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Author: Subject: Round tube chassis
chrisg

posted on 27/9/07 at 07:14 PM Reply With Quote
Round tube chassis

Hey Up

Just a little question to exercise the grey matter.

The question is this.

Would a round tube chassis be a DIY proposition to the AVERAGE locost builder?

I've considered things like Tubemitre which is a good thing and those wizzo tube cutters Which are expensive, is there a cheap version?

cheers

Chris





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MkIndy7

posted on 27/9/07 at 07:29 PM Reply With Quote
Maybe a silly question, but what are the advantages of a round tube chassis?

For the lo-cost fitting of most body/interior/dash pannels etc surely its much easier to mount to and use square tubes.

Could a normal hole saw be used on a jig... not sure the blades would last long tho.

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rayward

posted on 27/9/07 at 07:32 PM Reply With Quote
Ahhh brings visions of the Robin Hood 2B Chassis !!!!

anyway, tube notcher Here 150

Ray

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smart51

posted on 27/9/07 at 07:33 PM Reply With Quote
Cutting fish mouth ends on tubes may seem a lot of work over a square cut on a square tube but how many ends are cut square on a locost chassis? fish mouths on round tubes butt up nicely with round tubes whatever the angle.

Round tubes are lighter than square and their lightness to stiffness ratio is better.

I guess that you could use a mixture of round and square where appropriate / easiest for fixing bodywork.

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RichardK

posted on 27/9/07 at 07:41 PM Reply With Quote
I can't even cut box section straight

Rich





Gallery updated 11/01/2011

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nitram38

posted on 27/9/07 at 07:50 PM Reply With Quote
Do you mean like this?

Description
Description

Description
Description


I have a brandnew notcher, but I found it easier to offer the tube up and mark it off and use a softpad/flap wheel on a hand grinder to do the profiling.
It looks better in round but should also be stronger than the square equivalent, especially if it is rolled!

PS, Those 6 off 2 1/4" springs in the bottom photo are free to anyone who wants to collect them.

[Edited on 27/9/2007 by nitram38]






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RichieW

posted on 27/9/07 at 07:51 PM Reply With Quote
Think round tubes would be too much for me. I've got no engineering background. I'm slowly building my locost chassis and the square tube at least gives me points of reference with the four sides when cutting different angles at different ends of a tube. I dont know how I'd ever get the rotation right and align the fishmouths at both ends of the same tube for cutting.

I reckon the average to poor builder like me would have trouble getting his head round it.

Square is so much easier to visualise.

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chrisg

posted on 27/9/07 at 07:54 PM Reply With Quote
Looking good nitram mate!

The issues are the lightness/stiffness ratio but also the the project is "retro" and so the looks are important!

Thanks for the replies so far

Cheers

Chris





Note to all: I really don't know when to leave well alone. I tried to get clever with the mods, then when they gave me a lifeline to see the error of my ways, I tried to incite more trouble via u2u. So now I'm banned, never to return again. They should have done it years ago!

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iank

posted on 27/9/07 at 08:18 PM Reply With Quote
Some info on rortys site
http://www.rorty-design.com/content/tube_work.htm





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Anonymous

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Canada EH!

posted on 27/9/07 at 08:46 PM Reply With Quote
Round tube chassis

The interesting part comes when it's time to fit the body panels, a lot more work to bend the panels around a pipe than a flat surface, a lot of Locost builders have trouble with that back panel.
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chrisg

posted on 27/9/07 at 08:49 PM Reply With Quote
Not a problem with my own project as the bodywork is all GRP or single curvature aluminium.

I'd agree for a Locost (or any seven, really) it would certainly add work.

cheers

Chris





Note to all: I really don't know when to leave well alone. I tried to get clever with the mods, then when they gave me a lifeline to see the error of my ways, I tried to incite more trouble via u2u. So now I'm banned, never to return again. They should have done it years ago!

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Avoneer

posted on 27/9/07 at 09:02 PM Reply With Quote
And the man that wrote a book on building a chassis is asking us!

Chris - what can I say?

As a office junky and having built a chassis in square/round, I did find it a bit tricky and harder than square, especially fishmouthing with a file.

Wouldn't recommend a full round chassis for a novice.

Harder to measure and set square as well.

Pat...





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chrisg

posted on 27/9/07 at 09:09 PM Reply With Quote
quote:
Originally posted by Avoneer
And the man that wrote a book on building a chassis is asking us!

Chris - what can I say?

As a office junky and having built a chassis in square/round, I did find it a bit tricky and harder than square, especially fishmouthing with a file.

Wouldn't recommend a full round chassis for a novice.

Harder to measure and set square as well.

Pat...


Thanks for the input Pat

The chassis in the book is square tube of course, I'm just guaging opinion.

PERSONALLY I'd be able to make a round tube chassis in my tea break, obviously.

Cheers

Chris

PS how's your dental insurance?





Note to all: I really don't know when to leave well alone. I tried to get clever with the mods, then when they gave me a lifeline to see the error of my ways, I tried to incite more trouble via u2u. So now I'm banned, never to return again. They should have done it years ago!

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Mark.

posted on 27/9/07 at 09:12 PM Reply With Quote
Flap disc in an angry grinder is best cheap way of profiling tubes...there is a nice way to make patterns so easier to repeat the tubes you need but involves grp.
Mark

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caber

posted on 27/9/07 at 09:58 PM Reply With Quote
You still need to do fishmouths for the wishbones and trailing arms. I used a pillar drill, hole saw ( a proper expensive starret one) and machine vice bolted to the tilting table. It worked better than my attempts at jigging up some of the compound cuts on the square tube!

Caber

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Mark.

posted on 27/9/07 at 10:02 PM Reply With Quote
Make a "wrap" in grp once you are happy with the profile...easy to repeat time and again. No need for expensive gear then just an angry grinder with a flappy disc.

Mark

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Minicooper

posted on 27/9/07 at 10:11 PM Reply With Quote
Here is a cheaper one

http://cgi.ebay.co.uk/Car-Frame-pipe-tube-notcher-tubing-notcher-cutter-NEW_W0QQitemZ140161262656QQcmdZViewItem?hash=item140161262656&_trksid=p328 6.c38.m63.l1177

$85 dollars shipping to UK makes it all together 75 they also do heavier duty ones as well.

I have the rollcentre version, it's well made and heavy duty and if you haven't used one, in about two minutes you will have a excellent fishmouth ready to weld, it use to take ages using e a grinder and it's no where near as good

Cheers
David

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worX

posted on 27/9/07 at 10:22 PM Reply With Quote
I'd do the same thing except instead of the machine vice I welded together two lots of - a piece of 2" angle onto a 2" flat and drilled the flat so it fit the Pillar Drill bed bolt holes and then used the second one to rest on top of the piece of work so that it was clamped down if necessary (ie when fishmouthing an ultra long piece of steel!)

Steve
quote:
Originally posted by caber
You still need to do fishmouths for the wishbones and trailing arms. I used a pillar drill, hole saw ( a proper expensive starret one) and machine vice bolted to the tilting table. It worked better than my attempts at jigging up some of the compound cuts on the square tube!

Caber


I've just re-read that and it doesn't even make total sense to me, so I'll take a couple of photos if anyone needs me too!

Steve

[Edited on 27/9/07 by worX]

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timf

posted on 28/9/07 at 08:20 AM Reply With Quote
or make your own tube notcher





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Hammerhead

posted on 28/9/07 at 09:31 AM Reply With Quote
Flak Monkies website has a program that creates paper templates for fishmouths. Wrap it round the tube draw round the template and start cutting.

Tube notcher would be easier though.






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smart51

posted on 28/9/07 at 10:07 AM Reply With Quote
quote:
Originally posted by Hammerhead
Flak Monkies website has a program that creates paper templates for fishmouths. Wrap it round the tube draw round the template and start cutting.



Does it print onto masking tape?

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Hammerhead

posted on 28/9/07 at 11:05 AM Reply With Quote
quote:
Originally posted by smart51
quote:
Originally posted by Hammerhead
Flak Monkies website has a program that creates paper templates for fishmouths. Wrap it round the tube draw round the template and start cutting.



Does it print onto masking tape?


could print onto sticky a4 stickers from Staples or other office suppliers.






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nasty-bob

posted on 29/9/07 at 07:59 PM Reply With Quote
Whats wrong with a hacksaw and a half-round file. Doesn't take that long really.

But I guess I cheated- used a chopsaw and a half round.

Saw that someone asked why round is better than square. Round is better in torsion square better in bending. Really only the centreline of the chassis is in true torsion and the sides are in mostly bending. There is a point somewhere in between where square becomes favourable over round.

But then that all changes depending on how your dampers are mounted.

Apologies if someone had beat me to it with the answer.


Oh... and round just looks much nicer.


Used a bit of both in mine.
link

[Edited on 29/9/07 by nasty-bob]






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chrisg

posted on 30/9/07 at 08:19 PM Reply With Quote
That looks nice Bob!

I might have a go at building one of those DIY notchers.

Next question

Material?

mild steel or something more exotic?

Cheers

Chris





Note to all: I really don't know when to leave well alone. I tried to get clever with the mods, then when they gave me a lifeline to see the error of my ways, I tried to incite more trouble via u2u. So now I'm banned, never to return again. They should have done it years ago!

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Mark.

posted on 30/9/07 at 09:05 PM Reply With Quote
4130
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