The steel blades do not dull so quickly if you keep from rototilling with them.
In 20 years of sharpening for a living I have not seen a carbide brush blade.
The most durable clearing saw I see is the 24t Husqvarna in blued steel sometimes labelled "electrolux motor" on it.
I would advise against using circular saw blades for this purpose.

"I would advise against using circular saw blades for this purpose."
Don't ever do that. Circular saws turn at 3450 rpm and a brush cutter will scream at almost three times that speed. A saw blade could shatter if it hits an obstacle and it will certainly spit carbide tips.

That blade you've got is what I've heard referred to as a scratch tooth blade. When I got an FS250 Stihl trimmer, I bought a sample of each blade that my Stihl dealer had. So I have a blade like yours also. I found it to do a credible job on some of our one year's growth underbrush, but it dulled extremely easily.

The blade I like the best of that lot is a 22 tooth blade, whose teeth look vaguely like chainsaw teeth. You can sharpen it with a chainsaw file. Even though it is also just tool steel, I can get several times as much clearing done on a sharpening. My blades are all 8". I'm going to try some 9", I think my trimmer can spin that diameter.

These blades are very generic, as long as you get the proper arbor size, you can run anything available on yout trimmer. If you think there is a possibility your trimmer can spin 9", I've include a link for the only carbide tipped brushblades I've found.

Good luck. Mike

Here is a link that might be useful: carbide tipped brushblades

The absolute best brush blade for 1"-4" brush(and bigger depending on trimmer size) is called a Beaver Blade.They can be bought in 8"-10"-12" diameters.They have actual round chisel chainsaw teeth riveted on the blade.I have a Stihl FS 250 and use a 10" Beaver Blade on it.I have actually cut soft wood trees that were almost a foot in diameter with it.Sharpens easy with a 7/32 file.I bought my 10" blade for $24.New teeth can be bought when you wear it out,but almost cost as much as a new blade.Just be careful what you cut,mines only been sharpened twice and has seen a lot of use.Doug

Where did you find a Beaver Blade for $24? I have only found them in the $34+ range, also I only found 7", 8" and 9" flavors. Any info on your supplier?

Thanks.

I adapted a NB351 Robin Trimmer (I think that is the model designation) to use carbide blades. I had a special washer made to center the blade which cost $50.00 about 10 years ago. This setup worked fantastic in cutting 10's of thousands of saplings, acres of brush and, small trees up to 4 inches in diameter where a bushhog couldn't reach. I have never had a blade to shatter or break in about 200 hours or more of use unlike plain steel blades where I had the teeth break off and on one occasion sending a little missle whizzing through the grass beside me. However, I must admit I have seen carbide teeth gone or wore down next to nothing when I replaced blades. But, like I said, I have never had any problems in the 30 or more blades that I have probably used. Despite the fact I have started wearing heavy duty boots, greater wisdom in my old age has got me asking where have those worn tips go and, why haven't I ever had one hit me? I don't think it is just luck. None the less, age is making me more cautious and I am going to look into the beaver blade for my new SRN 400U Echo. Where is the best place to get these blades in terms of price? Thanks

Beaver Blades:
7" @ $34; 8" @ $37; 9" @ $43 from:
mfgsupply.com

Manufacturer's Supply
P.O. Box 208
Medford, WI 54451
800-826-8563.

Here is a link that might be useful: Manufacturer's Supply

What if I use a 1" step drill and cutting oil to open up the 5/8" arbor hole on a decent circle saw blade?

As far as I can tell from the (really good manual) the actual head rotation speed on my Husqy 223L is within the rpm range of the Irwin Marathon blades.

Motors rev up to 9000 but the shaft gearboxes are about 3:1 to get useable power to the spindle arbor.

I want to try it on my TroyBilt TB90. The (lame) manual doesn't give as much tech data as the Husqy, but I suspect the relative speeds are about the same.

Any words of wisdom out there?

TYPO:
The gearbox ratios seem to be about 3:2.

If the motor is running @ 9000 rpm, the sindle arbor is probably turning about 6000 rpm.

If the motor is screaming @ 12000 rpm, the sindle arbor is probably turning about 8000 rpm.

I have an old Homelite trimmer from the late seventies to early eighties. It came with a brush cutter attachment which in turn came with an 8" "scratcher" blade and a three bladed thing called a "tri-arc". I wanted to cut down a bunch of saplings and the more than 25 year old scratcher blade was so rusty and dull that I decided to try an old 7-1\4" circular saw blade. I didn't know if it would fit but since the Homelite has a 5\8" arbor it did.
This old Homelite uses 16:1 fuel mix; thats 8 ozs. of oil per gallon of gasoline. I doubt if that thing has ever ran faster than 6000 r.p.m's. It also has a centrifugal clutch so if I hit anything it will "clutch out". The brush cutter head is also solid cast aluminum; not that lame stamped sheet metal. It's true that they don't make them like they used to.
Now back to that 7-1\4" saw blade. It wasn't working in the saw so well anymore so "to the brush cutter with it!" As soon as I start to cut, it slows down-that's to be expected. When I went to refill the fuel I noticed that a couple of the carbide tips were gone, probably because I got into a bit of steel fence wire. Now even though it wouldn't cut lumber anymore, it went through saplings nicely(way to recycle). Something to remember about a typical framing blade is this: They tend to be made to go through at least a few nails before they wear out. They are also made to flex enough to cut slight gradual curves. In general they're pretty tough.
If you're worried about a blade hitting something and shattering then keep your eyes peeled and made sure the area is clear before starting your cut. If you think your power head spins too fast then don't run it at full throttle. Use your head. Do your homework. Go to the web site for your trimmers manufacturer and find out how fast it spins. Lastly listen to what Norm Abrams says and WEAR YOUR SAFETY GLASSES!!
Carbide tipped saw blades eat through saplings with ease. I recommend them, but I also recommend using common sense. They aren't inherently safe in the first place which is probably why they aren't sold in the large national home improvement centers. Those who still make weed eater brush cutter attachments make the arbor bigger than what circular saws use for a reason. They are trying to make it hard for you to put one of these blades on your weed eater. I just got lucky with my old weed eater. The world wasn't quite as safe back then, (or were people mostly smarter back then?).

Check these out. Carbide tips brazed on , flexible steel. Sounds cool. I may try them. See link.

Here is a link that might be useful: Carbide tipped brush blades.

I've been in the resharp business since '84. Look around and any carbide resharp guy can put carbide on your old steel blade. I've found that instead of the silver solder, it is best to braze them on. Sure, they wear down and rocks can shatter them. be careful and don't ram into rocks. The tooth replacement should be approx $1.50 per tooth

Has anyone seen a blade with chainsaw teeth riveted to the blade (Not a whole chain like the beaver has). I have seen one on the internet but did not bookmark the site. Thanks

Has anyone seen a blade with chainsaw teeth riveted to the blade.

I think you mean RazorMax blades. I have no experience with them (just bought my brushcutter!).

Here is a link that might be useful: RazorMax blade

I have a high wheel trimmer and I was wondering if anyone has tried to put one of these blades on their high wheel trimmer, did you have to make any adjustments and what were the results. Thanks

If you follow the links for RazorMax blade posted above, you will also find a Total carbide tipped brushcutter blade mentioned. I don't have experience with it, but am considering getting one.

I looked for a decent brush cutter blade forever and ended up going with a circular saw blade. The arbor didn't quite match up so I had to make my own reducer and it vibrated pretty bad (cut awesome though).
I just ran across these carbide tipped brush cutter blades by Tenryu and I'm going to try one next time I need one.

Here is a link that might be useful: Tenryu Carbide Tipped Brush Cutter Blades

I first used Homelite XL brushcutters in 1970 and '72, brushing trails. Used std 10" circle saw rip blades. Harder blades would be silly because you WILL kiss a rock and you need to be able to file it. Sharpened w/ flat mill bstd file, round file to gullet when needed. Teeth looked funny after a few filings but we learned to make 'em "hungry" for brush. Now I'm shopping for a brushcutter and WISH I could find an old XL. These modern saws have odd arbors, won't take std cheap blades, and generally look light and wimpy. I want a workhorse that won't cost a fortune to keep in blades.

These are currently available on Ebay.
http://www.ebay.ca/itm/310280796455?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
Does anyone have any experience with these ?

Now that's weird: I first saw this site when surfing with my Droid phone. It allowed me to post a reply WITHOUT making me join the forum. I'm the Lane Dexter above. Then I went back to this discussion thread from a PC at work. It wouldn't let me post until I joined. I would not let me use Lane Dexter (my name), so I tried Hamilton Felix and it refused. Then I tried HamiltonFelix (no space) at it accepted. So after considerable runaround (initial membership confirmation said I had to log in as Lane), I'm a member. Yay.

I still want a heavy duty brushcutter/clearing saw. I want to use a 10" blade, with as few teeth as I can; one doesn't like filing any more than necessary.

I sure wish I could still find a Homelite XL in good shape, but it's a bummer when your favorite tools are only listed under "vintage" or "collectors" sites. Sounds like I'm stuck with buying something that locks me into their proprietary blades. I suppose the biggest Stihl is my best bet.

I got these and they are the best. Carbide teeth are super strong. They last super long and they cut just about anything.

Here is a link that might be useful: Carbide blade website

You can use a 8inch carbide tip table saw blade on your echo srm - 210 . I have an SRM -230 and it works great with the 8 inch 24 tooth table saw blade . Be careful of the kick back .