Another marking problem

[WolfieParticipant @wolfie]

[WolfieParticipant @wolfie]

Further to the question I asked earlier I have another marking problem. Imagine a piece of drainpipe around 3 1/2" in diameter. At one end is a rounded hemispherical cap. At the other is a ragged cut. I need to mark out a cut line so I can cut it parallel to the rounded end. Obviously I can't balance it accurately enough on the rounded end, and neither is the ragged end good enough to use.

How do I do this??

[Michael GilliganParticipant @michaelgilligan61133]

Assuming that the thing has some readonable length [which you do not mention], just wrap a sheet of paper around it. … a strip from a sheet of A3 would be good.

Provided that you have one good straight edge to the sheet, it's a simple matter to align it; add a strip of tape, and mark your tube with a permanent marker.

MichaelG.

[WolfieParticipant @wolfie]

Brilliant, thankyou

[jason udallParticipant @jasonudall57142]

If a flat surface with say a corner is available…..bring top of dome ( or cone or any “right” end..) into contact…measure from that “fence”..mark with scribe block or felt tip pen held at required distance..roll object against scribe……I have made that sound more complex than it is…

[Steve SharmanParticipant @stevesharman33815]

How long? Last time I had to do something like that I took the tailstock off the lathe, dropped the tube between the slideways, set the distance with the saddle and used the end of the bed to hold the pencil against.

[JasonBModerator @jasonb]

Paper method works quite well, another option is to stand an angle plate* on end and clamp the pipe to the inside as it effectively gives you a large Vee block. Then just use a height gauge to scribe the line around the job.

* needs to be one thats machined all over not cast on the inside

[WolfieParticipant @wolfie]

Excellent ideas, thanks chaps

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