I have a 22x30 Hberg die cutting press. My press has no packing behind the jacket. All the packing is under the plate on the bed below the die. The jacket is not as high as the bearer on the cylinder. I have run presses in the past with packing behind the jacket bringing the jacket to bearer height. Which is the proper way to set up the press and why? And if it is best to put packing behind the jacket, how do you put the packing in place so it will stay in place?
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Hi Chuck, take of the jacket and with a micrometer measure the thickness of the jacket and add hard packing up to bearer hight, on the leadiing edge of the cylinder there should be 4 spikes or 4 studs,which hold the packing and cutting jacket in place.If you have spikes they can be unscrewed and replaced with screws
You will likely find the spikes along the front of the cylinder may have just been unscrewed and reversed , you should have packing for the sake of your peripheral measure and .047” is that typically recommended for die cutting on a ohc however if it is a cutting and creasing press ohcc&c .059” the machine no will distinguish the two .
If you start out running as the plate by the swing arm indicates you are there or close at 1.2mm .
You never want all your packing under the form as too much will bring the chase up into the cylinder grippers ,and there are a few around that you can see evidence of that in the state of the scale at the lead edge of the chase and in some cases you can see the marks on the grippers themselves ! The packing measure includes the jacket….
The amount of packing will also vary depending on the height of your rule. less packing for.937 versus .918. It is best and safest for your jacket to start low and slowly build until you start cutting. a little tedious but cheaper than damaging your jacket. Be sure there is nothing under you form.
Thanks for the help. I want to ask Peter: My press is a converted printer. The bed has been ground. I have enough packing under the plate so I can pull packing out when a customer sends in a .937 die. Normally I die cut .918. My jacket is a .030 box maker. Are you saying .047 brings me to bearer height and I should put .017 packing under jacket to get to bearer height? Also, we use printers paper packing. How do I get it to stay in place under the jacket when I put jacket back on? Will putting packing under it make the cyl less spongey? Thanks
It is a basic starting point to have the cylinder packing and jacket total .047 the rest of your efforts go beneath your bed plate which will depend on the depth of the bed as re ground and the height of your cutter . We were taught to use 21.8mm crease and 22.30 cutting height with bedblates and packing .
As far as anchoring the packing beneath the jacket goes just fold a hook over the grip edge and let the sheets hang on the pins or just fold one of the packing sheets over the tip and use gum or glue to hold the rest to it , all you want is to stop it riding back and rippling beneath the jacket .
I doubt if your cylinder is actually spongey but if you have soft packing you might notice especially if over packed up top .
Having re read the original post you already know the principle involved with these machines you have a fixed gap (bearer to bearer) and you are pushing the jacket ,packing ,die ,bedplate, and job through the gap created by the undercut .
If your bearers are worn your packing height may not be .047.
I run one that has .045 packing. If I run it at .047 the magnetic dies I use will walk backward.
If I under pack it they will walk forward.
I also have a ground bed and have it set to pack a .032 plate under .918 steel rule. This, combined with a .045 jacket + packing allows me to die cut almost anything without the die walking or the form shrinking and/or growing.
The easiest way I have found to pack the jack is to load the jacket without packing and snug it down once to seat it.
Then I get the tail lined up so I can just access the release and unload the tail of the jacket. Then I slip my packing in between the cylinder and the jacket.
Although this “could” leave a small void of no packing at the lead of the jacket, I haven’t had a problem to date.
Hope this helps.
Thanks will be taking jacket off in near future, will let you know how it goes
Chuck ,you should have a friend help when changing your jacket , although it can be done alone its easier with someone winding over by hand and ready to jump on the brake . there are risks with motoring the press through the process because you need to ease through the cycle without the stiffener ripping the swing arm grippers off.
|nferno , you have a point re wear in your bearers but you wont know that till you try and once established you can adjust accordingly but the spec was .047 and in most cases 002 will let you get on with a tissue swap for a thin sheet , thats not horrific for fify years old really .