That part shredded appeared to be about 20 grams, and take about 45 seconds. Assuming you never get tired, that's 37 minutes per kilogram. Even at minimum wage ($8/hr) and virgin ABS prices ($5/kg, shipped), virgin ABS delivered to your door is cheaper, even before considering the cost of the machine.

https://www.youtube.com/watch?v=_3MQdP0BCOc

http://pages.ebay.com/link/?nav=item.vi … mp;alt=web

At least then one might be able to recycle enough plastic to justify the cost, providing plastic bottles, tv sets, or another source was found.

n2ri wrote:

just found this old topic pic and thought of this topic lol

http://www.soliforum.com/topic/1917/new … -solipony/

How is this relevant at all to this thread?

the picture of grinder. an early post on this talked about hand cranking

just found this old topic pic and thought of this topic lol

http://www.soliforum.com/topic/1917/new … -solipony/

How is this relevant at all to this thread?

http://www.soliforum.com/topic/1917/new … -solipony/

The blades won't be that expensive to cut.  It will cost more in material than cycle time.  I get parts from a contractor with a Mach 3 for less than a buck a minute pump time in small batch without having a special  deal with the vendor.  I get 2 or 4 sheets cut at a time.  I've been quoted as high as  3 plus a minute at some shops and I have access to a couple fo Mach 2s and a Mach 3 for a couple of bucks a minute.  You could plasma cut those teeth or cut them in a CNC router or mill.  Dirt cheap.  Programming for any of those process for 2.5D is simple.  If it's a low cycle type machine you don't need to get too esoteric with the material.  I think a retail price of 300 is pretty optimistic but I'd still like to see a BOM and some drawings.

The fact remains - time spent is time spent, regardless of who own the machine! If the waterjet is being used to cut blades, then it can't be used to cut (paying) customers parts. A water jet and a CNC can be used to cut parts worth a whole lot more than $5 shredder blades.... so the "cost" is the profit lost on the machine while it is being used to cut blades. Not to mention how expensive water jets are to maintain - one of the most expensive pieces of equipment you can have in a machine shop in terms of upkeep, water jets cost upwards of $50/hour in power/consumables alone. Abrasive water jets do about 12in/min, so that's a blade a minute - or $1/blade in consumables alone. I don't understand why a business owner would feel comfortable letting hundreds (thousands?) of shredder blades be cut for free on a water jet for a side project. I am sure you knew all of this already and I am just overlooking something like a big dumb idiot per usual.

Seems like a poor use of a very expensive asset, but what do I know.

Do you also do the CNC programming for free? How about cutting and loading the raw material? Even if the machine is magically free (or more specifically the machine's owner would rather you use it for free than it produce revenue on more valuable parts), your time needs to be factored into the cost of the part, easily driving it up towards $5/blade. Failing to value your time and machinery is not a sustainable business model.

But you have this all figured out, so clearly you don't need me. I really do wish you the best, like Superdave said a success in this area would only serve to further my interests, both from a business point of view and from the point of view of advancing the 3D printing community.

PS: You may want to check out the results of my 100% recycled ABS print test:

http://www.soliforum.com/post/69095/#p69095

It would appear that recycled ABS does not have the same layer bonding as virgin ABS.

I am also eagerly awaiting the results of your PET filament from water bottle testing, to support the claims you made about recycling water bottles. No one has ever been able to make  quality 3D prints from water bottle PET, so if you're able to it will be quite exciting. Be advised that there are many flavors of PET, and water bottles use a different composition from say, Taulman's PET filaments.

Let me ask you this: Have you gotten a single quote from a machine shop yet?

Why would I? I have full access to a machine shop. We have a flojet waterjet, 2 FUNUC CNCs and 3 lathe machines (amongs other machines). I've been using these machines for years and I can do all required programming.

As I said, just because you (and I'll be careful not to hurt your feelings) did not see it possible to make an affordable personal shredder for plastic recycling using your sources, it does not mean it can't be done.

I think I've answered enough of your messages. I'll leave others to contribute to this thread now and will be back with more information once the product is ready or major milestones are reached.

Take care,
F3

Just because you failed at something

Stuff like that is pretty offensive, I'm not sure how you could think otherwise.

I didn't fail - I didn't even try! I explored the space and realized it wasn't economically feasible unless I either violated the 2.3x BoM rule (and I am happy to elaborate on why doing so is a bad idea), or found some magical way of machining very hard metal blades without using CNC, waterjet, or laser as all the shops I found to do that here in the US were too expensive, and all the stuff overseas was too expensive to ship ($10/kg) unless you got a container. I was trying to save you the trouble by explaining that, and I even gave a breakdown:

So please tell me where I "failed" in the above (and don't forget to add a ~100N-M gearmotor, current sensing, H-bridge, microprocessor, and safety interlocks) to the mix, since you are going with a motorized design. Otherwise, this isn't going to be much of a conversation - its going to you saying you think you can do it, and me explaining why it can't be done (at the pricepoint/quantity).

I believe this wholeheartedly! So please tell me - where am I wrong in the above price analysis? So far all you've done is try to build interest for something you want to sell (and tell me I should be scared of your extruder). You haven't contributed anything to the community.

... I'm not being closedminded. All I've done is state facts. Whether you find them inconvienent or not doesn't make me closedminded.

A good starting point would be to explain where I've gone wrong in the above BoM+gearmotor+electronics, all for $175 ($130 now that you're selling for $300). Even if you cut the blades out of 6061, I don't think you could get the material and machining under $3/blade and $2/spacer, and you have 12 of each in your design. (btw with only 12 blades at .25"/ea, you're looking at a total length of 3". That's some pretty small failed prints. You need more blades. If you choose to instead make the blades thicker, machining costs go up, and granulate size increases which is no good.)

Even before machining, 3" stainless round bar is going to run you about $10 per inch - that's $3/blade after accounting for kerf, before you've even cut it. If you drop down to 4130 steel, you're looking at about $6/inch, so $2/blade. Keep in mind that's all before machining.

Let me ask you this: Have you gotten a single quote from a machine shop yet?