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Author: Subject: How do I cut accurate angles?
LoCorun

posted on 31/12/05 at 02:13 AM Reply With Quote
How do I cut accurate angles?

Well, I've got the tube and atleast some of it is cut to length. How on earth to I get cut the angles? I was originally thinking using a protractor and marking a line... But all protractors are too big.

I don't have a mitre box and I'd rather not get one unless I have to. The book doesn't say you need one (though it doesn't say how to cut the angles either...).

What have you guys done and what should I do? :-)

Also, how accurate do the angles really need to be?

Thanks.

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Alan B

posted on 31/12/05 at 03:11 AM Reply With Quote
You need a proper engineering protractor....here is an example...click here.....then enter 2061 in the search box and then scroll down to the protractor.

As for accuracy, set it as close as you can with the naked eye and should be close enough. In reality you can possibly be a couple of degrees out before you have a gap too big at the joint, but aim for the best you can.

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bigdaddyadd

posted on 31/12/05 at 07:55 AM Reply With Quote
I would mark each part by hand if you are only planning to build the one chassis and cut with a very thin disc on a 4.5" grinder. The reason for this is that several of the tubes have double splays and if you are fairly new to welding having a touch on edge but a big gap for the other 3 will leave you struggling to fill gaps. The easiet way is with a square and a steel rule. calculate angles from given dimensional lengths and lengths from given angles with trig. All the calcs you need can be found in the back of zues pocket book. (get one from tool suppliers)or if you are struggling I could send you a copy with a few pointers.
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caber

posted on 31/12/05 at 09:10 AM Reply With Quote
Print out Mc Sorely plans preferably on A3 paper and lay the tubes over the plan to scribe the angles. Don't trust a chop off saw to give accurate angles :-( guess how I found out! Cut tubes with angle grinder and finish to the scribe line with a flat file if you want dead accurate alignment otherwise you will end up filling gaps with weld!

Caber

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Hugh Paterson

posted on 31/12/05 at 09:47 AM Reply With Quote
Protractor and adjustable bevel gauge, two 4 1/2" grinders one with a thin disc cut off blade one with a ali/zirconium buffing disc to take to the scribe line. Flat files are for blacksmiths
Shug.

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907

posted on 31/12/05 at 10:05 AM Reply With Quote
Machine Mart do a very nice combination set.
Cast Iron, not cheapo ally.

Not up to Moore & Wright or Mitotoyo (speeling), but then it's not £200.

A sliding square makes a great backmark.

Paul G

(The top pic is their protractor, I havn't got one of these.)


How do you do a Link?



[Edited on 31/12/05 by 907] Rescued attachment protractor-combination-set.jpg
Rescued attachment protractor-combination-set.jpg







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rash

posted on 31/12/05 at 10:29 AM Reply With Quote
"Flat files are for blacksmiths"
flat files are for engineers grinders are for lazy gits

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907

posted on 31/12/05 at 11:31 AM Reply With Quote
quote:
Originally posted by rash
"Flat files are for blacksmiths"
flat files are for engineers grinders are for lazy gits





And band saws are for engineers who are lazy gits.






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andyps

posted on 31/12/05 at 12:17 PM Reply With Quote
I'm using a "variable" set square which I made at school (many years ago) - I knew it would come in useful one day! The McSorley plans on A4 are accurate enough for me to line up the square, set its angle and then scribe it on the tube. Then I have to try and guide the hacksaw accurately. All my gaps should be weldable





Andy

An expert is someone who knows more and more about less and less

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Gav

posted on 31/12/05 at 12:28 PM Reply With Quote
I did mine with a combination set and its resonably accurate.

The worst bit was marking/cutting the compound angles on the "L" section and the two diagonals for the section behind the seats.

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mangogrooveworkshop

posted on 31/12/05 at 12:34 PM Reply With Quote
quote:
Originally posted by 907
quote:
Originally posted by rash
"Flat files are for blacksmiths"
flat files are for engineers grinders are for lazy gits





And band saws are for engineers who are lazy gits.




And what about a fluid cooled bandsaw.........







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Wadders

posted on 31/12/05 at 12:39 PM Reply With Quote
Theyr'e for rich engineers who are lazy






Originally posted by mangogrooveworkshop
quote:
Originally posted by 907
quote:
Originally posted by rash
"Flat files are for blacksmiths"
flat files are for engineers grinders are for lazy gits





And band saws are for engineers who are lazy gits.




And what about a fluid cooled bandsaw.........


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JoelP

posted on 31/12/05 at 12:44 PM Reply With Quote
im disillusioned with band saws, mine just wont cut perfect even after some fiddling. Plus it derails itself now and again, which wastes more time than using a grinder would. Id love to get a bigger band saw, but cant bear the risk that it would still be crap.

plus it cant do compound angles or extreme angles.

[Edited on 31/12/05 by JoelP]





Beware! Bourettes is binfectious.

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907

posted on 31/12/05 at 01:02 PM Reply With Quote
quote:
Originally posted by JoelP



plus it cant do compound angles








Waddayamean?

Say 30 sloping @ 10 deg....

Set vice at 30. tip up 10.

job done.

(mine was £175 by the way. Less than a dishwasher)

Paul G






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JoelP

posted on 31/12/05 at 04:28 PM Reply With Quote
ok, so you can wedge it to compound angles! mine was about 200 from machine mart, i think a large work support would make it better.





Beware! Bourettes is binfectious.

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Hugh Paterson

posted on 31/12/05 at 05:48 PM Reply With Quote
Compound angles eh, that would be my nice German tungsten tipped dry chop saw that cost squat when the blacksmith next door went bust, now if I could only find the bluddy blade fer it. He got it from an auction and it lay the corner of his workshop for so long it ended up covered in offcuts.
Shug

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emsfactory

posted on 31/12/05 at 05:55 PM Reply With Quote
ive got the 200 odd quid clarke job too. Very happy with its accuracy. Much better than pissing about with a grinder. The belt can pop off if you dont have it tight enough or if the piece your cutting is not supported properly. They can pinch towardes the end of a cut.
Having a crap blade doesn't help either.

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emsfactory

posted on 31/12/05 at 06:00 PM Reply With Quote
Got this for my lathe. Works well for the bandsaw too.
http://www.axminster.co.uk/name/coolant/sfile/1/jump/0/product-Axminster-Coolant-System-21084.htm
If you cant spring to that a wee squirt with lusol or WD40 on the blade as you start to cut makes it run nice and smooth.

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LoCorun

posted on 31/12/05 at 06:42 PM Reply With Quote
Went down to B & Q Today. I got this cool protratory thing, basically it's like a set square but it allows you to set the angle. It looks perfect for the job. I hope to have a rolling chassis by March. *crosses fingers*.
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David Jenkins

posted on 31/12/05 at 08:37 PM Reply With Quote
I've got a good hacksaw...

2 factors in its favour:-

1. Cheaper than a grinder or a band saw

2. Really quiet when working late at night in the garage.

Bonus factor - gave me a work-out every time I did some cutting!

It did help having a good hacksaw frame, and good blades.

I'm sure that I wasn't much slower doing it by hand, when compared to the time needed to set up a machine.

David






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Hugh Paterson

posted on 31/12/05 at 08:43 PM Reply With Quote
David.
IMHO hacksaws are usefull for developing barmaids Biceps and nowt else
Shug.

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Simon

posted on 1/1/06 at 12:40 AM Reply With Quote
I cut out all my chassis tubes with a hacksaw (in two days) - by the time you get to the last few tubes, you'll be cutting perfect angles without measuring them

ATB

Simon






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