing of choice for the seat post dia,if you build seatless,its unimportant,but under 26 youl end up with less seatstay welds,making it weaker.

thats so far what i can tell on the tubes,josh can give more precise info for sure

Edited by FamilyBiker
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this!

it even would be enough to have a simple,workbench mounted one like the early marinos were welded on.

was basically a steel plate bolted to the table with a rotating arm that has a scala to adjust its angle to take tha headtube.

and 2 old dropouts with a rear axle to hold the rear triangle in place,and some kind ob misused headset mounting press to hold the bb shell

edit:

pereee.jpg

basically like this,later there was a "table mount" version of it

Edited by FamilyBiker
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There will be constructions to hold things in the correct place, but not to the precision of exact geometry.

If you could lay your hands on a frame you want to copy I'd walk you through the jig build.. most of my stuff is bespoke so simple jigs is what I do best, easy and cost effective

*edit* just re-read your post properly. I sounded a bit condescending, soz.

Edited by f**megently
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If you could lay your hands on a frame you want to copy I'd walk you through the jig build.. most of my stuff is bespoke so simple jigs is what I do best, easy and cost effective

That could sound interesting but what os the estimated time to make one? I also have to make a large write up for next year so can't spend all my time in the workshop

I have my maladie with a snapped Chainstay and lots of hammer dents that I'd like it to match f that helps

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If you've got steel, summert to cut it with and a welder... about 2 hours. You don't even need a tape measure! (but have one just in case :) )

*a snapped frame might not be so easy, but do-able

The frame isn't warped and still holds its shape

How exactly do you do it?

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Yep I'm a fabricator, amongst other things. I restore classic cars, there's some posts in the car thread of some of the stuff I do. I'm the main fabricator, I make chassis/repair sections, body panels/sections, sub frames, gearbox mounts ect that are no longer available due to age or just rarity. I also do mechanical, electrical and interior work, basically everything car related.

I used to do gates and railings and fitting the automation, and I was in refrig for 10 years. I've been a busy boy :)

Not on Facebook bud. Dunno if you've done any pics yet cuz I haven't checked but soon as I see some I'll sketch summert simple for you.

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