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Discussion Starter #1
how many people shim when they install rub bars? I don't know why i never heard of doing this before? I can understand if your main crop is corn or like wise but here when I thresh some baked in 6% dns that is baked in I will close the concave tell it is darn near hitting . I was surprised how much shims some of them needed. I am excited to see if I notice much difference...
 

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never heard of shimming, bolt and go, is concave adjusted pinch point, thershing is done in the first two concaves, yes they are shorter, called kickers out with material, scott.
 

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its part of the PDI in our area since the specalty rotors came out..if they are not shimmed the white caps will be bad...we can clean the sample up other ways without shimming but costs capacity
 

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Makes a big difference in harder threshing wheat, standard or
speciality rotor. It is suprising how far the rasp bars can be different from one another.
 

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Discussion Starter #5
i agree redfan i was suprised how far some of them were out. I am even more suprised that my head was stuck in the sand (or somewhere else..) and never heard of shimming before
 

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There's really no reason for you to hear about shimming unless you are in an area with large quantities of crops that require shimming the bars.

"Here" in the willamette valley oregon, a lot of small seed legumes and other small seeds are harvested. Shimming the bars on all makes of machines has been a common practice for many, many years. However, this is also due because we run a rubber insert in the concave(s), and many with the conventional combines, use rubber cylinder bars as well as rubber concave inserts.

The purpose of the rubber concave insert(s) is to allow the rasp bars to "burn in" to the material creating a zero clearance. Likewise the rubber cylinder bars are to reduce even further the damage to the seeds, but it is not common practice on the rotaries to do more than the concaves. Even then, the knowledge and products today for the rotaries have allowed many to thresh the small, fragile seeds without the rubber inserts. But I digress.

Here's a pic or two of some older concave inserts I have. I have not used them for some time now as I have gone to using some of Ron Kile's reverse angle rasp bars and have had good luck threshing the clovers and other hard thresh grains without the inserts.




The "rubber" is actually a urethane mixture. It is bonded to the steel plate. A shimmed rotor/cylinder against this setup will create a very nice zero clearance threshing action, with the urethane adding an extra amount of material retardation.

So ya, shimming the bars is a practice that is sometimes needed, but is also sort of location and rotation specific.
 

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We shim every new combine that has gone through the dealership and whenever a set of bars get changed on older machines. No corn here, just cereals, lugumes, pulse and oilseed. It's suprising how far some of the bars are out from new. They were really bad a few years back, probably pre AFX so we kept putting in complaints and now they have it pretty right from factory. We have a jig for the pre and 88 series and use the centre module support in the 10/20 series for rasp bar height. Doing this along with re-setting the pinch point does make a difference to the machine.
 

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Discussion Starter #8
caseihaxialflow do you go off the book for pinch point any good tricks for pinch point thanks
 

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Depends on the series


On the 21/2300 series I go by the book. Can't remember which bar of the concave it is - 12th to 14th?

On the 10/20 series we have tried some right on the bottom and then some with the pinch point slightly to the right of the rotor. Either way we have found it will work well.
You can put a sieve offset in to tilt the grain tray to counteract the overload that may be caused by the setting the pinch point at the bottom of the rotor. 6 of one, half dozen of the other.
I hope I have expained myself ok


FYI - the shim washers that we use are 9/16 x 15/16 x 0.28"
 

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We use auto body fender shims. 1/32, 1/16 and 1/8 if I remember correctly! Set up your square and loosen the bolt slightly on low bars, slide appropriate shim in and retighten, not too big of a job. If we have 1 or 2 that are higher than the majority we grind them down a bit so we don't end up shimming them all. Its usually the ones near the seam that need shimmed.
 

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I highly recommend that small tube rasp bars are not shimmed. The rasp bars are designed to lock onto the mount on the rotor to prevent rotation. When shimmed rasp bars don't sit tight against the mount and can loosen up and then the bolt can't handle the load of the bar and breaks off. Sending a rasp bar through a combine makes a mess, seen it about 5 times all had been shimmed.
 
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