R. Cott. 25

Further to the floor joist/heat board questions...

The grooved chipboard supplied is likely to lead to a lot of waste. Basically because joints must be supported. Noggins as discussed is one solution but an alternative would be to route a fresh groove on a 100mm radius to turn the pipe into the next slot.

I have a 1/2" router with the appropriate cutter but don't have any jigs or supplied kit to do the job safely.

ISTR John posted a circle cutting jig design but I have not found it in the Wiki. Any pointers?

Reply to
Tim Lamb
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Plenty seem to crop up on youtube, but really as it's hardly for finish carpentry, an offcut of 6mm MDF with screw holes drilled to allow it to replace your existing router base, a big hole in centre for the bit and a small hole for a pivot is all you need, rather than a fancy jig one that's adjustable for various circle diameters ..

Reply to
Andy Burns

That sounds familiar. I suppose as I only need the 100mm radius, a single peg hole in the router base would do the job.

There is likely to be a similar job where fresh grooves are needed in the *overfloor sheets* this is a 40mm thick exp. polystyrene sheet, coated with baking foil.

The suppliers blithely say that the installer may chose to cut additional grooves!

Reply to
Tim Lamb

The only thing I can recall that included a circle cut operation was: (see about 3/4" of the way down...)

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You could copy that type of arrangement by just fixing a strip of ply to the router base (say 5" wide by a however long you need) and use it as a trammel - stick a panel pin/small screw through it and into the floor at the right radius, and route round the focal point of the pin.

I think for a 100mm radius, I would simply get a offcut of thinish ply or mdf (1/2" thick or less), and cut (jigsaw, sand etc) the profile you want onto a corner of that. Then slap a guide bush in the bottom of the router (if you want an exact 100mm radius - then allow for the radius of the guide bush when setting out your template curve). Add a straight fluted cutter of whatever size you need for the pipe, position the template and route round the corner. (also with a template, you just line up the ends where you need them and don't need to worry about getting the centre of the curve in the "right" place).

You can either add a couple of small screws to temporarily fix the template to the floor, or simply make it big enough to kneel on it to hold it in place for routing.

Reply to
John Rumm

Not that although I did read it.

Routing polystyrene is going to be messy and the sheets are light enough to carry across to the workshop. I have no experience of using a guide bush but plenty of scrap Jablite floor insulation for practice.

I like the idea of a kneeler with a couple of suitable *bumps* to cut round.

Thanks

Reply to
Tim Lamb

mount blades to a little lump of wood to cut it.

NT

Reply to
tabbypurr

Hot 'knife' made from a loop of e.g. 1.5mm^2 wire and a beefy transformer?

Reply to
Andy Burns

Probably the professional way but won't there be fumes of something nasty?

I have tried the router which gives a fairly clean cut on Jablite but chews the aluminium skin on the floor sheets.

Maybe cut the ally and peel off using the block and blades followed by the router and guide to tidy up.

I'll bet the professionals don't go to this trouble as it is all going to be covered in 18mm chipboard.

Reply to
Tim Lamb

Might be a good way to get rid of the ally surface.

Perhaps one blade in a block but offset such that both sides of the cut can be done with one guide but travelled in the other direction.

Reply to
Tim Lamb

The routing jig works:-)

Mind, cutting progressive 18mm deep slots with a radiused cutter is slow. I may decide to use a straight flute and then finish off with the radius. Adjusting the router for each cut is not practical so screwing the jig down should allow me to repeat the operation using the same screw holes.

Sadly Erbaur have fitted cart springs to my cheapo m/c and saw horses/work mates do not provide a safe workbench.

Reply to
Tim Lamb

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