[DonFrambach]

I just received two new 16" 20mm rails and 4 trucks that were advertised as "heavily preloaded for metal working machines". While they do work, I'm surprised at the force necessary to move the trucks on the slides. Everything is nicely lubricated, there is no corrosion, and the stiffness is the same at all points on both rails.

I'm a newbie so maybe this is fine but I thought that there would be much less resistance.

[harryn]

Could you tell us a bit more about them ? Are they ball bearings or glide slide type ? Brand / model ?

[ger21]

If you put a lot of downward force on them, do they move easier (smoother)? They should. without someone actually seeing them, it's hard to say. Does it take 10lbs of force to move them? 20?

I just bought a set of 20mm rails and the seals make them seem stiff.

[Zumba]

They're supposed to be like that.

If you want them to slide like roller skates, you want no-preload trucks.

Heavy preload means higher accuracy at the expense of reduced efficiency.

You should be fine as long as you're not running tiny steppers on a 24v power supply. Worst case, your rapids will be decreased a tad.

[DonFrambach]

Thanks.

They are 20mm ballbearing linear slides. I bought them from HomeShopCNC.com

Another dumb question. The slides are going into a 'Z' axis so there won't be miles and miles of travel. I assume that the heavy preload will mean they will only last 100 years for my hobby use instead of 1000 years. Does this seem reasonable?

[neilw20]

You will have to find out later.
Data not ready.

[Zumba]

I assume that the heavy preload will mean they will only last 100 years for my hobby use instead of 1000 years. Does this seem reasonable?

Pretty much.