# Stihl KM-56 vs FS-56 vs RS-90



## vestaviascott (Mar 7, 2009)

I'm looking to buy my first weed trimmer/brushcutter. I have an 1.25 acre lot. The back of the house has a creek with lots of privet brush and heavy weeds.

In researching the purchase, I found some really positive Youtube reviews for the Stihl weeders. In particular, the FS-56 model as a bang-for-your-buck option. 

I went to the Stihl dealer today and thought I was going to walk out with an FS-56. However, when I told the saleman I needed it primarily for heavy brush and weeds, he told me that since it has a spring-based shaft (unlike the solid shaft of the RS-90) it cannot reliably work with a steel blade to handle my brush cutting tasks. Interestingly, the split shaft version of the RS-56 (The KS-56) has a solid shaft like the RS-90 and KM-90.

So, I'm leaning towards the KM-56 due to the fact I can use attachments and my first attachment purchase will be the brush cutter so that I can deal with the privet and heavy brush in the back yard. I understand that it also works with third party attachments (I have a Ryobi weeder attachment).

Should I go with the KM-56 and a brush cutter attachment, or go with the RS-90 and buy a blade attachment and nut coupler for it? Same money either option.

Any advice? I'm on a budget.


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## vestaviascott (Mar 7, 2009)

Correction: I said RS-56 has a "spring" based drive shaft. That should have been "cable-based" drive shaft. That's the main reason I'm considering the other units that have a solid shaft.


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## drew53813 (Jun 25, 2014)

Not fully educated on every model, however the stihl stuff I own i.e. chainsaw, back pack blower work to perfection. I have beat the crap out of them and they still start right up. Cant go wrong with a stihl.


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## vestaviascott (Mar 7, 2009)

Thanks Drew. I appreciate the feedback on Stihl. I'm definitely sold on the brand and reputation and the local service network and 4 year warranty is peace of mind.

I'm just torn between which model to buy. I think I'm leaning to the RM-56 with a straight line trimmer and I'll buy blade and nut/coupler for it for my brush cutting.


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## drew53813 (Jun 25, 2014)

Buy the biggest one you can within your budget. You don't want it bogging down and slowing up your cleanup process. After a few uses, you will be glad you did.


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## asnigro (May 16, 2015)

I guess I never really considered the shaft components when purchasing? What are the differences supposed to provide?

I am in a similar situation to you, river in back yard that has growth between my mowable yard that I wanted to keep trim. I purchased the FS 56 C-E (bike handle) model after researching online and talking to the guy in the local True Value. At the moment, I do not plan to use the metal saw blade attachments but they are available to use on this trimmer. I do consider perhaps getting the poly blade head for thicker growth if I get behind on the trimming schedule.

I am quite happy with the bike handle option though. Easier to stabalize the cutting head through thicker brush. Easier to fight the head from bouncing to the side after hitting something like a stump that was hidden amongst overgrown weeds.

I will say that the "AUTOCUT head" hasnt been as "auto" as I'd have liked. I havent found the tapping action to yield extra string to come out, but maybe Im doing it wrong and need to re-read on how to perform the "TapAction (TM)".


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## vestaviascott (Mar 7, 2009)

asnigro said:


> I guess I never really considered the shaft components when purchasing? What are the differences supposed to provide?


Someone more experienced with the trimmers can hopefully help here, but what I understand based on the information given to my by the guys at the Stihl dealership...

The FS-56 has a cable like, 1/4 inch shaft (same type shaft found in almost all box box trimmers). The RM-56 and all of the professional line of trimmers, have a larger (appx 1/2 inch to 5/8 inch diameter) round steel shaft. 

The larger shaft minimizes kick back when there is resistance on the trimmer head. Such as when attacking larger diameter privet and tough brush.


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## joecaption (Nov 30, 2011)

I've never seen a trimmer or even a pole saw with a 1/2" or 5/8 Shaft.
I own two FS 90 R's.
One I've owned for at least 5 years.
Only thing I've done to it is change the carb. once.
They both start on first or second pull without even using the primmer bulb.
One gets used with the chain saw attachment, and hedge trimmer.
Goes through just about anything like butter.
I'm wacking at least 13 yards a week so if it can hold up to that it sure will work on one yard for many years.


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