Below is how I would do it if you are making multiples or even just using the same size timber and want to save setup time
Use an L-shaped corner bracket, ensure it’s square using a dial indicator or even by jogging your machine up and down along the side of the bracket.
Draw your job in CAD software with the timber drawn to size. Place 8mm (can be whatever size your T-Track bolts are, 8mm is what mine are) squares between each sheet of timber where you will put the hold down bolts. This will align the timber correctly when you lay it out on the machine.
when you set up the job, put the first piece of timber into the L bracket and place 8mm bolts with washers to hold down the timber in the place that you’ve drawn the 8mm squares in CAD.
install the rest of the pieces of material with bolts between each board - as you’ve set it up in CAD. Ensure that your bolts are hard up against the timber otherwise the gap between boards will be more than you allowed for.
Be aware that the washer on the hold down bolts will sit over the board a little, when you design your job make sure you allow for some space for the tool to clear
If you have trouble getting the boards to sit hard against the bolts try putting timber spacers between the boards next to the bolts to space it more evenly
This will allow you to use a single zero for the job, and also mean much more secure workholding. You could even put cam clamps on the right hand side to secure it further (though I don’t think this would be necessary)
Wow this is great. Thank you so much for the detailed response. The main thing I’ve gathered is incorporating these “hold-down” bolts into the assembly. I see now that this would be fairly easy to add to the setup to get some added support in the Z-direction. I Also love the L bracket on the left hand side. I think I’ll create one that can attach into my T-Track on one side.
The problem with a lot of these methods, is that without something backing-up wood, you’ll get some tearout.
Take a look at the pics in this thread:
…and you’ll see my solution. It is my binder-clip hold-down method. It is a piece of wood that is routed to create a lip around the edge. Then the workpiece can be held to the wood using binder clips, and you can even place a piece of disposable something between the workpiece and the jig to prevent tearout.
It really works well, I almost always come back to it when I need a high quality finish or if I want to crank-out several of something quickly.
This is exactly how I did my recent Christmas baubles project. All 4 panels cut at the same time. The jig is uniform in all 4 panels and the Z for each is the same. Each panel to be cut sits on its own waste board which is levelled and each panel is uniform in thickness. The CAD incorporate the jig into the design so its easy to only cut the panels and not the jig.
Tabs, 3 on each. The design is carved both sides and the boards are pre-finished so double sided tape etc is not an option for me. I found the size of the tabs is important, not too small as to break with the cutting forces put on them and not too big as to be a pain afterwards. I find that 3mm wide and 2mm high is my Goldylocks size.
I use 4 stencils one for each panel. They are cut using the same design file. The stencils sits on another jig away from the machine on top of the panels about to be cut and the design is sprayed on with acrylic paint. 2 reference pegs keep everything in alignment as they pass through the process. you can just see them in the first pic there. Pre-finishing makes the whole process much faster as they are mostly done coming off the machine, just trim the tabs and a light sand around the edge. There is greater material waste, but the labour (the biggest cost by a mile) is much less than dealing with baubles individually. I cut 864 baubles in just over 7 days the whole deal took about 36 hours.
I’ve realized that a big problem with my setup is board thickness. Even when I joint and plane every board, it might be unrealistic to expect every piece to be the exact same thickness. Especially when I’m using onion skin as a workholding method. Either way this setup is much better than my last, thanks to everyone for all the advice.
I’m assuming you are just cutting out the pieces.
I’m quite new to this, more experienced users please correct me if I’m giving a bum steer!
If your boards are not exactly uniform in thickness, you could maybe account for this by setting your z to the thickest board and then adjusting your stock thickness to that in your toolpath. You would obviously need to do this each time you cut a batch, but it shouldn’t add much to the time.
If you are resigned to clamping in this fashion with varying board thicknesses, then you probably should Z-zero to you wasteboard surface. That will require some recalculation of your toolpaths as a minimum.