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Further Math On Adhesive Sheets

A project log for Sexy Gantry

Documentation of my journey to a commercial enterprise around hobby machining, specifically cnc, even more specifically 3d printing.

Daniel GraceDaniel Grace 08/08/2022 at 16:430 Comments

Phase One Update

I am ordering the bigger plate today. It will take a few days to be available, and I hope to have some basic jigs set up in that time frame. Then I can cut the first potentially-sellable product without a magnetic plate. No big update on that, because it's boring, but it's important.

Phase Two Update

I got the quote back from Germany. They were very nice, answered my questions, sent over a bunch of info. I could influence these numbers by buying more in bulk, but the ultimate price per Voron 0.1-sized plate would be approximately $5.14 USD. That is technically doable, I would still turn a profit at my target price point, but it would take a pretty large chunk of the profit out. I am also impressed at this listing: https://www.fabreeko.com/products/graviflex%C2%AE-200-high-strength-magnets As far as I can tell from their supporting document they are getting exactly the same deal as me, so they are getting something like $2 profit over raw material costs, which isn't a lot for cutting it into pieces and packaging, etc.

Let's break down all the options with this new info:

Old Possible Source One: McMaster-Carr Acrylic

Comes in awkward sizes, I would be applying the magnetic sheet later in the process and more times. Each unit I buy would make 8 plates. Comes out to $2.41 USD per v0.1 plate.

Old Possible Source Two: McMaster-Carr Rubber

Comes in much better sizes, making the manual labor part better. Each unit I buy would make 400 plates. Comes out to $1.68 per v0.1 plate. The main downside here is that the rubber adhesive is untested, but it's the cheapest total cost.

Old Possible Source Three: McMaster-Carr + 3M

Buy no-adhesive sheets from McMaster-Carr, apply "fancy" brand-name adhesive that is technically better and might justify a premium from my customers. The magnets make 400 plates per unit ordered, the adhesive makes 720 plates per unit ordered. The total cost is $1.67 each for magnets, and $0.67 each for adhesive, or a total of $2.34. Only slightly cheaper than McMaster-Carr Acrylic and a worse process. This is only worth it if the 3M name is a reasonably large sell. It is better on paper, so I don't have to sell my soul to market it as an upgrade.

Old Possible Source Four: schallenkammer

Each unit makes 324 plates, and the effective cost is $5.14 each. I open myself up more to the effects of shipping and international stuff. The brand is not as well known (though other people DO sell their product to the 3d printer crowd), and likely can't justify a premium just because of the brand. I thought I had a unique selling point when I saw that they offered colors, but one of the things they said is that the colored versions aren't rated for the heat, so that's a non-starter. I can't really think of a way to keep this option around.

So now we have a new set of options.

New Option One: Lowest Price

The lowest price for me (and thus either the lowest price for customers, or my highest profit) is McMaster-Carr Rubber. This would impose upon me a short-term price because I couldn't morally offer this without doing some testing of my own, but it would be the cheapest long-term.

New Option Two: Most Premium

Using 3M adhesive isn't that much more expensive in raw material costs. It does take a bit more process, and I don't know how bad that will be precisely. This is somewhat up in the air, but gut feeling is that I would have to sell them for $2-$3 more to justify this. That's not a big difference, and I could probably add more than that onto the price if I wanted to maximize profit.

New Option Three: Safest

Doing small sheets of McMaster-Carr Acrylic isn't the easiest workflow, but I have a solid idea what that workflow is. It's a known product in the community. It's basically the same price as everything else. This is definitely the safest choice.

I think for now I will leave it at that and not make a final decision. The decision will come down partially to whether I am going for mass market or premium, and whether I feel like I can afford to do the experimenting with the rubber adhesive. I will punt on those decisions for later.

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