Sheet Metal Parts

All DXF files for the enclosure are located in the github repository at https://github.com/Laser4DIY/Laser4DIY_Enclosure. The parts are lasercut 1mm stainless steel sheets. The assembly guide has some notes on laser cut metal parts, see Building your own Laser4DIY device.

The metal sheets need to be bent. The repository also contains bending plans (in the bend_diagram subfolders), please refer to them and to the CAD files in the repository and the images below.

Some additional notes for making the bends:

• The enclosure needs to be lightproof. This requires the metal sheets to be precise (the laser cutting process should give you very good tolerances) and also the bends should be done precisely. While there are some tolerances allowed here, try to make them as good as possible, saving you additional work afterwards.
• The designs assumes a bend radius of 1mm
  
  
  In some places a shim metal piece is used to enable bent sheets touch closely, also see step-by-step guide below
• Make sure the MainSheet is bent symmetrically. The position of the holes on both walls need to be on the same height. You can guarantee this by using a mechanical stopper at the right position for both bends. Also make sure that the distance between the walls is correct. You can check this easily by using the CompartmentRightSheet and checking if it fits nicely between the parts.
• The LidChannels have two bends, each around 25-45 degrees. The exact angle is not important, but the two bends should have the same angle.

Assembly of the Sheet Metal Parts

Below is a step-by-step guide for assembling the metal parts. Some general notes on the process:

• The parts are connected by rivets. We recommend 3x6mm aluminum rivets for connecting 2 sheets (2mm) and 3x8mm rivets for 3 sheets (2 sheets + shim)
• If you need to make corrections, you can remove rivets by drilling them out with a 3mm drill bit

Start with the MainSheet:

Add CompartmentRightSheet (and connect it with rivets)

Add 2 CornerBrackets (again, connect them with rivets, we omit this in the following steps)

Add BigShim and LabyrinthSheet. Only use rivets for the holes in LabyrinthSheet, leaving the other holes open for now

Add CompartmentLeftSheet. Now use rivets for all holes in BigShim 

Add 2 more CornerBrackets:

Add CornerBrackets on all 4 corners:

Add 2 Shims, one on top of CompartmentRightSheet, the other below. Do not rivet them down. Instead, add BracketRight, and use rivets to connect the 3 pieces together.
The third image shows a section view of the result.

The same steps are repeated on the other side. Add 2 Shims, add then BracketLeft:

Add the 2 LidChannels:

Add the 2 brackets for holding the laser chamber:

Enclosure Lid

For the lid, 4 metal pieces have to be spot welded to the main sheet. make sure the pieces sit flush to the edges of the main sheet:

The 2 handles (3d printed, STLs are found here: https://github.com/Laser4DIY/Laser4DIY_Enclosure/blob/main/3dprinting/handle.stl) are mounted using 2 M4 screws. Use screws with flat heads. 

Test for Light Tightness

The enclosure must be light tight. There should be no direct way for light shining out of the enclosure. To test this, put a light inside the enclosure, close the lid and inspect the enclosure in a dark room

• Make sure that there is a rivet or screw in every hole. Screws must be secured with thread locker/sealant or by using lock nuts
• Inspect all edges and corners
• Make sure that there are no gaps between metal sheets where light can shine through. This can happen when the connection (spot welded or rivetted) is not good or when metal sheets are dented/buckled.

Safety Switches

The magnetic safety switches consist of two parts: the actual switch is located inside the enclosure, while the activating magnet is mounted at the bottom of the lid. The following image shows the two parts (lid not shown). Each of the parts has a 3d printed bracket (STL again available in the repository: https://github.com/Laser4DIY/Laser4DIY_Enclosure/tree/main/3dprinting). The lid bracket is mounted with screws to the lid, the magnet to the bracket. The switch bracket is mounted with screws to the side of the enclosure. 

The switch bracket has slot holes, allowing for some adjustment of the distance between switch and magnet. For safety reasons, mounting with (only) slot holes is undesired. Therefore, there is an additional mounting hole in the side of the enclosure. When you have found a suitable position for the switch, drill a hole into the switch bracket through that additional hole and fix the bracket position with an additional M3 screw. We recommend doing this step at a later time, when the electrical assembly has been done to allow for checking the activation of the magnetic switch.

There is a second safety switch on the other side of the enclosure, it is mounted the same way.

Safety Circuit and Electrical Setup

The two cables coming from the supply unit are plugged in into sockets at the back of the enclosure. For details on which components to use, see BOM below.

The safety circuit uses a safety relay and to standard relays, redundantly allowing to cut off power supply for the laser. The safety switch monitors the state of the magnetic switches at the lid as well as the proper functioning of the other relays.

Again for details on which components to use, see BOM below. The PNOZ S3 safety relay is operated in mode A, In2-.

For mounting the relays (and later the electronics components) we place two pieces of DIN rail in the electronics compartment. Wiring is done using terminal blocks

BOM