You are not logged in. Please login or register.
SoliForum - 3D Printing Community → Projects → Personal Mini Shredder
It depends on how long you want them to last between sharpening. You'd at least want stainless. I assumed if he was designing for hundreds of pounds of shredding (which you'd need to make something like this worthwhile) that he'd go hardened.
15kw laser sounds pretty nice though! I looked at getting some 1/4" blades waterjet cut, still way too expensive for the desired price point.
As for your point about safety any design should incorporate a dual chamber that allows adding material to the chamber while access to the blade area is still blocked. You could then close the first door and pull the slide to drop material into the blades.
Absolutely, with electrical/mechanical interlocks as well. Any less than that would be deemed negligent by a court of law most likely. Those things cost money (as do 150N-m gearboxes) which is why all inexpensive (home use) shredders are manual.
By the way, apparently Filabot's Reclaimer uses a chainsaw blade to get around the manufacturing blades issue. It also seems that it doesn't work very well.
- At the price of $439 plus tax $475+ for me location, it's really a HUGE disappointment and an even greater waste of money!
that junk yard guy looks like he just made the grinder of scrap parts laying around ($1,200 I think not). the grinder looks like one used in sewer treatment plants to break up incoming solids.
the grinder looks like one used in sewer treatment plants to break up incoming solids.
Well, you would be incorrect. Here's what he has:
http://filamaker.eu/product/mini-shredder/
After conversion to USD and shipping, it cost him $500. Then that gearbox and motor are easily $700 brand new - sure he got them used, but do you think the OP could sell used parts in his design? I personally wouldn't, but it sounds like he's already doing things I deem unsafe/unwise.
that junk yard guy looks like he just made the grinder of scrap parts laying around ($1,200 I think not).
You're missing the point.
My point was that you need a very large motor to power this machine. That particular motor and gearbox (in the video) are easily $700 brand new (single unit quantities). You cannot source a suitable gearmotor for much under $100, and that's in large quantity from China.
I think a plastic grinder for home use could be crank type using a system like the chipper on old Bolens garden tractors only about 1/3rd the size with say a 6 or 8 inch inlet hopper with a drawer type input drop for safety and either find a metal band/drum with rasp blades built in (like Bolens used but smaller) like the hand rasps of the past 30 years have or make one. then fab a housing for it with a snail shell shape which forces plastic towards blade drum as crank is turned and housing is tilted so as pieces go through drum into center they tumble out into container. housing also would resemble a squirrel cage blower like on a home furnace only smaller. be like sharpening a big pencil.
if cranked backwards the blades on drum dont bite into plastic and just let it bounce on drum. turning correct direction lets blades bite chunks off plastic and the fall through the small holes into drum since the blades are like the wood rasps with small perforated spring steel with tiny carbon/diamond on most rasps chisels welded on inside edge of holes. also some cheese graters are like this but without added chisels.
n2ri wrote:the grinder looks like one used in sewer treatment plants to break up incoming solids.
Well, you would be incorrect. Here's what he has:
http://filamaker.eu/product/mini-shredder/
After conversion to USD and shipping, it cost him $500. Then that gearbox and motor are easily $700 brand new - sure he got them used, but do you think the OP could sell used parts in his design? I personally wouldn't, but it sounds like he's already doing things I deem unsafe/unwise.
n2ri wrote:that junk yard guy looks like he just made the grinder of scrap parts laying around ($1,200 I think not).
You're missing the point.
My point was that you need a very large motor to power this machine. That particular motor and gearbox (in the video) are easily $700 brand new (single unit quantities). You cannot source a suitable gearmotor for much under $100, and that's in large quantity from China.
PARDON me but how can I be incorrect about stating what something LOOKS LIKE?
fr333n3rgy wrote:1) Not all shredders are manual - most are electric or fossil-fuel powered (again, no homework).
I'm not sure why you continually feel the need to insult me.
You must not be reading what I'm saying, so I'll try to clarify for you.
There's a reason all consumer-oriented shredders on the market are manual.
fr333n3rgy wrote:3) I am just supplying parts and plans for a kit-form shredder (read my original post).
There is definitely liability in that.
http://tucson.com/news/local/crime/judg … 65918.html
Kit airplane manufacturers get sued all the time for injury/death.
fr333n3rgy wrote:P.S. If you're cranky about people being able to recycle their own materials at home, wait until you see the filament extruder attachment for it.
I am not cranky one bit - Its just that I've designed exactly what you showed in your CAD rendering in the OP. I've been there, done that... and I'm trying to save you the trouble but you seem to be uninterested in listening to those that have come before you, so I wish you the best.
fr333n3rgy wrote:Your feedback and requests are as always welcomed.
Apparently not. I'm not sure why you'd come into this forum and be so adversarial. I'm quite happy to share my experiences openly, you on the other hand don't seem as open to receiving them.
It was never my intention to insult you (and I don't believe I did), however if you perceive I have, then I apologize. On the other hand, you should be more supportive of new projects and offer constructive criticism instead of just trying to shut down a project before it starts (and that was what you did). I guess you dismissing this idea before it left the drawing board got to me (I have some Italian blood lol).
Just because you failed at something, it does not mean others can't succeed at it.
One thing I learned in life is that as much as we all want to think we're the best at what we do, there is always room to learn new tricks and there is always someone better out there (we may just not have met them yet).
Therefore I would like to offers some friendly advice (honestly). Be open minded and give the project a chance. These forums are for people to discuss and contribute to the common good and help each other.
Now, let's stop this right now and if you have some advice, share it with us so that we can avoid making the same mistakes. As I said in my OP, the goals are clear. Can it be done, I believe it can. I have the resources and connection to get things done.
I am not saying me or my partners will not make any mistakes, but I am am determined to get this done as I believe in the cause, and it will get done.
Since you keep saying that "talk is cheap" all I can say is, be patient, contribute with your constructive advice, or just stay back and see how this develop. Wait for it to fail (if it does) and then go for it if you want.
Thank you for your comments - no harm done, no hard feelings, life goes on 
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:
Lets assume you're able to machine those teeth out of hard steel (or conversely, soft steel and then heat treat them) for $5/ea. Even a small shredder needs 10 teeth per shaft, plus the cleaning spacers (do not need to be hardened). You're looking at ~$150 before you've even made a chassis (6061, I'd assume) and bearings. You might be able to do it with a BoM of $175.
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).
One thing I learned in life is that as much as we all want to think we're the best at what we do, there is always room to learn new tricks and there is always someone better out there (we may just not have met them yet).
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.
Therefore I would like to offers some friendly advice (honestly). Be open minded and give the project a chance. These forums are for people to discuss and contribute to the common good and help each other.
... I'm not being closedminded. All I've done is state facts. Whether you find them inconvienent or not doesn't make me closedminded.
Now, let's stop this right now and if you have some advice, share it with us so that we can avoid making the same mistakes. As I said in my OP, the goals are clear. Can it be done, I believe it can. I have the resources and connection to get things done.
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?
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
I'm moving this to Projects, maybe you'll find more interested folks there. Clearly you aren't interested in discussing pros and cons of various approaches, or sharing any details on your approach (you haven't even mentioned what material you plan to make this out of).
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.
I like the idea. I'd like to see more of it. I don't think the regular home/hobby users even at 300 or so would benefit from from it but I'd rather pay 500 ofr something that works rather than get a granulator at auction for the same price, not knowing if it works and having to ship it.
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.
Any news about extruding and printing in HDPE, PET, and various other plastics found in bottles?
Just posting that I enjoyed reading elmoret's explanations.
just found this old topic pic and thought of this topic lol
http://www.soliforum.com/topic/1917/new … -solipony/
just found this old topic pic and thought of this topic lol
How is this relevant at all to this thread?
n2ri wrote:just found this old topic pic and thought of this topic lol
How is this relevant at all to this thread?
the picture of grinder. an early post on this talked about hand cranking
For only a little bit more it seems like it might be possible to get something like one of these used industrial grinders if one had the space:
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.
I have one. Check out this post: http://www.soliforum.com/post/69064/#p69064
Why not start with the guts of a paper shredder and modify to suit.
mightyshredder, personal shredder - project update. Still within budget, using stainless steel teeth.
https://www.youtube.com/watch?v=_3MQdP0BCOc
The granulate is too large to work with the filastruder from what I saw in the video; spending your time hand crank re granulating the granulate is not a valuable way to spend your time, assuming your time is worth something.
To expand on Ggalinsky's point:
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.
SoliForum - 3D Printing Community → Projects → Personal Mini Shredder
Powered by PunBB, supported by Informer Technologies, Inc.
