TEMPLATE PLATFORM FOR LASER ETCH MACHINE - 3D PRINTED

This project came about because I wished to address two main issues regarding my laser etcher.

The major issue I wanted to fix was to find a way to accurately and consistently position items for etching. To make a decent product the etched image needs to be (generally speaking) centred on the workpiece. Even a slightly offset image ruins the appearance of the product, rendering it unsaleable, and a waste of raw materials and hence a waste of money. I found it frustrating and difficult to always place workpieces correctly in relation to the origin.

The second issue wasn’t such a big problem, but I decided to address it at the same time as fixing the first issue. I decided I wanted to ensure that once positioned the workpiece and laser machine would remain in registration during the etch. In other words, I wanted to make sure the laser frame did not move, in relation to the workpiece, even by a tiny amount, during the etching process.

I will further discuss how this project addresses these issues later.

Step 1: About Tinkercad

For this project I utilised Tinkercad to model my designs, which were then output on my 3d printer. But I must stress, this project shows my model as it was built in Tinkercad, it’s not meant to be a detailed or exhaustive tutorial in all the nuances of building a model in Tinkercad.

However, just a quick peek at the general principles of Tinkercad may be useful for the handful of folks who may not be familiar with it.

The Tinkercad paradigm involves the construction of models through the assembly of subcomponents made up of 3D primitives. The primitives are added together, and ‘holes’ can be made by adding voids to the model. These boolean operations are a simple way of making fairly complex models from very simple primitives. One of the great things about Tinkercad is that you can ‘undo’ any model all the way back to the very simple primitives just by repeatedly ‘ungrouping’ the model.

Picture 1 shows a Tinkercad Roof primitive, together with the first page of available primitives. Tinkercad comes with a large number of primitives which can be formed into sophisticated shapes. In this picture I have already modified the appearance of the primitive.

Picture 2 shows the Roof primitive as it appears when dragged from the menu of primitives onto the Tinkercad workspace.

Picture 3 shows the way I made the triangular profile narrower and taller, to make my template spars - described below.

Picture 4 shows how I extend the length of the Roof primitive.

Picture 5 shows how different primitives can be juxtaposed prior to ‘welding’ them into complex models.

Picture 6 shows the two primitives welded into one via the menu ‘Group’ item. This grouping can be undone at any time - sequentially in the making of the model.

Picture 7 shows another primitive, this is one of the two ‘Hole’ primitives - there is this cylinder and a cube. However, one of the great features of Tinkercad is that any of the simple primitives can be designated as a hole. Adding a hole to a solid has the effect of removing the shape of the hole from the solid.

Picture 8 shows the effect after the ‘Group’ operation, which welds the pieces together, the hole becoming a cutout.

In summary, this was not intended to be a detailed look at Tinkercad, just a very quick and simple overview. However, Tinkercad is so simple to learn and the functions are so very easy to comprehend, no more detailed explanation is actually required. Just go play with it, if you haven’t already.

I find Tinkercad extremely flexible, and as long as you can visualise what you want, and understand the boolean operations, it’s really easy to create a viable model. 

There are, obviously, some fairly serious limitations in functionality in Tinkercad, compared to a fully fledged 3D modelling package. But having said that, it’s got an easy learning curve, and can produce (more or less) what you want. The limitations of the system may make the build process slower, and involve many more steps - and probably result in a less-than-perfect result, but you can produce models which suit your purpose. And it’s free - what’s to grumble about :) 

Step 2: Template Design Criteria

In order to get consistent placement of workpieces for batch production, obviously I was going to need a template method.

I watched a lot of YouTube videos and saw some great ideas, but many of them, relied on semi-permanently positioning the laser machine on the worktop, and positioning the template in relation to the machine frame, on a semi-permanent waste board, or something similar.

Fixing my machine or the template to the worktop was something I didn’t want to do - I was looking for flexibility and simplicity, so I needed to move things around easily whenever I wanted to. I was also looking to the future, which may involve the acquisition of a rotary module. This would require the laser machine to be capable of raising and lowering, so any kind of permanent or semi-permanent fixing was not for me.

I tried a lot of different positioning techniques - some worked better than others, most of my attempts were based on YT videos I used for research. Some positioning techniques described on YT show gridlines marked on the work surface. This is OK if it can be guaranteed that the work surface and machine can be locked together, but most systems I saw did not have the kind of flexibility I required, as mentioned above. None of the positioning techniques I tried were totally satisfactory.

Eventually, after a lot of consideration and weighing up the options, I decided that flexibility, and the ability to set up, and break down the template system, I needed a method whereby the template was attached to the laser frame, but neither the template or frame were attached to the worktop. The system I imagined would ensure the alignment of the frame and template was always consistent. Furthermore, by attaching the template to the frame it would reduce or remove any differential movement caused by vibration. I decided I needed a template which was attachable to the frame, but also quickly and easily detachable.

I did some measuring, and took note of clearances required, dimensions and attachment methods. I noticed that the template would need to be offset from the frame, and set lower than the frame, for clearance.

I believe I have achieved those goals.

The first dozen or so pictures below show the template and it’s structure, I am showing the Tinkercad creation method in reverse, more or less, because this seemed to be the simplest way of showing it. If I started with a few 3D primitives, and then showed the building method, you’d have no idea where I was going until the end. So I decided a backtrack story would work better.

Picture 9 shows the completed template I designed in Tinkercad. My goal was to get rigidity but keep weight to a minimum. I certainly didn’t want the weight of the template to introduce vibration problems.

It can be seen in Picture 9 that the ‘deck’ of the template has a closer spacing of the support spars near its ‘origin’ than at the periphery. This was done because most of the items I wanted to etch were small, like coasters and key fobs. Larger items get sufficient support even with wider spaced spars further from the origin.

Also, it will be noticed that the template platform is slung lower than the mounting points, and is offset from the machine frame. These features ensure that a) the platform is low enough to accommodate the workpiece and still allow free movement of the laser module across the platform, and b) the offset means there’s no chance of the module gantry fouling on the template structure.

Picture 10 shows the platform spars in more detail, with the green Tinkercad Roof profiles clearly visible.

Step 3: Platform Construction Sequence

Picture 11 shows the platform as it was built, prior to being welded to the attachment point subcomponent. The platform is made up of the green Roof shapes, simply narrowed in the base and stretched in length. I chose this profile because it is strong enough through the height section, but is reduced in weight by being triangular rather than rectangular in section. As there is no requirement for lateral strength, the triangular Roof cross section is perfect, having strength and rigidity vertically.

Picture 12 shows the alignment edge of the platform disassociated from the lattice spar section. The alignment edge, made up of rectangular sections, is taller than the rest of the platform so that workpieces are dressed to this edge, ensuring consistent and repeatable positioning in the Y axis. There is a similar raised ledge on the attachment component to ensure the workpiece has consistent alignment in the X axis.

Step 4: Method of Attachment of the Platform to the Frame

Picture 13 shows the subcomponent which attaches the template to the laser machine frame. More details are provided later. This view shows both the offset and the lowered features of the template platform. This structure is attached to the laser machine frame by way of three small M4 screws and rotating T-nuts which are slid into the frame channel and are tightened by way of the screws. I felt three attachment points were a good balance between adequate rigidity, strength and simplicity. It has turned out to be a fine arrangement.

It can be seen that the central mounting point is not actually in the middle of the template edge, it’s closer to the origin. This is to allow for extra support near the origin because that’s where most of my projects are etched.

Picture 14 is just a different view of the partially disassembled template structure.

Picture 15 depicts one of the template frame mounting points and the associated screw and T-nut. 

Step 5: Attachment Component in More Detail

Picture 16 is another close-up of the attachment subcomponent, but I changed colours simply for clarity.

Picture 17 shows the way I use ‘holes’ to cut away parts of the model. I needed to chamfer these shapes to make sure the attachment points did not obstruct the module gantry in its travel.

Picture 18 shows the attachment points prior to the boolean extract operation which created the offset of the platform away from the laser machine frame. There is a nut on the gantry carriage which could possibly foul the template if this offset was not provided.

Picture 19 is a detailed view of one of the mounting points, showing the chamfer, the offset of the structure and also the provision of the mounting screw holes.

Picture 20 shows how the template frame appears when attached to the machine frame by way of the three mounting points.

Step 6: Other Templates Using the Same Methodology

Picture 21 is not related to this main project, but shows my template created purely for etching circular coasters. I have a good source of coaster blanks and making a template even more directly suited to this particular product was a very sensible thing to do, as far as I was concerned.

Picture 22 is another idea - I have drawn (though not yet 3d printed) this individual spar support. I could easily make any number of these, and space them according to the size of the item being etched. Maximum flexibility and customisation. It would not be for batch production, as it wouldn’t easily offer accurate and repeatable registration. However, I feel there may be individual projects where something like this may come in handy.

Step 7: Photos of the Completed Template Platform

PLEASE note, the attached photos appear to show a distortion in the template platform. This distortion is in the photos, not in the physical model. The template itself is perfectly flat and level.

Photo 23 shows the finished article as it appears when attached to the laser machine frame. It was made in PLA on my Creality 3D printer. I didn’t use particularly fine layer settings (0.2 mm,) but all the parts have excellent rigidity and adequate strength. The structure is rigid, stable and light.

What can be clearly seen is an individual screw and T-nut, attached on their own to the frame. This screw is a permanent fixture on my machine frame, I never remove it. This is the device which ensures that the template frame is always in the same place, whenever I mount it to the frame. As long as I move the template up to this screw when mounting it, the origin of my job will always be the same. This method of ensuring consistent registration has worked perfectly, I have attached and detached the template dozens of times, and yet I produce coasters etc with consistent accuracy. This template attachment system has proven itself for over a year and I couldn’t be more pleased.

Photo 24 shows the mounting point and the location/registration screw in more detail

Photo 25 shows the way a workpiece is arranged on the template platform. I now use my purpose built template for round coasters, but this example was one I had to hand. I make lots of rectangular things, such as coasters, boxes, plaques and key fobs, so the main template gets lots of work.

Picture 26 shows how I can do cuts on the template, without cutting through its plastic structure. It’s not something I often do, but if I need a quick cut and I don’t want to dismount my template, I just use this silicone mat and go ahead with the cut.

Step 8: Conclusion

I set out on this project with a simple aim, and I believe I have achieved my goals. I believe my requirement to consistently place a template in relation to my laser machine frame has been fully accomplished.