The Home Machinist!

Simplest form, ya, a jig saw with a fine blade and medium speed to keep blade heating down. I have 3 Jig saws that are used for various things. The thicker the plywood, the more the tendancy is for the blade to deflect sideways during fine adjustments of path. With cutting from the backside on fine hard faced birch or oak cabinet grade plywood, this bit of wiggle can get a serious problem on the front side. So beware. I have had good success with doing the fine face cutouts in thin Luan, or 1/4 inch cabinet ply, and layering the result onto a backer, that is cut form the front side under a protective layer of Blue painters tape, to avoid marking the face. I have only done this once, some time ago. Since then I have made cab parts from 1/8 sheet steel, with a smaller window welded behind, to give depth.

Just as an aside, I have seen a short combine with many windows, that was very good. The builder started by scribing the wood with a straight edge and mini edge plane with a single tooth for the cut. After each side panel was done, the slightly oversized blank was sawed at the belt line, where the window bottoms would be. a piece of trim would be milled to cover the cut and provide the bottoms of the widow sills, where exposed. Now the remaining upper blank could be band sawes with oneof those fine fret blades, and get into the tops simply by swinging the blank around. He claimed it left very clean straight holes, that required very little extra work. Many ways to skin a cat.

All in all, the result will be more your skill, rather than the fancy tool you use. I bid you peace.

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Big Dave

Be Alert! The world needs more Lerts.

I showed up at my friend's house last night to work on the project and he had a surprise for me: a brand new oscillating saw with a segment blade. Using that tool, we first cut to the corners and then connected the lines to complete the window cut. Though the first window wasn't perfect the window frames will hide it.

He also had a really old, dull scroll saw which we tried as an experiment by drilling out the windows and then threading in the blade and cutting. It too worked but it was very slow and prone to jam.

If I ever build coaches or cabooses I will definitely use a router and create a proper template, but for this project I can safe that the oscillating saw and segment blade worked really well.

(four windows down, four windows and two doors to go...)

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

You can see in my you tube videos how to cut them out. In the video I"M cutting them in 1/8 aluminum but the procedure would certainly work in wood.

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ALLWAYS OPERATING MY TRAIN IN A SAFE MANNER USING AUTOMATIC AIR BRAKES

As wood worker, what kind of bit are you using in the router to cut aluminum?

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C.P. Mahony
One Inch Foreman
LALS

I used a special carbide cutter designed for use with CNC machinery. it is .250 in dia.

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ALLWAYS OPERATING MY TRAIN IN A SAFE MANNER USING AUTOMATIC AIR BRAKES

I use a cutter designed to cut formica, you know, one with a ball bearing on the end.

I use four pieces of wood to layout my opening and set the router to be guided by the wood pieces.

Bill

If the window fit is critical, one wants to be sure of the true cutter diameter diameter when using the ball bearing carbide trim router bits. Two years ago when I was cutting out many window and door openings in my caboose there was a hard lesson learned. I made up the router template on the mill with the digital readout and never checked the true diameter of the cutter that was claimed to be a 1/2 inch cut. I allowed for .500 diameter and began to wonder why things did not fit as planned. When I measured the cutter with a micrometer the answer was very apparent. The cutter was undersize by .005. I measured all of my cutters and found them to be undersize. I then went to several local suppliers and measured all the trim bits in stock to see if I could find one that was full size so my template would be useful. Not a single cutter was full diameter of .500. Some were in the .493 to .490 area and still being sold as 1/2 inch cutters. The USA made cutters and the imported cutters were all guilty of being undersize.


I ended up making a new set of door and window templates based on the cutter diameter I had to work with and will never trust a manufacturers listing again. The new templates have served well and I even wrote on them in permanent marker the cutter diameter required for best results.

PeteM has the right idea. Make a 4 sided template (piece of plywood with a hole in it) that has a set of 90 degree indexing boards on the back of it. Use double sided tape to hold it on your material. Use a wood router with a 1/4" diameter plunge bit and a guide collar in the router.

The trick I found that helps me cut with a hand held jig/saber saw is to buy a top of the line saw. I have 3 Bosch saws that are the best. Next is to buy the right blades. Again Bosch has one heck of an assortment. I can cut 3/4" veneered ply with almost no tear out even using a standard up cut blade. You have to practice with a down cut blade for a few cuts otherwise you will find it will bounce around on you big time if you aren't careful.

Now another way is to cut them with a Fein multimaster tool. Basically a very expensive ($300+) vibrating blade. But it is one sweet specialty woodworking tool.

If you have a mill, clamp the work to the table with scrap underneath.Use an endmill,3/16" should do it to mill the plywood out. You will get smooth edges,square sides and done fairly quickly once you set up.I have used a drill press in the past but my cross slide vice is a bit sloppy.I prefer the mill.
mike

I would vote for a laminate trimmer with a small router bit. Sort of a roto-zip on steroids. Porter Cable makes a nice one, I think the base adjusts like a full sized router. Make a hardwood template use a collar and have at it. A little chisel work will square the corners.

Next choice would be to drill holes in the corners of the window and use a scroll saw. Super fine cut and with the right balde no tear out on the bottom.

Rick

You need to build a routing jig. Whether you build one or one hundred, a jig will ensure they will all come out identical.

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Mr Ron, Almost as smart as the average bear.

What about that new Rockwell 3-3/8" +/- circular saw with a plunge cutter?

I don't have a router.

Also, does it make sense to put a scrap piece underneath? Does that help prevent tear-out?

Tks,
Brian