View Full Version : chipper/shredder project

05-02-2004, 01:29 PM
I'm thinking of building a Chipper/Shredder to clean up branch and clippings around the yard. Have any of you built one of these and any words of advice? Basic plan would be a cage on a shaft for the hammer section with a side feed chipper. I'm kind of getting ideas from the commercial units, and see they are all pretty much the same. My lathe swings only 14", so that would be a factor. I haven't decided whether to power it with a gas engine, electric motor, or hydraulic motor. I realize this is not really machining, so maybe I should be on the welding and fabricating (dark side) forum instead.

05-02-2004, 01:55 PM
I have an old unit made by Ariens which mounts to a snow thrower and is connected with belts and centrifugal clutch. Maximum size for chipping is about 1-1/2 inches or so. You really don't need a lathe to build one.

[This message has been edited by gvasale (edited 05-02-2004).]

Mike W
05-02-2004, 02:04 PM
I have a commercial one. It scared me everytime I used it. I took off the 10 hp engine to use on a generator project. http://bbs.homeshopmachinist.net//biggrin.gif

05-02-2004, 03:00 PM
A Old construction story is that a guy recently divorced walked up to one, throwed his walled down on the ground and dove in head first.

Imagine the mess that made.

If you find a way to grind carpet fiber up to make blow in insulation you'd get rich around here. It has sand in the glue holding the backing on.

Ohh yeah wood.. Perhaps opposing saw blades on a double shaft arrangement?


05-02-2004, 03:11 PM
Cogitating along these lines for some time now. No hurry, but could use a shredder about twice per year for making green waste into fine mulch.

http://shop.woodcraft.com has a 4 1/2 in. diameter wheel, fitted with an endless length of saw chain around the circumference. It is designed for heavy power wood carving, when mounted on a Makita type, sidewinder or angle grinder.

Could several of these, or copies, be mounted side by side on a common shaft, and spun around 3,600 rpm? For safety a required enclosure would guide material in and a chute would allow shreds to fall out the bottom. I believe I could temporarily mount such a shredder to the front of my lawn mower. The power belt would be rerouted from the mower blades to the shredder.



05-02-2004, 04:04 PM
I built one a few years back along the lines you describe. Two compartments, one inch shaft thru them supported by pillow block bearings. In one compartment I had an auto flywheel on the shaft. 180 deg.apart on the flywheel I had bored two large holes. Over the holes I bolted on blades. The chips were cut by the blades and passed thru the holes out the bottom of the compartment.
In the other compartment on the shaft was mounted flails that were pivoted to swing. These passed thru fixed pairs of metal. This side handled small stuff. The flywheel side handled limbs. Used 6 hp motor and ran it about 1800 rpm. It worked but constantly stopped up. I believe it needed a blower inside to blow the chips out. It actually was pretty scary. I got rid of it as it was more work than it was worth.

05-02-2004, 05:07 PM
Checkout these guys,they build the best,maybe scale one of their designs down.


05-03-2004, 08:28 AM
Oh,I just remembered I have some cutterheads like 6" od and 6 or 8" wide that carry four knives,if you want one you can have it for the shipping.

Paul Gauthier
05-03-2004, 10:56 AM
I have thought about making one also to mount on my tractor's 3 point hitch. I have a troybilt chipper vac that I would use as a model. If you visit these guys www.drchipper.com (http://www.drchipper.com) you will note that all of thier chippers have 14" flywheel with 1 chipper blade. I am thinking of using 2 or 3, 5 inch blades. If you have access to a troybilt you can see how they are made and can either scale up or down.
I don't see it as a particular difficult item to built, just time consuming.

Paul G.

05-03-2004, 11:18 AM
I have a small 5Hp chipper/vac.
I use it several times a year.
Its good for about 1.5" dia limbs max. and does a really good job.
The feed tube is about 4" I.D. on top and tapers down to about 2" on the bottom.
The vast majority of limbs that I cut is under 1" and I find that I have to push hard sometimes feed the branches.
This can be like trying to stick a worm up a wild cats...
I would like to see some sort of power feed that would pull the limbs in. (without pulling my arm in with it.)

Tom M.

J Tiers
05-03-2004, 01:18 PM
I dunno if you need to make one, but of course any project is valid.....

We have two varieties. One is a 5HP big-hopper vertical shredder that takes misc stuff, but not too many larger branches at one time. It is basically a small sileage cutter.

The other is for branches up to about 1 1/2". it has no real hopper, but a tube to slide the branch through to the chipper.

Sounds like you are trying to make what we used to call a "tree-eater" that takes stuff up to a couple inches. They look like a big woodworking jointer with a side hopper.

The ones I have used had about a 20 or 25 HP gas motor and spin pretty fast. I don't know if hydraulic would do the job.

05-03-2004, 02:54 PM
I built one that chips 4" dia. branches through the side feed chute and grinds branches in the top hopper up to about 3/4" dia. I used an old Amerind-MacKissic shredder as a pattern but have seen similar shredder designs in Northern. The side feed cutter plate has one blade 1/4" thick by 4" so it takes a 1/4" bite each time it comes around. Two short pieces of angle welded to the back of the plate blow the chips into the main feed hopper and then everything goes out through a screen with 1" holes.

I use a 13hp Honda engine and two belt drive with a mechanical clutch - - it is difficult to start without some kind of clutch.

I don't remember the main shaft rotation speed but can get that for you if you want along with general dimensions.

It works great for cleaning up general branches and limbs. It gets used several times a year and makes good mulch. While I can feed in a 4" branch it is a little slow at that dia. - - 3" stuff goes in as fast as you can push it in. I do end up changing the chipper blade often - - a sharp blade makes the chipping much easier. The blades in the large hopper are pivoting type hammer blades that I made from S7 bar stock and had hardened - - they are about 7 years old and still doing fine.


[This message has been edited by kruszert (edited 05-03-2004).]

05-03-2004, 03:29 PM
Thanks a lot for your thoughtful replies. Thanks weird science for your offer, but shipping costs would probably not be worth it. Wow those guys at morbark have some cool machines, but 1000 hp is a bit overkill for me! Kruszert, yes, that is exactly what I had in mind. Questions: What is dia of main shaft? I was thinking of 2" stock machined down to 1" for bearings and pulley. Did you make up some bushing type bearings, or use ball brgs? Did u use shear pin? or will std. keyway/pulley be reliable enough?
What is Dia and width of Flywheel Flail unit? How many flails/hammerblades? I was thinking 2ea 12" dia x 1/4" mild steel circles welded to the main shaft. And 3ea 1/2" x 4" hammerblade bolts. Am I on the right track?

05-03-2004, 10:38 PM
OOOPS!Didn,t notice your in Canada,40lbs would be kinda pricy http://bbs.homeshopmachinist.net//biggrin.gif

Did you look at Morbark's smaller models?My neighbor is in the tree service he has one that uses a 25hp Kubota diesil engine,the thing I like most about it is that it has hydraulic infeed rollers to feed the branches in automatic,a lot safer and the feed rate is controlled.Buddy told me that most of the accidents with the old chippers is when the limbs are thrown in the machine sucks them in so fast that if a shirt sleeve or something gets caught its too fast to get away from.

05-04-2004, 10:50 PM

You are on the right track. This is where it would be nice to have a digital camera for showing the design but unfortunately I don't have one so I'll have to do the best I can in describing the parts while answering your questions.

1. shaft - - the original shaft was 1" with a 6hp motor. The shaft was the only part I used when I built mine with the 13 hp motor and it broke in about 6 months. I now have a 1 3/16" shaft from a good grade of steel which has worked for years. I would have used a 1 1/4" shaft but the flange mount bearing housing increased in size and would have interfered with the side feed chute. The shaft on my shredder is 19" long.

2. I use flange bearings on the ends of the shaft. On the cutter wheel side I used a two hole flange due to space problems with the side feed chute. On the other side I used a four hole flange type bearing - - the shaft comes out through this bearing and has the sheave attached using taper lock and key. No shear pins. I like the taper lock design for things like this that take a lot of beating but I can't say that a standard keyway won't work.

3. The chipper blade is mounted on a 1/2" thick wheel 14" O.D. Blade is supported with a flat bar welded to the wheel and held on with three 5/16-18 flat head socket screws. A slot is cut in the wheel to let the chips go through. Wheel attaches to the shaft using a taper lock and key bushing - - the socket is welded into the wheel. On this I strongly recommend the taper lock type attachment. The wheel and assembly have not been balanced and with all the stuff that goes through I don't think it is necessary.

4. Welded on the main shaft are three 1/4" thick square plates 7.5" x 7.5". In the corner of each plate is a 5/8" hole. The pin that holds the hammer blades goes through all three plates. There is an access hole in the body of the shredder to install/remove the pins and hammers.

5. There are 6 blades(hammers) on each pin (24 in all) and they have spacers such that they are staggered and cover the entire width of the shredder chute. The blades are 3/16" x 1.5" x 3.5" made from S7 steel and hardened to Rc 55. The blades are sharpened on the edge in direction of rotation. There are no stationary blades in this shredder but I have seen shredders that have them - - not sure what is best.

6. speed of the shredder is 2333 RPM; I use two cog type B belts.

7. I have a mechanical engagement type clutch which was awful expensive. You can get a centrifugal type clutch or you could use a belt tightening system but you will need a clutch. Starting without clutch is a problem.

If you get really serious on this project I could send you a few pictures and I have the parts manual from the original shredder which shows an exploded view - - not sure how well it would copy but I could try.

Let me know if you have any other questions.


[This message has been edited by kruszert (edited 05-05-2004).]

Paul Gauthier
05-05-2004, 10:52 AM
Sounds like a serious beast. Maybe you could find a friend with a d-camera??? I would sure like to see pics of it.

Paul G.

05-05-2004, 08:35 PM
Reggie, Thanks for taking time with helpful details. Good advice. I will use the taperlock and key as you suggest. The 7.5 inch square plates are a great idea. Much stronger than what I had in mind. That would give about a 9" pin to pin distance and with the 3.5" hammers, will give a swing of about 15". Great idea to taperlock the chipper blade flywheel as well (that way it can always be disassembled if balancing is needed or???) Only one more question, What is the total width of your hammer section? I was thinking about 4", but now I'm thinking a bit wider maybe 6" would work better with respect to the feed throat, but want to be sure I don't want to create stalling problems. What is a cog type B Belt. Is that related to a Size B "V" belt? I'm getting excited about getting started.. I've already picked out a piece of scrap to turn down for my main shaft.

05-07-2004, 09:27 PM

The width of the shredder housing is 8 7/8".
The three plates holding the hammers are
7 5/8" wide. The pins that hold the hammers have a rounded head on one end kind of like a carriage bolt and a cotter pin at the other end. Now this is REALLY important - - the plates are not centered in the housing - - the pin head has about 1/4" clearance from the wall and the cotter pin end sticks out about 3/4". This way if the cotter pin comes out (and I have lost several) the hammer pin cannot back out enough to pull out of the plate and release one of the hammers. The pin just rubs against the housing and makes some noise to tell you there is a problem.

The wider housing is prefered cause it is difficult to get branches that spread out into the top hopper. You don't want to have to spend too much time with a lopper cutting them up to get them to feed in. I rarely stall my shredder - - only when I put in green branches about 1" dia. and say 8' long with lots of leaves and branching have I gotten a wrap that shut me down.

Cog type belts are the ones with the notches on the I.D. I think they do a better job for higher horsepower stuff and can be used for smaller diameter sheaves but then I can't say that I really know this for sure.

As far as what this thing looks like - - it doesn't look much different than what you might see from Troy Bilt or something at a local lawn center until you get up close. It is a lot better built and will easily do what I want without problems.

One more thing - - on the motor you use put a GOOD air filter - - not the oil soaked sponge type. With leaves and branches being ground you can make a lot of dust that clogs a cheap filter quickly.