Screening slivers/long strips out of chip - Star/Disc screen?

Has anyone here got good experience with screening woodchip?

We run a laimet electric screw chipper.

Using our chipper we get very little fines or large chunks in our chip, but what we do have is a lot of long strips / slivers or whatever they are called. No matter how we get it set up or sharpened these bits always seem to appear/

Because of this we have to have someone hand grading these pieces out over an elevator. Volume is usually ok for 1 person to cope but as the screw looses its edge they can get more and more. So we want to try screening the chip instead to hopefully save on manpower.

From what I can gather because of the size of our chip and the nature of the strips, a normal vibrating deck or trommel is no good as the long bits tend to just get stuck in the holes and block up.

So ive come across star/disc screens and from some videos they look like they could be spot on. Good chip falls through while the strips get pulled over the discs.

This sort of idea

Would probably want 100mm gaps so anything bigger than that is screened out.

The only things I can find seem to be from abroad and like £30-80k or more or not quite suitable.

Our output isnt huge maybe 5-6 ton an hour so dont need anything massive.

Does anyone know where I may be able to find something suitable? Or recommend anyone who may be able to build something for a reasonable price?
 
Has anyone here got good experience with screening woodchip?

We run a laimet electric screw chipper.

Using our chipper we get very little fines or large chunks in our chip, but what we do have is a lot of long strips / slivers or whatever they are called. No matter how we get it set up or sharpened these bits always seem to appear/

Because of this we have to have someone hand grading these pieces out over an elevator. Volume is usually ok for 1 person to cope but as the screw looses its edge they can get more and more. So we want to try screening the chip instead to hopefully save on manpower.

From what I can gather because of the size of our chip and the nature of the strips, a normal vibrating deck or trommel is no good as the long bits tend to just get stuck in the holes and block up.

So ive come across star/disc screens and from some videos they look like they could be spot on. Good chip falls through while the strips get pulled over the discs.

This sort of idea

Would probably want 100mm gaps so anything bigger than that is screened out.

The only things I can find seem to be from abroad and like £30-80k or more or not quite suitable.

Our output isnt huge maybe 5-6 ton an hour so dont need anything massive.

Does anyone know where I may be able to find something suitable? Or recommend anyone who may be able to build something for a reasonable price?
Look up oscillateing screens for wood chip
Does your chipper have a screen in it ?
We found spec was lost on chip when screen run empty
 
if you you tube screening biomass woodchip a video should come up of goodechips homemade screener Its made from a potatoe riddler . They screen both woodchip and the laimet chip for CHP or google goodechip give them a ring
 
Just looked at the video I chip for a guy who has this set up . He still gets slithers through when he buys pre chipped wagons in from the saw mill
 

DGC1

Member
Location
Scotland
Use a vibro deck like powerscreen warrior 800 and on the top deck you need to put a solid plate over the 1st half of the deck that the feed lands on.... this means that the long bits don’t land vertically in the holes and block them
The chip lands on this flat plate and organises itself flat before passing seemlessly onto the open screen deck

Grids are cheap & easy to change so you can play about with sizes but I would say 100mm is too big.
Punch plate is indestructible and maybe better than mesh but a lot more expensive per sheet

If you want to take out fines simply put the bottom deck in and if u don’t leave it out

Warrior can be used to screen soil or stone or hired out at app £1000 week so pretty flexible bit of kit and easy to move around
 

renewablejohn

Member
Location
lancs
Get yourself an old combine. The straw walkers are great for slithers and the sieves great for taking out the fines. Better if you can find a combine from someone who also harvests beans and peas as you have more sieves to work with. Anything you dont need weigh in for scrap.
 
Thanks all for the info, a few things to look at.

Our chipper doesn't have a screen on it no. The wood is chipped with a conical screw, and then fed through a recrusher to break up the end noggins. We get very few fines its just the long strips that get worse the longer the chipper is in use before sharpening.

I've looked at oscillating screens a bit, are they good with any sort of size chip or is there a limit? We are a bit bigger than g50.

Have found that video busy daddy, looks interesting. Id better give them a call we did speak briefly before we got our Laimet. Do you mean he still gets slithers after grading it?

Thanks DGC1 looks like a pretty hefty bit of kit, do they do anything smaller?

Combine idea looks interested but maybe a bit too much engineering required for myself.
 

Watching this it seems quite a few of the long bits tend to bounce and fall through the screen with this style. I guess that is a lot of the problem with them being long but thin? Especially when the rest of the chip is rather chunky.
 

Fowler VF

Member
Location
Herefordshire
Old quarry screen should work, they are usually way too big for what you need, but they still do the job. new screens of all sizes and types can be bought cheaply, so you can play around with the right sizes. 2 deck allows you to take out bigger bits on the top screen and fines on the bottom. Make your own legs, conveyors etc.? Or theres a guy that rents a workshop off me that would do the whole job for you. he has done a lot of wood chip conveyors, screens, ash augers etc etc over the years.. You should be able to adjust the amount of shaking, doesn't need much for wood chip, most of these were built to shake the hell out of soil and stone, built like tanks, last forever. Either that or a small trommel, but small secondhand ones are hard to find.
e.g.
https://www.pqs.uk.net/used_plant/348/powerscreen-screen-box

These people will make up any size, type or shape of screen to fit any deck;

https://www.brimonn.co.uk/

used_plant_348_1_main.jpg
 

Fowler VF

Member
Location
Herefordshire
Watching this it seems quite a few of the long bits tend to bounce and fall through the screen with this style. I guess that is a lot of the problem with them being long but thin? Especially when the rest of the chip is rather chunky.

Mostly down to the amount of shake you put on and how steep the screen is set. less shake, steeper screen and the stuff tends to run down faster, the bigger bits skid over and the long bits don't get chance to get bounced into being end on. Also depends on type of mesh, punch plate is flat and doesn't jiggle the chip so much, woven screen is more aggressive. trial and error for the specific material I'm afraid! As has been said, a blank bit before the mesh allows the chip to settle and for those slivers to lay themselves flat so they skid over when they get to the screen part.
 
Cheers for the info. Looks cheap enough to try and give it a go I suppose.

Is there much to say between the gyrating ones vs the vibrating? I guess vibrating more chance for the longs to bounce and go through?

Went and had a look at the forestry show today not a lot in the way of screens though they had 1 small gyrating one that they wanted £40k for!
 

renewablejohn

Member
Location
lancs
Cheers for the info. Looks cheap enough to try and give it a go I suppose.

Is there much to say between the gyrating ones vs the vibrating? I guess vibrating more chance for the longs to bounce and go through?

Went and had a look at the forestry show today not a lot in the way of screens though they had 1 small gyrating one that they wanted £40k for!

Can pick up an old combine for 2k
 

DGC1

Member
Location
Scotland
the ultra screen not set up well for what your after
as said above....
needs to have 1st section of the top deck blanked off with solid plate
set a lot steeper
punch plate and maybe even the last section blanked off
less aggressive screen action
more flow across it

iv tried building screens twice and although they've worked ok you cant get the feed right unless you have a proper feeder setup like the ultra or the warrior

why not try hiring a small screen for a week and do a big pile
iv got a warrior on hire at the moment for £160day and its a simple job to blank the top section, you simply weld a small steel plate onto the top of the 1st deck section

try to get one with punch plate top deck
 
All these screens seem to be working on g30 or g50 chip why do you need to get rid of the slivers on such a large chip size they must be long bits
 
100mm long is about the longest our augers seem to cope with, we get strips anywhere from 20-30cm up to nearly a meter.

Added a pic.
 

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Yeah I don't really want to have to go through the hassle of changing chipper if we can come up with a simplish solution. However it wouldnt be totally ruled out if nothing else worked.
 

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