Messages

1741

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 01:05:14 PM »

I'm having trouble finding the correct heights for the various models, so many different series, models and mk's!

Well, nothing wrong with 2500mm/min, provided you only want to cut 12mm thick slabs all day Surprising how much sharper it looks as the acceleration went up.

1742

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 10:55:24 AM »

Thanks Hood, Interesting.

It looks like a series 1 BOSS would fit in, trouble is they are rare now

Hmmm...

1743

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 10:08:39 AM »

Thanks Hood, pretty snappy I had to de-tune my plasma a fair bit as was shaking itself enough  to give slat-wobble which wrecked the cut.

Don't forget though that this new project is a heavy old milling machine, not plasma, I have no idea what acceleration does to a mill but i'm fairly certain it's not as important as a plasma.

1744

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 07:47:22 AM »

Nice job there, thanks.

The Z always seems to be the weak link on conversions from what i have been reading.

I am liking the idea of closed-loop steppers, the drivers can ramp the current up/down depending on the load so if there is a tight spot which you get on worn machines it will ramp up to overcome it, if it still can't then it faults out, normal steppers would just stall.

2:1 or 3:1 reduction on X&Y ?

1745

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 06:27:23 AM »

Just had a lengthy chat with my supplier of bits and they seem to favour heavily 8NM stepper-servo's for this task. The specs read well, basically a closed loop stepper and DSP drive with variable current etc. Price was about £250 per axis for motor and drive/cable.

Being stepper also means i can use my existing knowledge of BOB's and USB motion controller etc.


More options to throw in the pot.

1746

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 05:30:26 AM »

Sounds good, yes this two registers on the front of the quill are for position references.

As for speeds, does it really matter on a mill? Most of my cuts are way lower than that as the motor speed is pretty low anyway.

Does acceleration make a difference?

Will check out the servos and thanks again for helping so much, its looking interesting now.

1747

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 05:01:45 AM »

Thanks Hood, looks good.

I know there is one in there, but the top thrust bearing seems to be hidden??

1748

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 03:59:13 AM »

Thanks, that seems to make sense, what sort of screw dia on that ?

I gather a smallish motor is only needed on the Z?

Still not sure as to stepper or servo, read good things about both, servo's do seem better but at cost.

Also still have to find a screw conversion kit.

1749

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 03:36:11 AM »

thanks,

I think height is going to be the killer, they are just too tall to fit in

Its looking like my only option is to retrofit the standard machine, the two main stumbling blocks on that appear to be the cost of the screw kit and the way the quill is driven.

1750

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: May 13, 2016, 02:21:44 AM »

Thanks all, yes its all down to space and power I think as primary concerns.

I would not convert the BP without going ballscrew - the screws are knackered and I would want the freedom to climb mill at will without worrying about backlash grabbing the bit, I tried it manually and its a bit scary

I have no idea what I will do yet, this is a growing dilemma - each answer brings more issues.

Probably the only machine will be a BOSS or Interact but did they come with ballscrews??