Is 12mm/2mm ballscrew for Z-zixs router undersized?

[NC_jimbo]

So if I had a 12mm with 2mm lead ballscrew with C3 spec, what are the issues in trying to use it for an accurate but still rugged wood router. Router size is 48x30x8" primarily for cutting wood and plastic. The Bscrew has a Dynamic load rating of 2000N/200Kg

Minus: It's going to be a little slow due to lead
Plus: But hey it's only Z-axis and I'd mainly cut flat stock with little Z action
Plus: It's a C3 accurate rod and the nut is a zero rated backlash

Minus: Only has a 2000N rating
Plus: I'd counterbalance the Z-head to take majority of weight off.

Is there a reason tha I'd woudn't want to do this?

[Zumba]

They'll be just fine for such a short length.

My main beef with small ballscrews is that it's more difficult to turn the ends of them accurately on the lathe. Too flexy.

[ger21]

12mm isn't much smaller than the 1/2" acme everyone uses. Should be fine.

[Zumba]

BTW, another problem I have with small screws is that it's more difficult to find suitable end bearings.

The smallest readily available angular contact bearing is a 7200/7000 with 10mm ID. Turning a 10mm journal on a 12mm screw means that you'll still have a lot of thread left where the bearing slips on.

I'm curious as to what those 1/2" screw people are using. Skate bearings perhaps? Kinda defeats the purpose of having a nice screw to begin with.

[ger21]

Skate bearings perhaps?

Yep. Or, 1/2" ID bearings with some type of shaft collar (or actually nuts) for locating the bearing.

[Zumba]

Cool... a well made shaft collar would definitely work. The longer the better I'd imagine (for better axial parallelism).

[NC_jimbo]

The spec for the 12mm Bscrew shows a 10mm end. Looks like a go.

[Armstrong]

I used to have the same problem. But I realized that they should be fine.

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