shearing collar not flush with the casing

Hello fellow printer,

I need some help with putting the shearing collar back on the Heidelberg platen. I inspected it for fractures and now it doesnt fit flush where it was. I was setting up to print and forgot i had the die cut jacket and a matrix on. On the first impression a loud noise was heard followed by weak impression.

To take the shearing collar out I was turning the flywheel by hand to put the press on pick up position. But i had impression on and on closing the platen did a “clack” noise and the collar poped out. Then found that the collar was fine so was going to put it back but now the piston does not retract at any position of the press cycle. And now the shearing collar doesnt fit flush.

What have i done? Any ideas?

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The shear-collar is probably fractured. The thrust collar often gets jammed into it.

Did you read this topic by chance?

Thanks Anony Mouse, i did read that post earlier and was helpfull. However, this time the problem is getting the shear collar in and not out.

I tried a replacement one and it still doesnt fit flush. It is a problem with the piston not returning it seems.

Is the impression off? Press open?

I tried both. Picking up position.

The shear collar protrudes like in the photo.

Did you assemble the disk, shear-collar and thrust washer onto the bolt before inserting into the bore, as described in the manual? I believe the thrust collar needs to fit into the recess in the shear-collar.

If so, and it still protrudes, I might try pushing the tailpiece (piston) back by putting the disk and center-bolt in place (without the collars), backing the center-bolt out a turn and giving it a good tap with a dead-blow hammer. The disk should keep the bolt from driving the tailpiece too far.

But that’s just my take… perhaps another member has a better idea. Peter L. has almost surely dealt with this issue.

Problem solved. Thanks to Typenut.

This is what he recommended:

“insert the collar and the pressure plate with the bolts, cycle the press by hand, off impression and in a clock wise fashion tighten the bolts, but not one all way in and than next, turn each bolt one turn in succession and continue.”

Are the impression settings the same as before?

A shear collar can look perfect to the naked eye after a pressure release , look carefully with a glass or handscope and the inner areas of the ring will show tiny cracks radiating out from the centre. they are a near perfect fit into the back of the machine , the more grief removing it the more likely its blown . It is prudent to always keep a couple of spares if you are printing large areas of text or solids on heavy stocks , a large solid job on 450gsm and a double pick up will almost certainly blow a collar .