Chipper/Shredder/superfine Mulcher

Intro: Chipper/Shredder/superfine Mulcher

Can I present Vampira , my home-made chipper,shredder and superfine mulcher

I was lucky enough to borrow a friends Titan machine for some 10 weeks to run it ,dissect it and make some improvements of my own to the output and weight of the machine.You will need to acquire a petrol engine , like mine , which came off my idle cement mixer , minimum 4 HP. BTW the Titan had a 15 HP engine as standard !

The principal behind most of these machines , is a flywheel with knives attached, running in an enclosed drum , with flails fitted .Two chutes , one vertical to shred leaves and twigs , one at an angle to chop the heavier branches , and the chaff to be expelled ,in the commercial unit , out of the bottom .The weight was a big concern, the engine was a monster 15 HP, and the metalwork was over engineered too heavy for me to manoeuver .I have broken down the construction into steps , I have used a combination of stick welding and pop riveting on the thinner steel

Step 1 Body of the machine , the flail chamber

Step 2 The flywheel , knives and flails

Step 3 The top chute

Step 4 The side chute

Step 5 The wheels ,foot and the front and rear handles

Step 6 The manual clutch arrangement

Step 7 Two crude homemade machines I fashioned to do the bending and rolling necessary

The tools I possess to make this machine are , Stick welder,angle grinder,set of metric taps and dies,the above homemade tools ,a paint sprayer ,pillar drill 13cm max ,pop riveter , thats about it .If you follow the sequence you

will; be able to make the machine without any trouble, so I wont give you a cutting list , just get the parts as required.

If anything is not clear , message me or comment thanks, sorry if the description is a little verbose, but I need you to have all the info to build the machine well.

I have embedded a video of the machine working , it can be found here at Vimeo

STEP 1: Step 1 the Case or Flail Chamber and Screen or Sieve

Here are the case dimensions , and figures I give in brackets will be the dimensions of the commercial machine, you are welcome to use these, but the machine will be cumbersome, I needed a lightweight machine that I could wheel round easily.

Case was bent for me on a press brake , most yards have these machines and guillotines to bend and cut metal, case is formed from 2mm(4mm) sheet steel

You will need a strip of metal the same thickness and 17cm wide ,to form the round part of the casing which keeps the two halves apart , and seven 17cm rods round or square, drilled and tapped to take the M6 bolts .You only need to weld the case to alternate rods.I made a rough roller out of scaffold pole to roll this item and also the chute for thick sticks .I wont give you a shopping list for metal , it is simpler to explain stage by stage , so you will get the picture of how the whole unit functions .

Having got your case bent, bolt the two together , and get the metal shop to drill the 20mm(22mm) hole as a pair for the flywheel axle .You could drill it yourself with a 13mm and then file it out , but the yard did it for me at the same time I got the flywheel cut and drilled 20mm to take the axle .You need a pair of plummer blocks , mine had 4 boltholes as against the commercial unit of two bolt holes.The axle rod is secured in place with two allen screws per bearing , but for belt and braces, I grooved the axle to take a circlip. The 4th photo shows the flywheel in position with its flails so you can see and mark the circle they describe, so you can roll the sheet of metal to form the box sides.

Be careful on choice of bearing block , mine are hunky, subsequently not a lot of clearance between them and the frame of the side hopper......ONLY cut out the shape on the knife side for the anvil when you read the next step

There is one small improvement to be made here, the screen or seive , join it to the output lip , take it down past horizontal , and the vibration will self clean from any chips stuck on it ,see photo 5

The screen plate is e 2mm galv steel about 37cm long and the throat welded to it is about 14.5 cm long, but leave everything overly long , you can always trim it up after .The Titan has 20mm grid holes, mine has 13mm grid holes , and the chippings are much finer , but you can choose for yourselves. I simply stuck kids graph paper to the steel and then centrepunched the graph so holes would have some metal round them and then drilled the 13 mm holes out and bent the piece to fit with the rollers. This plate is a source of annoyance , because on the Titan , if you got a jam up you had to remove 2 rods from tubes top and bottom , clean the jam, and reassemble , trying to fish the rods back into place is not an easy task .My method , with one bolt and another at the top is a bit better , but if anyone comes up with a neat solution to remove this guard and replace it quickly , please let us know !

STEP 2: Step 2 the Flywheel,flails and Knives

you need two plates cut and drilled as a pair from 5mm(6mm) steel size 24 cm x24 (27x27), and any holes you make ,please drill them as a pair and the unit will stay square and true.You need some 12mm round rod for the spacers to space the cheeks correctly, and some weldable hinges , which form two functions , they space the flails and I think uniquely the create a force fan draught that expels the chippings with vigour. (The commercial machine lacked this feature).Outside cheek to cheek is 15cm , to fit the flail case of 17cm, knife side bolt protrusions are ground below thickness of anvil , pulley side bolts will then clear the inner wall comfortably

The weldable hinges should be a running fit on the rods.From outside edge to edge the finished flywheel is 15cm , try and make this exact, then you have room in the case without fowling the sides or bolts.

4 flails each rod , 4 rods total 16 flails , I made a crude jig to sharpen the flails , as in the original the leading edges were blunt. The knives that you see bolted to the face of the flywheel were bought on Ebay at a good price.The flywheel is tapped to take them and they are bolted on with allen key headed csk bolts secured on the inside with nylock nuts,take note of their positions, one angle is right on the edge of the flywheel , i.e. as far out as you can go , the sharp knife edge is exactly on the diagonal.The pictures show the two knives (commercial unit only had one), and the circle the flails describe. My gap here is about 1 to 1.5 cm , and the original machine discharged at the bottom , so it would clog itself up, thats why I took it another 90 degrees and fan assisted it !

The flail rods are tapped both ends and then screwed and welded into the face that carries the knives only, as is the 20mm axle , that is welded onto the knife plate .You can get at the knives if you take off the hoppers , they will need resharpening periodically.If you need to maintain the flails , the case cover motor side needs to come off.Make a replica of the knife side , run it around the outside of the case, making sure the knives appear in the cutting hole as in the last diagram.You can then cut the hole and weld on the anvil 5 or 6mm U shaped plate to match the bottom of the hole,where the sticks are cut.

STEP 3: Step 3 the Top Chute

This hopper was larger in the commercial machine , some 49 x 37 cm square and 130cm from the top of the box

I found that leaves and twigs tended to stick as they went down , so you would have to constantly prod them with a long piece of wood to keep the machine running .I made my chute 31 x31 cm at the top with a simple taper on all the sides ,and the height was 110cms .If there are any of you out there with long arms , or indeed anyone that will use the machine ,please make sure you cant get your fingers anywhere near these flails keep to the manufacturers height, they spin like a turbine and will amputate your digits in a trice , so be warned ! The metal I used was galvanised steel around .5mm, bent on my homemade bender with flanges of about 1.5 cm , and then pop riveted together , top chamfered and a flap with a piece of springy plastic sheet, so you can put the debris down the chute without it spitting back at you .Make the sides overly long , and the bottom end a tad smaller than the dimensions , so it can sit in its collar. The chute has to go into a square hole 14cm x 14 cm , so make these panels ,say 13x13 at the bottom narrowest end and keep them long , say 150 cm , pop the 4 panels together and insert them in the collar , pop rivet them in place and then trim them top and bottom to length.Add a plastic sheet loosely hinged by two bolts , so the stuff can go down , but not spit back at you , in spite of that my vid shows it without , because the sun made it brittle and it cracked , so I do need a better source of good plastic

STEP 4: Step 4 the Side Chute (branch Hopper)

This is a little more intricate than the previous chute , it has to cover the hole in the side of the case , where the knives rotate and chip the branches on the anvil .I again used the homemade roller to roll it in two pieces and pop rivet the top to the bottom.I rolled the bottom half from a piece of 50 x 50 cm x galvanised steel .The diagram above is the measurement of the commercial sleeve my interpretation as well .You will need to make a flange to bolt it to the main flail chest , I have put the angle in too , you can use a smartphone app to measure this angle , so it matches.You also need to make the end plate ,two in fact , one is the end , and one detaches , to put a sheet of rubber between the two in case the wood spits back, when you push the branches in .Max stick thickness on the commercial machine was 4.5 cm , you need to trim off heavy side branches ,so you can juggle the wood thru this plate ...thats why you have a strange shaped hole on the plate end.In the vid Vampira eats the sticks like a vacuum eats spaggetti , I will chip wood upto about 3.5cm , any larger is firewood starters for my fire .

STEP 5: Step 5 , the Wheels , Foot and Handles

I placed the wheels to pivot the heavy part of the machine , so it was easy to wheel around. The foot was made from flat bar , and two big black rubber sink stoppers came in handy for the grips , to stop the thing sliding when running, but to be fair there is very little vibration at all .The handles are made from steel gas tube , the thickness of a cycle handlebar , indeed thats what the grips are .The front handle is useful if 2 people want to carry it downstairs , and I wire a trug on the front handle , when I want to collect the chaff for my barrel composter.

Wheels , pneumatic 30 cm diameter ,wheelbase 70 cm outside diameter, ground clearance is 16 cm and height to top of case is 56cm . I think the wheels at the rear are the best combo, but make the mounting brackets identical and you can swap the wheels to the front and vice versa

STEP 6: Step 6 the Clutch Arrangement and Clutch Cover

On the commercial machine , it sports a centrifugal clutch, on the engine top pulley , to be fair you can get these with a 2 cm bore on Ebay for around 125 pounds , but for me I decided to put the engine on a moveable tray and use a long manual lever to engage or disengage the engine.You simply cannot start the engine with the flails engaged , so a clutch is absolutely necessary , (for safety reasons too).I can give you the dimensions of the commercial unit , it is 6.5 cm front to back , diameter around 10 to 11 cms on the engine shaft , driving the bottom pulley around 16cms .I did try other ideas ,like a jockey wheel , but that would make the cover too wide and ungainly

My clutch lever , the long rod came from a woodworking clamp that had broken , I took the bar and cleaned it ,left it long until it was fitted.If you get a jam-up then the belt will slip on the pulleys, you can see the flywheel shaft go visibly slow and labour , hence the white cross on mine . .

Photos show the engine mount that moves back and forth to take the play out of the fanbelt .I borroed 3 sizes from the garage , to see which slipped over the pulleys and tensioned best

STEP 7: Step 7 , 2 Homemade Tools Used in Making the Machine

This is the roller and bender , I made the roller bed length 50 cm to take care of the branch chute, and the pulley cover, and the bender bed is about 150 cm long . They were made just for this job , you can find plans anywhere for these machines . When rolling the pulley belt cover , find as tin the same diameter and use that as a guide for the circles either end

Comments

[StephenS74]

This post is awesome. I plan to use it to make my own set up. I will be using a 5 HP electric motor instead of gas. Yes I will be tethered but it is what it is. My question is what RPM does your blade assembly turn? What is a safe but still powerful speed? My motor spins at 3450 RPM and I plan to pulley down the blades to 500 to 1000 RPM. The lower the RPM the larger the driven pulley so I don't want a huge pulley in the way. Thanks.

[philip.ryan.948]

ssegu2 . I must admit it loves crispy material , stems and leaves that are sun-dried , but when the stuff is in damp clumps , the screen does tend to get blocked by the material that has been chomped . Maybe a different screen made out of vertical rods may let the wet material thru easier. I will be using the mulcher to pulverise some twigs , next summer as I am very interested in rocket stoves , was thinking of using the chipped wood instead of pellets to run a rocket stove .

[philip.ryan.948]

Hi Stephen , your 5 hp motor will be well powerful enough .I cant tell you the exact rpm of the blade , with the idea of tensioning the fanbelt , the drive takes up gradually and smoothly , and if you do get a jam because you overload then machine , then the belt does slip , as a sort of safety measure . The pulley on the motor was original from a cement mixer, the lower pulley that runs the blade, I turned on my small lathe , so neither are huge , almost a 1:1 transfer. When you come to build it ,if you have any questions just ask . Phil Ryan

[StephenS74]

Thanks for the quick reply Phil. I see idle for the Honda GX120 is about 1400 RPM. I am assuming you run Vampira at idle when using it? If so and 1:1 ratio I might be able to go higher speed than 1000 RPM. I was basing my range on some info I read on line where a similar unit ran at 500 RPM. That seems a bit low to me. I can easily and cheaply find 11" pulleys that would put me right under 1500 RPM. They seem to go up exponentially in price as you go any larger.

[philip.ryan.948]

Stephen , just took the side off to show you the pulleys , they are equal in size @ 7 cm diameter each . The top pulley was original off the motor, in fact it had seized on the shaft , so I turned up the bottom pulley from a piece of 3 inch stock ally. You need slack in the toothed belt to enable you to start the Honda, any drag makes it hard to turn over quick enough . I made the engine float on the top , and tension the belt by moving the lever into drive.The commercial unit had an auto clutch on it , but I decided to keep it simple , you could try another pulley idler , fix the motor down and use a 3rd pulley to tension the belt .I start the Honda ,part choke and then engage the drive at about idle, but I have to get it on half throttle when I chuck a lot of twigs and leaves down the hatch.Be careful , my friend who has the Titan, by accident threw in a piece of stone , which wrecked the flails ! . You also need a good flexible plastic sheet to stop the stuff flicking back out , plastic doesn't seem to last long in the sun !

[philip.ryan.948]

Stephen , when you said 11 inch pulleys , maybe you were thinking of a flywheel , you absolutely do not need anything like that , the flail and knife assembly has ample inertia to act as the flywheel , once its moving it carries a lot of inertia

[StephenS74]

Phil no the 11" pulley is not a flywheel. The pulley is spoked and has no mass to act like a fly wheel. This pulley is only changing the drive ratio from 3450 RPM down to a lower speed for safety. If you run Vampira at half throttle then your shredder speed must be very high. I'm going to try to keep mine below 1500 RPM. I won't know if a clutch or method to slack the belt is needed with the electric motor until I run some tests. Thanks for your help.

[ssegu2]

Came across this post while searching for a diy weed pluveriser. Phil do you think I can adapt this for this purpose. I am interested in pulverising aquatic weed to prepare it for use as feedstock for a Biogas reactor.
What and how would I have to modify to fit my purpose?
Great post by the way👍

[compadrelucas]

This will be my first project. it will take months in weekends time, but I NEED this machine so much

[philip.ryan.948]

Lucas , you will need a little bending and a rolling machine , I made both out of scrasp tubes and angle iron , nothing fancy but good enough to make the lighter hopper and pulley guard , the main case, was bent for me in the metal shop where I bought all the metal , as was the 2 cm diameter hole drilled in the centre of the flail plates

[callhow]

Resembles my old/antique Roto-Hoe unit. Is that what you referred to as a commercial unit" ? Your build seems almost exactly simial to my units (have an 8hp unit for heavy-duty chipping with 12' flywheel (keeps inerta going) & a simple 3hp unit foe easy stuff. Pics enclosed for you. Nice build!

[philip.ryan.948]

nice pics , the flails are almost identical , the spacers I used weldable hinges , so the flats act like a fan blade , you are right 4 hp is the bare minimum for this machine , I did intend to try and lathe up a centrifugal clutch for it , but that will be later . Rocket fires spark my imagination , so thats next on my bucket list !
thanks for coming back to me , sorry I took so long to reply

[philip.ryan.948]

Calhow , thanks for the pics , yes its has the same flail idea , that I copied off the commercial unit , it was a Chinese Titan or similar 8 hp . I ran that machine , and found two snags , one the perforated screen kept getting clogged up , and also the output was under the machine , so it constantly needed clearing . Between thise flails I added a swivelling plates that acted like a force fan , and re-directed the chaff out horizontally . Nice pics thanks .

[explosivemaker]

A well thought out submission that should be recognized. Nicely done.

[philip.ryan.948]

Thanks for the comment

[acheide]

Nice. This looks suitable to add to the back of my tractor. Thanks.

[philip.ryan.948]

Tried towing the Titan on the back of my Jeep on a rough stone road, was very top heavy....needed a second person to stand at the back and ride shotgun...the wheel base needs widening , (which I made adjustable ,using a tube within a tube for the axle).Have not yet tried to tow mine to friends,as I am getting attached to it ,lots of garden to mulch up !!