Bridgeport Manual to CNC conversion...

[Chaz]

Id buy this but its too tall and probably needs more power than I can provide.

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

[Muzzer]

Nice to have full enclosure! When you run full coolant and decent toolpaths, you get stuff everywhere.

There is also a Taiwanese VMC on ebay similar price, possibly better quality and condition, less well known.

You would run these off a VFD. Usually only the spindle needs 3 phase and you can run the coolant off single phase with a motor run cap to create the 3rd phase. The other stuff in the cabinet can usually be rewired for single phase without too much buggerage. And if you need to restrict the max power draw, you can change the VFD parameters or worst case get another VFD where you can do that. If you are drawing 10HP you will be shifting some serious swarf, so dialling it back to a few kW won't be a big issue.

[Chaz]

Nice to have full enclosure! When you run full coolant and decent toolpaths, you get stuff everywhere.

There is also a Taiwanese VMC on ebay similar price, possibly better quality and condition, less well known.

You would run these off a VFD. Usually only the spindle needs 3 phase and you can run the coolant off single phase with a motor run cap to create the 3rd phase. The other stuff in the cabinet can usually be rewired for single phase without too much buggerage. And if you need to restrict the max power draw, you can change the VFD parameters or worst case get another VFD where you can do that. If you are drawing 10HP you will be shifting some serious swarf, so dialling it back to a few kW won't be a big issue.

Yep. Are you talking of this machine? I cant find any specs for it ... https://www.ebay.co.uk/itm/TRYAX-B5A...kAAOSwivNbO2fM

There is also this, no specs that I can find - https://www.gumtree.com/p/other-powe...26159?srn=true

[Muzzer]

I was talking of this but now I look again it's the size of a bus. https://ebay.co.uk/itm/DAH-LIH-MCV-1....c100005.m1851

The second one looks like a classical Bridgeport based machine but a proper CNC system from new. Might be OK but has only 5" quill movement and no enclosure(!).

Quite a few nice looking VMCs on Craigslist around the £5-6k. Didn't know Craigslist had become so established over here. It's the default marketplace over in Canada / US - must keep an eye on it now I'm back in UK.....

[Muzzer]

That Tyrax looks pretty nice but as a non-runner the price seems a bit high. Perhaps you should offer half of that and see if they bite. They obviously don't think it's worth fixing it themselves...

The Centroid controller should be OK to work with. The issues are likely to be with the spindle and drive (at least). Could be a risk hence don't offer too much. Who's going to pay £3k for it?

[Chaz]

I was talking of this but now I look again it's the size of a bus. https://ebay.co.uk/itm/DAH-LIH-MCV-1....c100005.m1851

The second one looks like a classical Bridgeport based machine but a proper CNC system from new. Might be OK but has only 5" quill movement and no enclosure(!).

Quite a few nice looking VMCs on Craigslist around the £5-6k. Didn't know Craigslist had become so established over here. It's the default marketplace over in Canada / US - must keep an eye on it now I'm back in UK.....

Yep, but many scams on there ..... perhaps most.

[Chaz]

That Tyrax looks pretty nice but as a non-runner the price seems a bit high. Perhaps you should offer half of that and see if they bite. They obviously don't think it's worth fixing it themselves...

The Centroid controller should be OK to work with. The issues are likely to be with the spindle and drive (at least). Could be a risk hence don't offer too much. Who's going to pay £3k for it?

It does seem high however the machine looks fairly new. There are 2 bids on it already (lets assume they are real) ..... suppose Id pay £3K for it if the spindle wasnt too difficult (expensive) to fix or replace. Even putting on a smaller spindle if possible will work.

[Chaz]

Might not be the same machine but they are large.

Anyone want to co rent some workshop space in West London?

https://www.aptint.com/en/used-secon...0-z-560mm_3157

[Davek0974]

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.

[Muzzer]

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.....

That's why I fitted a 1604 ballscrew on mine where the old quill stop / feed trip rod went. That reduces the overhang by a factor of 2 or so. Also makes for a more compact installation. Having said that, there are many professional installations that seem to last, as long as the bolt doesn't work loose.

There's an Ozzie guy who did the same thing as me although his is sort of upside down compared to mine. Worked out nicely. This vid shows the way he did it:

https://youtube.com/watch?v=RsUnoXgF...Nr5wQ&index=21

https://youtube.com/watch?v=4CXcWXZj...Nr5wQ&index=19

When you change your leadscrews over to ballscrews on a BP you get to realise how much spring there is in the yoke (in the saddle, holds the leadscrew nuts) and bearing brackets, even if you were to eliminate the backlash. Puts all the bollocks willy waving about "holding tenths" into perspective. In comparison, my Shiz is rock solid.