The Museum of HP Calculators

HP Articles Forum

[Return to the Index ]
[ Previous | Next ]


Flatten vintage wrinkled HP card holders

Posted by Mark Hoskins on 28 Feb 2003, 12:41 p.m.

Getting the HP 40-Card Holders Warps and Wrinkles Out

Perhaps this technique is not at the top of your list of HP Calculator repairs, but itís something that has been helpful for me. Some of the old card pacs could damage the magnetic cards if they warp or wrinkle too much causing bends in the cards. Itís also then easier to use the cards as they slip in and out smoothly.

This technique works great for moderately wrinkled plastic magnetic card holders. I use an iron and three or four 5x7 cards to straighten things out.

Getting the Holder Ready... Place blank individual cards into the holder- magnetic side facing out, or reverse of what you would normally place them. They seem to slip out easier for me after they have been heated. Fill every slot. Be sure to push them all the way to the end of the holder slots. Remove any little bits of dirt or whatever that may become burned-in to the plastic.

Apply the Heat... Get a flat thick old software book preferably that has a smooth back cover when pressed down by the iron will give you a flat sturdy surface (maybe a little over an inch thick). Start out by covering the backside of one of the holder slotted pages with two index cards and position it out onto the book. Be careful about ink writing on either the book or the index cards, keep ink away from the plastic as it can transfer onto the plastic. Set the iron heat a little lower than the cotton setting. Press hard on the plastic for a short time. Sometimes I overlap the lower third with three index cards.

Apply the Heat to the Backside... Move the iron firmly down and concentrate the heat evenly. By your motions of moving the iron apply less heat to the lower third of the page. That is the portion of the page that gets the most heat and tends to over melt the pages. ONLY APPLY THE HEAT TO THE BACK SIDE FOR ABOUT 8 SECONDS. Thatís pretty fast. The task here is to warm things up for the holder front-side heating session. You will also notice that the book will begin to get hot as you process more and more pages.

Apply the heat to the Clear pocketed Front Side... This part is important to the final ability to remove the inserted blank cards. Youíll be able to wiggle them out, it will just take longer if you over heat the page. This side is also quick at about 10 seconds. Move the iron back and forth minimizing the heat to the lower third again.

I like to cool down the page quickly after heating it with the palm of my hand. Itís not all that hot. You can also rub out any remaining wrinkles with your hands that might have persisted.

Cover Page... This page is frustrating, as it seems to re-wrinkle after heating it, or warps a bit. Apply only the slightest heat to this one maybe 6 seconds and then repeat. Rub it out just after heating. Pull down on the open slot at the spine to get it even.

Hope this approach works for you as well as it has for me. Let me know of any improvements you might have discovered at waterhosko@aol.com. Best Regards, Mark Hoskins

Password:

[ Return to the Message Index ]

Go back to the main exhibit hall