Laser Engraved PUGkin (Pumpkin)

• *I have a three month pro membership to give out to the first person to have made there own laser engraved pumpkin and post a photo.*

Introduction;

First things first, sorry. I can't say how sorry I am for the pun (or should I say Punpkin) in the title and the following puns, jokes and bad ideas to follow.

This is my second instructable and if I'm honest I wasn't expecting to make an instructable for this but after making the pug design for my third pumpkin I kind of had to even if just for that title. Personally with access to a laser cutter at school there is no other way to make amazing engravings on your Halloween pumpkins. Its not to difficult the most difficult part is most likely picking the pumpkins which is step 1.

You are going to want to pick a pumpkin that fits the following criteria I got mine from Morrisons as they are the best in terms of size to price;

• Needs to have a reasonably flat side at least A5 sized
• Scars are to be avoided but small flat scars that are mainly on the skin are ok
• look for a good stem while it doesn't affect the engraving it means its a healthy pumpkin
• Look for soft spots and avoid along with, mold, wrinkles or open cuts that would indicate damage
• Place your pumpkin on a flat surface to check to see if it will sit flat after being carved (I didn't and ended up with rocks holding up two of mine)

If you have the time it can be worth going and cutting out a cardboard sheet with the size you plan to engrave on. From then you just need to buy your pumpkin if your doing other shopping it can be worth asking them to keep them at the till while you do.

Holding your pumpkin in place is difficult the fast action of the laser can cause it to shake if not secured. For the succouring of the base I use a triangle made for a the kitchen when placing hot pans onto as to not burn the surface, basically it is just 3 pieces of 1 inch thick MDF cut and made into a triangle.

Using this you can hold the pumpkin in place inside the placer cutter easier than using cardboard and stocking the sides however if necessary you could just use cardboard to keep your pumpkin in place.

The next step is making your design, there is a range of ways you could do this but image preparation in most designs is the first part of the etching process is to prepare the source images. Over-detailed or overcomplicated images do not present well (see picture 2). Therefore, it is necessary to prepare your artwork with love and care before etching.

Flattening the colours
This is the simplest method of image preparation. Simply open a colour image in your software and change the image mode to black and white.
This tends to work well on images that were originally black and white. It is important to know, this technique will not always work well on images that depend on colour information. From my testing human and canine faces do not tend to work unless as a cartoon.

Thresholding
The thresholding method converts the source image to black and white based on the luminosity of each pixel. Bright areas will end up as white and dark areas will end up as black. To apply, open an image in Photoshop and choose Image > Threshold. Then, adjust the slider on the histogram to change the luminosity threshold.
This method is very effective on evenly-lit images. However, if an image contains a shadowy area, all of the detail in that region will be lost by the threshold. Partition the image into sections or blend multiple thresholds together by duplicating the source layer to avoid detail loss in dark areas.

Vector Tracing (My main method)
Start by opening an image in Adobe Illustrator and select Object then Live Trace. Adjust the threshold, blur, path fitting and minimum area settings to produce a vector version of your image.
The tracing results in extremely clean, sleek images. But, since it is based on selecting a threshold value, it suffers from contract issues.

Monochrome inverted;

For black and white images, everything that is black becomes white. The laser will etch any black (dark) areas of the image, removing the outer flesh. On the pumpkin, these areas are actually lighter than the surrounding negative space. In order for images to appear positively on the pumpkin, you must invert your final image before engraving.

When it come to using the laser cutter it will change depending on the pumpkin, laser, age of laser, and the design itself. In general I have found that on a HPC 60w Laser it works at around 300 Speed 25 Power (with 25 leeway on speed and 5 on power) it just so happens that the settings for pumpkin also are the same as for engraving leather so you can use that as a starting ground.

In general I have found that it takes around 5 to 10 runs to make a meaningful engraving on the pumpkin. So of course there is problems with this first off the smell is bad I mean it leave the lid shut and extractor on for at least 5 minutes when finished. The second problem is curvature the design can be missed off or burnt around the edges due to the pumpkin curving away from the focus point. To fix this you can do one of two things move the bed up and down during the engraving or invest in a rotary attachment.

From there just set to engrave every so often pause the program to wipe of any juice or burn residue that is building up.

Hollow out like a normal pumpkin, to make it easier by cutting the hole into the bottom of the pumpkin as the inside guts are attached from the top to the bottom and by cutting the bottom the guts will almost all come out at once.

Make sure to put extra pressure on the side with the engraving so the light shines through better with this you are aiming to have the side with the engraving as thin as possible. At this stage if you wanted to you could take the opportunity to make any holes you want in the pumpkin or to scrape the engraving deeper.

For this you can use candles but I would recommend using LEDs and they are brighter and produce a better glow. For mine I had a spare 5m strip of LEDs and used that them rolled into a ball and placed in a plastic zip-lock bag.

From here just put on show and wait for the visitors and comments of "wow your getting good at this..." its up to you to decide what to tell them.

Win a pro membership.

I have a three month pro membership to give out to the first person to have made there own laser engraved pumpkin and post a photo.