Bridgeport Manual to CNC conversion...

[Davek0974]

That was a long day!

Stripped the head, cut away the small web of cast at the bottom of the quill slot, altered the screw connector by welding on a 13mm thick bar underneath, the end of the bar was milled to the curvature of the quill before stripping, fitted up, refitted the Z drive and shimmed the connector, power head back on, motor back on, encoder back on, tested.

The connector now has an extra 25mm of contact below the quill bolt which is a massive improvement over the first attempt, this makes a big difference to the twisting effect on the quill bolt and is now far more rigid in the downward direction which is what matters.

Total backlash is now down from 0.6mm+ to 0.1mm and I also discovered that most of that backlash is caused by the BK screw block not clamping the screw correctly - this was always there but never spotted it before. I will strip that block and see whats wrong with it - either crap bearings or sleeves too short and the nut not reaching properly.

I don't think this one is getting any stiffer (ooh err!)

[Clive S]

It's always nice when a plan comes together

[Davek0974]

It's always nice when a plan comes together

Thanks, it wouldn't have worked without removing that little web of casting though:)

[Davek0974]

What can make the tool not follow the path correctly?

Did some work today and as seen here its clearly pulling away from the corners far too early - corner rounding?



Not quite so clear here...



Cutter was 2mm at 23000rpm, 1000mm/min, X&Y speed set at 3500mm/min and 350mm/s/s in motor tuning.

[JAZZCNC]

Your getting because of constant velocity and tight radius most likely caused by low accelleration. Try setting accelration higher and see if better.

[Davek0974]

Ok, what sort of acceleration should i be aiming for if i have a top speed of 3500mm/min and bearing in mind this is a Bridgeport with a fairly heavy table;)

[JAZZCNC]

Ok, what sort of acceleration should i be aiming for if i have a top speed of 3500mm/min and bearing in mind this is a Bridgeport with a fairly heavy table;)

I'd up it until starts stalling motors then back it off 25%. 750s/s would be nice figure to aim for.