YAJCMT: Yet Another Jinma Chipper Modification Thread

[rswyan]

I bought one of these a number of years ago ... didn't really do anything as far as setting it up beyond the basic assembly of the unit. It performed relatively well initially ... aside from the normal stuff like the wobble-joint on the feed roller drive shaft and the feed roller drive belt self-destructing ...

I fixed the wobble-joint by welding on 1/2 impact universal joint I picked up at Harbor Freight and replaced the drive belt with something of decent quality from NAPA.

After that the performance of the unit decreased over a fairly short period of time to the point where the unit achieved the dubious status of "something that I have to fight in order to use" ...

At that point it got parked ... as interest in using it was no longer very high. If I had to guess the unit probably doesn't have more than 30 or 40 hours of use on it at most.

So here's the list of mod's I plan on doing to make this thing a useful tool ... rather than something I have to fight with when I'm using it:

1. Replace all he Chicom grease fittings. I did this yesterday so that's a done.

2. (Further) modify the top link attachment point so that I don't have to remove the pin to hook it up.

3. Modify the discharge chute so that it's 2' higher ... so that I can easily shoot the chips into our Country Mfg. dump cart. (Bonus: no more inadvertently smacking my head into the discharge shoot)

4. Modify the discharge chute so that it rotates at least 180 degrees.

5. Modify the feed roller so that it is more aggressive and grips the wood being fed more securely. This one will like have two stages: 1. an initial quick modification to test out a theory, and 2. an optional rework of the feed roller if I'm not satisfied with the performance of no. 1

6. Relocate the bar that raises the feed roller to the rear of the unit and make it foot operated.

7. Modify the rear portion of the feed chute so that it tapers/flares outward at least as much as the front portion ... which will hopefully facilitate the unit being more inclined to pull stuff in.

8. Add some storage capacity ... mostly for premix and bar oil for the chainsaw, perhaps a scabbard for the chainsaw as well. I have a bottom drawer steel wire basket scavenged from an old freezer that should work nicely for the former.

9. Sharpen the knives using the planer knife jig on my Delta Sharpening Center. This will be a "wet grind" and the knives should be near razor sharp when finished (which could make installing back into the chipper interesting ... )

10. Adjust the knife/anvil clearance.

11. Add a pair of 48" long PT 4" x 6" to the base of the unit to raise it up, and bring the drive shaft more in line with the PTO on the Kubota.

 

[rswyan]

As far as modifying the chute the first thing was to come up with some tubing to extend it ... McMaster had some that would have been suitable ... but it looked like the minimum quantity was a 5' length ... which was 3' too many.

So I called a local heavy-duty truck place - Cross Truck Equipment - and asked if they stocked any 6" exhaust tubing. Sure enough, they had it in stock ... and 2' of it was about half the cost of the 5' length at McMaster. Dunno exactly what gauge it is but it's at least as thick as the metal on the original discharge chute and likely thicker ... maybe 1/16" or better:

This is "aluminized" steel tube ... it's weldable ... supposedly just sounds a little different when you weld it.

I did end up ordering a couple of 6" steel flanges from McMaster ... one to serve as as the base (welded onto the chipper) and the other to be welded onto to the pipe in the picture above. These will be coupled together with a clamp I'll fabricate.

The flanges at McMaster are called "angle rings" and are intended to be used for joining (lightweight) steel pipe/tubing together. Can get them with or without bolt holes ... I got the ones without. They are 1/8" thick. McMaster item no. 1764K51 ... around $5 a pop.

 

[rswyan]

These two pieces of sheetmetal at the outlet were tapered inward to fit inside the discharge chute ... introducing a slight restriction into the discharge path. With the 6" tube that's no longer necessary ... so I bent them back out even with a hammer:

 

[otlski]

Looking forward to your progress. Please let us see the final results in action. I've had mine for five years or so and only had one problem. A chip jam caused a friction ignited ember which when fanned by the rotation cause quite the smoke show.

 

[rswyan]

Looking forward to your progress. Please let us see the final results in action.

Will do.

The flanges for the chute swivel came in from McMaster yesterday.

They look like they should work fine ... although they will require a little modification I hadn't counted on: the flanges appear to made from angle which has been formed into a circle, are welded on one side, and have some bead sticking up (on the outside)

I'll probably weld them from the other side as well, and then grind all the beads flush.

I've had mine for five years or so and only had one problem. A chip jam caused a friction ignited ember which when fanned by the rotation cause quite the smoke show.

LOL ... I'll bet it did ...

 

[rswyan]

Which reminds me ... I ran across a mod in one of the chipper threads that someone had done to improve the chipper's ability to expel chips ...

Involved drilling some holes in one of the (blade ?) access covers ... my questions are:

1. Did it work as expected to improve performance ?

2. If so, A. which cover ?, B. how many holes, and C. what size holes ?

 

[445A]

Just an idea: rather than grind the welds on the chute rings, get a piece of high density plastic and make a large washer. this will make the two rings slip/rotate more easily. The holes you are referring to are to let air into the chip housing so the chips may be carried out by air flow. I believe this chipper is a disc style. If so, are there any pieces of angle welded to the back side of the disc? If not, and room permits, add at least one behind both of the knives. Keep in mind the thing needs to be kept in balance. These will help funnel the chips to the outside of the disc and act as a fan to move the air to aid in chip discharge. Check out Bandit industries chippers. Cool project, keep us posted.:thumbsup: 445A

 

[rswyan]

Just an idea: rather than grind the welds on the chute rings, get a piece of high density plastic and make a large washer. this will make the two rings slip/rotate more easily.

Great idea ... :thumbsup:

Only downside is my dimensions (by electing to go with 6" tube on the disc housing outlet) puts me into a 12 x 12 sheet of plastic which is a little pricier rather than a 6 x 6 ...

McMaster has a a 12 x 12 x 1/4 sheet of self-lubricating UHMW polyethylene for $15 ... that ought to work I would think. Has a similar coefficient of friction as PFTE. And it should save having to screw around with drilling and tapping for grease fittings.

The holes you are referring to are to let air into the chip housing so the chips may be carried out by air flow.

Right (the disc/chip housing)

I believe this chipper is a disc style.

Correct.

If so, are there any pieces of angle welded to the back side of the disc?

There are pieces of angle on the backside of the disc ... not sure if they are welded or just cast ...

If not, and room permits, add at least one behind both of the knives.

My understanding was the holes were to be drilled in the outer portion of the housing ... not the disc/flywheel itself (the disc/flywheel already has a number of holes in it ... in addition to the slots in the disc, which are just below the knives, and which the chips travel through)

Keep in mind the thing needs to be kept in balance. These will help funnel the chips to the outside of the disc and act as a fan to move the air to aid in chip discharge.

I'm not planning on drilling the flywheel ... due to that exact reason.

Check out Bandit industries chippers.

Will do.

Cool project, keep us posted.:thumbsup: 445A

Thanks, I will ...

Should have some pics of the discharge chute mods by morning ... welded some of it up earlier and I'm liking it so far

 

[rswyan]

Running a little behind ... got distracted into doing some clean up in the shop ... lol ...

All this needs a little tweaking and some clean up (cut off/grind sharp points etc.).

I welded on some 1/8" flat/bar stock to close/cover the backside (bottom) of the bottom flange and then welded on the bottom flange:

 

[rswyan]

I placed the 6" tube down into bottom flange, slid the top flange over the tube and lined things up and then welded the top flange onto the tube:

 

[rswyan]

Before I put the tube into place on the bottom flange I stuck some washers down on the flat "ledge" ... to shim up the tube and provide clearance so that the tube wasn't dragging on anything in the lower part of the bottom flange.

The tube extending into the bottom flange helped to align everything and alleviate the tube edge being in the chip discharge path:

 

[newbury]

Q - Why did you choose the rings w/o holes?

It looks GOOD.

 

[rswyan]

Q - Why did you choose the rings w/o holes?

Because with the clamp design that I'm going to use they really aren't needed.

The clamp ring will be a piece of 1/8" x 1" flat stock that has been formed into a circle/ring that fits around the outside of the flanges. It will have a long nut (aka coupling nut) welded to it on one end and a piece of small diameter tubing welded on the other.

A piece of of threaded rod - which fits thru the small diameter tube and has a "T" handle welded on the one end will be used to draw the clamp tight. The clamp will also have "tabs" (1/8" x 1" x 1") welded to it on top and bottom, which serve to capture the two flanges together vertically.

So to tighten it and hold the discharge chute in a fixed position you just screw the T handle in, and even when it's somewhat loose for adjustment/rotation, the flanges are still captured together to prevent the discharge shoot from falling over/off.

It looks GOOD.

Thanks !

 

[rswyan]

This is the (unfinished) band clamp which will secure the upper flange on the chute to the lower flange on the chipper itself:

It's made from a piece of 1/8" x 1" flat stock that I formed by bending it around a 125 cf shielding gas cylinder. The forming isn't perfect ... but it doesn't really need to be: when it's tightened up it conforms to shape of the flanges. I did give it few taps with hand sledge the first time I tightened it around the flanges ... just to try and conform it to a little better fit.

I used a couple of metric coupling nuts (one longer, one shorter) and some metric threaded rod ... all extras that were left over from the install of the rooftop AC unit on my van. One nut is welded to some 1" angle (also trimmed on one side) which itself is welded to the band.

The rods on the "t-nut" were what was left of the pins that I had to drill out when I shortened a couple of load bars to fit the van. Also used some 3/8" I.D. steel brake/fuel tubing that I had lying around ... it is welded to another piece of 1" angle (also trimmed on one side)

On the tubing I really would have preferred to have used something with a little thicker wall ... but this will probably work fine. If it don't then I'll cut it off and weld on something heavier.

The thread rod is just screwed in to the coupling nut that is welded on the angle/band. Dunno ... probably will Loctite it in there. Didn't really want weld it ... seemed a little too permanent.

Still need to weld on the tabs on the band to finish it.

 

[rswyan]

In the picture below is a piece of 1/8" x 1" flat stock that I formed with a hammer around a piece of 3 1/2" O.D. pipe ... it is the mounting surface for the chute rotation handle and serves to spread any force exerted over a larger area of the 6" tube.

Beating it around the 3 1/2" pipe got it fairly close ... and a pair of large hose clamps (52's) strung together got it close enough to tack in place:

 

[rswyan]

Tacked:

(That rusty old thing just below it is the 3 1/2" O. D. pipe that I used to form it )

 

[rswyan]

Stuck it on the pipe rollers and welded her up:

 

[rswyan]

Looks like I missed getting a shot of the T handle that is used to rotate the chute ... you can barely see it in the bottom of the picture below, just to the right of the rollers:

The image above was actually intended to show the loop handle that I put on so that the force applied to turn the chute would be balanced and there would be less of a tendency for the chute to bind while being rotated.

 

[rswyan]

Probably pretty much done on the chute rotation handles ... might add a couple of rods for braces on the t-handle tho':

 

[rswyan]

One of things that I felt really needed some work was the feed roller ... specifically the teeth. So the other day while I was Harbor Freight I picked up a 4 piece set of (large) files for $8 which included a double-cut coarse triangular file.

As I see it, the problem(s) are several fold:

1. The teeth themselves are small ... based on what I've seen on other wood chippers.

2. The tips of the teeth are too large, are mostly flat (rather than pointed) ... and have too much surface area to allow easy penetration into the wood.

3. The teeth are irregular and inconsistent in size.

So I attempted a little "dentistry" ... originals towards the left (and very bottom right), sharpened top and towards the right:

We'll see how this works ... if it works at an acceptable level then fine.

If not, it could be time for a more serious rework.