Never heard of a roto zip but

Never heard of a roto zip but googled it.  Guessing it's almost as messy as a standard jig saw blade.

Reported there is a jig saw blade you can get that eliminates the dust, or most of it, when using.  

The Blade Jim is Referring to

Is like a knife that goes up and down. Supposed to be less messy. Never have tried either. I have used a rotozip cutter but never on homosote. If you have lots of homosote to cut, doing it outside if possible cuts down on the mess inside.

Espee over Donner

Rotozip

I have used a "Rotozip" to cut switch mechanism slots in the roadbed.  

Lots of dust.  Very hard to cut in a straight line.  Almost impossible to cut a smooth line free hand.  You would have to have some sort of fence to hold it and would have to feed fairly slowly. 

Based on my experience, I don't see any advantage over a saber saw or circular saw and bot of those have tons more control over the cut.

Most of my roadbed I cut with a utility knife.

For throwbar slots I drill a 3/16" hole in the center of the track where the slot goes, then from the bottom use a 3/4" spade bit to drill a hole through the plywood.  I then take the shop vac hose and stick it on the bottom of the plywood, the shop vac has enough suction to hold it there.  I then rout out the slot from the top and the shop vac sucks all the dust and cuttings up.

knife jig saw blade

Works great in homosote.  They do get hot, so either give them plenty of breaks and/or be prepared to replace them a bit sooner than you might think.  But it’s so much nicer than spreading dust all over the landscape - totally work it in my opinion.

I’d imagine a rotozip would make even more mess than a regular jigsaw blade.

how about?

an oscillating saw with knife blade? Anyone tried one of these on homasote? I don't have any homasote around here right now so can try it....DaveB

Oscillating saw with knife blade

In other words, a jig saw with a knife blade.  Works well in homosote, as I said above.  Something like this (depending on what blades your jig saw accepts):  https://www.boschtools.com/us/en/boschtools-ocs/t-shank-jig-saw-blades-specialty-t113a3-29701-p/

The value of a "roto zip" ...

... blade (actually a round spiral drill designed to cut laterally) is that you can change the direction of the cut for irregular and/or circular/oval cuts. Dremel, among others, make a cutter similar to the roto zip cutting bit (RotoZip is a brand name, by the way).

https://www.dremel.com/en_US/products/-/show-product/accessories/561-multipurpose-cutting-bit

Home Depot, among others, do sell the RotoZip tool with the spiral saw. They also sell the Dremel products as does Lowes.

In using a Dremel or other rotary tool, it works better to have an attachment (Dremel has one that is inexpensive, but only attaches to their rotary tools that accommodate it).

If you have a Dremel rotary tool that will accommodate it, then buy the kit - it comes with the cutters:

https://www.dremel.com/en_US/products/-/show-product/attachments/565-multipurpose-cutting-kit

The Dremel multipurpose cutting bit can also be used for penetration, so that a hole can be made with it.

In other words, a jig saw with a knife blade?

No, the oscillating saw I'm thinking about  is a specialty saw that vibrates the blade at a very high frequency. They use one version to cut off plaster casts without cutting the adjacent skin. Woodworker's versions can accept various blades; saws, scrapers, etc.  They are very handy for cutting square holes in hard to reach places as they will cut a stab cut with the end of the blade....DaveB

Ah Ha

The consumer version of the oscillating saw is called a 'multi tool'.
 

https://en.wikipedia.org/wiki/Multi-tool_(power_tool)
A [power] multi-tool, oscillating tool, or oscillating power tool is a  power tool that  oscillates (rather than rotating or reciprocating), powered by battery or mains. The name "multi-tool" is a reference to the many functions that this tool can perform with the range of attachments available. "Master Tool" is also a trade name used in North America, short for the original tool by Fein called the Multi-Master. Attachments are available for  sawing,  sanding,  rasping,  grinding, scraping,  cutting, and  polishing.

And yes it works good according to some.  I haven't tried it myself on homasote etc so can't comment about the dust creation.  Might depend on the blade used.  Try a knife blade of a really fine tooth.

The do however work wonders on extruded foam

Multitool

Sorry I didn’t get what you meant at first Dave.  Interesting thought.  I don’t have one of those, but they do seem useful.

TC when you saw they work wonders on foam do you mean cutting straight through, or for contouring, or both, ...? I’m always intrigued with a use for a tool I was unaware of before.

I could have used the

I could have used the Oscillating tool when cutting the bottom of the door trim to fit bathroom tile under it.  You may laugh, but I used a hobby razor saw to cut out the bottom - it was slow but worked.  Recently my wife and I were helping a couple next door remediate a bathroom floor that was rotted by water on both sides of the shower door.  They had an Oscillating tool that cut out pieces of old drywall and other things and it worked very well.  As a gift to my wife and I for helping them, they bought us a Rigid Oscillating too, very similar to the one pictured above.

Back to Homasote, I've used a utility knife to cut mine and it's virtually dust free.  I may try one of those knife blades next time I need to cut it.

I have used a knife blade in

I have used a knife blade in a saber/jig saw for years and it cuts clean, very little dust but like others have said the blade dulls quickly due to the heat of cutting. I think I have used the same blade for over five years by just filing it sharp every once in awhile.

I am thinking cutting 1/2" homosote with a utility knife would be pretty hard on the hand after a few cuts.

I also have an oscillating , saw which is handy as Jim has pointed out. Good to have quality tools for the right job.  

Barry 

Knife Blade for jig-saw

Have used one quite a bit.   Works awesome with almost no dust.   However, the heat is definanetly a problem for extended use.

Thank you Ken Rice for finding a T-shank version.   I haven't looked in a few years, but they didn't seem to make a T-shank, and the only older style jig saws I had were corded version.    have to get me some of those.

The oscillating tools work great, unless  you are going to be working on cuts longer than a foot....too slow IMHO.

When the oscillating tool idea was listed, first thing I thought of was a reciprocating saw.    Not sure if I've ever seen a knife blade for one of those yet either.   However, if there was, the thickness of the blade would likely cause more dust than a jig saw, but the longer length and mass of a recip saw blade might be able to handle/dissipate the heat better for long cuts and likely would cut faster.

A rotozip is hard to control.

Most drywall hangers miss a few times in each room and they use them every day. 
The oscillating tool is great for detail cuts. It also has a learning curve when you first use it. I got a cordless one for remodels at work. There are different types of blades but I have used what ever type I had to cut wood or thin metal. It can be tedious when trying to use it for a long cut. 

The only thing I would use a

The only thing I would use a roto-zip on is drywall. Cutting Homesote,  all I can visualize is a huge mess

Sharp Utility Knife

Having cut hundreds of sheets of Homasote over the past 40 years nothing works as well as a sharp heavy duty utility knife.  Four or five passes and it your through the board with no dust to worry about.

Sure, it's hard on the arms and hands if you have a lot to cut but there is little or now mess to clean up after your done cutting.

Andy H

Minooka, IL

2nd : Knife

I cut the majority of my Homasote with a utility knife.

Oscillating Multi-tool

Dremel also makes a line of oscillating tools - quite versatile. Prices range from $67 up (less for factory refurbished models). Check it out here:

https://www.homedepot.com/b/Tools-Power-Tools-Power-Multi-Tools-Oscillating-Tools/Dremel/N-5yc1vZc2b2Zgr

I have used the sabre saw with knife blade on soft material - be sure to get/use the hardened blade to maintain a cutting edge and work slowly or the hardening will disappear by overheating. My favorite collection of sabre saw blades is Skil Saw. I know not how the sabre saw ever got the name jig saw, but it never fit my vocabulary. I searched for the Skil saw set I last purchased, but could not find it - probably because they could not compete with the cheap chinese offering. Such is life - find an expendable product you like and a decade later it becomes as scarce as hens teeth. Tempts one to buy two or more of everything, once it is valued.