Spindle sinks overnight

[ger.wat]

We just got our new PRS going, after attaching the dust collector hose we find the spindle sinks to the table overnight, broke a bit off this morning when the operator tried to raise it using the directional buttons.

Question: Not wanting to reinvent the wheel... is there a way to adjust tension, counterbalance or otherwise prevent this?

[GeneMpls]

There are two springs on the back of the Z carriage- I think that shopbot has different springs for different configurations.

[Keith Larrett]

My Z axis has a pneumatic assist, so it will drop when I disconnect the air. I always park the machine in the same spot and pop a 2x4 cutoff under the spindle before disconnecting the air. It drops down and rest on the 2x4.

[Burkhardt]

I don't have a Shopbot but had the same problem. I installed a 20 lbs gas spring (a sealed pneumatic cylinder like the one that holds up the car hood) like this one: https://www.mcmaster.com/#gas-springs/=1a3z9cr. Unlike coil springs, the force does not change much over the stroke distance and they don't need a shop air connection. I made the mounting bracket a little flexible so that very small z-motions of a few 10/1000" don't make the gas spring move.

They are specified for 25,000 cycles and I was concerned about durability but after 5 years of moderate use, so far so good. They are anyway cheap enough to replace.

[Brady Watson]

We just got our new PRS going, after attaching the dust collector hose we find the spindle sinks to the table overnight, broke a bit off this morning when the operator tried to raise it using the directional buttons.

Question: Not wanting to reinvent the wheel... is there a way to adjust tension, counterbalance or otherwise prevent this?

If this is a new machine, call SB. ~ especially if you upgraded to a spindle last minute.

Normally the Z shouldn't drop. Sounds like they could have installed the wrong springs at SB.

-B