</font><font color="blue" class="small">( <font color="blue"> If you reverse the blade and direction of rotation, the blade will try to walk down the stump towards you and down into the ground. </font>
Do you think the dynamics of the stump grinder may differ from that seen with PTs? I would imagine the mass of the Magnatrac and the longer arm of the BH might change the behavior somwhat. Of course, this is pure speculation on my part. In any event, it is a neat modification. It is also interesting to me, after reading hundreds of posts in the PT section where PT owners are thinking of ways to use 3rd party attachments on their tractors that here is someone who has recognized the value of the PT attachments and made one work on their machine. You guys continue to amaze me. )</font>
I thought about mounting the blade differently so that chips would not come back at the operator. My original thought was to mount it so blade would spin horizontally and chips would go out to the side. I figured that this config would put too much of a side load on the backhoe so I kept the blade rotation in the same plane as the backhoe normally digs. I didn't really consider making it rotate up. The blade hub is not drilled all the way through, so you can't (at least not easily) mount it on the shaft the other way around and making the motor spin the other way. The easiest way to make it spin the opposite way would be by mounting the whole thing upside down so that the motor is on the left side of the unit and spinning in the normal direction. This would require grinding out a couple of welds on my bracket as one end is made to be narrower than the other end (with spacers welded on inside). I wonder why Power Trac wouldn't have done the same thing to keep the chips from flying toward the operator?
I haven't ever used a PT stump grinder, but I would guess that the dynamics would be somewhat different because of the shorter distance between the cutter and the attachment to the main tractor (on the PT). Although I was initially concerned that putting the grinder way out there with the backhoe arm at full extension would cause it to really be unstable, but it wasn't all that bad. I'm going to have to experiment lots more to get the technique perfected, but what I found works really well and protects the operator the most is to open the bucket curl almost all the way (this brings the blade guard pretty much vertical). Then, I move the cutter into contact with the stump using the boom raise/lower and dipper in/out controls. Then, curling the cutter down into the stump really plunges the cutter in. This grinds a slot like using a circular saw. What was a little tough was to make a series of slots with the amount of wood left in between thin enough to knock/grind off with side to side motion. The cutter kept falling off back into an adjacent slot. I'm thinking about a modification to add a indexing pin or plate that would go into a slot already ground and hold the cutter steady so that it could plunge another slot in the wood right next to it. The index could be adjustable so that the wood left in between slots could be varied as needed so that it could be easily knocked off. Sort of like making a half of a lap joint in a 2 x 4 by making a bunch of cuts across with the circular saw and then knocking the thin remains off with a chisel.
What would really be cool is something like what is shown in the attached pic which was my original inspiration for the attachment... a spinning drum with lots of carbide teeth (or a stack of PT type disks). Now that's what I call destructive potential! /forums/images/graemlins/grin.gif
Any other ideas would be appreciated.
John M
