Handmade shredder blades. Building compromise

It apiers to be no available lasercutting or plasma machine in my region.
So starting my shredder with most complex part – thats the blade as for me.
Gained succes, with simple drill and angle grinder.
So here I`m about to leave some foto, and a simplified scheme made by myself inspired by those that Dave constructed.
Ready for sugestions, questions …
1. Plain 9 mm metal sheet (size: 110×60 mm). Drilling 3 holes 10 mm, as on a scheme.
2. Alot of grinder work.

How is the progress?

I am also looking at an alternative to laser cutting to reduce costs.

@subside Awsome work. As a steel worker and artist all that grinding is worth it when you dont have access to a laser cutter.

Bro can i have found ur mail address??so that i can text u in inbox i need information about that.

@s2019, You don’t, sure. You could mill in every corner of the hex something out ( for min. 8mm cutter) and get around 🙂 but the problem is then that you have to change pretty much all designs involving 90 deg corners (side plates,…) too.
With a 8mm cutter, the plates won’t fit well anymore. unless you weld all together just but even though, a first time assembly with no experience, you have to open up all 2-3 times again. This can take 2 or more days btw.

Re-designing all for a mill is interesting btw. (2-3 days for the cutting, I never ever do this again)

I would go for laser; here in Europe it’s around 200 – 400 Euro, ‘just’. Even if you’re good with a file, it’s still pretty hard to get it spot on. We throw here a coin to choose the one who grinds the laser cuts, pure sweat work 🙂

@ppboys , Just curious, why do you need sharp corners to engage the hex bar?

ppboys – thank you! that’s exactly the information I was hoping for, and so fast too!

I see what you mean about the extra grinding work with the plasma cutting option. The back of my cuts usually come out pretty messy even when the settings are dialed in. And shoot I forgot about the corners issue with milling.

I wanted to find out whether it would make sense to use those machines instead because my maker space has them, but with the total project cost in mind, the ~$200 for a laser cut set seems like it is a worthy “upgrade”.

@whosmollyk : plasma cutter may leave lots of grinding work, unless it’s a plasma in the upper 4-6K like the hypertherm. CNC milling is even worst since you can’t make corners (hexbar) and other things … you could but it’s getting out of proportions and needs various design changes. you want all tight and precise as possible. tolerances are in the 0.2-0.4 mm range to make a smooth and well functioning shredder. Btw. just grinding a laser cut set will make you busy for 2-4 hours with a file.

This is really interesting! Good work! What did you notice to be the biggest negatives when making the blades like this?
I am considering making the blades with A) a CNC plasma cutter or B) a CNC milling machine and testing them with the rest of the standard shredder design, but I’m not sure what to look out for, or how tight the tolerances really need to be.

geonoregon dado blades, I think it is better for straight cutting, it`s teeth are to small, and it implies use at high speeds, high speed – means high temperature, plastics will melt and stick to blade. Prefer biger teeth and 60 rpm.

Has anyone thought of using dado spacer blades as shredder blades?  They look just like the shape of Dave’s shredder blades.

I originally wrote what became a long comment on this thread. I decided to post the question/suggestion as a new thread.  Take a look at it for an description of dado blades, and an idea which JUST evolved on using a upside down table saw as the basis for a shredder.


Yeah!, it would be awesome see in detaild how you do it!!

nice nice nice, thanks for sharing ! there are quite some people who might be interested in this build. Would be nice If you could add a little more detail on how you made those blades 🙂

Yeah now I can say it works. Tested it, now I know all the minuses of this construction. New photoes, and hope video will be also

Emmanuel Square section will do allso i think. Or even thin wall pipe as key axis will be beter.

hello everyone,

I have 5 iron bars (1150 * 40 * 11)  that i would like to use for make this shredder. As I calculated, i need 8 blades, I’ll have about 160 mm of shredding space.

But a question persist for me :
You are going to make the hexagon (2 h as you said), very complicated i think.
I wonder if a square is sufficient for this ?
Square section are more common.

Hello!!, this really works? I’m looking for alternatives to build the shredder without laser

@henna: Super interesting, but a lot of fumes ?
@subside: For easy grinding and machining steel you can invert tempering by heating metal to same temperature as mentionned before (a bit above red) and let it cool down very slowly entirelly covered by sand. When it is completely cooled down it will be very easy to machine your piece (and when you are done you can temper it again).

Je me suis trompé, j’ai mis deux fois la même image.
Elle est nettement plus simple et moins coûteuse à réaliser

Bonjour à tous,
J’ai trouver sur la page Facebook la même machine mais construite de manière
simplifiée. Page Facebook de la société qui fabrique les machines: