re-blading disk

[GRB054]

I have seen the discussion before but can"t seem to find it when I search- if you start out with 20" disk blades how far can you let them wear before you should replace- looking at a used disk and they are worn down to 17 1/2 on the rear (front recently re-bladed)
thanks
 

[DeltaRed]

I dont think that there is a 'formula'or spec.When the blades no longer do their job,its time to replace them.I think your disk needs the other blades replaced.Too much size difference.Dont throw the old blades away...they would be just to put on a disk with 16" blades.
 

[Dick2]

Normal disk blades are thicker above the cutting edge, which makes it harder for the disks to penetrate the ground. Disks in good condition can be "rolled" or sharpened to get a new sharp edge, unless that has been done a couple times before.

If yoy put on new blades, remember that the disks aren't tight unless the disks will ring when hit with a hammer. That means that you have to keep tightening the shaft nut until you can get the disks to ring.
 

[Leroy]

A lot depends on the type of disk. Blade spacing is one item to consider, does that older blade cut all the ground between what the front blades cut or does it just cut a furrow? Gang adjustability comes into play as well. If they will completely cut all the ground and not leave uncut strips then as long as you can get the depth you need you are OK. What size was it avaible from factory with, only 20" blades? or was it avaible with 18" or even 16" blades? If it was avaible with the 18" you are about where the orignal new blades were but if 20" was smallest avaible and a 22" was option then you would be due for blades. Never had a disk with that large a blade but on disks with either 16" or 18" the 18" would work a lot better and you could go down to the next smaller 16" in were and still be equivilant to what was avaible but by then you are starting to loose cutting ability due to loosing the concavity of the blades. When you loose to much of that you might just as well have a flat blade. So question is what was avaible on your machine when it was new, the 16",18" & 20" blades or 18", 20" & 22" blades or only 20" or 22" or possibly a 24" blade? Need to take that all in consideration. Some disks the blade spacing was as small as 5" while others will be 12" or more. Wider space requires larger blades.
 

[Teddy (punchie)]

I would use them until they are smaller on one end then the other. That be said the last disk blade on the outside is smaller, as to not cut too deep and make a ridge. I"d measure the whole set and then go from there if they are all right round 17 1/2 then sound like they were 18" blades and not too bad of shape. Now if you start at one end with 18" and the other end is 16" you are going to need to replace some soon.

I have an old drag disk that I have gone over 3 times and rebuild the blades many times some of the blades were 12" started with 16" best set I have ever used, old JD model no idea but easy to move light and cuts like it should no weight on top, nice and smooth finish.