From CAD To Template With A Laser Printer

This tutorial is intended as a supplemental to Chris Verhoeven's "The Comprehensive Guide To Body Template Making" article here on ProjectGuitar.com; Chris' tutorial describes techniques for taking a printed design applied to a surface (in his instance, glued to thin sheet stock) and shaping that before transferring it to thicker and more permanent material. Presented here is an alternative method of taking a design printed in real-world sizes from your CAD package to that first bit of template stock.

Chris' method is simple; print out your design and glue it to the sheet stock. Most people only have access to a standard format laser printer (Letter or A4). For obvious reasons, these might seem inadequate for the task since most of the templates we need to make (such as for body outlines) tend to be far larger. One solution might be to have your plan printed at a copy house straight to the appropriate size such as ANSI C or A2 which makes things a lot easier, even if it's a more expensive option. Printing a larger design over several small sheets and manually tiling them can be done within minutes, and with a little careful planning can be equally as accurate.

Applying the page(s) to your target sheet stock can present a problem; spray glue is expensive, ridiculously messy and a pain to apply paper onto. Once it sticks, it goes nowhere! Equally, water-based glues have their own difficulties with the paper rippling and distorting. Without a large press, the paper bubbles and adheres poorly. Worse, when shaping a paper-based template the edges "fluff up" and obscure the lines we're trying to shape to.

An alternative is to print directly to the sheet stock, or more accurately transfer a print. By taking the glues and reliance on paper out of the question, we can produce templates that are more permanent and far less hassle to produce overall.

Toner Transfer Method

Laser printers work by heating a solid ink powder ("toner") on a drum, physically pressing and depositing the molten ink onto the media. The toner transfer method reverses that process by using heat to re-transfer the toner from the media to the target workpiece.

Why am I using the terms "target workpiece" and "media"? Media in this case is normally printer paper. We're going to bend this a little and use something a little different in place of standard paper. Secondly, "target workpiece" is down to this method having its roots in a different technique; homebrew PCB production. In that, rather than transferring toner to a sheet of MDF, hardboard or plywood it is transferred to a plain copper PCB sheet as a "mask" before etching the circuit design. The overall concept is the same. We temporarily print our design onto paper and transfer it elsewhere using heat.

You will need:

• Glossy junk mail (with pages that will go through your printer)
• Painter's tape
• Craft knife or blade
• Steel ruler
• Clothes iron

For this demonstration, I'll be transferring a doublecut bass design to a sheet of 5mm MDF. A little preparation work on your drawing is necessary. Firstly, I made a mirrored copy of the items I wanted to appear in my plan and increased the line weights to 0,5mm (~0.02in). Secondly, I created a custom printer setting which prints darker and turned "toner saving" off. Having heavier line weights and darker printing loads more toner to the print media, making it easier to transfer toner back off and to the target.

Step 1 - Mark up your stock sheet

I'll be tiling four sheets of paper in a 2x2 grid. To give myself reference, I drew a line across the centre of the MDF sheet and added a small mark midway across. All of the sheets will align along their longest side to this line, with the corners coinciding at this midway mark.

Step 2 - Prepare for printing

I chose a mail order catalogue which is slightly smaller than A4 for the print media. The paper is semi-glossy and fairly thin. Not all paper works the same for this process, so run through these steps to get familiar with the process and try a few test pieces first. The binding is a typical hot-melt glue type, so I ran a hot clothes iron along the spine and pulled off the covers. Whilst still warm the pages were easily parted into smaller sections. The residual bits of hot glue should be trimmed off otherwise they'll happily end up on your printer drum. This is NOT a good thing.

I emptied the paper drawer and reset the guides to match the paper. On my computer I added a custom paper size corresponding to the physical dimensions of this paper which were 208mm x 279mm, or a little narrower than Letter.

This gives you an idea of the print settings for my chosen CAD package, TurboCAD. The "real" paper size consists of 2 rows and 2 columns (set in "Layout") of my custom-defined paper size. The virtual drawing sheet size is a breakdown of the CAD plan automatically sized to the printable area. Most importantly the print is set to 1:1 scaling along with adding in the chosen alignment marks.

Step 3 - Printing

Send your print job to the printer and manually load one sheet at a time. Doing this reduces the chances of the paper pickup taking several sheets at once and causing a jam. Load the paper so that the print will end up on the side that is the clearest - you need to be able to see the print to trim up to it! Check that the print hasn't wrinkled or smudged, and that the alignment marks are visible. Check that the pages line up with each other without gaps/overprint and that the dimensions of the drawing are in fact 1:1 in both width and height.

Step 4 - Transferral

Firstly - using your steel ruler and a blade, trim the excess margins from the pages where they mate so that they butt up to each other perfectly.

Align the edge and corner of the first page to the reference marks on your sheet and tape the four corners that the page lays as flatly as possible (unlike my example *cough*).

(Finnish women don't look like this)

Starting from the inside corner, place the iron on its highest temperature and leave it to sit for 10-15 seconds. After this, pick up the iron and place it further away from the corner with no overlap. Repeat this for the entire page.

(actually, they're not screaming under the heat so at least they seem resilient like Finnish women anyway)

What we're doing here is partially bonding the page to the sheet. The toner re-melts and sticks to both the iron and the paper. The page can be left a few minutes to cool, and then we can iron the page with some pressure! The glue on your painter's tape will likely melt during the ironing; making the pages prone to sliding and smudging the toner, so refine your technique with this in mind and don't drag the paper with the iron. Making sure than the sole of the iron is clean helps a great deal. After thoroughly pressing the paper down, the toner should ideally have "left" the paper and stuck preferentially to the target, hence why we used a glossier paper than standard printer paper; the bond between the ink and the glossier surface is weaker.

Carefully peel the page backwards from the far corner, examining the transfer as you do so. If areas are missing, carefully re-apply the page and re-iron, taking care not to add in any misalignment as you do so. Ideally, you should end up with something like this:

Transfers are rarely perfect due to a number of reasons; the cleanliness/smoothness of the target surface, and the paper used makes a difference. Your clothes iron needs to be as hot as it can manage. Again, find out what works best. All that remains is to repeat this process for all four sheets, aligning each one with the reference marks as carefully as you are able.

The toner transfer method is not perfect by any means, and is subject to tolerance. Knowing how and when tolerances creep in is essential in keeping this technique accurate enough for its purpose. The lower-left sheet has a slight misalignment; things like this need to be borne in mind if any of the items you have transferred contain critical measurements. Manually check and re-check every precise dimension and marking for suitability, and re-draw them manually if needs be.

Tips

• Include a long scale ruler on your drawing that occupies one sheet. This can help spot any dimensioning inaccuracies.
• Add a regularly-sized grid. 5cm or 2" gridlines expose any misalignment or distortion.
• Transfer the edges of guidelines to the other side. Place your sheet against a window and mark the locations of guidelines as they transition from one sheet to the next; this helps ensure that all sheets are aligned with each other since the print is on the underside.
• TURN OFF THE STEAM!
• Clean the (cold) iron sole with acetone before and after using the iron! Most importantly, you want the transfer work to go well. Secondly, you don't want to accidentally end up with melted toner or tape glue on your dress or your wife's dress shirt.
• Learn which things to include and not to include on your printed plan. Comprehensive is nice, but simple is clearer.

This technique is also a great way of transferring photos or designs to a workpiece. Everybody knows that a gift of a cat photo on a 2x4 serves as adequate forgiveness for returning the iron with sticky toner on the sole.