The issue I’m having is with regards to the legs and the slots they fit into.
With acrylic there is a tolerance in the thickness meaning the width varies dependant on what part of the acrylic you cut, so even if the whole sheet is “3mm”, the legs I cut could actually be as small as 2.6mm or bigger at 3.1mm.
The method that I have come up with to ensure I’m not wasting material, is to cut the legs out first, measure them with a key I have made (see below), and then cut a top and bottom with leg slots to fit those particular legs.
It’s very time consuming, when in reality I just want to be able to cut all parts and know they will all fit together no matter which parts I put together.
I’m in the process of talking to multiple manufacturers about getting this produced on a larger scale but no one seems to be able to provide any advice on this issue, and I don’t want to commit to getting them made knowing the legs might not fit. I’m hoping someone on here might be able to help/give some suggestions! Please!
Hi Kate;
I looked around and was surprised to find that acrylic plate (both cast and extruded) has awful manufacturing tolerances… What is the thickness tolerance of ACRYLITE® cast acrylic sheet? - ACRYLITE®
That site, hilariously, goes on with a boilerplate explanation of how tolerances are important (they are in many cases) but then lists their 3mm plate as having a tolerance of 2.3 → 3.7mm, humm.
Looking around; nobody else offers better tolerances; it’s clear that cast acrylic is hard to manufacture with precision…
So I can understand your problem; but also sympathise with cutting companies, without being able to order materials with reliable thicknesses they are in a bind.
I think the best ‘solution’ you may have is to choose a different material for the ‘legs’ (end pieces), pick something that you can source in a reliable thickness. Something slightly ‘compliant’ like a hard foam material may be ideal since it will give a very tight fit if cut accurately. If you dont need waterproofness then plywood might work. It might even look good
Alternatively, size the holes at tour plates minumum thickness and build a jig that can cut or sand down the ‘pins’ on the legs to that thickness. The end result looking like:
Edit: PS: This also explains why, over the years, I have ordered small kits that come with a ‘laser cut case’, these cases always have oversized slots and are really wobbly until you screw them together… I guess they have the same problem and have to size for the worst-case plate thickness.
I think it’s a common problem unfortunately and one that I will continue to find a better solution for, which I think lies in using a different material.
polycarbonate then. I know there are other clear ‘plastic’ materials and maybe they have better manufacturing tolerances even if they can’t be laser cut. There are services like Sendcutsend.com which could mill the legs if laser cutting isn’t safe.
polycarbonate does not cut well on a laser (brown, bubbled edges). It’s not my first choice to mill, and that won’t give sharp inside corners either. It is a lot tougher than acrylic which can be a blessing or a curse…
My approach here would be to go back to the design phase and redesign the assembly to be tolerant of the actual thickness range of available stock.
true, there are ways around the issue with the current material choice.
For example, acrylic adhesives are really really good so there’s little need for slots at all and there are other fastener choices.
I was personally thinking of dense Styrene Foam sheets, I have used them a bit, sold in multiple colors for the modelling community.
The black sheets I have used, 3mm and 8mm thick, cut like butter on my diode machine, it is almost impossible to go too fast ,and leaves a beautiful sharp edge. Usual warnings about highly toxic fumes and needing external ventilation go here…
Beause it is complient you can simply size the holes a fraction narrower and squeze the tabs in. They should grip quite firmly, and this foam is quite stiff and tough.
But… I dont know the OP’s requirements… how much weight does it have to support?, does it need chemical resistance?, how frequently it needs to be assembled/disassembled, etc.
This seems like a better option than complicating the design or adding fastners/adhesives etc.
ya, the collapsible requirement kicks adhesives out of the picture unless it were used just to add a bit of dimensionally correct material to the end of the sides which fit the holes consistently.
I was thinking wooden ends would look nice but they won’t clean up as good if there were chemical spills and anything porous is probably out of the question.
