calmer combine concaves deere product detail image
calmer concave kit for deere cellphone image


for John Deere Combines

New for delivery in 2023 & 2024 are Calmer’s first product for a part of the combine behind the corn head.  The culmination of 3 years of research in the shop and the field presents a solution for the most common problems operators of John Deere combines face in their day to day operation.  Marion took on the nagging and frequent problems farmer’s called him with in his role of customer service for the corn head products.  Facing the changing conditions of harvesting corn and soybeans around the world Marion dove into the threshing area with the same thought process of detailed examination followed by patient testing to find the results we all need.  As the descendant of a long line of entrepreneurs, Marion was born with the gift of finding tangible solutions to mechanical problems, and throughout his life, he has spent thousands of hours discovering problems and inventing solutions to harvest corn and soybeans more efficiently. 

PROBLEM: Round Bar Concave in Position #1

What Causes Rotor Loss?

The current John Deere round bar concave only has 242 square inches of openings to allow shell corn to flow from the threshing chamber to the auger bed. This causes a flow restriction which makes some kernels remain mixed in with material other than grain (MOG), which are then carried out of the rear of the rotor chamber and discharged on the ground (rotor loss).

SOLUTION: Install Calmer Enhanced Flow Round Bar Concave in
Position #1

How Calmer Enhanced Flow Round Bar Concave Solves the Problem

The Calmer Enhanced Flow Round Bar Concave has 358 square inches of openings. This represents a 48% increase in opening space which significantly increases flow rates when harvesting corn. The unique design of the Calmer Enhanced Flow Round Bar Concave allows shell corn to flow faster and reduces rotor loss compared to other concave designs.

Results: LOWER rotor loss when harvesting

especially high moisture corn

Calmer Concaves Running with Grain Monitor Results

PROBLEM: Splintered cobs in the grain tank.

What Causes Splintered Cobs?

For corn harvest, factory round bar concaves have narrow spacings that restrict corn from efficiently escaping the chamber. Combine operators often try to solve this problem by reducing concave clearance which is counterproductive because it increases compression on the cob. In turn causing more pressure splintering the cob  into small pieces. Those splintered pieces pass through the sieve and are not sorted out by the airflow making their way into the grain tank. An exemplary image of this issue stacking up in the tank:

splintered cobs in grain tank deere combine problem

SOLUTION: Install Calmer Enhanced Flow Round Bar Concave in
Position #1

How Calmer Enhanced Flow Round Bar Concave Solves the Problem

The Calmer Enhanced Flow Round Bar Concave is uniquely designed with wider openings compared to factory supplied round bar concaves. The desired result to avoid cracked cobs minimizes compression during threshing by allowing more material to pass through per second.  A higher percentage of cobs stay whole in the rotor area and are ejected as such. The reduction in small MOG particles reduces  the load on the cleaning system from splintered cobs.

Clean Threshing Results

You can expect fewer splintered cobs and a cleaner sample of shelled corn. Our after market concave upgrade also increases flow capacity and reduces kernel loss over the top sieve and out the back of the machine.

clean grain sample without shattered cobs deere combine

PROBLEM: Un-threshed Pods in Sample, Split Soybeans in Sample,
or Excessive Tailings

When harvesting soybeans, most concaves supplied by the manufacturer for corn harvest have openings too large to retain soybean pods long enough for them to thresh out of the pod fully. Un-threshed soybean pods or small grains fall through the threshing chamber into the auger bed and onto the top sieve. Once the un-threshed grain has moved into the cleaning system, it eventually overloads the bottom sieve causing pods to appear in the grain tank. The first response by the operator to simply tighten the bottom sieve sends the pods back through the rotor to be rethreshed which has the unintended consequence of splits beans.  So if you are seeing pods next to split beans, and a heavy flow through your return, you can bet that you need a cover plate for the first position.

solve soybean pods in grain tank with cover plates
soybean pods fall through concaves without cover plates

SOLUTION: Install Calmer Enhanced Flow Round Bar Concave in
Position #1

Calmer Pod Buster Cover Plates
Solve the Problem

The Calmer Pod Buster Cover Plates retain material to fill the large openings and create a mattress-type surface. This retains pods and causes them to gently rub against each other as they travel over the horizontal grain separation bars (see “solution” in below left image). This action more effectively threshes green and hard-to-thresh pods without damaging the internal soybean or grain.

calmer cover plates for deere combine concaves harvesting soybeans

PROBLEM: High Sieve Loss, Excessive Tailings, Chaff in the Grain Tank


Unnecessary MOG Falling Through Large Concave Openings in Chambers #2 & #3
What Causes the Problem? Factory concaves in chambers # 2 and # 3 have too large openings for harvesting soybeans and small grains because they allow excessive amounts of MOG to pass with the grain. Eventually, this threshed material enters the cleaning area, overloads the chaffer, fails to separate, and then gets walked out the back over the top sieve as sieve loss – see the “problem” defined in image below:

overloaded chaffer problems in deere combine harvesting soybeans

SOLUTION: Install Calmer ¼ Wrap MOG Limiting Concave Inserts into the Round Bar Concaves in Positions #2 and #3


Calmer ¼ Wrap MOG Limiting Concave Inserts reduce the size of the openings between bars by 42%, which limits the flow of excessive MOG leaving the rotor chamber and falling into the auger bed. Because the auger bed now contains a higher percentage of grain and a lower amount of MOG, less air will be required to separate the MOG from the grain on the top sieve. Consistent results in all soybean harvesting moisture and field conditions with lower sieve loss. Ultimately, fewer soybeans are walked out the back of the combine as sieve loss.  After installing the Calmer ¼ Wrap MOG Limiting Concave Inserts, you can expect a cleaner sample and lower sieve loss when harvesting soybeans and small grains backed up by our industry leading 100% Buy Back Guarantee.

¼ Less Work to Install

The Calmer Round Bar Inserts match a custom plate built into the mid-point of the concave’s arc which allows for one man install.  Easily installed mid-day, or removed quickly for a switch back to corn. The Calmer Enhanced Flow concaves have considered the needs of farmers who invented, tested, and proven their performance in hundreds of hours of lab and field testing.

Legal Notice

Calmer may, at any time and without prior notice, modify the content and operation of its website or this brochure, remove or modify the specific patents and/or patent list demonstrated in this brochure or on its website,

Calmer possesses a number of patent rights related to its operations, both foreign and domestic, including the following United States Patents: 11,058,058-Narrow Row Head Unit; 11,071,252-Stalk Roll with Multiple Flutes of Different Lengths; 10,785,911-Stalk Roll with Hybrid Flute Having A Sharp Edge and Two Blunt Edges; 10,674,665-Stalk Roll; 10,420,281-Narrow Row Head Unit; 10,045,483-Narrow Row Head Unit Ear Guide; 10,039,232-Stalk Roll; 9,554,511-Method and Apparatus for Stalk Shear Reduction; 9,560,804-Stalk Roll with Flutes Defining a Recess; 9,668,414-Stalk Roll with Series of Flutes Having Decreasing Lengths; 8,857,139-Method and Apparatus for Stalk Shear Reduction; 8,863,487-Narrow Row Head Unit; 8,464,505-Stalk Roll; 8,220,237-Stalk Roll; 8,171,708-Stripper Plate; 7,886,510-Stalk Roll; 7,373,767-Corn Head Row Unit; 7,104,038-Strategic Spatial Realignment for Attaching Cornheads to Combines; 5,704,202-Universal Corn Picking Row Unit; and D494,605-Low Profile Corn Head Row Unit Cover. Calmer also has patents pending pertaining to the threshing technology disclosed in this brochure. Any reference to a company that manufactures and sells combines, or to trademarks of the company are for informative purposes only. Calmer is not affiliated, associated, or otherwise related to any such company. Calmer possesses a number of trademarks. These trademarks are associated with Calmer and its products and are identified by the symbols ® or ™. © 2023 – Calmer Corn Heads, Inc., Lynn Center, Illinois

Calmer Limited Warranty

Calmer warrants our parts 100%. This warranty is good throughout the first season after purchase of the part. What this means is that if the part breaks within the first season of use, we will replace the part with a new one without charge to you. Calmer pays for the shipping both ways as well. In the alternative, if you wish, we will refund to you all of the money you paid to Calmer for the part. If the Calmer part does not work as you expected, we promise to work with you to adjust the settings and see if we can obtain satisfactory performance. In the end, if the Calmer part does not work on your farm to your complete satisfaction, we will refund your purchase price. Disclaimers: Calmer is not responsible for and does not warrant as to consequential damages or any other types of damages that may be claimed as a result of part breakage or unsatisfactory performance. In other words, except as stated herein, all other warranties or liabilities, expressed or implied, oral or statutory, including any warranty of merchantability or fitness for a particular purpose are expressly denied.