I would be interested in knowing this too. I used to have one electric one and I can tell you that it is no use even for regular garden twigs and leaves. It would clog up especially if they are damp. May be they will work for bark if fed slowly - never tried that.

I have tried electric blower-mulcher (Toro) for shredding straw (for oyster mushroom logs) and it works OK. It is a slow and clumsy process and the straw does need to be absolutely dry. May not be that much of issue with bark but the power may be an issue. When I get a chance I will try mulching bark.

Thank you! I'm really wanting to make a quantity of gritty mix. It's a slow/expensive process with a 50% return - so much of the bark is either too small or too large. If I could still use the bigger pieces, it would make a huge difference. I've tried using a hammer, stepping on it, breaking it with my hands (which works but takes far too much time after sifting out the big stuff and the small stuff.). etc.. There has to be a solution. Thank you for responding.

Bragu: do you mean a blower-mulcher or some other Toro product? May be we are talking about the same thing - I have a Toro blower-mulcher and it does have a metal impeller. I have not tried it for shredding bark though. All I can say it is a well made durable equipment. The bag, on the other hand, takes a beating and started to come apart after 5 yrs or so.

I just stumbled on a thread from 2014 or 2015 by someone who said he used this to reduce bark to usable fines. At $56 it would be worth it for someone who needs to break bark down regularly. Unfortunately I can't find the thread at the moment.

EDITED TO ADD: It apparently has plastic blades, but he hadn't had any problems---yet, at least. You probably want something more sturdy if you'll be dealing with really big quantities.

Toro electric blower & vacuum shredder

I found a different solution - I'll post it in a new thread. Thanks

litterbuggy - there is a metal blade version of the Toro shredder for $10 more or so. I have that and I use it to shred straw in addition to mulching leaves. I have had it for more than 5 years now and it is still going strong. I have not used it for bark though since I did not need it so far for that purpose.

Thanks, tropicofcancer. I have mixed feelings about it because I have no other use for such a thing. We'll see how I feel next spring at repotting time.