Introduction: Sizzix Big Shot Bearing Replacement

About: Full time Mechanical Engineer

This Sizzix Big Shot was not cutting out the paper properly on both sides. The right side, closest to the crank handle, was not applying enough pressure to the cutting die. This suggested to me that the rollers had become misaligned and most likely was cause by a damaged bearing. Time to disassemble and determine the problem.

Step 1: Tools

For disassembly you will need the following tools:
*Allen Wrench that came with the Big Shot to remove the crank handle
*Phillips Screw Driver

If you do need to replace the bearings you will need:
*Hammer (I like to call them persuaders) A medium size should work fine
*Bar of brass or aluminum to hammer on, so we don't deform the steel rollers
*Snap ring pliers, to remove those pesky snap rings
*Calipers, mm scale is preferred

Step 2: Dissasembly

Remove the allen screw holding the crank handle then remove the crank handle.

Now turn the machine upside down and remove the 4 large phillips screws in the middle section.
Remove the 8 small phillips screws along the left and right sides.
The 8 screws on the back and front do not need to be remove but if you want to go for it.

Now carefully pry the plastic sides off. They are attached with clips to the in-feed and out-feed table so be careful not to use to much force and break these. Ofter removing the sides the tables should slide out nicely and then the top and bottom plastic shields should be easy to remove from the roller frame.

Step 3: Inspection and Diognosis

Now look at the rollers and bearings. Does anything seem wrong or broken. Looking at this one you can see that three of the ball bearings have the metal shields still on them but the one near the crank handle has the shielding popped off. When I first took this apart the bearing was pushed halfway out of the frame also. This is the cause of our problem. The bearing failed and caused the rollers to become misaligned, they no longer run parallel to each other and exert less pressure on the side with the failed bering. This will need to be replaced.

Step 4: Remove the Bearing

Now to remove the problem bearing so we can measure it for a new one.

First remove the metal gears. Using the snap ring pliers remove the two snap rings. The gears will then slide off the shaft. Place these in a safe place.

Now on the left side the shafts are held in place by two metal plates. Remove the four phillips screws and slide the plates until they are out of the groove on the the end of the shafts.

It is time to use some persuasion to remove that bearing. Place the brass bar on the end of the roller as show in the picture. Make sure you are on the opposite end of the problem bearing. We want to push this bearing out. Using a hammer strike the brass bar to push the bearing out slowly. You may need a bigger hammer or more force, the small hammer originally picture was too light for this job but the medium hammer worked nicely.

Measure the bearing so we can find a replacement. This one measure 12mm ID, 30mm OD, and 9mm Width. Looking on McMaster-Carr and Granger this appears to be a non-standard size. I incorrectly ordered a 10mmx30mmx9mm bearing when I originally looked at this machine. The shielding has the number 6200ZZ and a quick search on McMaster gave me that size so without measuring I ordered 2, don't make this mistake, measure it before you buy a replacement. I search on eBay for "12x30x9 bearing" and there was one seller in China with the size I need for $5.

Here is the eBay store:

Step 5: The Bearing

I though it was interesting to look at how this bearing failed.

Since the shielding was easy to remove we can look inside at the ball bearings. From the picture you can see that the bearing cage broke and all the balls were able to group together where they jammed each other up. The center of the bearing no longer rotates. With one side lacking any ball bearings for support the roller was able to deflect when cutting and could not provided enough pressure to the cutting die.

Step 6: Putting It Back Together

Now that we have our bearing check to make sure it is the correct fit on the end of the shaft. Also make sure it will fit correctly into the frame.

Place the rollers back into the frame and start the bearing. Using the brass bar and hammer gently tap on the bearing while making your way around the outside. You want it to go in evenly so that it does not bind on the shaft or damage the bering. An arbor press would be useful here. Once the bearing is in place make sure everything moves freely. Now to reassemble everything.

Reassembly is the same as disassembly just in the opposite direction.

Step 7: Test the Repair

Get a cutting die and try out the repair job. The die now cuts on both sides like it did when it was new!