Late to the party, but for what its worth, I had an old miter saw that was maybe 100.00 when I bought it 5-10 years ago. A cheap ryobi one. I put a 14" metal cut wheel on it and used it for my exhaust. Worked just fine. Some of the plastic guards became a little charred and I took odd the sawdust collection bag, but it was effective enough.
I've put the wood blade back on since and it works just fine.