cutting a large cylinder at an angle.

  1. johnser

    johnser Member

    Messages:
    1,534
    Location:
    North Cornwall
    I'd like to chop a thin walled cylinder at an angle, much like I'd achieve by putting a bit of pipe in a chop saw. However, it's about 2ft diameter.

    Any nifty tricks to get a good mitre angle?
    Have angle grinder or plasma at my disposal so really looking for a way to mark accurately...
     
  2. anto44

    anto44 Member

    Messages:
    847
    Location:
    ireland
    I have an app that can be used. To make a paper template to wrap around the pipe to mark it. If you get the exact diameter in mm i can post a screen shot of the measurements.
     
  3. eLuSiVeMiTe

    eLuSiVeMiTe Member

    Messages:
    4,151
    Location:
    Bedfordshire England
    Got a cross line laser level.

    Wrap the beam around as far as poss then turn and align to previously marked a couple of times to complete.

    Never tried but can't see why it wouldn't work.
     
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  4. anto44

    anto44 Member

    Messages:
    847
    Location:
    ireland
    here's an example
    Screenshot_20181108-181756_Flat Pattern.jpg
    Screenshot_20181108-181810_Flat Pattern.jpg
    Screenshot_20181108-181826_Flat Pattern.jpg
    Screenshot_20181108-181841_Flat Pattern.jpg
     
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  5. Paul.

    Paul. Moderator Staff Member

    Messages:
    5,638
    Location:
    Northampton. UK
    A template as Anto44 says is the proper way to do it, its a simple enough development.
     
  6. julianf

    julianf Member

    Messages:
    3,325
    Location:
    devon, uk
    Have you got a laser level? Im wondering if you couldnt use that to mark out one side, and then rotate it for the other?


    edit: im sure a template is better though!
     
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  7. anto44

    anto44 Member

    Messages:
    847
    Location:
    ireland
    If you give me the dimensions in the pic above and how many divisions you want it to have I'll post the measurements and you can draw it out on paper
     
  8. johnser

    johnser Member

    Messages:
    1,534
    Location:
    North Cornwall
    That looks ideal! Can I ask what the app is?

    Nope, unfortunately not. I had thought something like that might work though.
     
  9. johnser

    johnser Member

    Messages:
    1,534
    Location:
    North Cornwall
    I'm a while off chopping yet...
     
  10. anto44

    anto44 Member

    Messages:
    847
    Location:
    ireland
    It's called flat pattern, it's a free to download app. Here's all the patterns it can do
    Screenshot_20181108-183316_Flat Pattern.jpg
     
  11. Ruffian Member

    Messages:
    976
    Location:
    Devon UK
    Small Cut's at 2 points, (top and bottom of angle)

    Use a piece of elastic or string and wrap into those 2 cuts. Gives nice straight lines. Especially if spray paint over the string then remove gives you a nice sharp line to follow.
     
  12. 8ob

    8ob Member

    Messages:
    2,534
    Location:
    moscow on thames
    Curv o mark is a good tool for marking angles on pipe, there was a thread on here somewhere about all this but I cant find it :dontknow:

    Good for any pipe up to about 48" diameter

    [​IMG]

    [​IMG]
     
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  13. bigegg

    bigegg I drink and I know things. Its what I do.

    Messages:
    4,602
    Location:
    Leeds, West Yorkshire
    when I asked the question earlier this year, I was pointed to a tool which was basically an articulated arm carrying a piece of chalk on a "v" plate base.
    the base rested on the cylinder (is it orange? :whistle: ) and the arm swung round to a particular angle, then the arm carried the chalk along that angle, around the cylinder.

    it's still on my "to do" list, and I've forgotten the name of the tool.
     
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  14. bigegg

    bigegg I drink and I know things. Its what I do.

    Messages:
    4,602
    Location:
    Leeds, West Yorkshire
  15. chris pruteanu Member

    Messages:
    219
    Location:
    ROMANIA
    Thats ingenious and the way i'veit done a few times cutting large pipes...
     
  16. Bladevane

    Bladevane Member

    Messages:
    323
    Location:
    Harwell, Oxon
    Wrap a length of string around the cylinder, secure it with masking tape at intervals then draw the cutting line on with a sharpie. Templates will need a piece of paper (or bits stuck together) over 6' in length.
     
  17. Paul.

    Paul. Moderator Staff Member

    Messages:
    5,638
    Location:
    Northampton. UK
    Not really, the biggest one I've done was a 2 mtr dia hopper that had to have a 30 deg sloping top cut on it, I drew it out to scale to get some dimensions, drew vertical lines on the job all the way round the circumference and marked the cut points direct on the job. it was a 5mm wall hopper and was then cut with oxy acetylene.
     
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  18. cumbriasteve

    cumbriasteve Moderator Staff Member

    Messages:
    9,439
    Location:
    Cumbria UK
    A hillbilly way is sit it in a tank of water at the angle you want then chalk mark the wet line, seen the old guys do it a few times down the old loco yards.
     
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  19. johnser

    johnser Member

    Messages:
    1,534
    Location:
    North Cornwall
    Thanks for all the replies - that app looks ideal!

    Ha! Love it, that's the sort of thinking I were after. Backup plan

    It's for an oil drum but didn't want to start off yet another thread about how not to blow oneself up. Needless to say, precautions will be taken.
     
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  20. 8ob

    8ob Member

    Messages:
    2,534
    Location:
    moscow on thames
    I can see you getting thrown out of the Lido trying to pull that stunt :laughing:

    Bob
     
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