Chipper Jinma Chipper Self Destruct

[Smalljobs]

I've had my chipper for many years and am pretty familiar with all the usual repairs, knife replacement, feed roller problems, etc. Last year I replaced the knives and used factory fasteners, self locking nuts, torque wrench, etc. It ran fine all summer.

Last week I was chipping some small 2" pine windfall and it began to self destruct so I immediately shut it down. I'd been running it for around a half hour before this event.

One blade had completely fallen off and the other still had 1/4 of it attached. I've not yet gone into the bottom of the housing to see there are any whole screws or just failed screws. The anvil was 50% torn off along the length. One of the ribs in the back of the flywheel is missing a good sized chunk. Inspection of the main flywheel shaft showed no movement or looseness of the pillow blocks and no movement of the shaft itself. The clearance between the rear of the housing and the flywheel ribs was close and seemed consistent.

I read a lot of other posts about the flywheel and shaft moving but I don't think that's the case here because the debris and dirt around all the mounting points is not disturbed.

Before I decide what do with this I wonder if anyone has any theory?

The branch that I was chipping still had some snow on it and maybe there was a stone frozen in place but I cannot imagine a stone causing all this. I've had small stones in the past but they bounce around and I shut it down. This seemed to be a complete and instantaneous failure.

 

[BrokenTrack]

Any chance you hit some hardware?

Probably a remote chance, but we were sawing lumber one time on a an old rotary sawmill and hit a fence insulator. It destroyed some teeth on the blade, but it went whizzing by my head, and that scared me the most. I was about ten years old at the time.

 

[DMW]

Checking the bottom of the housing will give a better idea what happened. Trees have habit of picking up drebris. Found this in the ash trayof my wood stove this winter. Firewood had been cut and split, never saw it.

 

[Wyobuckaroo]

I got a pickup and trailer load of firewood from a dangerous tree removal arborist. Two short lengths of about 12" diameter tree were joined by a short chain like shown and 2 lag screws about 1/2 x 8"... I was able to split all of this apart on the splitter and even reuse the chain on another project.

Knock on wood, this all the hardware I have run into..... so far....

 

[Wyobuckaroo]

A few years ago memory says the Jinma chippers were the most price competitive of what was available then.. However memory says they also had a lot of less than impressive to down right bad user reviews then.. It would seem the Woodmaxx (?) is a relabel of the old Jinma design, near as I can tell.. Has there been improvements ?? No idea...

I'm still in the market for a chipper, and leaning towards the BX42 clones as nothing I will chip will be very big, and power feed to save time is no issue for me. Besides the fact the BX42 clone is considerably cheaper than other options.. Now to figure a way to save on freight charges....

 

[darmstrong2319]

I had something similar happen to my Jinma chipper it busted 1 chipper blade and banged around till I got it shut down. I cleaned the blade slots out and put new blades in. Its worked fine after that, after awhile I got to where I don’t use it any more so its just sitting out back. Once in awhile I’ll walk by and turn it with my hand its been a good one

 

[oosik]

I fell a VERY large Ponderosa pine down at the far end of the old garden site. It had a vertical chunk of angle iron embedded in the lower trunk. It was 2"x2"x6'. Probably the attachment point for a gate. I lost a chainsaw chain to this abomination.

This is what is left of it. View attachment 649668

 

[grsthegreat]

ive had my jimna 6 chipper for 10-12 seasons of use. never had any issues. i changed blades last year and had a time trying to get nuts/bolts apart. never had any issue with parts coming loose. very odd

on my 3rd set of teeth now. does a good job of chipping my mostly pine stuff thru 6", though i generally leave anything over 5" for firewood.

 

[LD48750]

I broke a blade & the bed blade when I ran a piece of metal through my 10year old 8".
Changed them & been running them fine ever sense.

BTW found a good price on blades Jinma(R) Compatible 6" PTO Chipper Knife - American Cutting Edge

 

[Smalljobs]

One of the exposed fracture surfaces shows corrosion while the balance is a fresh fracture. It suggests there was a pre-existing crack which was the root cause leading to failure. Once that piece let go, everything else failed.

I think the crack in the blade has been there for a while. I recall a rock bouncing around in it last year and maybe that's when a crack initiated. Fortunately I have stash of spare knives and anvils. When I bought two chippers and a backhoe I included all sorts of spare parts plus spare parts for the tractor itself. Unfortunately, I didn't plan on a spare flywheel!

 

[Smalljobs]

Here's the back side of the flywheel. I'd like to find a way to fix it. Since I bought it factory direct I'm trying to get a price for the flywheel alone and ship it back with some other things.

 

[LD48750]

Jinma Wood Chipper Parts | Jinma Woodchippers | Circle G Tractor Parts

 

[Smalljobs]

Thanks. I know where to buy the flywheel but I'm not ready to buy one if I can repair it or find another way.

 

[aczlan]

Thanks. I know where to buy the flywheel but I'm not ready to buy one if I can repair it or find another way.

That looks almost like it is cast, if it's cast iron you will have a very hard time welding it, let alone welding it and then getting it balanced again.
If it is cast steel, that is easier to weld but you will probably still have to figure out how to get the whole thing rebalanced afterwards.
Either way, you're probably going to have to get the whole thing up to 400 degrees or so before you start to weld it and then keep it warm so the whole thing can slowly come down together in temperature.
If you don't do that then the piece that you weld back on will just break right off.

Aaron Z

 

[Smalljobs]

Thanks Aaron. It's cast and I'm familiar with the weld repair problems. It just won't be worth it because of the danger of it failing, or just plain warping the flywheel and creating a new problem.

I think eventually I'll have to buy another flywheel. We've been importing custom machined parts, 12VDC wire harnesses, and hydraulics for many years from China so my first step is to see if it makes sense to just import another flywheel or to import a couple of chippers and sell one, while keeping the other one for myself. By starting over with another one, I can keep the existing one for spare parts but I already have spare bearings, gearbox, in-feed roller, etc.

 

[mikester]

Does anybody use a slip clutch to prevent tractor damage from incidents like this? I hate the idea of damaging an expensive tractor because of a cheapo chinesium chipper self destructing.

 

[Smalljobs]

Does anybody use a slip clutch to prevent tractor damage from incidents like this? I hate the idea of damaging an expensive tractor because of a cheapo chinesium chipper self destructing.

I doubt a slip clutch would have made a difference. Once something fails, the flywheel momentum will just keep it going. Once the blade failed, the flywheel just coasted to a stop after I shut the machine down and disengaged the PTO.

I've found this China chipper to be of high value after using it for hundreds of hours with no issues. It's been reliable and easy to maintain. At this point I'm pretty sure a stone cracked a cutting knife last year and led to the recent failure. It reminds me of the new factory issued small block Chevy 350 crate motor I bought from a GM dealer. After 26,000 easy miles, a rod bearing let go and the motor self destructed and cracked the block.

Maybe it was made of "cheapo gmnesium" or else "cheapo Chevrolite".

 

[LD48750]

Does anybody use a slip clutch to prevent tractor damage from incidents like this? I hate the idea of damaging an expensive tractor because of a cheapo chinesium chipper self destructing.

No, not on either of my tractors.
My brushog is harder on the tractors then the chipper & it doesn't have one either.

 

[grsthegreat]

I have a slip clutch on my tractor.... since unit was new. I consider it very cheap insurance.

 

[Smalljobs]

We're really getting hammered with high winds plus COVID 19. A huge tree fell down today along with limbs all over the place. Just ordered a new flywheel from Circle. My Jinma 284 now has over 700 trouble free hours and will be really helpful to move this tree, especially with the BH and thumb.