Bridgeport Manual to CNC conversion...

CSMIO unit on order, motors on order, ball-screws ordered, wallet crying :(

Panel controls...

With the Bridgeport you have to run in reverse when in low range, is there a way to have this done in Mach3 or will it still be a Hi/Low selector switch on the panel?

The VFD for main spindle, with the vari-speed mechanical system I'm not sure if i should try using the vfd as variable or leave it fixed at 50Hz, the top speed is limited to 3500rpm absolute max as it tends to wreck the spindle bearings above that and low down it probably would not have the torque needed, so stick with mechanical ?

Main spindle on/off manual control - would these buttons control Mach3 or would they control the vfd directly?

Just looking for ideas here.

Food for thought...

While waiting for the screws & motors to arrive, should I strip her down to the bones and clean / paint the old girl ;)

Would take a bit of effort as it would need space clearing to get the engine hoist in to lift the head, ram, collar, bed and knee off.

Could be useful as it would allow me to check for worn out bits, split lube pipes etc.. Would also make the build and wiring a cleaner job by getting rid of the grime and muck.

Hmm....

Quote:

---

Originally Posted by Davek0974

Food for thought...

While waiting for the screws & motors to arrive, should I strip her down to the bones and clean / paint the old girl ;)

Would take a bit of effort as it would need space clearing to get the engine hoist in to lift the head, ram, collar, bed and knee off.

Could be useful as it would allow me to check for worn out bits, split lube pipes etc.. Would also make the build and wiring a cleaner job by getting rid of the grime and muck.

Hmm....

---

Yes and get the knee saddle and table reground and turcited. Speak to slideway services, they quoted me by far the best price

Looking at replacing the mechanical speed control and back-gear with an AC servo motor, something like this...

http://www.aliexpress.com/store/prod...760988112.html

Should give full power across the board I think, also no loss in the drive belt and no changing gear for low speeds.

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.

Quote:

---

Originally Posted by 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 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.

Attachment 18486

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 ;)

Quote:

---

Originally Posted by JAZZCNC

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

Quote:

---

Originally Posted by Davek0974

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.!

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.