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[sinjon]

I need to cut some small clear discs for portholes, ( I worked in the aircraft industry building flying boats - don't ask - we called them port lights) I have tried using 'Kristal Klear' but the dia. is just a bit too big, I need about a 1/4'' dia +
Has anyone got a good system for cutting out small dia. discs from clear plastic?

Colin

[John W E]

Sinjon - you know the paperpunches that you can punch holes in paper with - for loose leaf folders - well, if the clear plastic you are trying to punch isn't too thick, you could use this method. 

Or, some brass tubing 1/4 inch bore, with theouter edge sharpened like a chisel, soft wooden block, place your plastic on the wooden block, place the sharpened brass tube on the top of the plastic and with a sharp belt you should have cut a clear disc out.

 

aye
John e
bluebird

[Colin Bishop]

Best thing to use is a hollow steel punch. They usually come in sets. Squires do two sets. One is  2-10mm 8 pieces ,the other is Imperial 3/16th to 1/2 6 pieces. Both sets cost £10.99 each. I have a 9 piece set which goes up from 3/32-1/2 and which I picked up at a show or stall somewhere for around £6.

Revolving punch pliers are also handy but usually only go up to about 5mm. Try Googling "hollow hole punch" and see what you can find.

Just seen Bluebird's post - the paper punches work well too and are just over 1/4" in diameter - what you are looking for!

Colin (the other one!)

[HS93 (RIP)]

Ive started to use perspex rod cut it of I use a lath but a razor saw does as well and then use 600/1500/2000 wet and dry it does where the end of your fingers away though but you get a nice piece of glass and if you make it a tight fit no glue , you can leave it a bit longer if you are using lights, it picks it up better.  Peter

[Bunkerbarge]

This is an idea if you have a lathe.

The last time I did it I machined a steel tube of the diameter I wanted, cut it in half and squared up both ends in the lathe.  I put one end in the headstock and the other in the three jaw in the tailstock.

The perspex sheet I cut into small squares just slightly bigger than the finished size and then I clamped the peices of perspex between the two ends of the tube by using the tailstock feed.

Then I filed the edges of the perspex down to the diameter of the tube making small circular peices of perspex.  It sounds a bit of a fiddle but once I had got into the swing of it I produced eight fairly quickly.  The advantage with this was that I could use fairly thick perspex that I could then glue into a brass tube giving a nice realistic depth to the port and it's hole.

[HS93 (RIP)]

 A picture of finished portholes and the type of rod used ,I could not find the rod I used for these but this is the same rod. Peter

[Bryan Young]

I need to cut some small clear discs for portholes, ( I worked in the aircraft industry building flying boats - don't ask - we called them port lights) I have tried using 'Kristal Klear' but the dia. is just a bit too big, I need about a 1/4'' dia +
Has anyone got a good system for cutting out small dia. discs from clear plastic?

Colin

Just thought I may add another method. If your scuttles (portholes) have a brass surround, then why not place the brass "tubes" on to a bit of perspex and fill them with clear casting resin. They can be easily removed from the perspex and trimmed off.
"Works for me"  BY.

[sinjon]

I was attempting to scribe round the inside of a circle template with a compass point - it didn't work, my thanks to you all, I can now go and play, I hope with some real success.

Colin