How to cut square holes?

[Len Woodruff]

I need to cut several sqaure hole in a cowl to match the photo below. I tried drilling a small hole then using a small square file to finish it. But it wasn't clear enough.

Any other suggestions?

[Ace-Garageguy]

54 minutes ago, Len Woodruff said:

 I tried drilling a small hole then using a small square file to finish it. 

That's always worked for me, in 1:1 too.

[Len Woodruff]

6 minutes ago, Ace-Garageguy said:

That's always worked for me, in 1:1 too.

Thanks Bill. I will give it some more tries.

[Ace-Garageguy]

6 minutes ago, Len Woodruff said:

Thanks Bill. I will give it some more tries.

Those thin areas separating the holes takes the delicate touch of a brain surgeon, especially in thin styrene stock, but it's doable.  

Edited May 27, 2023 by Ace-Garageguy

[NOBLNG]

You could also cut some fine sandpaper into very thin strips. Then draw the strips back and forth through the hole to get a nice smooth finished edge.

[R. Thorne]

You might consider sanding twigs or sticks.  These are 1/8” wide.

[Bugatti Fan]

Depends on the finished sizes required.

There are miniature broach tools for making square holes from pre drilled round holes. A jewellery tool supplier will probably hold them. Not sure about places like Micro Mark, but worth a look.

[70mach1]

Why not cut a large rectangular hole then add the thin divider strips?

[Len Woodruff]

2 hours ago, 70mach1 said:

Why not cut a large rectangular hole then add the thin divider strips?

That has crossed my mind. But I wanted to check out other possibilities that would be more accurate.

[Shark]

I drill a hole in each corner, then drag the backside of a #11 knife between them.

[70mach1]

You can round off the inside corners with thick ca and a sharp toothpick if that is a concern

 

[Bugatti Fan]

Some innovative suggestions already made on this thread.

May I add that cutting square of rectangular apertures takes patience and concentration to ensure squareness and definition when using drills and miniature files, and the preliminary marking out has to be accurate, particularly when cutting equally spaced rows of holes. No easy quick way around this, and it will be time consuming when attempted.

Edited May 31, 2023 by Bugatti Fan

[Straightliner59]

15 minutes ago, Bugatti Fan said:

Some innovative suggestions already made on this thread.

May I add that cutting square of rectangular apertures takes patience and concentration to ensure squareness and definition when using drills and miniature files, and the preliminary marking out has to be accurate, particularly when cutting equally spaced rows of holes. No easy quick way around this, and it will be time consuming when attempted.

But, done properly, definitely worth the effort!

[Ace-Garageguy]

2 hours ago, Bugatti Fan said:

...cutting square or rectangular apertures takes patience and concentration to ensure squareness and definition when using drills and miniature files, and the preliminary marking out has to be accurate, particularly when cutting equally spaced rows of holes. No easy quick way around this, and it will be time consuming when attempted.

Exactly

[ColonelKrypton]

the best tool I have found for making small square and rectangular openings is a small triangle needle file, also called a tri square file. A drilled hole to start and then careful and methodical work to square up the corners.

Needle files ( Swiss pattern needle files) are commonly available in 10, 14, 16, and 20 cm lengths ( approximately 4 inch,  5-1/2 inch, 6-1/4 inch, or 7-34 inch respectively from tip to end of handle ). The shorter files will have a smaller profile than the larger.

Also, it is handy to have a safe edge on your file. A safe edge is one without teeth and lets you work right up edges safely will not cutting into some part that you don't wish to. Some files will already have a safe edge but for those that don't, a few minutes spent with a bench grinder and a gentle touch so as not to over heat will result in a file that has a safe edge.

cheers, Graham 

Edited May 31, 2023 by ColonelKrypton
corrected information on needle file lengths

[Len Woodruff]

8 minutes ago, ColonelKrypton said:

the best tool I have found for making small square and rectangular openings is a small triangle needle file, also called a tri square file. A drilled hole to start and then careful and methodical work to square up the corners.

Needle files are commonly available in 14, 16, or 18 cm lengths ( approximately 5-1/2 inch, 6-1/4 inch, or 7 inch respectively ). The shorter files will have a smaller profile than the larger.

Also, it is handy to have a safe edge on your file. A safe edge is one without teeth and lets you work right up edges safely will not cutting into some part that you don't wish to. Some files will already have a safe edge but for those that don't, a few minutes spent with a bench grinder and a gentle touch so as not to over heat will result in a file that has a safe edge.

cheers, Graham 

That's interesting. I was using a small square jewlers file. I can see how the triangle file might bee easier to use.

[ColonelKrypton]

I re-read what I typed with regards to needle file lengths and noticed I made a mistake which has been corrected in my original post.I have a collection of needle files which are mostly the 14cm length ( 5-1/2 inches ) but I do have a select few of the 10cm ( 4 inch ) which are invaluable for getting into small places to work on small details.

Your local hobby store many not likely have these sizes in which case you can look on eBay or my preference is a good online jewellers supply.

For example, my goto places:

in the US  https://www.riogrande.com/product/tools--equipment/files/  or in Canada: https://www.gessweincanada.com/category-s/10441.htm

RioGrande also has crimp tubes which I know some use for detailing.

Be careful though. If you are a bit of tool nut like I am and like using good quality tools you may find that these suppliers have much to offer and you will end up spending more than you thought you might. 

I also like to use a good handle on my files. As I have gotten older and have developed a bit of arthritis, the handles make it easier to hold and control the files.

This is my current favourite handle:  https://www.riogrande.com/product/nylon-needle-file-handle/114047GP/?code=114047  You only need one of two as the files are easily changed as needed.

cheers, Graham