Routing Plastic

[ByronBlack]

I wanted to ask a quick question:

Is it possible to route into the white low-friction plastic that Rutlands sell for jig making? If so, would I require a special router-bit or specific speed setting?

 

[Neil]

Its not only possible, its also just about the easiest, nicest material to route that I know of! Ordinary router bits are fine - in terms of speed I've always just used normal settings for wood, but maybe Scrit will correct me.

<edit> I've just routed some to make up a new split fence for the router table:

Cheers,
Neil

 

[Alf]

Planes nicely too...

 

[Neil]

Planes nicely too...

Doesn't it? Such fun that its very easy to plane past the line

cheers,
Neil

 

[Newbie_Neil]

Hi Neil

Planes nicely too...

Doesn't it? Such fun that its very easy to plane past the line

That's why you shouldn't use your Makita planer on it. :lol:

Cheers,
Neil

 

[Alf]

Planes nicely too...

Doesn't it? Such fun that its very easy to plane past the line

Good heavens, no, that's never happened to me... :^o :lol:

 

[Neil]

That's why you shouldn't use your Makita planer on it. :lol:

:roll: :lol:

Cheers,
Neil

 

[Scrit]

Ordinary router bits are fine - in terms of speed I've always just used normal settings for wood, but maybe Scrit will correct me.

Oh, if you insist....... firstly, Byron there are plastics and plastics. The low friction stuff is probably HDPE (high density polyethylene) otherwise known as UHMW (ultra high molecular weight) plastic. It has different machining characteristics to nylons or Delrin which are sometimes (albeit rarely as they are more expensive) sold for the same purpose.

As Neil says HDPE machines well with ordinary 2-flute straight cutters, but if you go to spiral cutters and reduce the rotation speed on a 1/2in diameter cutter from 24,000 rpm to 15~18,000 rpm the surface finish is actually better. About the only other points to make are that the material can be a bit "grabby" and so if you are machining profile (curved) edges it is best to remove as much waste as possible with the band/jig saw before routing the edges otherwise that grabbiness can turn into a hefty kickback or worse still a climb cut. I've experienced both. Because the material does compress under cutting pressure a better finish can be obtained by making your edge cuts 0.5mm oversize then doing a final pass at the required size if at all possible. When sawing the swarf can and will ball around the blade of your table saw even when using special plastics blades, so frequent stops are required to clear away the waste below the table. The only other thing to say is that HDPE is all but impossible to glue to anything, so your fixing methods must allow for countersunk screws.

Incidentally HDPE machines well on spindle moulders (preferably with a power feeder) and thicknessers (with a limited depth of cut) as all you need to cut it is HSS or even tool steel tooling and cutting it has minimal blunting effect. That means a cheap way to machine it is to use HSS spirals (really meant for aluminium) such as those from Clico - and as the HSS starts out with a sharper edge than TCT the surface quality is even better, however avoid using engineering spiral mills as they clog too easily and generate really fine swarf which balls around the cutter and can surface mark the material.

Scrit

 

[gidon]

Ooh - thanks for that Scrit - just got some and was wondering whether I could put it through the thicknesser .
Cheers
Gidon

 

[Neil]

Oh, if you insist.......

I knew that there would be more to it than I thought! A mine of information as usual, Scrit =D>

Cheers,
Neil

 

[ByronBlack]

Now thats a top notch answer! Cheers peeps. I'll go ahead and order some stuff.

Scrit, you say it's almost impossible to glue to anything - what about to itself? For instance, I want to make a 3 ply sandwich of 6mm stuff. If I can't glue it are there plastic fixings I could use?

 

[Scrit]

Ooh - thanks for that Scrit - just got some and was wondering whether I could put it through the thicknesser .

Just be very careful. There are two firms in this vicinity who actually do this - from talking to them I've gathered that they've modified standard woodworking machinery to have different feed rates (faster in fact), lowered the infeed roller to get some extra feed pressure and they take extremely shallow passes. On an unmodified machine I'd suggest a fresh set of blades, feed through on the skew and don't machine too wide a piece as it takes a lot more horsepower to machine HDPE than most hardwoods simply because it is much tougher and denser.

Scrit, you say it's almost impossible to glue to anything - what about to itself? For instance, I want to make a 3 ply sandwich of 6mm stuff. If I can't glue it are there plastic fixings I could use?

The only stuff I ever found which would make this material adhere to a metal surface was a double-sided pressure epoxy tape which cost the earth and wasn't noted for an extra lomg life. It didn't work brilliantly on plywood or MDF, however. Double sided tapes (and I tried quite a few) are very variable in their holding power (from rubbish to so-so) and all will eventually suffer from creep. Same for contact adhesives, an because HDPE is almost completely impermeable so there is no solvent-type cement which works on it that I've found. The manufacturers I've bought from recommend fixing with steel screws or double-sided tape for thin pieces not subject to large loads

Scrit

 

[Smudger]

Is this the same material that is used for kitchen chopping boards - it seems to be? I had been thinking of popping down to Robert Dyas to see how much some boards would cost, to make up some jigs. I was thinking of screw fixings.

 

[Scrit]

Is this the same material that is used for kitchen chopping boards - it seems to be?

Yes, but chopping boards are generally made from the softer less dense 250 or 375 grade (or even softer medium density) polyethylenes. The stuff used as low friction is a true high density, either 500 or 1000 grade. The denser it is the better the wear characteristics and the easier it is to machine - the lower density stuff suffers tremendously from compression-springback, especially with carbide tips or blunt HSS, so a smooth surface finish can be difficult to achieve. And you can't flame polish, abrade or scrape the stuff, either.......

Scrit

 

[Smudger]

Ah well. Off to Axminster then. Thanks, Scrit.

 

[Joe90]

HI

Axminster were selling some cheap in their Sid's Savers clearance offers sheet... I got a piece or two for £5 I think... 915mm x 100mm x 10mm thick. I think they still have smaller pieces in the list. One side is usually 'smoother' than the other it seems....

It really is great for fences for router tables etc, no 'stick slip' effect... much better than melamine or any other material in my opinion...

I also used little pieces to make washers to use under the cam clamps available from Lee Valley in Canada, it makes the clamps very easy to operate but it does compress over time and needs to be replaced eventually...