diamond core drill for SVP

[Robbox]

I've seen other posts around this subject, but I live in an old cottage with 500mm+ solid stone walls. I'd like to route the SVP outside to release valuable space in the bathroom. Is this something for the professionals or if I hired the kit, something the plumber/fitter could do?
I can see problems like finding a long core section for the thick walls and since the SVP is in a corner, it may get cramped with a long core and the large drill.
Would a 127mm core give the necessary wiggle room over 500mm+?
Would it be possible to start the hole with a short core and then add extensions?
One final Q, can I reduce the SVP to 75mm to make the job easier. This reduction would only be for the venting section above any inflow sections.

 

[RedHerring2]

I've used a 127mm core drill for 110mm soil pipe, no problems.

Yes. you can start with a short arbor then change to a long one, but I don't think you'll get one long enough to go through 500mm. The normal practice would be to put the drill through and work from both sides. I've used a short one to go through 250mm wall. The long arbor maybe 200mm so you'll get close.

But, my experience of stone walls is that they are not solid stone all the way through, Usually they are made up of two skins of stone with rubble in the middle.
If your walls are random/rubble stone walls you're probably just as well to knock the stones out and rebuild around the pipe.

When I used a 127mm drill it was going through old imperial bricks, with a black interior and a double skin wall. It was a long hard slog. As I had four holes to do, after the first one I did just the first 20mm or so, then knocked the rest through with the SDS drill on hammer only.
By contrast. doing a 75mm core drill through lightweight block and concrete block, (250mm cavity wall) yesterday was a piece of cake.