I'm after a couple of bits of MDF to fit speakers to my car - 2 rings approx
6 inch OD and 5 1/4 inch ID, and if there's some easy way of doing it, and
ideally the rings would be tapered, so that I can have the speakers pointing
upwards out of the bottom of the doors, and a couple of bits that are
straight on 3 sides and wavy on one of the sides, probably in around 9mm
MDF.

For some idea of how the rings would look, here's an ebay listing for some
in the US.
http://cgi.ebay.co.uk/6-5-3-4-MDF-Di...d=p1638. m118

Obviously the almost rectangular bits would be fairly simple to cut with a
coping saw, but I'm a bit stumped about how I'd get a taper with the rings.
Are there any places that'll supply the wood and cut it? I very rarely do
any kind of woodwork, so buying a lot of tools isn't going to happen,
although there is a lathe in the shed that I could use, although I can't see
any way of using a lathe to get a taper...

"SNIP

For some idea of how the rings would look, here's an ebay listing for some
in the US.
http://cgi.ebay.co.uk/6-5-3-4-MDF-Di...d=p1638. m118

Obviously the almost rectangular bits would be fairly simple to cut with a
coping saw, but I'm a bit stumped about how I'd get a taper with the
rings. Are there any places that'll supply the wood and cut it? I very
rarely do any kind of woodwork, so buying a lot of tools isn't going to
happen, although there is a lathe in the shed that I could use, although I
can't see any way of using a lathe to get a taper...

Using a wood lathe it would be fairly simple. Make a false faceplate from a
piece of MDF. Attach to one side of it a pice of wood which will lift one
edge of the mounted work off the faceplate to the angle of taper you need.

Roughly cut the workpiece circular and mount it on the false plate via
screws in the central waste, with one point on the faceplate and the other
side resting on your previously attached scrap. The back face is now
leaning at the required taper angle, as is the front, but you can now turn
away wood from the front to bring it back parallel with the faceplate,
thereby creating your taper.

Now turn the outside circular and finally part off the ring to the required
diameter from the front.

The work will be a bit unbalnced so you'll need to run the lathe slowly to
avoid vibration.

You can do the same thing perfectly easily on a metal lathe as long as it
will swing the diameter.

"Norman Billingham" norman.at.tumulus.org.uk wrote in message
...

"SNIP

For some idea of how the rings would look, here's an ebay listing for
some in the US.
http://cgi.ebay.co.uk/6-5-3-4-MDF-Di...d=p1638. m118

Obviously the almost rectangular bits would be fairly simple to cut with
a coping saw, but I'm a bit stumped about how I'd get a taper with the
rings. Are there any places that'll supply the wood and cut it? I very
rarely do any kind of woodwork, so buying a lot of tools isn't going to
happen, although there is a lathe in the shed that I could use, although
I can't see any way of using a lathe to get a taper...

Using a wood lathe it would be fairly simple. Make a false faceplate from
a piece of MDF. Attach to one side of it a pice of wood which will lift
one edge of the mounted work off the faceplate to the angle of taper you
need.

Roughly cut the workpiece circular and mount it on the false plate via
screws in the central waste, with one point on the faceplate and the other
side resting on your previously attached scrap. The back face is now
leaning at the required taper angle, as is the front, but you can now turn
away wood from the front to bring it back parallel with the faceplate,
thereby creating your taper.

Aha.

Now turn the outside circular and finally part off the ring to the
required diameter from the front.

I've since had a second look and I've worked out that I'll need the baffle
to be rectangular rather than round to allow everything to mount up
properly. I presume my best bet would be to start with a circular bit of
MDF, put the taper on, then cut the centre hole out with a coping saw and
square the sides off? I assume it'd be a pain to be working on a big
rectangular bit of MDF on the lathe.

The work will be a bit unbalnced so you'll need to run the lathe slowly to
avoid vibration.

You can do the same thing perfectly easily on a metal lathe as long as it
will swing the diameter.

Now all I need is a couple of scraps of MDF to meddle with.

On Sat, 29 Dec 2007 18:41:28 -0000, Norman Billingham wrote:

Using a wood lathe it would be fairly simple.

Does MDF turn?

--
Cheers
Dave. pam is missing e-mail

Does MDF turn?

FWIW

Tried it once and once only! Turns into a horrible dust, ended up
using a full face mask with air supply!!

On Sat, 29 Dec 2007 15:58:20 -0800 (PST), wrote:

Does MDF turn?

Tried it once and once only! Turns into a horrible dust,

I'm not surprised at that considering it's little more than dust in the
first place. But did you mange to produce what you wanted or did it just
fall apart or tear?

ended up using a full face mask with air supply!!

A proper mask should be used when ever machining or cutting MDF, the dust
ends up very fine and gets deep into your lungs...

--
Cheers
Dave. pam is missing e-mail

"Dave Liquorice" wrote in message
ll.net...
On Sat, 29 Dec 2007 15:58:20 -0800 (PST), wrote:

Does MDF turn?

Tried it once and once only! Turns into a horrible dust,

I'm not surprised at that considering it's little more than dust in the
first place. But did you mange to produce what you wanted or did it just
fall apart or tear?

ended up using a full face mask with air supply!!

A proper mask should be used when ever machining or cutting MDF, the dust
ends up very fine and gets deep into your lungs...

A bit more test fitting and so on suggests I won't be needing the lathe now,
but thanks to everyone who gave advice. It all sounded complicated so I'm
mildy relieved (a thousand other jobs to do on this car).

On 29 Dec, 22:57, "Dave Liquorice" wrote:

Does MDF turn?

Yes, and tolerably well. You even get nice shavings from it. Surface
is a bit poor though - needs something to fill it, such as car
bodywork sprayable primer (under paint).

Valchromat (self-coloured MDF with extra resin content) works even
better. This will sand and take a waxed finish.

As a way of making huge bowls and closed forms from glued-up stacked
rings, it's well worth experimenting.

Dave Liquorice wrote:
On Sat, 29 Dec 2007 15:58:20 -0800 (PST), wrote:

Does MDF turn?
Tried it once and once only! Turns into a horrible dust,

I'm not surprised at that considering it's little more than dust in the
first place. But did you mange to produce what you wanted or did it just
fall apart or tear?

ended up using a full face mask with air supply!!

A proper mask should be used when ever machining or cutting MDF, the dust
ends up very fine and gets deep into your lungs...


I've routed it and it routs well, so it must also turn fairly well.

Not the material I would use for turning though.

Dave Liquorice wrote:
On Sat, 29 Dec 2007 18:41:28 -0000, Norman Billingham wrote:

Using a wood lathe it would be fairly simple.

Does MDF turn?

Yes. At school I made a plug for vacuum-forming by turning a block made
of stacked layers of MDF. Worked quite well. Obviously I had to finish
it with some sort of smooth sealant for release; I don't know if the
surface would have been acceptable without it.

I don't remember using any sort of PPE except goggles though; this would
have been the late nineties.

Pete