Option screens for MacKissic/Merry Mac chipper shredders

[JackyJ]

This spring I purchased a MacKissic TPH-123 chipper/shredder that came standard with a screen with 1" holes. These units have a hammermill, and whatever goes down the chute gets flailed until it's small enough to exit through the screen holes. The 1" size is good for chipping branches, so it's met my needs so far. But with leaf season coming, I'm wondering about getting the optional 1/2" hole screen. I compost all my leaves, and I'm hoping the smaller size will help the compost process work faster, and also make the shredded leaf piles more compact and thus easier to move around my property.

They sell screens with 1/4", 1/2", and 3/4" holes, plus some with larger oblong openings that I think are for wet materials. Anyone tried some of these, and if so, is 1/2" best for dry leaves? They're pricey at $119 each, so I don't intend to buy more than one. I'm a little concerned that the smaller screens will just slow down the machine, without making a significant difference to my composting and mulching.

Thanks!

Jack

 

[frugalangler]

When I've shredded leaves for mulch I used the bigger one, but for compost finer will definitely make them more compact, but you'll have to turn them more often if you're composting.

 

[oldballs]

I've got the towable model, stand alone, but I think the available screens are essentially the same. I use the oblong screen most of the time because there are often time larger limbs/sticks that I feed into the hopper. It seems that the combination of larger limbs/stick and leaves is my usually chore. And the resultant shredded/chipped end product is really a good mix for garden paths and mulch under cedar hedge rows.

If I was just doing leaves, or just chipping I can switch to the 1 inch round holes screen and end up with a finer end product if so desired.
Cheers,
Mike

 

[CalG]

Heck! I have troubles with the oval hole screen clogging on leaves unless they are just the right moisture content.

Not sure what that is, or how to measure, but I know it when I see it. Clogged screens slow things down so badly. I prefer to shovel material through for a second pass rather than put up with clogged screens. I try to hold back on some easy chipping branches etc, so that can be run through either the chipper or the shredder to clear the screen when needed.

 

[Ken M]

I have a 1984 Mackissic 12p (7hp) w/ 1" dia, 3/4" dia and the welded bar screens. I run all kinds of organic stuff through it. For dry material (and dry leaves) I almost always use the 1" dia screen. If leaves are not dry or are damp or have really thick tough stems the 1" occassionally will clog and bog the machine down. At that point I switch to the bar screen to get things mixed, shredded and condensed. After this drys or molds up it will go back with the 1 dia. for a finer shred. I have never had much luck with the 3\4" screen. Clogs too easily. Anything slightly damp just gets extruded out. I was told some folks use the finer screens to crack corn and mix or blend grains. Wet clumpy leaves? Run through with the bars or usually no screen at all. I did see they now have the oval screens and I think that would be a good match for not so dry leaves or other more course material.

Feeding the hammer mill by hand works the best. My setup with the infeed hopper allows me to fill it by hand or front end loader. I can control how much goes down the chute and avoid clogging.

 

[Ken M]

Found this photo of the screens.

 

[JackyJ]

Found this photo of the screens.

View attachment 521634

Thanks for that pic! It's helpful to see the relative sizes. Glad I asked about these, since it sounds like I should be thinking about either the oval holes or barred model. I've seen no significant clogging issues while running green leaves through the 1" screen, but they're always going through with branches that keep things clear, I guess. I now see that damp leaves can be a real problem.

 

[oldballs]

Safety note............on one occasion I raised the exit gate to a higher setting. Using the oblong screen, doing some smaller cedar branches that were tossed into the hopper, a "stick" flew out the rear (not suppose to be standing there), hit my right leg just below the knee. It swelled up big time and left a bruise mark that is still there years later.