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!