Hi Builders
I'm reading the book using a dictionary because my language is spanish, and I just have started welding classes this week, so as you can see, I am very new.
I've found my first problem when I started cutting some tubes to test my welding.
My plans are to cut my tube lengths using a hacksaw, but I found out that it's not easy to cut square faced ends, and I don't want to think about angle cutting or even measuring angles.

any suggestion? thanks

Juan

Buy yourself an attachment to turn your large angle grinder into a chop saw.

Its money well spent.
Cheers,
Bob

Unless you want to go to the expense of a chop saw or an angle grinder attachment that performs a similar function I would suggest that all you need to do is practice, you will soon get the hang of hand sawing.
Cut the tube 1 or 2mm oversize and tidy up the cut with a file or angle grinder.



Mick

[Edited on 11/11/04 by Mix]

You will need a couple of marking-out tools:

- a scribe (a hardened sharp point to make scratches on metal)
- a protractor (click here)

Mark the metal with the scribe and protractor, so that all the angles are correct and the end of the last line meets the start of the first one.

Hacksaw close to this line, then use a file to finish it off. You'll now be exactly right! (or good enough for welding, anyway).

Some people use an angle grinder in a mitre frame, but I found the hacksaw and file method worked perfectly OK.

Hope this helps!

David

make or buy a saw guide block

atb
steve

It sounds as if you're just hacking straight through with the hacksaw. Don't.
Mark a scribe line on each face as described above and saw on the waste side if the scribe line on each face separately.
If you just hack straight through tube the saw kerf will wander & you can't stop it. It's also impossible to cut the more acute angles.
No big deal - doesn't take long. I hacksawed my chassis in about 2 days work - welding took rather longer.
Bob C

Draw your angles on all sides of your metal and cut one side at a time till you get better at it. It takes longer but there is less tidying with the file. You soon get good at filling gaps with the welder if your cuts are not perfect.

Get an angle grinder with the really thin ( less than 1mm) blades.
You'll be through each tube in about 10 seconds!

Also, you probably know this from reading the forum, but don't cut all your tubes at once as there are mistakes in the book cutting list.
Goto http://www.mcsorley.net to get an accurate chassis plan.

Also, get in contact with Alez on this site as he lives in Madrid.

Hope that helps,

James

I am at the same stage.
A mitre cutting jig with fine blade and adjustable angle works very well, just needs a touch with a file to de-burr.

Try not to leave gaps due to wonky cuts that need to be filled by the welder - it leads to distortion of the chassis. Snug fits are best.

If I have a compund angle to cut on a square tube, I scribe the line on every side and then hacksaw down one side at a time, turning the tube 90 degrees in the vice after each cut.

The angled grinder jigs are ok for 90 degree cuts, but the one I have is not made very well, the pivot has a lot of slop so I don't use it for anything that needs good accuracy.

I cut tubes when I needed them, using a hacksaw and file. I'm fairly good with these tools, and could cut and finish a piece in well under 5 minutes (after marking out).

I know an angle-grinder jig might have done it quicker, but I did most of my work in the late evening and didn't want the noise, burnt metal smell and the pervasive abrasive dust everywhere (I have a number of machine tools nearby) - my garage is attached to the side of the house, and I wanted to stay on good terms with my neighbours!

Anyway, I find hacksawing and filing strangely relaxing!


David

There is a perception that it's easier to build a square-tube chassis then round tube. Cutting square tubes in a single plane is one thing, but just wait until you have to cut the tube when it's coming in at an odd angle to meet two other square tubes. Much, much more difficult and a hacksaw or even bandsaw won't get it done. This is where using round tubes is superior. Carefully pick and choose what type of tubing you want where. Square tubing is normally used only when paneling needs to be attached. IIRC the locost doesn't have many/any compound off axis junctions, but just be aware round tubing is easier to deal with in that case.

kb58 - sorry, but I disagree with almost all of that!

I had no problem with odd angles in square tube, but had to use that mitre software on my PC to get round tube correctly cut (I hate welding round tube as well!)

...but that's just my opinion (see sig below)

David

Sorry, just thick I suppose but I can't see how cutting a compound mitre using round section can be easier than using square section. (Assuming using only basic hand tools).
Would you enlighten me ?

Cheers Mick

I guess it's because you don't get the 'angled in 2 planes' problem you get in square (e.g. the uprights on the radiator mount on the chassis). You're always going to get 'angled in 1 plane' on round! However, I always found getting the angled cuts in the correct orientation at each end of round tube very difficult - that's MUCH easier in square!

David

David
I think you've hit the nail on the head there. With round section there is no easily identifyable base reference whereas with square there are four.
I'll be sticking with square section wherever possible.

Mick

Oh and wasn't KB58 refering to a three tube junction.

[Edited on 11/11/04 by Mix]

Thank you guys, lots of good advice , Im sure that I could do the job now.

Pablo

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Originally posted by blueshift
Try not to leave gaps due to wonky cuts that need to be filled by the welder - it leads to distortion of the chassis. Snug fits are best.

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Originally posted by gazza285
Leaving a slight gap is actually the prefered method of welding thin wall tubing as the weld then fills the joint (rather than sitting on it), leaving a stronger weld. It also allows for the weld to be ground down flat without too much strength loss.

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Rorty... that's one heck of an avatar. Was that lifted from a video game or digitized footage of an actual model. Pretty amazing if it's computer amimated.

Very informative post. Thanx guys, cleared up a few issues I had myself.

Agree with Rorty re no gaps. Been practicing on 2/1.6/1 mm for the past few months MIG/TIG. Found that any gap tends to distort the piece when fully welding - even after clamping and tacking. Also found that 1.6 is thin enough so no gap is required. Have'nt tried bevelling yet but will do so.

Always used soapstone markers then got scribe a few weeks back - much more accurate, better fitup.

That's 15 years of pipe welding experience up the spout then.

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Originally posted by cassidym
Very informative post. Thanx guys, cleared up a few issues I had myself.

Agree with Rorty re no gaps. Been practicing on 2/1.6/1 mm for the past few months MIG/TIG. Found that any gap tends to distort the piece when fully welding - even after clamping and tacking. Also found that 1.6 is thin enough so no gap is required. Have'nt tried bevelling yet but will do so.

Always used soapstone markers then got scribe a few weeks back - much more accurate, better fitup.

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gazza, I do humbly apologize for contradicting you and must admit that I'll never be able to equal your welding skill as a pipe weldor.

But it really do seem to be easier for a newbie weldor like me to maintain correct alignment on thinner materials when there is no gap.

For the past few months I've also been welding sheet metal panels into one of my cars and have done extensive research beforehand. The general consensus was to maintain a slight gap BUT I've found one article where the guy recommended no gap. Tried both ways and concluded that a slight gap not only leads to misalignment but also easier to burn thro. No doubt that as my skill improve (hopefully) I'll be able to weld thin materials with a gap but at this stage it is too much of a batlle.

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Originally posted by gazza285
That's 15 years of pipe welding experience up the spout then.

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Mark, for a newbie's education - how do you make allowance for the contraction?

Currently distortion is my main enemy and I still have'nt got that intuitive understanding of distortion and how to manage it properly.

After I had fully welded my chassis, I had 3mm lift on the right and 4mm on the left, I cut the (quick look in book!) TR tubes 2 and 3mm too long and wedged them in after raising the chassis on spare bits of rhs/erw. This dipped the chassis by 1mm on both sides. After welding it was true on both sides. If the chassis had drooped, I would have cut them short and let the distortion draw the chassis up.

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Originally posted by Mark Allanson
... I used to use blade wedges and chalk (yes, Rorty chalk! ...)

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My accuracy greatly improved when I started using a scribe.

A problem still is when I want to draw a line across all faces of the tube. The round edges of the corners throws me off by a .05 to 1mm which I find unacceptable.

I've tried diff. techniques to extend the line but it's still a 50/50 type of affair.

Thanx guys.

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Originally posted by cassidym
A problem still is when I want to draw a line across all faces of the tube. The round edges of the corners throws me off by a .05 to 1mm which I find unacceptable.

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Why do I suddenly feel so stupid! zaz

Very, very obvious solution - thanx pintoman. vc

Sorry bout the extra words at the end of each sentence.

No it's not a foreign language - it was my 1 year old son who helped me with my reply, little bugger.

I had 3 year old grandson helping me modify an airbox the other day. His solution to what to cut it with, some scissors .

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Originally posted by cassidym
Sorry bout the extra words at the end of each sentence.

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