How heavy can my Z axis be?

[waynec]

I'm getting ready to rebuild the gantry on my PR. I torched the old one with really bad welding, and I'm using that as an excuse to upgrade and install new BWC rails, and a new gantry that will look alot like Shopbots new PRS machine.

Not long ago I picked up a linear actuator that has a precision ground screw drive, and very precise rails. I'll just need to make a plate to mount the router to, and I'm good to go. Problem the thing is HEAVY. I'll weigh it today, but I'm sure it goes 60 lbs.

So, assuming I will build a gantry that is stiff enough to handle both the static weight and the dynamic load, how heavy can my Z axis be before I run into inertia issues?

I think I can use a gas shock to counterbalance the weight of the router and its mount. The issue I'm concerned about is more about the inertia of all that mass of the entire Z carriage, including the router and mount, bearings and rails, etc.

How much weight can I safely use on a Z axis carriage before I find inertia problems?

Any other problems I should be aware of with this sort of tonnage on the gantry?

Thanks- I just did a mock up in wood to work out the placement of tabs and holes. I'm almost ready to go to the machine shop with it.

Wayne from White Salmon