X-axis idler pulley

[Chris Fastie]

Maybe the second or third most inevitable failure of a MakerBot Replicator 1 is the x-axis idler pulley at the leftmost end of the bot. The belt that goes around this pulley drives the extruders back and forth (left - right) along the x-axis. The OEM pulley is black plastic and rotates around a steel axle. 

Without lubrication the plastic wears away exposing internal fibers which grab the axle and start turning it. The ends of the spinning axle then quickly wear into the plastic x-end bracket which has to be replaced (not cheap or easy). The recommended lubrication every 50 hours is critical to prevent this failure. Or you can replace the plastic pulley with an aftermarket version with ball bearings which does not require lubrication. I bought a pulley from ALM gear for $18 and after 1000 hours of printing installed it yesterday.

One fewer thing to worry about during the next 1000 hours.

[Chris Fastie]

So much for 1000 worry free hours. Below is today's message to Al Maddas who makes and sells the idler pulleys.

Hi Al,

I installed your idler pulley on my stock Rep 1 on January 21 and have put 300 hours on it since then. I noticed a new clicking or creaking noise a few weeks ago, but could not locate it, and never suspected the pulley. But it got louder and I began to suspect it might be the pulley, so yesterday I installed the washer that you ship with it and put some silicone grease on the washer. Today it was loud again and when I looked closely I found two steel rings between the pulley and the washer. So it looks like the bearing at that end failed. When I removed the pulley the race fell out, and I found only four ball bearings, and one of them is only half there. I think there was another complete thin ring that I lost before I took the photo.

I re-installed the OEM plastic pulley and everything is quiet again. I haven’t heard about this failure happening very often, so maybe it is a rare event. I thought you would be interested to hear about this. I don’t know how hard it is to press in a new bearing, or whether I should replace the entire thing.

Thanks,

Chris

[Chris Fastie]

Al Maddas' response today:

Hi Chris ,

Yes that is very rare i have only had 2 others go bad out of over 700 .

I will send you a replacement . The bearings can be replaced but its tough getting the old race out.

I have about 6500 hrs on mine and no problem so i apologize for the inconvenience and a new one will go out before the days end.

Thank You , Al  

[Liz Barry]

that's great!

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txt only: +1 336-269-1539

@lizbarry

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