MikeR
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| posted on 9/12/10 at 05:28 PM |
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How to form 1.6 / 1.2mm mild steel
Theoretical question time before i spend time in the garage trying this & get depressed when it doesn't work.
I want to take a 50mm tube with a wall of 1.2 or 1.6mm mild steel. I want to then expand the end of one of the tube so it flares out. In an ideal
world i'd want to flare the last 50mm of tube so it goes from 50mm to 75mm wide with a rolled end. Reality is i think thats going to be
impossible, i'll accept something far less extreme, if i could take the last 10mm of the tube and take it from 50mm to 60mm that would be ok.
So, how do i do it using hand tools?
Current thoughts are to take some flat sheet, cut a donut out of it and then place that in a wooden former and either hit with a hammer or a negative
of the former until its the shape required. This would then be welded onto the end of hte tube. Or to do something similar but place the former in the
tube. I was thinking of making the former out of plywood and using a router bit to make the nice rounded shape (no idea yet how i make the negative of
the former).
Before someone suggests ali - my concern is how to make it fit onto the existing mild steel, i can weld steel.
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fha772
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| posted on 9/12/10 at 05:41 PM |
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Buy 1 of Bergen Tools Exhaust/Tail Pipe Expanders on eBay (end time 05-Jan-11 22:16:01 GMT) , they work for me 99% of the
time.
[Edited on 9/12/10 by fha772]
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MikeR
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| posted on 9/12/10 at 06:06 PM |
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I'd looked at those - but heard that they were only good enough to remove a dent from a pipe, not to flare them. Don't want to sound rude,
have you actually used them successfully (don't want to waste money buying them based on comments i've seen previously) & will they do
a rounded 'trumpet' end or just open up the pipe a little to allow another pipe to slip into it.
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oadamo
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| posted on 9/12/10 at 06:09 PM |
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i dont think you will get it from 50 to 75 by hand try to find a metal spinners it will prob take them 5 mins to sort it for you.
try birmingham metal spinners he will tell you if it can be done.
adam
edit found his number,
GB METAL SPINNING
68a Glover Street
Bordesley
Birmingham
West Midlands
B9 4EL
01217735444
[Edited on 9/12/10 by oadamo]
[Edited on 9/12/10 by oadamo]
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2cv
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| posted on 9/12/10 at 06:25 PM |
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Hi Mike, if 907 doesn't respond to this post you could drop him a U2U. I seem to remember some time back that he expanded a piece of tube by
pressing a mandrel into the end. I can't remember the details but if anyone can do it he can.
However, I very much doubt if you could go from 50 to 75mm in one step.
Would a rolled cone be a solution?
[Edited on 9/12/10 by 2cv]
[Edited on 9/12/10 by 2cv]
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DavidR
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| posted on 9/12/10 at 06:33 PM |
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These may work
http://www.skatoskalo.com/tube_expanders.htm
There used for boiler / condender tubes so are capable of bending quite thick walled tube.
They will be prohibatively expensive to purchase new , but you may pick up one on ebay - they have been about for over a hundred years
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James
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| posted on 9/12/10 at 06:41 PM |
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Sorry, can't help you with this.
Just wondering what you want it for? Something on the car? Just wondering if there was an alternative that 'The Collective' could come up
with! 
Cheers,
James
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MikeR
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| posted on 9/12/10 at 08:15 PM |
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Its to make an inlet trumpet...... something like this ....
fficial&client=firefox-a&um=1&ie=UTF-8&source=u" target="_blank">http://www.google.co.uk/images?q=inlet+trumpet&oe=utf-8&rls=org.mozilla:en-GB fficial&client=firefox-a&um=1&ie=UTF-8&source=u
niv&ei=HjUBTZilF8aZhQeSkqDuBw&sa=X&oi=image_result_group&ct=title&resnum=2&ved=0CC0QsAQwAQ&biw=1264&bih=584
I realise i can't do it properly (the example of 50 to 75mm isn't the exact sizes i need but a good example of what i was trying to
achieve in an ideal world), so i'm just trying to flare out the end of the tube.
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interestedparty
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| posted on 9/12/10 at 08:16 PM |
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Inlet manifold I reckon, plenum variety.
edit, 2 minuutes too slow.
[Edited on 9/12/10 by interestedparty]
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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907
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| posted on 9/12/10 at 08:42 PM |
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Hi Mike
IMHO it would take too much force to stretch 2" pipe that much. (with nomal garage tools)
To give you an idea, to swage 2" stainless from 2" o/d to 2" i/d takes a force greater than 8 tonnes.
How do I know that?
Because my 8 tonne jack wouldn't do it so I bought a 12 tonne one, which does it with ease.
Your best bet is to develop a cone from sheet. I'll do a post later to show how its done.
Do you have a height for the cone?
Cheers
Paul G
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MikeR
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| posted on 9/12/10 at 09:20 PM |
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I don't have a height off hand, as i was trying to figure out what i could do and then match that with the inlet tube length i've
calculated.
I think i've found a simple, perfect design and very cheap solution ............. hopefully it will work out (yes i'm being secretive,
if it works i'll let you all know).
Still interested in the shaping a cone from flat sheet though.
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2cv
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| posted on 9/12/10 at 09:31 PM |
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If all else fails, I could roll you a cone Mike. Let me know or U2U if of any interest.
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907
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| posted on 9/12/10 at 10:01 PM |
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Draw a side view of the cone, but carry the side lines up to form an apex point.
You should have this.
 
Description
Set compass or dividers to dim "A" and mark a circle.
From the same centre, mark a circle with the compass set to dim "B"
You now have a circle within a circle. (like a polo mint)
Mark a line from the centre till it meets the big circle. (a radius)
Bit of maths now:-
We need to find the distance round a 3" circle so we multiply 3" by pi ( pi = 3.142 )
3 x 3.142 = 9.426
So the distance round a 3" circle is 9.426 inches
(in metric 76.2 x 3.142 = 239.4 mm)
Back to the cone marking:-
From the end of the radius line we need to measure round the big circle 9.426"
and draw a line back to the centre. You now have the shape to cut out.
When the cone is rolled (or tapped round a bit of pipe to form the shape) these two
straight lines meet up and form the weld seam.
p.s. I can do this in metal quicker than write it out. 
edit to add second pic.
Shallow cones have a small cut out. Steep cones have more cut out than cone.
 
Description
Cheers
Paul G
[Edited on 9/12/10 by 907]
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MikeR
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| posted on 9/12/10 at 10:13 PM |
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Thanks - when it gets a bit warmer i think i'll have a go at that for fun. My (hoped for) solution costs less than a pound and has fully rolled
edges on the end of the cone...... if it works its a no brainer
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Madinventions
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| posted on 9/12/10 at 11:17 PM |
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This software may help?
Ed.
Mojo build diary: http://www.madinventions.co.uk
Solo music project: Syrrenfor http://www.reverbnation.com/syrrenfor
View my band website:
http://www.shadowlight.org.uk
http://www.eastangliankitcars.co.uk/
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RazMan
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| posted on 10/12/10 at 09:10 AM |
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I had a similar project in mind (for my inlet trumpets) and I found a supplier in Thailand who sells various trumpets in all sorts of sizes. Made from
machined alloy and they are good quality .... and cheap 
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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scudderfish
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| posted on 10/12/10 at 09:15 AM |
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quote:
Originally posted by RazMan
I had a similar project in mind (for my inlet trumpets) and I found a supplier in Thailand who sells various trumpets in all sorts of sizes. Made from
machined alloy and they are good quality .... and cheap
Link?
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RazMan
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| posted on 10/12/10 at 09:33 AM |
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Of course dear chap
http://www.akunar.com/AIR%20&%20FUEL%20FILTERS.htm
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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MikeR
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| posted on 10/12/10 at 09:38 AM |
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The only problem i had with that site is that the cost of posting 4 makes the ram pipes almost as cheap as uk sourced ones - at which point
you've got to decide who you'd rather deal with.
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RazMan
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| posted on 10/12/10 at 10:09 AM |
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Really? I just got 2Kg of stuff posted for $25 which offset the cost of getting UK stuff by a mile. For example their 50mm trumpets are $8.50 each and
with the exchange rate of 1 US$ = 0.633312223 GBP that makes 4 trumpets around £35 in total. Where can you get anything similar in the UK? Last time I
looked a single Weber trumpet was more than that price!
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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MikeR
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| posted on 10/12/10 at 04:07 PM |
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when i was looking last month i saw them for about 10 pounds a trumpet in the uk.
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