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Hey guys, I'm not entirely sure if this is the best place for this but I'll give it a shot. I make shadow boxes as a side business, and in order to streamline things I'm looking to get a custom plastic spacer created. I'm hoping I can come up with a CAD diagram, hand it off to a local plastic company and ask if they would be willing to make a few thousand pieces? Does anyone have a remote idea on how much something like that might cost? Either way, I know the first step is to create a CAD diagram to get an accurate quote but I don't have the software. However the spacer is incredibly simple so maybe I can hire a goon with CAD to create it for me. Would that belong in an SA Mart thread? I made a sample spacer out of acrylic as a test, it looks like this:  Piece of cake! The outer dimension is 284mm x 220mm, the inner dimension 274mm x 210mm (making it 5mm wide) and about 13mm tall, basically slightly larger and thicker than a piece of 8.5x11 paper that it would overlap. I imagine that the actual mold that would need to be created is something the plastic company would do, correct? Anyways if anyone has any information about this, or would be willing to create a CAD diagram for me, please let me know. Thanks!
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Feb 1, 2019 01:46
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You shouldn't need a CAD drawing-if you just take them your sample they should be able to quote you something off of that. Injection molding is usually very expensive unless you are going very large quantities because a mold/die has to be made, but if you need a few thousand, it might pay. There's a bunch of machinists and manufacturing types in the metalworking thread so you might ask there too. I would guess the way you've made it-ripping sheet stock and gluing it together might be the cheapest way. If you need it all polished and seamless etc. it might get expensive fast, but if you need several thousand I'm sure some shop will be interested. I'm always shocked how expensive acrylic is. If you could live with wood just nailed together you might be able to find a woodshop that might do them for maybe $20 a piece or less.
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Feb 2, 2019 01:31
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Those are big parts with a low production run (by injection moulding's standards)- I'm not in the industry but I'm dubious that injection moulding is the most appropriate approach here. I can't really tell what sort of geometries are involved- the design is effectively stacked "2D" slices, right? The spacer 'frames' the design with a cutout in the middle for the art, I'd think? If so, and if some limited assembly is acceptable to you if it comes out cheaper, I bet the cheapest approach would be to divide the spacers up into components that will nest efficiently on large sheets of material, laser cut the spacer from acrylic (altho plywood would be cheaper), and then assemble the spacers using a custom jig designed in concert with the spacer modifications so that you can make use of expediencies like locating holes + pins to easily index the spacer parts together with a minimum of fiddling. Doing the assembly yourself might not be practical or worth your time, but that's how someone else will be doing it, more or less, if they've ever tackled an assembly run of this scale.
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Feb 3, 2019 01:14
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These guys will custom fabricate for you. No clue on pricing for what you want. http://www.alliedplastic.org/ https://www.johnsonplastics.com http://www.regal-plastics.com/
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Feb 4, 2019 20:37
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Does it need to be transparent? What kind of strength are you looking for? Edit: You say a few thousand but are you buying for the long term? In other words, how many of these do you use in a day? 30 TO 50 FERAL HOG fucked around with this message at 01:16 on Feb 5, 2019 |
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Feb 5, 2019 01:10
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Sorry guys, I missed these messages until right now. In the mean time I went ahead and commissioned a CAD drawing from someone in the SA Mart thread although I haven't done too much with it yet. I did bring it to the local Liberty Science Center though and asked if they would be willing to 3D print up a prototype, which they hopefully will later this week. It does seem that injection molding might not be the approach for me (since a few companies quoted me a minimum of 1 million pieces haha). However I did worry that 3D printing is too slow - I was looking for a couple thousand just to last me a year or two, I would only be using a handful a day (10?). I would like them to be black though so you can't see the sides of the frames. I reached out to a couple local plastic companies though who are willing to give me some options. I think I'm gonna reach out to those 3 companies listed as well just to see if anyone has more options. I was given a recommendation on a Creality CR-10 3D printer which I suppose could be an option, if I knew how long it might take to print one of these..
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Feb 5, 2019 01:50
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3d printing something large with appropriate nozzle/settings can be surprisingly fast but 20 a day is a tall order unless you had several printers. You could also laser cut black acrylic in such a way that you would have 4 pieces (one for each side) and assemble them
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Feb 5, 2019 02:22
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If you want them black, do you actually need to use acrylic/plastic? In that thickness etc. it is going to be fairly expensive compared to wood or metal however you get in turned into a box.
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Feb 5, 2019 02:31
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I don't need any material in particular as long as its strong enough not to collapse under a few pounds of pressure. I just don't want to do any assembly myself. Question for you 3D printerers: Can you print multiple copies of a thing stacked on top of each other (but somehow separate them so they arent one solid piece?) Maybe thats a solution for printing 10 at once and leaving it running all day or something. Theres also the question of how much cost in filament it would take to create one of these to factor in..
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Feb 5, 2019 15:43
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3d printers are more in-line with prototype or one off/small run jobs. I would imagine the maintenance and cleaning required to keep it running 24/7 would be a nightmare. A single one of those would take about 8 hours with 100% infill on a 3d printer. If you are just looking for the sides and no backing having the strips cut (2k of each length) by a plastics company is probably your best option. Then just glue/assemble them when you are putting the shadow boxes together.
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Feb 5, 2019 16:25
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This all seems like a lot more trouble than making a couple jigs so you could, as someone else suggested, rip down sheet and glue up a few spacer frames at a time? I'd imagine you make a box the size of your inner dimensions, but instead of 13mm high, you make it, say, 300mm, giving you space to glue up a bunch at one time. Wax up the box so glue won't adhere your spacers to your jig.
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Feb 5, 2019 16:52
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Yeah I think you’re making this way more complicated and expensive than you need to. Talk to a custom cabinet or woodworking shop. Wood is almost certainly going to be your cheapest option-edge banded plywood or MDF mitered and nailed together with a black painted finish. Do you have a cost in mind per unit of what you can afford for these to still be profitable for you?
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Feb 5, 2019 17:01
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3d printing is absolutely the wrong approach for actual production of large, very simple parts, I'd rule it out immediately and definitively. Absolutely nobody production-manufactures things with 3D printing unless the part geometries can't be practically made with any other approach, or if the production runs are small enough that making the tooling for other processes will cost more in the end. 3D printing is extremely expensive and extremely slow, your product can be made very cheaply and quickly without needing much in the way of tooling made, the math is straightforward. For you 3D printing should be limited to prototypes only, but frankly even that is still a waste of money imo, this is stuff you prototype with hand tools because the design is so simple and fabrication needs no real technical skill. If you don't care about material beyond being sufficiently strong/rigid, this is a no-brainer- a cheap sheet wood product like hardboard, laser cut slices to build up the final product, pay someone else to assemble if you really don't want to do it yourself. If you're dead-set on no assembly at all it'd be easiest to CNC router the parts from said wood sheet product, but that will probably be much more expensive than lasering and assemble. Like, easily twice as expensive, probably more, and it'll use much more material to get the same result. It makes no sense unless there's a geometry/design requirement i'm not getting. Ambrose Burnside fucked around with this message at 22:32 on Feb 5, 2019 |
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Feb 5, 2019 22:28
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Can you explain how the spacer works, how it's visible, and things like that? Maybe a good solution is to design a better-automated spacer without impacting your product. From what I've gathered so far, a decent machine shop could probably come up with a reasonably cheap solution. I'd lean toward a multi-part solution because it's much easier to create two smaller, reversible rectangles (one for top/bottom and one for sides) than it is to create the whole thing as a single piece. Injection moulding is too expensive because moulds are expensive. It kinda sucks that this doesn't seem like something that could be done on a lathe, because that's a real affordable solution for this quantity. Khorne fucked around with this message at 07:00 on Feb 7, 2019 |
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Feb 7, 2019 06:52
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There are 90 degree clips which work for plastic and glass (I don't know anything about the linked vendor). With clips you'd still need to get the plastic cut but you avoid gluing.
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Feb 9, 2019 05:09
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First reaction is to find a water jet or laser cutting vendor that can handle the material and thickness. They can buy a sheet at thickness and cut the profiles out. There'd be a lot of waste (the closed area within the rectangle) so maybe you want a bunch of L shapes to maximize your yield. Of course Ls are one step closer to the ripping, cutting, gluing solution so it might not be worth it.
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Feb 18, 2019 22:00
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Wood. There is no reason to explore any other option than wood. It's cheap, plentiful, and in your case if it's going to be hidden, doesn't even need to be decent quality wood. If you find the right place too, you could even get an unlimited supply of free wood if you're fine with cutoffs and factory seconds.
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Feb 21, 2019 10:45
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Thanks guys, it seems like I may be better off with my current solution, cutting pieces of Frametek spacers: https://frametek.com/products/framespace/ Its annoying cutting them to size however so maybe someone can think of another option for cutting them in bulk? Right now I am using one of those paper guillotine things, but I can tell it isn't meant for plastic and I have to slam it down to cut through them. Is there some kind of compact solution for cutting multiple sticks of plastic to a specific size? I know very little about woodcutting tools so probably need to dumb it down for me if theres some kind of mini circular saw setup I could use. Here is what I am doing currently:  This works ok with one or 2 sticks, but I'd love to cut much more at once. End result: 
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Mar 11, 2019 01:21
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tabletop cutoff saw! https://www.amazon.com/Hercules-Ben...=gateway&sr=8-9
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Mar 11, 2019 01:50
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