How to cut MDPE pipe square!!!??

[wuptdo]

I am trying to cut some 20mm mdpe pipe square in practice for joining with some imperial 21.5mm alkathene with some phillmac fittings. This will be buried and I want to make sure this is pretty darn leak proof.

I have tried (and none of these are cheeaap!):
- non brand ratcheting 0-40mm cutters. These cleanly cut but there's so much play in the blade that getting a square cut is merely luck.
- a rotary 15-22mm plastic rothenburger cutter, this failed miserably. These don't actually get through the material, but even using them as a starting point it's not square!!!!!
- a 0-22mm rocut 28 rothenburger pipe pex shears. There's no play in the blade ... But these squash the pipe more than the ratchet ones and it's still not square!!!!

What am I doing wrong? Any tips would be massively appreciated. Do I have to straighten out the mdpe with boiling water before I cut it to get it square?

 

[conny]

Wrap a strip of newspaper/A4 paper around the pipe so that the edges meet perfectly.
Very carefully, with a fine tooth saw, cut along the edge of the newspaper.
If you are using pipe weld to join them together I'm sure it will be ok if it's not precisely square.
The only other way, if you want to be pedantic, is to sit it in a channel which touches on 3 sides of the pipe and, again, cut with a fine tooth saw precisely down the edge of the channel.

 

[^woody^]

It seems like its your technique, not the tools.

With ratchet cutters, if you close them until the blade touches the pipe, then rotate the cutters slightly to get the blade to bite and then tighten them they should cut squarely, I can't imagine how they would not.

 

[wuptdo]

To illustrate the play in the ratcheting non brand ones...

 

[^woody^]

But surely when you set the blade on the mark and it penetrates the pipe it goes through square with negligible variance?

If you are concerned, drop a shim in between those guides. Some cardboard for example.

 

[wuptdo]

Thanks again. I suppose it depends on your definition of negligible. See these two images and the insert as a reference. One I could agree with. One I certainly could not.

 

[wuptdo]

A shim between the guides is a good suggestion however I may give it a go.

 

[John D v2.0]

Why does it need to be so square? Those kind of fittings usually seals and clamps miles away from the end.
Leaks are more likely to be caused by forces on the fitting, for the sake of 2 minutes I'd probably wrap it in something compressible before burying it in anything hard.