The Home Machinist!

For my boxcab project, (though the question is equally applicable for caboose windows, coach windows, etc.) I am wondering the best way to cut the square and rectangle window holes. The sides/ends are made from 1/2" birch plywood and the window areas will be about 4" square or larger. I cut drill four holes in the corners and use a jigsaw with a clamped fence to get straight lines but this seems a bit unprecise and prone to mistakes. The windows will be framed on the outside with wood trim so they don't have to be perfect but...

Any ideas or suggestions? Thanks.

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"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

Ya, I have the same problem with jigsaws. The blades wander and go off angle some. One thing that can help is to use a good wood bit (not for steel) to drill holes to minimize breakout chipping. A 3/8 or 1/2 inch Forstner bit of quality can help if you drill from both sides.

I have had better luck using an aluminum angle clamped to be a fence while cutting. Then only dull blades bendo over sideways to give me fits.

I have taken to trying router bits in the mill for dead accurate x-y cutting of the window openings. It only leaves the round corners do cut with the saw. When cutting wood, you really have to remember to move or back off from a dimension, and not RUB. That will destroy the edge of the bit right off.

I cut sticks of hard wood with backangled corners, to glue sandpaper to for finishing the edges of cutouts. A rubber belt sander block willkeep the sandpaper cleaner and make the hand work faster. If I have a bit to do, I will make a pile of sticks in an hour and save whats left for other jobs, that require fine finish or smooth edges. The sticks remind me of heavy paint stirring sticks, only about 3x as thick. One edge square, the other a slight back angle. Wet/dry paper glued on with sanding disc glue. I use and old caster to roll the paper down smooth.

beyond that, I dont know any real magic. Neat and clean holes are a little finnacky work to accomplish.

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Big Dave

Be Alert! The world needs more Lerts.

Even more critical the more expensive your wood gets.

Nice stuff is the finished on one side, but also more money.

the drover car windows were fun.

Did what you said, used a jigsaw and got real close, and finished them with files, rasps, whatever it took. I now have a rotary sander and will try it next project. As you mentioned, the trim hides lots of crime.

Brian

For stuff like that, I put some good masking tape on both sides, and then clamp a board on the plywood to use as a fence for a straight cut. Don't get in a hurry.....crowd it too much and you'll start chipping the surface. Do try a bit of experimenting on some scrap pieces. A bit finer blade works better.

I've also pre-scored the cut with a razor knife on veneered things like birch plywood & interior doors.

Bill

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Today's solutions are tomorrow's problems.

Find yourself a fine tooth metal cutting blade.........sure it will take a while to make the cut.....but you will have a very fine cut.

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Dennis Blank Jr.
Rdgk1se3019@hotmail.com

Using a small router with a spiral cutting blade, a rub collar, and a routing template will get you very clean holes, very quickly. They'll be as precise as the template you make (using methods such as those outlined above).

Think about an alternate tool. RotoZip.

Layout your windows on the plywood. Clamp a guide on the outside of the windows so the RotoZip can't go outside your lines, and cut away. If you get away from your guide, no problem, just back up, get against the guide and push ahead again. No need for drilling holes the Zip will plunge cut just fine. You will need to practice on scrap first. The Zip is a bit touchy and is great for free form designs like yard art but it does a great job in a straight line as long as you have a good guide to run against. Basically, you can't go too slow but you can go too fast, tends to break the bits. An added plus, the Zip cuts need almost no sanding.

Don't say you can't do it. My wife cuts out dozens of Christmas decorations every year by herself. IF she can do it, so can you.

Just a suggestion. Good Luck with your windows.

Cheers,
Terry

Rptpzip....

Now where....

Does that fit into a Dremel?


B

A Roto-Zip was one of those must have tools, a few years ago. Basically a Dremel on steroids, a tiny version of a wood router, it can fit fine or larger bits with a collet change. It is very high speed, and therefore heats and eats bits like crazy.

I have one and found its use rather dismal. Once you start using it , it eats bits like pretzels go with beer. For me it was disappointing. A full sized router, tho clumsey, would be a better choice, I think.

Ya a single template, moved to repeat cuts for windows could be very good, if the setup was right.

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Big Dave

Be Alert! The world needs more Lerts.

I will take all of this to heart. The windows are two different sizes (4x4" and 4.25x4.5") and only 8 total (two per side, two per end) so I don't have to cut lots of windows. I will look into seeing whether anyone I knows owns a Rotozip, as I don't really want to purchase one. Time I have plenty of, so nice slow cutting is fine with me. In fact, it is preferred. It makes it harder to make mistakes.

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"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

Metal cutting blade for saber saw. Scribe both sides between holes with an xacto knife to minimize chipping. Cut full speed with saw and just go slow and stay on the inside of scribed line. By inside I mean on the inside of the window.

Good Luck,
Bill W.

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Plum Cove Chassis, freelance body - 2008
Wabash 569 - Allen Mogul - April 09-Jan 12
Bob Snippe Alco S-4 - Feb 12

I have a jigsaw. Are there special blades designed to cut 1/2" plywood? I like the jigsaw because I am familiar with it, and because it has variable speed. I have heard that the blades cut going UP, meaning I would want to cut from the back to minimize chipping/tear out.

_________________
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"