High accuracy transfer of cutting blueprint onto plywood

Question

I'm looking to cut a bunch of interlocking pieces from plywood. As a cheaper alternative to laser cutting (I've got a quote for 90 bucks) I'm exploring my options to do this by hand.

What would be the best way to transfer a schematic with very fine lines onto plywood sheets so I can cut it out with a hobby saw?

Most options I've seen so far seem very prone to smudging or other distortions. If you're transfering large, rough structures that isn't as critical.

My intuition tells me that probably the most reliable and error-tolerant way would be to print the schematic on paper, cut it out, tape it to the plywood and then carefully saw along the outline...

Edit: The parts I'm planning to make are relatively small, a few centimeters, so I should be able to fit a decent number on a single sheet of paper...

Answer 1

The toner transfer method of transferring an image onto a PCB should also work on wood.

Basically you laser print (a mirror image if you need to work from the front) on suitable paper (I've done this with inkjet glossy photo paper), then iron onto the material, and you get a nice clean black image.

You're limited by the size of the print you can make, or your ability to join prints together.

If you want to stick a paper template onto the wood as you suggest in your question, I recommend repositionable spray mount all over the back of the template. Taping is less effective once you start cutting.

Answer 2

Another alternative would be to use a home vinyl cutter such as the Silhouette, the Circuit or the Scan-N-Cut to cut out your template on decent quality paper. I use a silhouette to cut stencils all the time and as long as I use decent quality 40lb paper, the cuts are clean and precise. Regular card stock tends to get fuzzy in the corners making the resulting stencils unusable.

If anyone has a good source for 40lb paper, please list it in the comments. I've been buying mine at a craft store and even the clearance rack 30 cents per page is killing me.

Answer 3

If you are willing to cut out the pattern with a saw you could laser etch your schematic onto the surface of your plywood. The laser etched pattern would be extremely precise and it would give you a clear pattern to follow as you cut. Since you are just etching the surface and not cutting all the way through the laser doesn't need to be very powerful.

Other options available for transferring the image are: do a carbon paper transfer directly onto the surface of the plywood, use a projector (opaque or overhead) and project the image onto the plywood and trace it out or use a pantograph to create a proportional line drawing on the surface.

Or keeping things really simple just glue your uncut paper to the plywood and cut out the pattern. Saves you the hassle of cutting the paper with the scissors.

Answer 4

My intuition tells me that probably the most reliable and error-tolerant way would be to print the schematic on paper, cut it out, tape it to the plywood and then carefully saw along the outline

I was reading the post wondering if you would come to the same conclusion. Yes, I would think that this would be one of the easiest and most budget friendly ways to get your pattern onto the board.

Gluing the entire to your surface would not be required but everywhere near where you would be cutting would. If need be reverse the image before you print it and when you cut it the other side will be your intended design. Scraping the paper off after the fact wouldn't be too hard though.

Matthias Wandel uses that technique to make wooden gears (and other things...). Depending on the size of your design you could use something like Big Print which helps with accuracy on larger mediums.

As far as applying the paper template to the wood...

I always glue it on by putting a very thin coat of wood glue around the edge of the gear and then pressing the paper template on.

As long as the template it not going to move you should be able to cut out your design quickly and easily with hand tools like a coping / fret saw or even power tools like a bandsaw or jig saw. Routers with flush trim bits would also work everywhere except for fine detail areas.

The great marble music machine uses this technique as well (I know its another gears example but its really cool!)

Also for something small I strongly suggest using the same template for each one and not using a "good" one that you made as a template. Small errors will follow you that you might not see at first.

Answer 5

I agree with @john vukelic. I would start by trying to adhere the paper directly to the wood, but if that doesn't work, for whatever reason, a good quality carbon transfer paper should work really well for you. The type used with receipt books, etc. is easily smeared and can be difficult to remove, but transfer paper specifically designed to use for woodworking (which I have never used personally), or for art or sewing fabric (which I have used) is actually quite precise and can be erased. It is also readily available and not very expensive.

Answer 6

Borrow a trick from our sewing friends. They use a spiked wheel to "copy" lines on a pattern on to the fabric with a carbon-copy type paper between. The paper they use comes in different colours so that it's visible on the fabric. It's made for that purpose, so it should be better about smudging than office type carbon-copy paper (though maybe slightly more expensive). The spiked wheel has the advantage that if you apply enough pressure when using it on the plywood it will embed the colour slightly below the surface, making it more smudge-proof than a line drawn on the surface. I doubt, however, that the indents made by the wheel itself, without the coloured paper, would be enough to follow as the plywood is too rough to spot such small holes, but you could try it anyway.

Answer 7

As an alternate to paying someone to do the cutting for you, look for a local Maker Space. These places often have laser cutters available for use (and can teach you how to use them), for a typically nominal monthly membership fee. You'd be able to learn how to prepare your files and execute the cutting yourself, as well as have the ability to do additional similar projects or repeat this one.

Additionally, check your local library system. As maker spaces and similar technology has gained in popularity, many libraries have begun to add small maker space-type facilities within their systems. Again, there may be a nominal fee for use of the equipment here, but they could also teach you how to use the equipment and use of the laser cutting equipment may be free of charge as none of their own materials are consumed in the process.

Answer 8

A simple and effective way to do this is to use aptly named transfer paper. That is paper that has one side covered in graphite or other soft material so that when you press down on the "top" side it leaves a mark on the surface below it.

So you would lay the transfer paper, graphite side down, on your plywood sheet. Then attach your schematic print above the transfer paper. With this set up, as you trace the lines of the schematic it will leave said lines on the plywood.

If you are worried about smudging, you could then spray fix the resulting pattern after removing the paper.

This would by far be the most affordable, most direct way to do what you are after. Attaching just the schematic print to the plywood would invariably result in the paper losing alignment once you start cutting (and gluing it to prevent that would be a real headache when you wanted to get back to just the plywood surface.) It requires no expensive laser equipment or messy solvents and the transfer paper is easily sourced in many sizes.