# Replacing bearings with Drylin bushings

When I purchased my China made Anet A8 printer, it came with the ball bearing style linear bearings for the 8mm guide rods. While pulling parts out of the box and putting them together, I noticed several of the small ball bearings fell out of their respective holders. At the time, I really didn't know what to think of it (ie: were these just extra ball bearings falling out; were they actually needed). I put the printer together anyway and it seems to work okay.

I have noticed while I've been printing, there's a lot of noise during travel of the pieces. I'm not exactly sure where the noise is coming from, but realize it has to be coming from one or more of the bearings. To hopefully fix the issue, I've purchased some Igus Drylin polymer bushings to replace the linear bearings:

My questions are:

• When installing these bushings, should they be completely dry?
• Should I at least clean the rods?
• Are they completely maintenance free?
• Anything else I'm not thinking of to worry about?
• What was the exact model number of the bushing? RJM-01? RJ4JP-01? Or something else? – Greenonline Oct 22 '18 at 10:40
• The ones I bought are shown as RJ4JP-01-08 on Amazon.com. – Pᴀᴜʟsᴛᴇʀ2 Oct 22 '18 at 12:43

According to igus commercial documentation, these bushings:

• do not need any kind of lubrication,
• are not susceptible to humidity (but your steel rods might)
• work seamlessly in presence of dust (it gets expelled from the bushing with movements)

I've replaced all of my bearings with these, and in my experience, the above claims have been true so far. I must say that I am really pleased with them. Movement is smoother, and the noise is considerably lower.

I did clean the rods to remove any trace of lubrication prior to installing them. I did not dry them.

I believe that igus is also selling rods in a material designed to even further improve the qualities of these bushings, but it starts to become quite an investment.

• one should note, that bushings of this type are possibly "self lubricating" as in the plastic will get eaten away with wear. – Trish Aug 26 '18 at 15:05
• @Trish - They don't self lubricate, they are lubrication free. An analogy would be a hard wearing, non-stick surface such as Teflon. As there is minimal wear, their life expectancy is greater than that of traditional bearings. There is an online life expectancy calculator. – Greenonline Aug 26 '18 at 18:28

In addition to this answer and addressing Anything else I'm not thinking of to worry about? I would like to add that you should take care in installing the plastic bearings in suitable housings. It is best to lower the mass of the carriages by replacing the blocks and the bearings, there are a lot of printable bearing housings to find on the internet (e.g. Thingiverse). When installing plastic bearings, it is quite easy to get problems with bearings that bind, so take care when you install them and make sure the bearings do not bind (before you re-install the belt).

• I found when installing them, to leave everything loose (mounting screws) until the rods were completely back into place. This pretty much prevented binding. Yes, I was worried about that as well. – Pᴀᴜʟsᴛᴇʀ2 Aug 27 '18 at 21:02
• That is exactly how to mount them properly! – 0scar Aug 28 '18 at 6:09