Wobblycogs CNC Mk1

[WandrinAndy]

What is the maximum length length I could reasonably use RM1610 up to and still get a good feed rate? I see people talking about 7 and 8m/min as the top speed they run their machine at so 6m/min doesn't seem so bad. I suspect though that 6m/min on this length is like getting 100mph out of a Nissan Micra - possible, but not advisable.

In response to a query of mine Jonathan suggested that 6m/min is quite a reasonable speed and that the calculation of the critical speeds was quite conservative. Also seen JazzCNC often recommend that a machine is operated well within it's theoretical technical limits.

Am I right in thinking that the problem with the screw having a bend is a reduction in the critical speed?

I would guess that a bent screw would be unhealthy... It might also cause resonance, premature wear of the ballscrew assembly, and possibly binding?

If I understand correctly the critical speed is the point at which the screw starts whipping around, yes?

Yep, I think that's correct.

Just a quick Q Wobbly.... Am I right in thinking that you've extended your overall length 1500 -> 1800 in order to get a working length of 1220... It is possible to get working 1220 within an overall length of 1500?