Cutter bar knife sections

Under what circumstances do you select smooth, serrated or underserrated sections when rebuilding the knife? Thanks, Fritz

Smooth will do the job. Serrated cut tough stems better with the serration both helping to hold as well as cut them. Under serrated i have seen , never used. The over serrated give a flat contact with the guard to cut better. Not sure what the purpose would be for an under serrated section unless you were wanting to use a double knife so they would not catch on each other so bad.

I don't have a mower manual handy, but smooth lodger would get serrated sections and vice versa.

However - my MF32 sickle mower has serrated sections and ledgers and works great.

Go to Webb's Sickle Service website they have a very good guide explaining which type section you need to use on what type hay you're cutting.

Here's another discussion from days gone by on [i:654c4848f0]<a href="http://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=implment&th=137959">Section types for sickle bar mowers</a>[/i:654c4848f0].

We use smooth sections on our <a href="https://youtu.be/rnH8n4KOYoU">No. 5 mowers</a> and <a href="https://youtu.be/ZLND2DifdD0">39N mower</a> with guards that have ledger plates.

We use over serrated sections on our <a href="https://youtu.be/KcztYe4w5-M">350 mowers</a> with smooth guards.

Hope this helps.

This is from the 40's & 50's thinking. The smooth is for fine grass with both the same, no mixing types. The underserated is for coarser grass and legume hay, again no mixing of types. The Overserated was for combines for use in wheat, oats, barly, rhy type of plants and the guards for the combines were smooth from factory. The reason for the overserated type is they are supposed to be self sharpening and you just replace when they get a bit worn. We have sharpened many a combine overserated sections when they got to where they were not cutting corectly and if you watched how you did it you could get 2 sharpenings on a section before you had to buy the high priced replacements. I personaly on a hay mower would not uses anything but underserated sections with serated guards. The old highway mowers always ran smooth because of what they were cutting and they would change out the knife during a normal day at least twice and possibly 4 times to be able to keep mowing. They had a container mounted on the tractor that would hold about 6 complete knives so they always had a sharp one to use and a couple of spares for when they would break a section. And those mowers were always only a 5 foot bar. The overserated sections would actually cut a soybean stalk easier than an underserated would. I think the only reason they started putting overserated on hay machines wasthey were trying to get people to believe that about them being self sharpening and not sharpening but they would not last any longer that the underserated sections that you were supposed to sharpen and every time you sharpened them the factory thought they were just loosing a sale Like Jon's oil pan plugs. I bought my first mower 57 years ago an John Deere No. 2 open gear horse drawn mower But used Dads David Bradley for years before.. My second mower was an old COOP from dealers junk row that I rebuilt and used for several seasons on both hay and clipping wheat stubbles before we baled the straw.