Bridgeport Manual to CNC conversion...

[Davek0974]

Ok JAZZ, i'm sold on the CSMIO/A unit, does it have PWM output or is that an add-on? Controlling the VFD would be nice.

Will be reading up on that tonight.

Rigid tapping is a bugger because you need to get an encoder on the spindle - this is a nightmare the Bridgeport manual machines. Possible later add-on though.

Yes I think those motors will be Nema34 size.

[JAZZCNC]

Ok JAZZ, i'm sold on the CSMIO/A unit, does it have PWM output or is that an add-on? Controlling the VFD would be nice.

Yes it as Analog 0-10V Output for spindle Control built into it. Also has few Analog Inputs so can use Pot to override spindle speed and feedrate if desired.

[m_c]

A couple things to remember with the CS-Lab controllers, is if you want rigid tapping, you need to add the ENC/threading module, although not really an issue if you're happy to use a tapping head or thread mill.
Also, if you want to add a MPG, you need to buy the MPG module.
I would of suggested a KFlop+Kanalog (+ a Konnect if you need more than 8 In or 16 Out) as they'll do whatever you program them to do without any additional modules, however you need to know at least a little bit about C programming to get them working.

I was advised for my big mill, that the larger motors would be a better match. I was looking at 1000W 80 frame motors, and 1050W 110 frame motors, although I think I'll have to get 1200W to get the 3000RPM now. However I do think you could probably get away with the smaller frame motors on a standard Bridgeport, as it's not that heavy a table.

[Davek0974]

fitting an encoder to a BP is going to be hard i think, not many places to access the spindle, I have tapping heads so not really a concern yet.

I'm fairly well recommended from previous converters that 750w is a good match for this job, 3:1 reduction should help too.

I really don't want to get into C programming ;)

[dodgygeeza]

Then put an AC servo on the Spindle? I have done this on my MDI.
Its 3KW and 4KRPM. Bit small but i will see how it goes.

[Davek0974]

Control options...

Not sure we need a alpha keyboard for a mill, hows about a touch-screen monitor to do away with the mouse and a small numeric USB keypad?

Or

normal monitor (cheaper/stronger) and a track-ball and numeric keypad?

Looking at controls..
X/Y joystick
Z joystick
Knee up/down buttons
Speed override knob
Feed override knob
Cycle start
Feed-hold
Stop


Spindle motor...
This is currently run from a VFD but only at 50Hz, the head is the vari-speed unit with back-gear so i have 50-3000rpm but in two ranges and manual speed control. Whats a good option here - using the VFD won't address the variable torque ability of the vari-speed unit so can't just lock it in one spot.

Any cool options here to play with?

With a bit of fiddling the vari-speed changer could probably be motorised with a stepper and gearbox, not sure it's worth it?

Mach can obviously take over the Fwd/Rev function - still using the old switch but I wired it to the VFD so I can plug-reverse for tapping;) That was before i got the tapping head.

Any cool ideas?

[Davek0974]

Z axis...

It looks like I have four options here...

1 - Drive the Quill direct from the bolt point where the depth gauge mounts at the front.
2 - Drive the manual lever shaft on the right side
3 - Drive the power-feed clutch shaft on the left side
4 - Drive the knee lift

Points -
Option 1 seems to be the most common but adds a lot of bulk to the front of the head and costs a little Z axis travel.

Options 2 & 3 are similar, both will suffer from the rack backlash but option 3 is the neatest one, backlash can be reduced with the clock-spring.

Option 4 is a contender I think, it gives a massive 300mm Z travel, but suffers from stickiness and has backlash in the bevel gears. The force is reasonable - I measured my one and if my figures are correct, it needs approx 1Nm to lift the knee based on the handle length of 160mm and 6kg force on that handle 6kg / (1000/160) = 0.96Nm

The backlash is a factor but the Z is usually used to plunge or position - both of these are done in the positive direction so maybe backlash does not matter here?

Thoughts?

[Davek0974]

Based on advice, 750w AC servos and 2:1 is ideal on a bridgeport so that is whats going in, totally overkill for the Z axis but the price of smaller motors is higher so i cant see the point really, keep it all the same.

Got a few parts on the way - stainless panel mount keyboard, stainless panel mount trackball, some bits from the box at work - nice 10-turn pots and dials for FRO & SPO controls, a few spare relays and other bits and bobs.

Just about got a source lined up for a ballscrew kit - this bit really hurts the wallet :(

Does anyone have a drawing or sketch that would give me the dimensions of the right table (X) bearing bracket and the front (Y) bearing plate??

Mine will be missing as I have the original 6F power-feeds which will be taken off when i convert.

I can get the parts but the prices seem silly and they surely must be an easy enough part to make up from steel or aluminium?

Thanks