Mandrel bend cutting jig

I've now got myself a load of 32mm mandrel bends in 45 degree and 90 degree segments. However, I'll need to chop some of them off at other angles. They could be pretty tricky to hold while using a bandsaw or angle grinder to cut them to the required angle.

There are a few examples of 3D models that achieve this function on places like Thingiverse etc. Naively, I thought I might be able to download something that I could simply print out and use - something like these:

...but the only models I could find were expecting some form of payment, either as STL files or even as the printed items themselves, with prices ranging from ~£5 (model) to £40 (printed). Well fuck that. Apart from that being against my religion, many of them don't actually do what I need, not least being for the wrong diameter tube and none of them are parametric or even in Fusion format. Details, I know.

Fusion time:

What I want:

• Suitable for 32mm tube (ie OD, not ID)
• Settable at 5 degree increments
• Split halves, to allow easy setting and clamping
• 1mm gap between the halves so there's movement for the vise to clamp the tube
• 10mm dowels to hold halves together before being clamped
• Solid (100%) fill in ABS, so it can be solidly clamped

Like this perhaps:

Obvs you need to account for the diameter of the stop pin when setting the angular positions of the holes. Like this:

Lots of support structures in the various holes. This is my first trial attempt, using default settings (to save material). 

Came out OK but made a couple of enhancements to the design, namely:

• Rather than use 10mm dowels to align the halves, use M10 screws with captive nuts, so I can nip them up before going into the bandsaw vise.
• Use an M4 caphead screw for the tube stop. And provide a counterbore for the head on the reverse side - or in fact a whole series of them, one for each position.
• Reduce the gap between the halves from 1mm to 0.1mm. Yes, it still clamps nicely but doesn't wobble around.
• Use 100% fill, as I'm reasonably confident this is in a good enough state not to require further iterations.

And it finally printed out after 7.5 hours. Using the default fill of 25%(?) would have only saved me about 30 minutes apparently. The main difference of going for 100% fill is the cost of the material. Total usage should be around 187g. At about £15 per kg, that's about £2.85 for the final part ie not exactly extravagant.

But after some poking and pulling, it's all cleared out and working. Reamed out the holes with a couple of drills and it's a good 'un.

I will need to cut that M4 screw down to 45mm so it doesn't poke out. Later.

Also, the big M10 screws holding the halves together need to be 45mm long. Seems I have only one M10 caphead screw in my entire collection and it's about 60mm long. That's a great excuse to buy some 30, 45 and 60mm for my "stock". I'm not ready to do any pipe cutting and welding yet, so completing the final assembly of this thing can wait until I have the final delivery of u-bends from China and the screws from ebay.

Job done.