# Undermount sink jig - ideas please



## Gwilym (28 Jul 2009)

Hi all,

I've bought an undermount sink for a kitchen I'll be fitting next week - Franke ARX 160 if anyone wants all the details. The template it comes with for cutting is just a bit of flimsy card in the exact shape of the hole you need to cut out - not sturdy enough to guide a router, and even if it was, using it direct would result in a hole too big (by the cutter diameter) with the risk that any slip goes straight into the bit of worktop I want to keep. I want to have a "negative" template that I can route round the inside of (using 1/2" cutter & guide bush, ideally, though would go with a bearing-guided cutter if not) so that if I slip off the template it's the waste bit that gets chewed up rather than the worktop. Means I need to cut myself a jig 8.65mm bigger all round (offset of 1/2" cutter inside 30mm bush) than the bit of card (or the exact size & shape of the card if I go bearing-guided).

Short of drawing round it and cutting very carefully (not my forte!) with a jigsaw (or taking measurements off it and drawing from scratch with ruler and compasses), does anyone have any cunning ideas how to turn a flimsy "positive" template into a (pref 8.65mm bigger) negative one?

I'm sure there must be pro's out there who do this every week... what's the secret (or is it just a steady hand on the jigsaw?)!

Thanks!


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## jasonB (28 Jul 2009)

You can download the exact sizes from Franke's site. and make your template from these. Adjust to allow what overhang you want as some of then have no overhang

Or download a DXF file and put it into your CNC machine :wink: 

Jason

Click on "cut out download" from this page


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## Gwilym (28 Jul 2009)

Jason, thanks for the idea... unfortunately my CNC machine was in the boot of my Ferrari when it was nicked last week  

As for downloading dimensions, that still involves drawing and cutting with a jigsaw - I was hoping to avoid anything that involved making up a template from a drawing only - the chances of me getting the straight sides at a perfect tangent to the curved corners are pretty low, and trying to follow the line perfectly with a jigsaw will also probably result in a large pile of scrapped templates before I get one I'm happy with! Hoping somebody has a quick and infallible way to somehow make use of the card template... I don't understand what it's there for at the moment!!


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## Karl (29 Jul 2009)

Why not draw a secondary line outside your card template which reflects the offset of the guide bush and cutter which you intend to use. Cut out the template to this secondary line and transfer it to a large piece of MDF. Cut out the MDF and [carefully] clean up the innder edges. Hey Presto. A "jig" which can be clamped to the worktop. If you've done your measurements correctly all you need to do is run round the inside of the jig with your router and guide bush to make a perfect fit.

Cheers

Karl


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## jasonB (29 Jul 2009)

Draw it out on a bit of 6mm MDF. Use a circle cutting jig with your router to cut the curved corners then clamp a straight edge between the two circles touching the tangent and use a bearing guided cutter against that.

Should be quite accurate and all the lines will be straight.

When doing them with granite the usual way is to cut a rough hole in the template then reach up inside the sink with a marker pen and trace round the edge of the sink, this gives a 6-8mm overhang. Once back in the workshop the edges are straightened up and its cut out.

Jason


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## Racers (29 Jul 2009)

Hi,

I did one of these a while ago. I marked it out from the template on an old cupboard side added the offset 9mm on all the straight edges then using a compass I marked the corners. I can't remember if the centers are marked on the template or I found them by drawing lines 90 deg from the start on the corners then cut it out with a jig saw sanded it smooth, it didn't take long to do the jig, I cut most of the hole out using a circular saw and jig saw, then used the router to clean up the edge and round over the top.

Its a bit of a white knuckle job knowing one slip could cost lots but the flange on the sink is quite wide so you have some room to go wrong.

Pete


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## Gwilym (29 Jul 2009)

Thanks for the suggestions, guys... I'll let you know how I get on next week! Cheers!


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## Mcluma (16 Mar 2011)

Gwilym":2oixtzlb said:


> Hi all,
> 
> I've bought an undermount sink for a kitchen I'll be fitting next week - Franke ARX 160 if anyone wants all the details. The template it comes with for cutting is just a bit of flimsy card in the exact shape of the hole you need to cut out - not sturdy enough to guide a router, and even if it was, using it direct would result in a hole too big (by the cutter diameter) with the risk that any slip goes straight into the bit of worktop I want to keep. I want to have a "negative" template that I can route round the inside of (using 1/2" cutter & guide bush, ideally, though would go with a bearing-guided cutter if not) so that if I slip off the template it's the waste bit that gets chewed up rather than the worktop. Means I need to cut myself a jig 8.65mm bigger all round (offset of 1/2" cutter inside 30mm bush) than the bit of card (or the exact size & shape of the card if I go bearing-guided).
> 
> ...




what is your worktop?? if it is particle board an undermounth will look silly


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## jasonB (16 Mar 2011)

Its an old post brought back up by a spammer, don't waste your time with replying, I've already reported it and the spam has been removed

J


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