I'm trying to plan/design myself the basis of a seed drill, but having never seen one close up in the flesh, I'm unsure how the incline angle is setup for a double disc opener. Is there a hub for each disc that is welded on a incline to the arm/shank? Or is there some other way they are shimmed to be on an angle?
Double Disc openers - incline angle
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BertZegers
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The opener discs I know have a hub for each disc that is welded on a incline, or a thread for each disk that takes a bolt that holds the bearing. Most times the nut or bolt has a thread direction that fastens turning in the forward running direction of the opener disc.
Cheers BertZegers, That should help me. Thank you :thumbsup:
npalen
Elite Member
The trick is setting the angle between the two blades to control where the pinch point is located. I don't remember the exact numbers but seems like it should be about 30 to 45 degrees ahead of center. I'm thinking the angle needs to be about 5 degrees per side but I've forgotten that number also. Spacer washers are normally use to control the tightness of the pinch.
That 30 to 45 degree you talking about, you mean the leading edge where the blades make contact towards the bottom? ie where people take measurement for contact/separation of disc , that I've seen videos of people using business cards in between to measure?
So the way I understand it, need somewhere between 3 and 5 degree angle of between disc but at 30 to 45 degree forward of disc between vertical and horizontal axis if looking at disc from the side?
npalen
Elite Member
Yes, and to say it another way, the contact between blades is "ahead" of the blade centerline. This leaves more of a "W" shape in the bottom of the furrow rather than a true "V" but it's a happy medium.
The threaded mounts can be made by sawing round stock at the angle desired per side then drilling and tapping. (or drill and tap prior to cutting the piece off)
Need to have one side right hand threads and the other left hand as BertZegers mentions above. The threaded mounts can then be welded to the side of the vertical upright.
When thinking about the spread you want between the blades at the rear, consider that one degree angle is about 1/4" PER SIDE or 1/2" BETWEEN the two blades figuring 15" diameter blades. So a 2" total spread would theoretically require four degrees per side.
Edited: Removed sentence regarding angle change when bearings are preload after second thoughts.
The threaded mounts can be made by sawing round stock at the angle desired per side then drilling and tapping. (or drill and tap prior to cutting the piece off)
Need to have one side right hand threads and the other left hand as BertZegers mentions above. The threaded mounts can then be welded to the side of the vertical upright.
When thinking about the spread you want between the blades at the rear, consider that one degree angle is about 1/4" PER SIDE or 1/2" BETWEEN the two blades figuring 15" diameter blades. So a 2" total spread would theoretically require four degrees per side.
Edited: Removed sentence regarding angle change when bearings are preload after second thoughts.
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