What is the correct linear rail plug diameter

I plan to order plastic rail plugs for my shapeoko pro from grainger.com and was wondering what diameter to order.


0.245" OD should do it, well…a 0.250 probably for a good press fit


This is new to me.
Why would one do this? :thinking:

Thanks. I hope C3D has a recommended source for .245 dust caps.

Prevent dust from building up in the bolt holes on your linear rails and getting into your linear rail blocks and wearing out the bearings. Honestly I’m kind of surprised Carbide 3D didn’t included dust caps with the machines.


Thank you for clarifying.
What do these cost?

Dust caps are typically sold in bulk. 100 caps will cost you about $10. The problem will be 6mm OD caps. So far the smallest I’v found are 8mm OD.

Is there some sort of hack to fill them that is removable of course?

None that I’m aware of that wont lead to issues down the road

I am always one to try and think outside the box.
What about a 1/4 inch plastic or HDPE rod and cut to size?

My vote is for 3D printed TPU. Flexible and should be easy to press in and remove with a pick without an issue.


If you’re prepared to wait a few weeks they’re as cheap as one would expect on AliExpress

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Placed my order last night.

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Great idea but don’t have a 3D printer.

Is this the correct size?

Yup correct size. I ordered extra. I’ll send you some. Send me your address and a PM

Which one of the sizes is correct on the aliexpress site and how many would we need to order. Sorry I am currently waiting on my pro xxl so I can’t measure or count yet. I would be tempted to 3d print in tpu but they are cheap enough that I don’t think it would be worth the effort.

You know that saying, “when all you have is a hammer, everything looks like a nail”? Well I happen to be remodeling and just yesterday I was using silicone joint filler (the waterproof kind you use on tubs/showers), and looking at this post I wonder if it could be a temporary hack for you. Just a drop in the opening, wipe out the excess to get a perfectly flat “cap”, and if it does not work it can be removed in a matter of seconds and you are back to square one.


That is not a bad idea at all.

I think they’re HGR20 rails on the Pro XXL but I don’t have one so I can’t measure to check, sorry.