Shredder DIY

[prepman]

It would be much simpler with only one set of blades. I'd suggest without spacers and just have the teeth staggered to make a drum without any gaps.

The tooth size will give you the width of chip. Length of chip will be the circumferential distance that the tooth is in the wood until it crosses grain and chips early.
Chip thickness depends on the disc rakers/clearance behind the tooth and how hard you feed the wood.

I may have to make one as a chainsaw attachment.

I have also thought about single row with knife blades. Been playing with spacers. Need to find a cheap and easy option, like repair washers (big penny). Don't really want to part-off the little bit of 70mm round I have left. Large hole-saw and sheet steel? Steel stockists haven't got any off-cuts and I don't fancy buying a 6M length.
Like I say it's an idea in developement...if it works it works, whatever the final design. I just like the idea of using these cheap blades @ £1/ea

"Welsh Man Eaten By Rogue Garden Machine."

Hopefully not as grim as this...I was looking for cartoon image and came across this.

CCTV caught final moments of man who fell into industrial shredder at work

'The fact that we could not recover David has added to the anguish caused to his family, and denied them the chance to say goodbye to him with dignity.'

metro.co.uk

 

[gaz1]

Hmmmm...not exactly....

even if you take the grinder out of the option you will still be based around the rest of

as you need to change the blades and is roughly the same

now you can go down dado blades that is used with a circular saw

I have also thought about single row with knife blades. Been playing with spacers. Need to find a cheap and easy option, like repair washers (big penny). Don't really want to part-off the little bit of 70mm round I have left. Large hole-saw and sheet steel? Steel stockists haven't got any off-cuts and I don't fancy buying a 6M length.
Like I say it's an idea in developement...if it works it works, whatever the final design. I just like the idea of using these cheap blades @ £1/ea

Hopefully not as grim as this...I was looking for cartoon image and came across this.

CCTV caught final moments of man who fell into industrial shredder at work

'The fact that we could not recover David has added to the anguish caused to his family, and denied them the chance to say goodbye to him with dignity.'

metro.co.uk

have a look closer there is plenty of vids on 2 blades but you will see is jerking of the machine

a planner blade could be used but suffers where the blade shatters you see it more with planning doors

i like the shelix planner blades with higher rpms any repairs is just spin the head round and start again worth a look though

 

[prepman]

even if you take the grinder out of the option you will still be based around the rest of

as you need to change the blades and is roughly the same

now you can go down dado blades that is used with a circular saw

have a look closer there is plenty of vids on 2 blades but you will see is jerking of the machine

a planner blade could be used but suffers where the blade shatters you see it more with planning doors

i like the shelix planner blades with higher rpms any repairs is just spin the head round and start again worth a look though

Think we're digressing a bit here....but is all grist to the mill.

 

[prepman]

Well... found my spacers 20 off 50 62mm dia x 8mm thick @ £20 £17inc Delivered. In MS. So upto £34 total so far.
I've got 20M of 50mm x 6mm angle in short 14-30" lengths (ex scrap offcuts), so framework will be virtually free. Masses of 1- 4mm sheet and 12mm flat bar. So plenty to get on with.

 

[prepman]

Discs arriving 1st class post today....I'm all primed and ready to 'stumble' into action...

 

[prepman]

Possible spring clutch arrangement. cutaway image. ball races images are a bit on the big size. Box of shims arrived.

 

[prepman]

Tried a couple of ganged blades in lathe and still have fingers....it would appear that a single row is not the way forward. So a pair of ganged blades is the ultimate aim still. Now,,,gearing....gears or chain...chain would need an idler or the blades would be turning in the same direction not opposing.
So gears? not my area of medoratic.
ADDED. I have realised the gear diameters will need to be relative to the 85mm of the cutters unless I use intermediary gears which makes more complexity but allows adjustment for depth of cut.

 

[Screwdriver]

Looks like you have addressed the problem of side loading on the narrow blades with larger spacers. I think the next biggest issue with this design will be material being dragged too quickly into the drum. Have you considered having a feeder mechanism to prevent material getting jammed in between the drums?

 

[prepman]

Looks like you have addressed the problem of side loading on the narrow blades with larger spacers. I think the next biggest issue with this design will be material being dragged too quickly into the drum. Have you considered having a feeder mechanism to prevent material getting jammed in between the drums?

The feed rate should be controlled by the spacers, as they determine depth of cut.....the issue I have now that the spacers would have been better +3mm larger diameter, I have possible solution to that. Free turning rings on the spacers. This would reduce the friction loading. The material needs to feed at angle ~45?
Unless ......
and the project is binned.

 

[prepman]

To scale and more accurate image of final? project.

STL...

 

[8ob]

To scale and more accurate image of final? project.
View attachment 441932
STL...

I think thats going to grab the material and jamb, I would stick with the single rotor and make an adjustable finger anvil. You can then play with through feeds/bite by adjusting the anvil

Bob

 

[prepman]

I think thats going to grab the material and jamb, I would stick with the single rotor and make an adjustable finger anvil. You can then play with through feeds/bite by adjusting the anvil

Bob

I'm relying on the spacers to stop that...but it needs to slide over them not be mangled in. If they do not rotate i.e free from the shaft (slip rings) they'd be the same as static 'fingers' . I need to get some gears now. something I've never made in my 75yrs, read the theory etc...got some cutters ,,,never used. Got a dividing head..not used...what could possibly go wrong?
Is there a gear expert in the house? @pete ?

 

[8ob]

I'm relying on the spacers to stop that...I need get some gears now. something I've never made in my 75yrs, read the theory etc...got some cutters ,,,never used. Got a dividing head..not used...what could possibly go wrong?
Is there a gear expert in the house? @pete ?

I am liking the idea of the tct blades sandwiched between spacer plates, my worry would be the amount of chip/ green waste passing through and the ability of those sharp tips grabbing at material it can’t cut.

Bob.

 

[prepman]

I am liking the idea of the tct blades sandwiched between spacer plates, my worry would be the amount of chip/ green waste passing through and the ability of those sharp tips grabbing at material it can’t cut.

Bob.

Good point.

 

[prepman]

Can't say I'm liking the results so far....but the blades work ok. Getting the totally action is the issue i.e. getting the chip sizing.

 

[Kram]

Lets see then, any photos of it?

 

[prepman]

Lets see then, any photos of it?

Just the triple ganged blade assembly at present tested in lathe. The cutting action leaves a lot to be desired...but side-tracked onto the shaper and then on to fields fencing/tree-felling. So might be a while. However got some larger discs on order for spacers. For it to work it definetly needs 2 sets. Having a static opposing edge will just give a slitting saw. Short video on an adjustable action with opposing/counter-rotating, setup.
Need to produce a frame to test it for real,
The problem with the shredder is that the blades no matter how arranged whill still only work as circular saws...the smashing/mayhem type action is going to take some working out. Usually when I'm stuck on a solution, I just go off and do something completly different e.g ordering garden shed for swmbo 24yrs too late. Play chess/guitar/sudoku...or mess around on the quadbike......it's all go!

 

[gaz1]

from what i noticed on that early video that i posted is that branch had to be kept moving for it to work properly

for a sawdust machine you want plenty of blades

 

[m_c]

Is there any reason that you're aiming for sawdust?
Most conventional PTO driven chippers, you can adjust the chip size, it's just most people set them to produce fairly large chips as it means they chip quicker.

 

[prepman]

Is there any reason that you're aiming for sawdust?
Most conventional PTO driven chippers, you can adjust the chip size, it's just most people set them to produce fairly large chips as it means they chip quicker.

Whose aiming for sawdust?