How to measure the width of a disk

[Jziemer]

I'm looking at buying a disk and I'm not sure how to measure it. I've asked a few people and they have mixed opinions. Some say the front is the disk width and the extra on the back is the overlap width. The disk I'm looking at measures 18ft in the front would that be considered a 18ft disk or would the back be the actual disk width? Thanks in advance for the help
 

[Dalet]

The narrowest dimension in my mind is the width of the disc.
Not like TV's where they measure diagonally or some such crap!
 

[Leroy]

Both John Deere and McCormick in the operators manuals go with the cutting width of the back gangs, only on a single disk is the cutting width figured on a front gang and they only have that one so that is where you have to go but cutting width is width of widest part so that would be the back gangs and usually figured at full angle as if you set the gangs straight they will be a bit wider.
 

[urbancase]

i was always told the back gang was the width of the disc, the person that told me was an old IH dealer years ago. over the years he gave me a lot of pointers, i miss him not being around anymore.
 

[Jziemer]

To me it would seem like the narrowest part of the disk would
be the width of the disk and the largest would be for overlap. I
discussed it with a salesman and he said they sell them with
the back as the width but could go both ways. Thanks for the
comments.
 

[JD Seller]

That is easy to tell. The width of the back IS NOT the cutting width. Every JD sales guide explained how to tell the width of a disk. Here it is:

You count the number of blades on the front gang. Multiply that times the disk blade spacing. Then add the disk blade spacing one more time. That is the true cutting width.

So a 18 blade disk with a 7 inch spacing would be

18 x 7 = 126 inches Plus 7 = 133 inches

133 divided by 12 = 11.08 so it would be called an 11 foot disk.
 

[DiyDave]

I lay a tape measure on the ground, in the path of an area just disced. One end goes in the left valley, other end goes in the right valley. I don't measure from the ridge edge, cause that's overlapped on each pass. JMHO
 

[Leroy]

That is NOT the way it is in my JD operators manuals.
 

[Indiana Ken]

[Tx Jim]

This is from footnotes in the parts catalog for a JD 210 disk harrow
Last number for each is number of disk
(A) TOTAL QUANTITY FOR 3.5 M (11'4") SIZE IS 40.

(A) TOTAL QUQNTITY FOR 3.8 M (12'7") SIZE IS 44.

(A) TOTAL QUANTITY FOR 4.2 M (13'9") SIZE IS 48.

This is spacer between disk
AN183748 SPOOL, PLAIN-WELDED (7 1/4")