Converting a chipper/shredder to 3pt

[svdsinner]

Earlier this year, I rolled the dice at a garage sale and spent $40 on a Craftsman chipper/shredder with an engine that didn't start.

I tried some stuff and never could get the engine running, and ever took it to an local small engine shop and they told me it would be $300+ to get the old engine running.

I've been learning to weld/fabricate, etc. in the last few years and I thought it would be a cool project to remove the broken engine from the shredder, fabricate a mount and a 3 pt. hitch, and build a belt drive system to run the shredder at its standard RPMs off my tractor's PTO.

Although if it works, I'll get lots of use out of the shredder, this is 50%+ motivated by my desire to learn and practice fabrication skills, so I don't care if it is "more work than it is worth" or that the end product will be doomed to break (as long as it doesn't explode or create shrapnel or some other safety hazard) I'm aware that hooking a chipper/shredder designed for a 6hp small engine will, quite likely, grind its own teeth off over time when hooked to a 95HP PTO, even if a do use a belt system to keep it at the right speed and allow things to slip a bit. (That said, I do plan on giving this my best try to make it durable and workable and useful. I have an engineering degree and have reasonable odds of getting this to work. However, if I learn good stuff during the project, and the whole thing goes "poof/creak/bend/crunch" and destroys itself, I won't cry.)

A few things I'd like to learn/practice:
1) General practice welding/fabricating
2) How to build the implement end of a 3pt hitch.
3) How to build a "gear box" to convert a 540RM PTO to whatever is normal for a chipper. (I think small engines routinely run at 2200RPM, but I'm going to ask the shop where I took it and they said it wasn't worth fixing.) I know how to do the math/theory, but I'm sure there will be real-world issues like belt-tension that I'll need to figure out.
4) General stuff on how to fabricate with rotating parts and PTO shafts. All my welding/etc. has been on non-moving things. I know I'll need to support things like bearings, etc. Not sure the best/most economical way to do this.
5) What prefab PTO parts are available (Shafts, U joints, etc.), where to buy them and a vague knowledge of prices for future projects.

Any advice as I undertake the project?

 

[Djames55]

I would just get the $99.00 6.5hp gas motor from harbor freight tool and change out the old motor.

 

[CompactTractorFan]

OK, I thought you were going to convert it to a tractor with 20 PTO hp or less, but there is no way that converting it to 95 PTO hp is going to work or be safe!!! :confused2: That's roughly 16 times the power of the original engine!!! :confused2:

 

[o2batsea]

Attaching that thing to a way more powerful tractor PTO will give you nothing but trouble. First, it's a hammer type shredder ( NOT a chipper!) designed to spin at high speed. Running it on a 540 or even a 1000 rpm PTO will be far too slow. So you'll get an overpowered device that won't shred anything. At best it's good for twigs and leaves, so you gain nothing by adding power.
Do the engine replacement.

 

[svdsinner]

OK, I thought you were going to convert it to a tractor with 20 PTO hp or less, but there is no way that converting it to 95 PTO hp is going to work or be safe!!! :confused2: That's roughly 16 times the power of the original engine!!! :confused2:

No, not really. A 540RPM PTO spins at 540RPM no matter what the load (assuming you set the tach for PTO speed). The tractor isn't going to wantonly apply all 95 HP and make the PTO spin super fast. Governors are governors and PTO speeds are reasonably consistent no matter whether there is no PTO load or 90HP of PTO load.

Like I said, I'll build a pulley gearbox to make the main shaft spin at whatever speed it is designed for. (Yes, I know that 540 or 1000RPM would be too slow unless I use a gearbox) The only real impact of having tons more HP is that the blades aren't going to slow down under load near as much, and if I do something stupid like throw metal into the feeder, it will tear itself up instead of simply killing the motor. (Hopefully, if I design the belts right, it will just burn up a belt instead of grinding itself into oblivion in that scenario)

Djames55,
I can't just swap in a cheap Chinese motor. The thing has weird motor mounts/etc. and isn't conducive to a motor swap. Plus, like I was clear about earlier, this is a learning project, not just a "do it easiest and cheapest" project. I want to learn about PTO shafts and 3pt hitch stuff, and I figure this is a good project to help me learn.

 

[rswyan]

Go for it :thumbsup:

 

[handirifle]

I would say do it, but since there is a big power difference, add in some sort of a shear pin to the drive system, just in case you feed it something it won't digest.

Shear pins are great for this type of thing. Maybe one for an outboard motor? Looking at the original drive system sizes, plus finding out from a Sears repair shop what the operating RPM's are will tell you how to gear your PTO drive.

Sounds like a fun project.

Good luck.

 

[chopped]

Maybe a slip clutch
SLIP CLUTCH W/1-3/8X6 MALE X 1-3/8X6 - Agri Supply

 

[Craig Clayton]

I took a 3 PTH 5 " chipper shredder and made a conversion kit to make it run off of a 20 HP lawn tractor. I did not ruin the chipper as I had it running the other day chipping up 4 30 footer pine trees in the 3 PTH mode on the home property. The lawn tractor mode is when I transport it 100 miles away.
Craig Clayton

 

[joes_427_vette]

There is only one way to learn fabrication skills.... by doing. I love the challenge and it allows me to buy new tools to complete the job ( now the search for a plasma cutter is on ). I have drawn options on cardboard, tacked pieces together, and have learned there are more ways than one to get a particular result.
My latest project will be a lawn vacuum pto powered ( because my trailer unit is too bulky ) and collecting parts for a dump trailer to haul rock ( which I am blessed with alot of ). A grinder, Ellis bandsaw, Lincoln power mig and sturdy welding bench are " must haves ".
Don't be afraid to tackle metal. Its as easy to work with as wood and many times stronger. You will find your mind runs a hundred miles an hour when you choose between options and the final project gives you more reassurance you can. Good luck !

 

[tree grower]

I agree with rswyan--go for it! Nothing like the smell of burning welding rod and diesel fumes to get the creative juices flowing. Short of making a nuisance of yourself or stealing proprietary ideas, copy good designs by others. If you commonly carry a digital camera, take pictures. Ask like-minded friends if you can help them, and learn as you go. Stay tuned to this forum, and others like it. Browse thru the posts and read any that sound interesting for your project du jour. Gather all the information and opinions you can, and learn to sort the straight poop from the BS.

When you are at a stage when you can ask a focused question, you can expect several good answers from the guys on this site. Good luck, and we'll be looking forward to pictures as you progress.

 

[Treemonkey1000]

My thought would be to use the PTO to drive a Hydraulic pump that would flow enough power to spin it.

 

[tglass]

I have one of these chippers too. never use it because I have to move it around the yard by hand and the results aren't worth the beating taken to make it feed. I'de like to hook mine up to a 3-point too and make something to help pull the limbs in without takeing a beating in the process. Might be able to adapt one to do this, but that may cost more than a used one already to hookup. I'm not that much on chipping or mulch around the place, but it would be nice to have.

 

[Djames55]

I bet you have never used a cheap chipper like that. I can't wait to see this thing. Please make a video the first time you use it. They have a 5 to 8 hp motor for a reason. It's called 14 to 16 gauge metal. It will not hold up and will kill you.:thumbsup:

 

[handirifle]

Well, if he puts something in there to limit the amout of force the chipper will absorb, ie. a clutch or shear pin etc, there is no way it will do any more harm than if it had less power. The controlling factor isn't the engine, it's the drive system. If that has a safety built in, I see no problem.

He's not gonna run it at 10,000 rpm just because he has the horsepower.

 

[MikeInEburg]

When designing the gearing, consider that you will have plenty of power with your tractor at idle Only the tractor PTO won't be spinning at 540 RPM. Thus, I'd design for idle PTO speed and not 540.
Mike

 

[tglass]

sounds logical. now you don't have to pull the small chipper around by hand or start another engine. any ideas on limiting the pto power and how to make the limbs feed easier? possibly a relief valve to limit hyd. pressure?

 

[Sawdust Farmer]

When designing the gearing, consider that you will have plenty of power with your tractor at idle Only the tractor PTO won't be spinning at 540 RPM. Thus, I'd design for idle PTO speed and not 540.
Mike

Exactly! :thumbsup:

 

[NuBota]

svdsinner and tglass - please keep us posted if you attempt this type of project - like svd, I had been planning to do the same thing - just as a learning experience.

In my case I had "inherited" an MTD chipper (6.5 HP) for free a couple of years ago - it runs great, but was missing the leaf hopper (not a big deal because I wanted it mainly for chipping). With my typical OCD though, I wanted a "complete" unit - but the part was almost $300 - so I just monitored CL till a cheap one (<$100) popped up. Scored one for $75 that was missing the carb. So now I have a complete working unit and one without motor and hopper - perfect for a project.

Anyway - would be interested to compare notes...

 

[wldrbob]

run it with a v belt and you can have any speed ratio you need and it will slip if somthing goes wrong easy to set up and your tractor will only use 5 hp or so seemes like a fun project keep us informed