T-Rex - my towable wood chipper

[mrmikey]

That is a beautiful piece of work, my compliments.............Mike

 

[Snobdds]

Well... you now it is no use to re-invent the wheel...

When I started to design the chipper I of course looked on all available material of commercial chippers. I basically evaluated different solutions based on,

- how well will it work
- how hard is it to make with the tool limitations I have
- how much will it cost

My feed mechanism idea is certainly influenced by the Bear Cat chipper. I selected this approach because constructions that had the upper feed roller fitted to a linkage that was fitted to the infeed frame had so many parts fitted with various angles that I evaluated a little bit hard to make.

I have one question to you. How often do you grease/clean the moving upper roller frame of your Bear Cat chipper?

Well, I use mine primarily up at my cabin to chip up pine trees. I used it a lot for a five year period, and haven't even touched it in the past 2 years. I am in the process of building my cabin, but once that is done, I will get back to chipping some lingering piles I have. When I was using it, I would grease the entire thing about every ten hours of run time. For me that was about a weekends worth of time.

How do you run the belts off the crankshaft to the flywheel? Mine is lever operated and I stand on the lever and slowly allow the belts to spin the flywheel to match the crankshaft speed. Sometimes I get impatient and the belts start to smoke a bit from the friction. I was just wondering if you have a clutch mechanism or direct drive.

 

[ericm979]

For comparison purposes- my Woodmaxx 8H 8" hydraulic feed chipper's maximum feed speed is 23 meters/min (75 fpm). For small brush I'd be ok with it being faster. But as it is if I'm ready to feed another branch before the last one is done, I just stack them.

 

[Fastball]

Looks like a thing of beauty....good job, boyka!

 

[ruxu]

Well, I use mine primarily up at my cabin to chip up pine trees. I used it a lot for a five year period, and haven't even touched it in the past 2 years. I am in the process of building my cabin, but once that is done, I will get back to chipping some lingering piles I have. When I was using it, I would grease the entire thing about every ten hours of run time. For me that was about a weekends worth of time.

How do you run the belts off the crankshaft to the flywheel? Mine is lever operated and I stand on the lever and slowly allow the belts to spin the flywheel to match the crankshaft speed. Sometimes I get impatient and the belts start to smoke a bit from the friction. I was just wondering if you have a clutch mechanism or direct drive.

Yes there is a centrifugal clutch on the engine output shaft. It engages at around 1 000 - 1 300 rpm on the engine and two V-belts is then driving the chipper cutting wheel.

I have earlier also been using a rental Wermeer 160XL chipper that has a similar lever operated drive mechanism. The belt on the Wermeer is a single belt with two V-belt sections - not two separate V-belts. It seems to work fine even on a heavily used rental chipper.

 

[ruxu]

For comparison purposes- my Woodmaxx 8H 8" hydraulic feed chipper's maximum feed speed is 23 meters/min (75 fpm). For small brush I'd be ok with it being faster. But as it is if I'm ready to feed another branch before the last one is done, I just stack them.

As I had no idea how everything would work in the hydraulic feed so I wanted to stay on the safe side in order to not get disappointed with the hydraulic feed too. I just calculated that every rotation of the chipping wheel with two blades cuts ideally off 14 mm. Running at 1 300 rpm that makes 18,2 m/min. I have dimensioned the feed rollers according to this chipping capacity and also safeguarded the feed by putting in a flow regulator and a intelligent feed system. Ideally if the intelligent feed system works well I could take out the flow regulator as obsolete and use the full maximum feed speed of 18,2 m/min. The number of knives on the chipper wheel affects the maximum feed rate - my chipper has two knives, now I know I could have easily put in 3 knives and the 16hp B&S could have souped with it. Technically I could still put in 2 knives more and increase the total to 4 but then the intelligent feed system would certainly engage more frequently.

For comparison I have been using a rental Vermeer 160XL (8" capacity) several times with a max. feed rate of 49m/min. However a setting around 24 m/min seems to work best with various branch sizes. That feed rate is quite similar to your chipper.

If everything works OK in the long run and I for some reason would feel that the 18,2 m/min isn't fast enough I can slightly change the chipping wheel speed and put in a bigger volume hydraulic pump or maybe even ad two cutting knives. But what the heck - I am in no hurry, I am retired....

 

[Gordon Gould]

You have quite a broad set off engineering and fabrication/construction skills!! That is a pretty complicated piece of equipment you designed and built. It is great to see what can be achieved while having fun. Fantastic job and thanks for showing us what you did.

gg

 

[Joe Malovich]

ruxu, You'd want to set the engine RPM for maximum horsepower and not maximum torque, then adjust the gear/belt ratio to your desired flywheel RPM. By coincidence the HP/Torque curves might be peaking at the same RPM for your engine (I didn't look them up).

I also think modulating feed-rate would be better to keep the engine in the maximum HP range compared to bang-bang feed-rate which would make the engine chug thus lowering the RPM out of the maximum horsepower RPM range.