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Posted by Andrew VK3BFA on April 16, 2006, 9:41 am
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I want to turn up a round perspex piece to fit in a circular hole in
the front panel of a radio I am building. I start with a piece of
perspex 4 inches square, and turn in down to the required fit.
Had one go at it today - interesting. Generates enormous amounts of
swarf - ok, can live with that. Started by using a pointed tool to cut
it to roughly the right diameter - when it broke right through the
piece, it went "whang" and threw a big chunk across the room.
Mmm....not good.
Whats the proper way of doing this without generating missiles of
plastic (or steel, come to think of it.) - what sort of cutting tool
should I be using, and what speed should the lathe be running at, ie
fast or slow (yes, very technical..) Any lubrication required - it was
cool to the touch.
Its got a quarter inch hole in the middle to allow the vernier drive
shaft to pass through to the tuning knob - I cut the head off a bolt
and used this to chuck it to the lathe. Its got a bit of wobble,
probably need to get a straighter bolt - was grabbed out of the junk
box.. Is there a better way of mounting the project?
Words of competence?
Andrew VK3BFA.
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Posted by Tom Gardner on April 16, 2006, 10:57 am
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>I want to turn up a round perspex piece to fit in a circular hole in
> the front panel of a radio I am building. I start with a piece of
> perspex 4 inches square, and turn in down to the required fit.
>
> Had one go at it today - interesting. Generates enormous amounts of
> swarf - ok, can live with that. Started by using a pointed tool to cut
> it to roughly the right diameter - when it broke right through the
> piece, it went "whang" and threw a big chunk across the room.
> Mmm....not good.
>
> Whats the proper way of doing this without generating missiles of
> plastic (or steel, come to think of it.) - what sort of cutting tool
> should I be using, and what speed should the lathe be running at, ie
> fast or slow (yes, very technical..) Any lubrication required - it was
> cool to the touch.
>
> Its got a quarter inch hole in the middle to allow the vernier drive
> shaft to pass through to the tuning knob - I cut the head off a bolt
> and used this to chuck it to the lathe. Its got a bit of wobble,
> probably need to get a straighter bolt - was grabbed out of the junk
> box.. Is there a better way of mounting the project?
>
> Words of competence?
>
> Andrew VK3BFA.
I would think a hole saw or a fly cutter would do a much better job. A
lathe would be last on my mind and only after a few single malts.
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Posted by Mike Henry on April 16, 2006, 11:18 am
Please log in for more thread options
>I want to turn up a round perspex piece to fit in a circular hole in
> the front panel of a radio I am building. I start with a piece of
> perspex 4 inches square, and turn in down to the required fit.
>
> Had one go at it today - interesting. Generates enormous amounts of
> swarf - ok, can live with that. Started by using a pointed tool to cut
> it to roughly the right diameter - when it broke right through the
> piece, it went "whang" and threw a big chunk across the room.
> Mmm....not good.
>
> Whats the proper way of doing this without generating missiles of
> plastic (or steel, come to think of it.) - what sort of cutting tool
> should I be using, and what speed should the lathe be running at, ie
> fast or slow (yes, very technical..) Any lubrication required - it was
> cool to the touch.
>
> Its got a quarter inch hole in the middle to allow the vernier drive
> shaft to pass through to the tuning knob - I cut the head off a bolt
> and used this to chuck it to the lathe. Its got a bit of wobble,
> probably need to get a straighter bolt - was grabbed out of the junk
> box.. Is there a better way of mounting the project?
>
> Words of competence?
When I needed some 1/4" thick x 3" OD acrylic disks recently, I bought them
from McMaster-Carr. It looks like they may have been cut with a hole saw,
though without using the center drill as the disk is solid throughout.
For a one-off larger disk that has a center hole, I used a shop-made stepped
arbor, with aluminum disks on either side of a square acrylic plate and
turned it down on the lathe.
Mike
--
NewsGuy.Com 30Gb $9.95 Carry Forward and On Demand Bandwidth
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Posted by spaco on April 16, 2006, 11:21 am
Please log in for more thread options I think I'd band saw it to rough size first, then gently go at it on the
lathe to finish. You can put the part on a piece of wood while band
sawing so it doesn't scratch.
Assuming that Perspex is a clear plastic, like plexiglas, I'd use a
sharp tool and a very slow speed. The stuff heats up and becomes sticky.
Pete Stanaitis
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Andrew VK3BFA wrote:
> I want to turn up a round perspex piece to fit in a circular hole in
> the front panel of a radio I am building. I start with a piece of
> perspex 4 inches square, and turn in down to the required fit.
>
> Had one go at it today - interesting. Generates enormous amounts of
> swarf - ok, can live with that. Started by using a pointed tool to cut
> it to roughly the right diameter - when it broke right through the
> piece, it went "whang" and threw a big chunk across the room.
> Mmm....not good.
>
> Whats the proper way of doing this without generating missiles of
> plastic (or steel, come to think of it.) - what sort of cutting tool
> should I be using, and what speed should the lathe be running at, ie
> fast or slow (yes, very technical..) Any lubrication required - it was
> cool to the touch.
>
> Its got a quarter inch hole in the middle to allow the vernier drive
> shaft to pass through to the tuning knob - I cut the head off a bolt
> and used this to chuck it to the lathe. Its got a bit of wobble,
> probably need to get a straighter bolt - was grabbed out of the junk
> box.. Is there a better way of mounting the project?
>
> Words of competence?
>
> Andrew VK3BFA.
>
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Posted by Karl Townsend on April 16, 2006, 1:15 pm
Please log in for more thread options To hold and turn a thin piece of stock in a lathe, you can make a sandwich:
1.Scrap aluminum against the face plate or three jaw chuck with jaws
removed, 2. plastic piece, 3. scrap aluminum. Use the tailstack with a live
center to tighten against the faceplate, friction will hold everything. far
easier if you don't have a lot of material to remove.
Karl
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> the front panel of a radio I am building. I start with a piece of
> perspex 4 inches square, and turn in down to the required fit.
>
> Had one go at it today - interesting. Generates enormous amounts of
> swarf - ok, can live with that. Started by using a pointed tool to cut
> it to roughly the right diameter - when it broke right through the
> piece, it went "whang" and threw a big chunk across the room.
> Mmm....not good.
>
> Whats the proper way of doing this without generating missiles of
> plastic (or steel, come to think of it.) - what sort of cutting tool
> should I be using, and what speed should the lathe be running at, ie
> fast or slow (yes, very technical..) Any lubrication required - it was
> cool to the touch.
>
> Its got a quarter inch hole in the middle to allow the vernier drive
> shaft to pass through to the tuning knob - I cut the head off a bolt
> and used this to chuck it to the lathe. Its got a bit of wobble,
> probably need to get a straighter bolt - was grabbed out of the junk
> box.. Is there a better way of mounting the project?
>
> Words of competence?
>
> Andrew VK3BFA.