Bridgeport Manual to CNC conversion...

[Colin Barron]

I was looking at those machines too ;) theres some good stuff on there at present.

The worst part with a BP conversion is the Z axis/quill drive - it has to be canted out in front of the quill and all the force must go through a single bolt into the quill - that bolt was never made to take anything more than a quill-stop :)

As the screw is driving the quill from one side there is a lot of axial twist moment on the screw which is not good, they work but i don't know how long for.

At the end of the day with a BP you take a machine worth maybe £3k, spend £8k on it and its worth maybe £3k - there is no return value here.

The return is you have an accurate machine which weighs 875Kg, has a small foot print, low current, spares are cheap second hand because so many were manufactured, many conversions have been done on Bridgeports and ballscrew drawings are available, if it breaks you can fix it.

[Davek0974]

Of course, there is a value but you will never make money on a conversion.

Sadly the very flexibility of a Bridgeport is the downfall of a conversion - recently lost a fair bit of stock and time following a simple tool breakage, it was not working well, the homing position was off, just wrong, it took a while to discover that the small tool breakage had nodded and tilted the head by a few degrees in both axes!

It was only a small tool but must have bucked the head as it snapped, a fixed head machine with a table as big as the BP would be lovely but the height goes up due to having all the Z travel in the head not the knee and just won't fit :)

Lesson learnt - re-tram the head every time something happens!

Yes parts are plentiful, power is usable, rpm could do with being higher - currently running 1:1 3Hp motor at 4000rpm, I think she would take 5000 but the motor would not be happy so needs raising to maybe 1:1.5 ratio or so but then bottom end suffers and rigid tapping may not be possible, I was going to fit a servo drive up there but could not figure a suitable size unit that would give speed and torque needed.

Its a lovely machine though, helps even more as i spent so long using her in manual mode as well, get to know the sounds and feel of it so you can spot a CNC tool-path thats a bit over the top ;)

[Chaz]

Any reason not to go for this?

https://www.ebay.co.uk/itm/Bridgepor....c100005.m1851

Seller indicates its 2150mm to highest point. The newer interacts are too tall.

Thanks

[Davek0974]

Looks reasonable, what can be seen of the ways looks good, will have ball screws, my only thought is the z travel but it can be worked with.

[Chaz]

The head on these cant be tilted over can they? Just realised, I can just about do 2150mm but the garage door is lower, fail.

[Chaz]

A smaller Harrison 600 has popped on another forum. Worth looking at, even for some manual milling (and perhaps CNC conversion)?