Making sink cutout in existing worktop larger

[Con Owen]

Hi

Worktop is in situ. I have to make the existing cutout 480 x 950 larger to 492 x 982 with 15mm radius at corners (sink is Blanco Classic 6S). I cannot extend length to the left (dishwasher beneath) or the front which I would prefer, as existing cutout is actually touching the faceframe. So I will extend at the back, cutting this with a jigsaw, the rh side with a router as there is a cupboard beneath the worktop. Is there a better method? I am not sure how to do the radius. Would it give me the correct radius if I drill in each corner with a 30mm spade cutter with the outer edges of the cutter touching say the back edge cutline and rh cutline or use a compas and do a 30mm circle in each corner again touching the cut line on both cutline edgesand using the jigsaw? Beneath the sink there is a continuous tube all round (looks good quality) which I assume is to stop the ingress of water. Are these any good? Should I still use a sealant and if so which is best?

Cheers
Cono

 

[petermillard]

If there isn't space to get a plunge saw in there then a jigsaw's OK, probably with a downcut blade? Again, if you can't get a plunge saw in for the right-hand edge, then a router would do it, but it'll be messy.

There's usually a lip of 15mm or so on the sink, so the cut doesn't have to be that good to be honest; Multimaster might be a better way as it's a relatively short cut - you can double-side a disposable straight-edge to the waste side and cut against it.

Not sure you really have to have a radius at the corners; try a straight cut-out in a piece of scrap MDF and see of it's necessary; I always thought the radiuses corners were more because they were routed out <shrug> but I'm sure someone will be along to tell me I've been doing it all wrong for the last ten years, lol

HTH, Pete

 

[JoinerySolutions]

Jigsaw it. If you don't have a down cut blade or machine with a splinter guard score the laminate with a sharp marking guage first and cut to this scribed line. Pre drill the corners with a good lip and spur bit, 13mm would probably suffice in this case.
Regards Rob.

 

[Con Owen]

Hi

Was unable to obtain a reverse cut jigsaw blade that could cut to the depth of the worktop, 40mm. They appear to only come in 30mm depth of cut (yet Axminsters catalogue gives the depth of cut up to 40mm for the Bosch). I obtained these blades from a local source and had to take them back as the max depth was only 30mm. In the end I used a bimetal bladewith a chip guard in the jogsaw, it was a real effort to control and I was lucky that the blade was a good quality Bosch. I ended up with a very smooth edge with only one chip out. The router was excellent, just took it carefully doing passes of 4mm.
For future reference does anyone know of a supplier of jigsaw blades that will cut to 40mm depth?

Regards

Cono

 

[jasonB]

Always drill the corners even if its just with a small dia bit it helps prevent any stress risers where a crack in the laminate can start. A 30mm flat bit will be fine. (sorry Pete)

Bosch T101BRF blades will downcut 45mm in worktops, Axi or screwfix should have them. Don't use any pendulum action with the downcuts

Jason

Edit Cant see them on Axi but OK on Screwfix

 

[JoinerySolutions]

Hi

For future reference does anyone know of a supplier of jigsaw blades that will cut to 40mm depth?

Regards

Cono

Festool make blades that will cut 100mm, up cut type, but with the festool splinter guard system it has not been a problem. ( You use the blade in use to cut the kerf into the splinter guard). Most Festool dealers should have them, though not Axi in Bobbing Kent.