Chipper MacKissic Chipper Blade Removal

[popsjohn]

I recently purchased a MacKissic SC-183 Chipper Shredder at a Lancaster County PA Mud Sale. I knew it had some parts missing such as the battery, battery holder and belt guard but I got it for a good price and I knew the parts would be available. When I got it home I purchased a battery and started up the BS 16HP Vanuard engine. It started but smoked like crazy. Figured out it had gasoline in the crankcase. After oil change and carb rebuild engine runs fine. I also needed to reverse the hammers and replace some broken ones. It seems to shred very well.

My problem is the chipper blades. This is an older unit with two chipper blades. I determined that the gap between the wear plate and blades was too wide. Could not adjust to the correct 1/16" so replaced the wear plate. Chips better but still not what I think it should be. I attempted to remove the blades following instructions I was able to download. I can't get the bolts to move. Used heat as instructed but being a novice at this I don't know how much heat to apply. Any help or suggestions would be appreciated.

John

 

[oosik]

Welcome to TBN. Removing "corroded on" bolts. First I would apply a good rust solvent such as WD40 - let this soak in for a day or two. Then heat just the bolts with a hand held propane torch and use an impact wrench. This should do the job. You should not have to get the bolts really hot and you definitely do not want the blades to get really hot. If you can heat the bolt threads from the back side of the rotor disk - that will be better. Less chance of changing the temper of the chipper blades. You might have to do this more than once to break the bolts loose.

 

[oldballs]

Likewise, "Welcome" to TBN.

If oosik's plan doesn't work, try the MacKissic company direct via MacKissic Inc. or phone 610-495-7181. I found their people to be most helpful.

Cheers,
Mike

 

[CalG]

I've got the PTO version of the MacK biggest chipper. .

propane has not done the job for me when changing /sharpening knives. Neither has penetrating oil helped enough to show. An impact wrench on those allen heads is going to ruin screw heads, tools , and your entire day ;-) At least it did mine ..until.......

I use "the smoke wrench", i.e. oxy /acetylene with a small tip, put the flame cone right on the allen key hole and wait until the head turns blue . That is SMOKE'in hot! Don't worry about the knife, it's bolted to the flywheel plate that takes the heat away, That's where the heat your putting into the screw head goes also. (which is why the propane doesn't get the job done. I suppose propane would work if you heated up the entire wheel. but don't do that ;-)

First step is to clear the wrenching head out perfectly. The allen key needs to go all the way in. I use a sharpened bicycle spoke as a pick.
Then start with the heat. Get that screw head hot as quickly as you can. Small flame, right at the tip of the blue cone.
While the screw is piping hot , fresh out from under the torch flame, give it a twist with the allen key. (GLOVES!) One turn is enough, It might squeak when it moves, or maybe not. Then move to the next of the three screws. repeat the process until all are loosened. After all the screws are started, then go back and give each one a spritz with the PB Blaster or whatever is in your oil can.

If you look carefully at the blade design you will note that the body is tapered. As the blade takes the pounding and is driven back (there is no stop plate) the fasteners are stretched tighter than when first installed. That's why the things are so freaking tight.

I bought a box of new c'snk screws from Fastenall after the first removal trying to use the MacKissick instructions with punches etc. . I didn't think much of what happened to the fasteners and don't like messing with buggered internal wrenching screws.

So I pitch the 6old ones into the "screw bucket" and get out 6 new ones.

I put a small dab of never seize on the screw threads on installation.

This works for me, something else might work for you. please share any breakthrough methods! ;-)

 

[Cord]

Yea, those bolts can be impossibly stuck. The allen head doesn't help things either. You gotta get full engagement or you'll just round the head off. The last time I did this, I ended up welding some nuts to the bolt heads. The heat helped to break them free and I could put more force on them.

 

[narada]

I also own a MacKissic chipper and recently had some difficulty removing the bolts securing the chipper blade.

The manual states that "a small amount of heat from a propane torch" should be adequate, but unfortunately, straight propane didn't work for me. I did some research and purchased an oxy-MAPP torch kit, hoping that heating the bolts to higher temperatures would yield better results. However, when I got back home and tried it, my attempts were again unsuccessful.

I called up the good folks at MacKissic and was told that folks reported having good results with MAPP, and I was advised to continue applying heat for up to five minutes.

I followed the advice, and I don't think a full five minutes was necessary, but I did have to torch the bolts for several minutes, till they were cherry red and glowing, before I was able to loosen them successfully with a power tool.

The gentleman from MacKissic also recommended a product called "Aerokroil penetrating oil", which fortunately, I didn't need to use. However, after reading a number of reviews for this product online, I've gone ahead and purchased a can for next time, because this stuff seems to be universally hailed as a miracle substance for loosening stuck bolts.

 

[fruitcakesa]

I also own a MacKissic chipper and recently had some difficulty removing the bolts securing the chipper blade.

The manual states that "a small amount of heat from a propane torch" should be adequate, but unfortunately, straight propane didn't work for me. I did some research and purchased an oxy-MAPP torch kit, hoping that heating the bolts to higher temperatures would yield better results. However, when I got back home and tried it, my attempts were again unsuccessful.

I called up the good folks at MacKissic and was told that folks reported having good results with MAPP, and I was advised to continue applying heat for up to five minutes.

I followed the advice, and I don't think a full five minutes was necessary, but I did have to torch the bolts for several minutes, till they were cherry red and glowing, before I was able to loosen them successfully with a power tool.

The gentleman from MacKissic also recommended a product called "Aerokroil penetrating oil", which fortunately, I didn't need to use. However, after reading a number of reviews for this product online, I've gone ahead and purchased a can for next time, because this stuff seems to be universally hailed as a miracle substance for loosening stuck bolts.

I have used the "kroil" for years. We call it "the millionth of an inch lube" because it supposedly can penetrate gaps that small.

 

[hosspuller]

This may be superfluous to OP, but bears posting for anybody else. "Cherry red " Don't reuse those bolts. You've undone any heat treatment and reduced their strength. Loosing bolts in a chipper is an expensive disaster.

 

[RalphVa]

Never had that kind of trouble. I did drop the first blade I took off and had to loosen the bolts holding that back plate in place to get it out. Think I also cut a small opening at the bottom, too. After that, I learned to hold onto it good when removing that last allen screw.

You do have to use an ice pick or appropriate tool to get stuff out of the allen hole in the screw tops. Then rap the top of the allen wrench to seat it well into the hole. You MUST have a good allen wrench too: one that fits into a socket handle. Those 90 degree wrenches just won't do.

Only use blue thread locker when putting them back.

Mine is going on near 16 years now. Lots of chipper blade removals done. Told them recently when I contacted them (MacKissic) that it's good for another 100k hours now, regarding something that I needed.

Ralph

 

[Captain Dirty]

The inherent problem with flat head machine screws is that, as the the screw is tightened, it is drawn into the conical recess and the head is compressed, very slightly but often critically. The first time I removed the chipper knife on a Kemp chipper I had to carefully clean debris from the allen socket and may have pounded or honed the allen bit to get it to fit. When I re-installed the bolts I held them with the allen, tightened the nut with a wrench, and then discovered the head had compressed around the allen bit so tightly I could not remove it. My work-around was to hold the screw with the allen bit until the friction between the screw head and the conical recess was great enough that I could tighten the nut without turning the screw. To diss-assemble I would start to loosen the nut relying on fiction to hold the screw; when the screws started to spin I was able to insert the allen bit and hold the screws as I finished backing off the nut. Note that, on the Kemp, the machine screws were bolts that passed through the "flywheel" plate on the end of the drum and were secured with nuts.

I am not familiar with MacKissic chippers, but the parts diagram (911-0150 Basic Assembly) shows #27. 5/16-18 x 1" flat hd socket cap. There does not appear to be any nuts on the far side of the "chipper disc". Perhaps the chipper disc is tapped for the screws. It is not clear if it would be practicable to access the back side of the disc to use nuts.

If nuts cannot be used Torx head flat head machine screws may allow easier driver fitting and higher torque. McMasters-Carr has them, but $$$.