Multitool blades for sinking back boxes and cutting chases?

I have used carbide blades on breeze blocks and it works successfully, mainly to mark the peripheries of the holes plus a few cross cuts before gently chiselling out the remainder. Some boxes I sunk required no patching of the plaster such was the accuracy with the front plate completely covering any gaps.

Richard

Pretty well anything like that will do a clean cut into lime plaster. The problem is the vibration etc cause chasing out the brick or whatever behind it, if the plaster is not as secure as once.

For a delicate wall I tend to drill lots of small holes with an SDS drill. Fine where you have plenty free time. But for many it might be better to use a quicker way, and make good afterwards, as there's bound to be some needed anyway.

TC & diamond do the same job, TC at a fraction the price. The only reason to use diamond is if you're sharpening TC.

NT

In haired lime plaster you can cut the outline with a Stanley knife then remove the waste with e.g. an old wood chisel.

Thanks for the responses. A TC blade in a multitool worked well on the plaster but didn't touch the walls, which are built with particularly dense concrete blocks. Stitch drilling the blocks with the SDS, and breaking out with a scutch chisel, soon got the boxes sunk. This is the first time I've used a scutch chisel, previously using regular bolsters and SDS chisels - what a revelation! It almost makes box sinking a pleasure.

When the house was built the sockets were on the skirting and the cables were run in oval steel conduit. At some time in the past the wiring was replaced with PVC, using the existing conduit. I'm raising the sockets to about 480 mm so have had to carefully (using a dremel and nibbler) cut the conduit open so the cables can exit just above the sockets - fiddly but satisfying.

They must be some tough blocks. Sometime back I was running some conduit outside my daughters house over some dressed stone facings which occasionally required a slight groove cutting in the faces, having forgot my angle grinder ( I know it was a cardinal sin for someone on this Usenet group). Anyway, I used the multitool and it certainly did the job outlining the edges of the grooves, slower but certainly not struggling.

Richard