[Lester Perry]

I am getting into this scratch building stuff. Now I have a problem. I am trying to cut 2 1/4 inch half circles into sheet plastic. I have tried an exacto knife, small very sharp scissors and a drimel tool with a small mill tool in it. HELP I cant get a smooth even cut. What works here?

 

[T-Man]

Put up the dukes

Les, How about making a punch? 1/2 inch tube cut in half and a chisel to cut the straight?

OR a half moon branding iron with heat to melt.

The punch has a chance if the plastic is thin.

 

[tankist]

how about cutting bit more and then filing to exact shape?

 

[T-Man]

I'm assunimg he wants a hole. The filing idea may work. I like it. Cut the hole and use precision hand files to shape.

 

[stationmaster]

I use a precision fine toothed hole saw on my drill press. I don't even remember where I got the thing. Probably from Dad's tools when he passed away. I sure don't remember buying it.

Bob

 

[tankist]

oh, i gues i missed it is a hole. 2.25. and a half a circle one.
id do what i usually do with any iregular holes, voids - mark the contour you want. go with a very small drill bit making lots of small holes on the inside of the contour , break or snip with cutters the inside piece, file to exact shape. can take a bit time.

 

[T-Man]

Your good. I have done that with sheet metal for larger holes. It makes sense. One more reason to get a precision drill set.

 

[yamahammer]

At harbor freight they sell a gasket punch set that works perfect, punches from 3/32 up to 1/2. 9 punches for 6.49

 

[tjcruiser]

Lester,

How thick is the sheet plastic?

Could you make a male pattern of your intended shape out of something rigid (like 1/8" thick aluminum), lay that down, and then carefully trace around the outside in several passes with an pointy Xacto knife? It seems to me a rigid pattern would help keep your blade cuts in the proper position and smoothness.

TJ

 

[Lester Perry]

This is almost 2 years old. I solved the problem but don't remember how. I think I used a circle cutting attachment for dremil tool made 4 holes side by side in straight line then cut through the center

 

[tjcruiser]

Sorry, Lester ... I didn't look at the dates. Thanks for the update, though!

TJ