Cut 150mm pipe neat and square

[Why Not Indeed]

I need to trim down some 150mm ducting for a hood extractor.
How can I do this neatly? I don't have a 150mm mitre box.
I have various hand saws and lots of scrap wood.

 

[Why Not Indeed]

At the risk of answering my own question, I think the answer is to build a 150mm mitre box out of scrap wood.

 

[Burnerman]

I wrap a length of broad sticky tape (Gorilla or similar) and pass it round, so the edges join. The broader the better really.
Then, it's out with a suitable back saw, a bit at a time. It's certainly accurate enough!
John

 

[Harry Bloomfield]

How can I do this neatly? I don't have a 150mm mitre box.

Elastic band, slightly tight around the pipe, adjust it so it square, then use the band to mark up a cut line. Saw, using the line you marked.

 

[Why Not Indeed]

I rigged this up and the ratchet strap did a lot of the work here:

The ratchet strap passes under a piece of timber that you can barely see in the picture, which is screwed in to the bench.
The resulting cut was much neater than expected.

 

[johnny2007]

I wrap a length of broad sticky tape (Gorilla or similar) and pass it round, so the edges join. The broader the better really.
Then, it's out with a suitable back saw, a bit at a time. It's certainly accurate enough!
John

This

 

[morqthana]

I need to trim down some 150mm ducting for a hood extractor.

Will it be visible once cut and installed?