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