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Author Topic: Bridgeport Knee Mill Conversion?  (Read 159076 times)

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Offline Davek0974

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Re: Bridgeport Knee Mill Conversion?
« Reply #500 on: September 12, 2016, 04:27:48 PM »
Got it working now :)

Modified post - I can now use a tapping op with feed-in at feed-rate then a dwell and feed-out at retract-rate, just what the doctor ordered :)

I just have to make some notes on using it as i need to make sure the retract height is at least 5mm above the surface as when the tapping head is in reverse the tap protrudes 5mm more than when it went in :) The dwell will need setting on the job as it will be speed dependant but the tapping head has a limit of about 800rpm anyway.

Should do the job nicely i think :)
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Bridgeport Knee Mill Conversion?
« Reply #501 on: September 19, 2016, 02:20:38 PM »
New spindle arrived today, did it fit my 3d designed and cnc machined quill clamp?

Damn right it did, fitted like a glove  ;D ;D

Setup the VFD - totally different than the mini-mill, the CSMIO seems to be far better and with spindle pulleys at std setup - 0-24,000 rpm it matched speed 100%, no messing no fuss.

Just got to finish machining the sub-table now, could have got it done at the weekend if i didn't bend the probe on my Haimer  ::) and no, I didn't remember to order a spare tip  >:(

Got two on the way to me now though, lesson learnt.

In the above post, i mentioned being able to set the feed rate and retract when tapping with the TapMatic head - This was wrong, the post calculates all the settings based upon the tap pitch chosen in the tool library - much easier, I just need to get the actual speed as close to selected speed as possible.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Bridgeport Knee Mill Conversion?
« Reply #502 on: September 21, 2016, 06:24:26 PM »
Get an encoder, rigid tapping is sweet :)
Hood

Offline Davek0974

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Re: Bridgeport Knee Mill Conversion?
« Reply #503 on: September 22, 2016, 02:25:23 AM »
Yeah but no but...

Would it be as sweet with an old motor and vari-speed mechanical drive on top ??

Doubt it.

I will revisit the servo replacement at some stage, just a matter of cash and finding the right motor that will do the speed and the torque/power needed.

I already have the ENC module fitted so thats one step further ;)

Just need a motor that can do 3000rpm with the same sort of torque/power as the old motor has AND be able to run on my limited power supply of course - I cant just bung on a 5kW servo and gear it up for the speed as it would pop the supply breaker :)
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Bridgeport Knee Mill Conversion?
« Reply #504 on: September 23, 2016, 05:35:32 AM »
Think I may have found a working motor replacement setup...

Motor...
https://inverterdrive.com/OrderCode/22060/

Drive...
https://inverterdrive.com/OrderCode/27487/
Plus the braking resistor.

Would be in sensorless-vector mode, will still need an encoder on the system somewhere.

At 1:1 it seems to have most of the torque needs met, maybe push a little belt reduction and go to 125Hz to boost the low end a bit further while keeping the top end.

Hard part is mounting the encoder - will have to go on motor shaft as the draw-bar means i can't use the spindle shaft - guess that will mean i am limited to 1:1 ratio??
« Last Edit: September 23, 2016, 05:42:40 AM by Davek0974 »
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Bridgeport Knee Mill Conversion?
« Reply #505 on: September 23, 2016, 02:54:36 PM »
Tested the tapping head tonight in some scrap, should work very nicely, only needs a short 0.8s dwell at the mid-point to allow the clutch to disengage. Have to do the spot-drill and drilling as one setup then follow with tapping as the knee has to drop a lot to fit the tapping head in  ;)

Also discovered that run-from-here seems to make a mess out of tool-length offsets, no damage as it was only dry run and also the first time i tried RFH, In the end it was safer to do the part of code i wanted as a separate file, i think i'll keep that in mind.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline mc

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Re: Bridgeport Knee Mill Conversion?
« Reply #506 on: September 23, 2016, 03:02:04 PM »
Hard part is mounting the encoder - will have to go on motor shaft as the draw-bar means i can't use the spindle shaft - guess that will mean i am limited to 1:1 ratio??

Got any photos of what space is available?
There is nearly always some way to mount an encoder.
Reflective optical encoder just needs a stripped wheel. Large bore encoder discs are available, which you could possibly mount on the toothed spindle pulley. Third pulley running on the belt between the main pulleys, or on the motor shaft, but both those options would need to allow for a gearing ratio. If you do need a spindle index pulse (Would it actually be used?) you could then use a slot sensor via a notch on the spindle pulley flange.

Offline Davek0974

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Re: Bridgeport Knee Mill Conversion?
« Reply #507 on: September 23, 2016, 03:14:47 PM »
Still researching this, i was looking at mounting a differential output encoder somewhere in the head, maybe a small pulley mounted on the spindle running a lightweight toothed belt - plenty of room in there when the mechanical speed stuff is pulled out.

I am pretty certain it needs an index pulse.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline mc

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Re: Bridgeport Knee Mill Conversion?
« Reply #508 on: September 23, 2016, 03:29:37 PM »
I'm sure Hood will give a more definitive answer, but I can't see any real reason why an index pulse would be essential on a mill that doesn't need any sort of spindle indexing.

If you've not looked at it already, US digital (www.usdigital.com) is probably the best place to see lots of encoder options.
Maybe also worth checking British Encoder (www.encoder.co.uk), although they're mostly complete units i.e. you can't get sensors and discs separate like you can at USdigital.

Offline Davek0974

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Re: Bridgeport Knee Mill Conversion?
« Reply #509 on: September 23, 2016, 03:38:18 PM »
Thanks, thats a good point, will be fully researching this before diving in :)
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives