Bridgeport Manual to CNC conversion...

[komatias]

Bingo! Much better than your VFD approach. Have a look at the ones rated for spindle usage. They will work better at higher rpms. i have specced a GSK one on my new machine. Now you do not really need to have it go full servo unless you want to do rigid tapping.

[JAZZCNC]

Bingo! Much better than your VFD approach. Have a look at the ones rated for spindle usage. They will work better at higher rpms.

I agree George the AC Inverter Spindle Motors are the correct approach but they are still often controlled via VFD or Inverter. My Semco Mill as 5Kw Inverter Spindle Motor and that is controlled via ABB inverter.
Difference between ordinery motor being will spin to 7500rpm and still provides lots of torque.

The latest AC Asynchronous Servo Spindle Motors are great but would be completely OTT for Old BP like this and cost more than the whole setup.

Personaly for the price of cheap VFD I'd use what you have. If the BP motor is upto it and you have tapping head don't see the point.?
Edit: I might be tempted to remove the Variable drive setup and go direct drive but wouldn't bother with Servo unless need the Indexing etc it provides. Even then this is possible to lower degree by fitting an encoder to vfd provided it supports this option.

[Davek0974]

Hmm, got the head apart now, to refit it will need new bushes in the sheaves plus a new drive belt, probably £100 odd? I already have a VFD on it but only use it as a converter at 50Hz.

OR

I can pull the lot, fit a 1.8kw AC servo rated to 3000rpm, 1:1 poly-v drive and along with the back-gear if ever needed would give me full control from G-code - total cost about £400

So we are looking at about £300 difference for luxury servo drive??

What to do ;)

[JAZZCNC]

I can pull the lot, fit a 1.8kw AC servo rated to 3000rpm, 1:1 poly-v drive and along with the back-gear if ever needed would give me full control from G-code - total cost about £400

So we are looking at about £300 difference for luxury servo drive??

What to do ;)

Thats £300 extra for what.? Ridgid tapping that you don't need.! Indexed postioning you don't need because no ATC.!
Controller will give you every thing you need regards speed control etc from G-code using VFD just like it would if Servo so don't see the point.
Only advantage I see is the indexing and possibly extra torque at lower speeds, but you have back gear so not problem.

Save the Dosh and spend it else where.!

[Davek0974]

Yep, it was a nice thought but had a good think over dinner and using the existing motor and VFD is the sensible option. As said, rigid tapping is not needed and using the variable mechanical drive with the VFD as well will give full spread of speed and torque from 40 to 3000rpm if using back-gear or 400 to 3000rpm in high alone. My tweaked macro will tell me where the mechanical dial needs to be so problem really.

It was a nice thought but a luxury and cash will be needed for fitting out the cabinet etc, when i find one big enough.

[Davek0974]

CSMIO, servo motors and drives arrived a minute ago, all looks very heavy-duty indeed, just ordered a DB25 break-out block for the MPG unit and one of the neat little power divider blocks from CS-Labs :)

Got the mill head stripped, paint on order, removed all the surplus gears and junk from the head.

Wondering about doing the neat Z axis fit where the ball-screw takes the place of the feed-stop screw and is a 1605 unit OR doing the more common fit where the ball-screw sits in front of the original feed-stop screw position???

The only downside I see with the first option is that the pulley sits at the bottom of the screw right in front of the spindle nose.

[komatias]

I will send you a photo of my setup later on. I have made parts to allow me to use the manual quill with the removal of a single screw.

Also look on CNCzone for SCzEngrgGroup's conversion of the bridgy.

[komatias]

Personaly for the price of cheap VFD I'd use what you have. If the BP motor is upto it and you have tapping head don't see the point.?
Edit: I might be tempted to remove the Variable drive setup and go direct drive but wouldn't bother with Servo unless need the Indexing etc it provides. Even then this is possible to lower degree by fitting an encoder to vfd provided it supports this option.

Davek,

see what the man says above. no point in going servo on a bridgeport.

Either way, do look at getting a power drawbar and some quickchange TTS type tooling