Disc Harrow for 3720

dkhntr04 · Sep 13, 2013

I am in need of a disc harrow to finish prepping some land. The ground is fine sand and has been worked twice with a heavy disk (Wishek) and field cultivated twice. I need to disk it primarily to chop up the sod chunks that are laying on top.

I am leaning towards the Woods DHM6 or DHM7 due to weight and local dealer availability. I know that I should be able to pull the 6', but do you thing I can go with the 7'? I need to cover a lot of ground so the extra foot of width would be nice. Tractor has cab, loader, loaded large R4's, and will have my heavy 500# skidloader bucket on. Total tractor weight with operator will be around 5700#.

wolftree · Sep 13, 2013

The rule of thumb usually is 5hp/per foot of disk. I do not know your drawbar or pto horsepower. If you are 35 HP+ at the PTO or drawbar you should be good for a 7 foot disk.

jenkinsph · Sep 14, 2013

There is only about 80 lbs difference between the two disks so I think you could go with either one. Both are fairly light weight disks and should be an easy pull, still if needed you can adjust the gang pitch to lessen the load.

jeff9366 · Sep 14, 2013

I pull a 16/18", 567 pound, 5'-6" Howse tandem disc harrow behind my Kubota B3300SU over sandy loam without problem.

With your much larger tractor I would think you could pull an 8' Disc Harrow.

What diameter discs are you considering? 20"?

How many discs?

jenkinsph · Sep 14, 2013

jeff,
the op is looking at 800 to 900 lbs with 18" blades, 7.5" spacings.

deere5105 · Sep 15, 2013

An 8' with 20" blades on 9" spacing with a 4" frame will spin all four on my JD 5303 when buried to the axles in soft loose soil. If all you are doing is pulverizing the surface soil either should work. I may be under estimating the 3000 series units, but I would think a heavy 7' unit fully engaged would be quite a load.

Edward. S · Sep 15, 2013

wolftree said:
The rule of thumb usually is 5hp/per foot of disk. I do not know your drawbar or pto horsepower. If you are 35 HP+ at the PTO or drawbar you should be good for a 7 foot disk.

Rule of thumbs aren't really good to go by because I have a 100PTO HP tractor and I only pull a 14 Footer and it doesn't want anymore in certain conditions.

foggy1111 · Sep 15, 2013

HP is not the issue here. You will have plenty of power.....but tires and traction is going to be the issue. Not sure what you have for tires. I have industrial tires which are loaded with rimguard on my 3320. I have a 5.5' box frame KK disc. I pull it fine....but would not like any more disc if I have it set up aggressively and deep in sand.

Just re-read your post with tires and weight. Hmmmm. Any way you could try a disc before buying one? I still think I would play it safe with the smaller disc you mentioned.

wolftree · Sep 15, 2013

Edward S,

I agree, rules of thumb are only a very rough guide at best. Soil type, hills and tractor weight all have to be figured in. Where I grew up, we figured 1 HP / inch of moldboard plow until you reached 4 bottom. After that you added another 10 horse or so to compensate. My clay soil here would push that to 1.5 HP/ inch. Throw in my hills and you better figure 2 HP/inch with lots of front end weights and rear wheel weights.

This probably is why tractors under 100 HP usually are made in increments of 5- 10 HP.

dkhntr04 · Sep 15, 2013

Thanks for all the replies. I'm thinking that I will stick to a 6' disc based on my original thoughts that have been verified by your input. For this project I could probably do fine with a 7' since I will be running in the 7 or 14 degree setting. I do however want to be able to pull this disk in the future at full tilt and sunk to the spools in heavy ground when needed.

Foggy, I don't know of any discs that I could try before buying. What kind of ground are you running that 5.5' disc in?

EverythingAttachments · Sep 16, 2013

Check out our Everything Attachments Box Frame Disc Harrows. Our frame is built very similar to the Woods, but we improved the design in a few areas to increase the usability and durability. We do have a larger box frame harrow featuring a Cat 1 and 2 hitch that is 1,100 pounds+.
Our 16 blade model is 66" wide and the 20 blade is 82" wide when set for cutting.

Our shipping is free to a commercial business or supporting freight terminal within 1,000 miles of Newton, NC.
Travis

Rmd8136 · Sep 16, 2013

I have the DMH6 and pull with a 5065e, MFWD. I chose the 6 foot over 7 because the weight (lbs) per blade is higher and it therefore cuts better. The 6 footer weighs about 820 lbs and with 20 blades it is 41#/blade. The 7 footer has 24 blades and comes in about 37#/blade. I have used all the adjustment holes and it cuts great. Obviously the steeper the cut angle (up to 21 deg) the more resistance to forward movement and therefore power to pull. I think you will like the DMH6. It is not HEAVY duty but it suits my needs for wildlife food plots in my soils: sandy loam and clay loam and a Wateree Rion complex (near Lake Wateree, S.C.). Before I bought a disc I never thought about weight per blade and cutting ability, which is dependent on total disc weight and number of blades. The Frontier I was looking at (1276) had a 9 inch disc spacing vs 7.5". It was more expensive (about $2200) but not built any better. The Woods I got new for $1550 painted JD Green. I am tickled.

jeff9366 · Sep 16, 2013

Check out my March 2013 post on considerations when selecting a Disc Harrow for a compact tractor:

http://www.tractorbynet.com/forums/attachments/275147-disc-harrow-primer-howse-disc.html

foggy1111 · Sep 16, 2013

dkhntr04 said:
Thanks for all the replies. I'm thinking that I will stick to a 6' disc based on my original thoughts that have been verified by your input. For this project I could probably do fine with a 7' since I will be running in the 7 or 14 degree setting. I do however want to be able to pull this disk in the future at full tilt and sunk to the spools in heavy ground when needed.

Foggy, I don't know of any discs that I could try before buying. What kind of ground are you running that 5.5' disc in?

My soil is sandy loam.....mostly with sand below the top few inches. Think about it.....when working the disc to the max depth......you will bury those disc blades up to the spools and you have to pull it thru a soil mass that is 5.5' wide by about 10" deep - twice! (tandem disc). That is allot of soil to move.

jimgerken · Sep 18, 2013

I have a 3720 with 360 lbs of weights per back wheel, and R4 tires. Loader on, 4wd, lo range. I bought a 10 foot JD RWA wheel disk at auction a few years ago. It is too big for this tractor, but not by a lot. If I am careful with the hydraulics to keep a little tire pressure on the soil so it doesnt dive in too deep, I can pull it at 4mph. I would like to be going faster, but that is it with this setup. I wouldn't operate it all day this way, I would wonder about hydro heat buildup. But for a few acres it sure works OK. I know three point disks pull harder and float to follow the contour less compared to wheel disks. So if it has to be a 3-pt, I would buy the 7 footer. If I had a choice I bet an 8 foot wheel disk would work fine.

MtnViewRanch · Sep 18, 2013

There are so many variables that without actually seeing where a person will be disking and what they want to use to do the disking, all any of us can do is give advice based on our own experience. This is a situation where it is very easy to give the wrong advise. Every year we read what size disks people pull. Often I would say that what is said is unbelievable. Don't get me wrong, I don't think anyone is lying, just that their very different circumstances allow them to do so and very seldom do those same conditions exist elsewhere.

What I think is odd, is that here on TBN where pictures are a HUGE thing, very seldom do we see any disking pictures.

jimgerken · Sep 18, 2013

The disk is actually a fairly scientifically designed implement. Most tillage tools just drag thru the dirt, but the disk has a shearing action that goes way beyond everything else.
I will make sure I get some pictures next time I hook up the old RWA.

dkhntr04 · Sep 21, 2013

Update,

I've been looking hard at a variety of units and am leaning towards the Land Pride DH2572 over the Woods DHM6. (20) 20" blades, 7.5 spacing, and 47# per blade. The Land Pride is definitely in the next category up as far as weight and construction stoutness. It also allows 100hp so I have the flexibility if I up size the tractor down the road. Thoughts?

jeff9366 · Sep 21, 2013

I think the Land Pride DH2572 - 20/20" (47 pounds per disc) will be an excellent selection.

I have had good experience with my Howse 16/18", (37 pounds per disc) discing Florida sandy-loam.

I think you will find the lever adjustment of the gang angles a useful feature.

Post some pictures of the lever adjustment when your Land Pride arrives, please.

Check the axle nuts on arrival and keep them TIGHT during the first 100 hours of operation. That should give the discs and axles time to settle in and thereafter you should only have to "ring" the discs to check of tightness occasionally.