Marking new products

Just a couple pictures of my first try on (re-) marking the new plastic products.

Very useful if you want to recycle them again.

Let me know what you think.



Great! looks awesome, dont forget to mirror the stamp 😉

I’ve been working with a University and our project’s kicking into high gear. I figured we’d need to stamp plastic. In Australia, shipping and currency means the stamps from Hakkens would cost $32AUS.

The material I’ve gathered from school is PET, we’d still need to make a stamp none the less. (side note: sports carnivals are brilliant places to get a lot of bottles.) I figured I’d build a stamp. The uni has a CNC mill, so that’s no problems.

The only thing is, in the video about stamp, Hakkens says that this one is hammered, and I’m just wondering how that works without heat. Could I have a pic of the whole thing Stijn?

Sorry if this was a stupid question, this is my first real engineering thingo so I don’t really know what I’m doing.

Would it be possible to create a 3d printed stamp, and then make a mould using the aluminium cast method? Would the aluminium be durable and detailed enough?


Yes, the steel stamp was actually the 3rd one in the photo above (‘right way’ round). The problem is that the background is raised and needs to be pressed all the way into the aluminium, which takes a lot of force (more than 10 tonnes it seems) to leave a good impression with the details raised.

The 4th stamp (steel, background milled away) worked much better on aluminium, but this creates an aluminium stamp with the detail recessed, which does not leave a clean mark on the plastic.

Cool. Too bad it didn’t work out though. What went wrong?
Did you mill the steel first?

I decided milling each one individually takes too long, so I made a negative from steel, hardened it, built a 10t hydraulic press and attempted to press out the stamps from aluminium. The results weren’t great.

Hi @Andyn,
Have you been working more on this? I’ve tried it out myself but didn’t get too great results because of too aggressive speeds I used (I think). Which of those designs in the picture works best so far? I’m gonna get a better milling bit for doing this and get another go on it soon or later.


Good idea, You’ve probably seen circular date stamps on moulded plastic. These are a similar thing, usually a series of wheels as part of the mould that you can turn to point to the correct date or other information. Sometimes there are boxes and marks can be made in them with a centre punch.

I’ve been putting some more time into this, here is the V2, slightly bigger and engraved more deeply to leave a better impression on the plastic. The problem is these take a lot longer to make and I won’t be able to make them as cheaply as I want in order to make them accessible to all. I also tried engraving the symbols into the stamp, rather than standing out from it, but this did not work as well on the plastic.

I’m now working on V3 which will be slightly smaller and I’ve decided to drop the letters underneath, as these aren’t really necessary. I hope to be able to produce a batch of these soon.

(below some of my other attempts)

Excellent work @stijnid and @andyn. If either of you do a production run, I’d be interested in getting a set.

I have been thinking of marking the plastic too, and it would be good if we could add it into the forming step instead of a post-process.

Taking Dave’s welded trash can mold as an example, I’m imagining a hole drilled in the bottom with a slight recess milled in (either hex or circle shaped, respectively). By having the stamp on a threaded rod, it could be inserted into the mold and tightened on the outside — thus allowing the stamp to be swapped if you use a different plastic with the same mold.

I might not be explaining it fully and it might be a dumb idea too.

Maybe you could make the patterns linear so that one could add positive and negative wires on them, turning it into a kind of soldering iron. You could be free of the lighter and the sod.

HM! great work and cheep.
I think we could upgrade this marking system.

cool/clever solution @jegor-m! gonna try it out here 😀

@andyn, @stijnid, @jerzeek, @davidpaag

Guys, may I propose a cheap and accessible version of the marking tools. As you can clearly see below, all you need for this option is a couple of paperclips and needle nose pliers.

I tested it on the hot glue while it was hot and highlighted it with a marker. The handles for these mini-stamps can be made later using plastic, wood, resin or something else.

Will test it on a piece of plastic later.

Good stuff guys. Let me know when it’s for sale 😉

I used a propane torch to heat it, not very accurate, the soldering iron idea is much better and also provides a convenient handle to hold it by.

The cutter I used was just the broken shank of a carbide end mill that I sharpened into an engraving cutter, you can buy similar cutters for milling tracks on PCBs. I took 0.25mm deep passes 0.1mm apart (raster style), 0.5mm total depth. I think it needs to be deeper for more relief and I could also optimise the toolpath.

Nice work Andy!
I made the logo 11 mm tall.
What cutter bit are you using? The sharp letters look great.

Did you use a torch to heat it?
I guess electric heating (like the soldering iron) makes it easier to get the temperature right.

Can’t seem to attach a .txt file

This idea appeals to me so I tried it myself. If you have a CNC machine the code I wrote for this is below. The triangle part of the logo is 7mm tall and the text below it is 2mm tall. It takes a bit of practice to apply the right pressure and temperature to leave a good impression on the plastic, it might help if the stamp was a little bigger and engraved a bit deeper, @stijnid what size did you make yours? Needs more experimentation I think, but I might be able to make a quantity of these and sell them for only a few euros each. What happened to the Precious Plastics marketplace idea?