Introduction: Makerbot Replicator 2 - Belt Tension FIX

Picture of Makerbot Replicator 2 - Belt Tension FIX

The design for this sucks. There is a metal axle rubbing against a plastic slot. It will eventually wear through and cause the belt to loosen. Following the standard procedure to tighten the belt will only fix it for a short while. This problem has been getting worse steadily, and finally got to a point where the belt was always skipping teeth during each pass back and forth. I seem to have fixed it and am glad to share how I did it.

Step 1: Testing the Damage

Picture of Testing the Damage

First loosen the 4 hex screws on the stepper motor on the opposite side of this roller. As in the pictures, if I press against the loose roller, the worn damage is so bad that the roller easily slips forward into this hideous angle, which is the source of the belt skipping noise of print failure.

Step 2: Remove Belt Roller

Picture of Remove Belt Roller

If you look closely, you can see that the metal has warn away at this black plastic.

Step 3: Buy These Washers

Picture of Buy These Washers

I needed only the #6-1/8, but was forced to buy the entire econo pack. You will need 6 of them.

Step 4: Disassemble the Carriage and Carve a Bigger Notch

Picture of Disassemble the Carriage and Carve a Bigger Notch

Follow the procedure on the Makerbot tech support for removing or replacing the upper XY carriage. basically had to remove all of the tiny screws that pop out the top of the Makerbot and carefully pop this black plastic part out with finger pressure.

I carved out this notch by placing one of the washers over the spot I wanted, and tracing it with an exacto blade. I then ground the U shape out with a rotary tool and cleaned it up again with the Exacto blade, testing the washer fit the whole time. I only went the depth of one washer.

Repeated on the other side.

Step 5: Place Washers

Picture of Place Washers

Adding 3 washers to each side, and a bit of white grease between the plastic and the first washers, slide the much stronger part back into place.

Tools used shown in background.

Step 6: Reassemble

Picture of Reassemble

After putting it all back together, I ran a 10 hour print that was all round shapes, and it printed more smoothly and better aligned than I can remember. Printed several things since and it is still perfectly aligned.

Printed examples:

The same part, white print shows before when the belt is loose, how badly a cylinder shape printed.

The black was printed after the belt roller fix, showing the way the part is supposed to be.

Comments

JCC4 (author)2015-05-24

One other thing I forgot to mention. Be sure the roller spins smoothly before you reassemble the unit. If the space is not wide enough the roller will not spin, and if it's too loose the part may fall out when you put tension back on the belt. Grind carefully just to get the bulk out. Use the knife to fine tune it the shape. Test fit and spin the roller many times as you are carving.

tomatoskins (author)2015-05-25

Great fix! I love simple things like this!

JCC4 (author)2015-05-24

If this is your first time carving into plastic with a Rotary Tool (Dremel Tool), you should practice on something else first.

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