Bridgeport Manual to CNC conversion...

[Davek0974]

I'm losing the plot here Boyan, I'm talking about the bearings inside the 1-1/2Hp spindle drive motor are buggered. ;)

[Davek0974]

Drop-plates for X & Y servo motors - 10mm, 12mm, 15mm thick ally??

[m_c]

Drop-plates for X & Y servo motors - 10mm, 12mm, 15mm thick ally??

Thicker will be better, but it will depend on servo shaft length/pulley thickness as to what's practical. Some form of box section would be better/stiffer.

Regarding the motor bearings, unless the motor has some odd wiring/end cap configuration and/or you damage the windings trying to lever the end caps off, stripping it and replacing the bearings shouldn't be a problem.

[Boyan Silyavski]

I'm losing the plot here Boyan, I'm talking about the bearings inside the 1-1/2Hp spindle drive motor are buggered. ;)

I was saying if it works for removing ball screw backslash and the ball screw is in fact a more complex ball bearing , its worth a try at the cheap price of it. How fast this motor moves? 1200rpm? Same as ball screw.


I see as a better idea changing to cheap Dc motor or better servo motor. And why not a cheap modern normal motor , disassemble, weld some shaft and machine it on place. That would be super simple. And a bracket adaptor

[Davek0974]

I'm going to have a go at dismantling i think, try that first.

A 2.0kw AC servo would be best but a toss-up between money and easy-fit;)

[Davek0974]

Well, I spent a good few hours trying to dismantle this motor while being very careful not to risk damage, I could not even get the drive disc off the long shaft, seized well on. There is also a pressed-on fan at the top to shift which would likely bend/break so i carefully replaced what i had done and left it.

So my choice is now to build the cabinet and wire for the VFD / motor OR throw one of these in...

http://www.aliexpress.com/store/prod...037588952.html

I have asked the guy for a 2kw or 2.2kw 3000rpm unit but not had a reply yet, seems the bigger servos don't have the speed needed.

Fitting would be easy, but the only benefit i would really see is the easy and accurate speed control - I don't need/want rigid tapping although i think it would be useful for smaller taps maybe - what is needed to gain rigid tapping?? Is it just a setup option or do i need more CSMIO modules??

[Davek0974]

Pulleys/belt - 44t HTD8 x 30mm should handle it ok.

[m_c]

You'd need an ENC module if you wanted to do rigid tapping.

The motor will most likely run for a long time before the bearings get bad enough to cause issues. If you could get some fresh grease into them, it would most likely make them last even longer and quieten them down.

[Davek0974]

I guess if i do fit the servo, adding the enc module is a no-brainer really, daft not to fit it.

The bearings are sealed and hidden completely in this motor, i could likely get some WD40 in there but no grease. My main issues with fitting it are that it will fail some time, probably when i need it, and will then need my cabinet pulled apart to change from VFD to serve drive etc.

It sort of becomes a "might as well fix it now" option i think, then i can benefit immediately from the improved speed control etc. If i sell my tapping heads they would likely fetch enough to pay for the servo drive anyway :)

[Davek0974]

Hi all,

been a while since this thread

For those who don't know, my Bridgeport was rebuilt with servos and larger motor, plus i added an auxiliary high speed spindle for aluminium work. The job in hand is shown in the pictures below, 5mm Aluminium, lots of holes and intricate features. I use 2mm single-flute and 5mm single-flute carbide tools for these.

Previously, I had already built a custom mini-mill to make these (and learn CNC) and still have this (its currently up for sale but no takers yet).

My reason for adding the aux spindle to the Bridgeport was two-fold - one, to save space and two, to make more use of the very expensive Bridgeport conversion which would otherwise only see intermittent use.

Now, when doing these on the Bridgeport, I am seeing bad vibration or chatter on the tool, it appears to be vertical oscillation but tonight also suffered bad enough radial oscillation to break a 5mm tool ! When it goes into oscillation it makes you jump as its very noisy and you instantly know it will end badly either in poor finish or broken tooling. Tonight I was testing tool sent from my supplier as a "Better" option this was a two-flute carbide, probably the reason for the breakage as two-flute tools need a more rigid setup.

So, something is not happy - my reservation is the spindle mount (shown below) - its canted out over to one side and although it's clamped to the quill and into an R8 collet in the main spindle, it must be allowing deflection from the cutting forces.

Ok, so I have a bad situation, is there a way forward here?

Obviously I can take the dust-sheets off the mini-mill and carry on but I just don't have the space long-term and wanted to make more use of the Bridgeport as mentioned. I really want a one-size fits all solution here.

If I run the small tooling on the BP main spindle at 3000rpm (top whack) the run time per part-set will go from about 30minutes to several hours probably - feed rates go from 900mm/min to 25mm/min so i don't think thats an option - it needs more RPM's.

What can be done here guys???

Spindle-speeders?? I have seen these but they have mixed reviews and i doubt they would like a 5mm tool much as mostly used for engraving etc.

One idea I quite like is to spin the ram on the BP around and build a custom Z-axis completely, and mount it where the BP slotting head normally sits. This could be built as heavily as desired with linear guides and a servo or stepper etc.