Messages

1081

General Mach Discussion / Backlash...

« on: September 28, 2016, 01:32:51 PM »

I'm just at the final stages of testing on my high speed spindle attachment for my Bridgeport, running cut tests now.

Would backlash make holes smaller or bigger?

The holes are 3.1mm being cut with a 2mm single flute endmill and are coming up a little tight.

They are ok on the other machine so my guesses backlash?

1082

General Mach Discussion / Re: Run a macro from a button press??

« on: September 28, 2016, 01:25:35 PM »

Well, tried several styles of issuing a runscript command from within the macro pump and none of them worked.

The pump is running as the last attempt was...

Code: [Select]

Dim Response
If IsActive(INPUT1) Then
Response = RunScript("M889")
end if

Message "Result = " & Response

That little lot returned a value of 1, trouble is I have no idea what a result of 1 means, but it proved the pump and script is running

Nothing happens, no errors or any activity, if i MDI M889 it functions as expected so the target macro is fine.

Looks like runscript does not function in this version?

1083

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 28, 2016, 10:15:56 AM »

Parts on order, went for the Ac motor with vfd and braking resistor with encoder fitted somewhere

Be good to get rid of the clattering vari-speed stuff up top at last.

1084

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 27, 2016, 09:31:08 AM »

Small encouragement from CS_Labs....

With their ENC module, a vfd and encoder, activate the Pid loop in Mach3 using their settings, it will give reasonably closed-loop operation as far as speed regulation goes as well as real-time display of actual rpm on the screen

Sounds good to me, I have the ENC module already so thats one step less.

1085

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 27, 2016, 08:53:14 AM »

Thanks Hood, I think the servo idea has been passed now, will focus on what is achievable with a vfd/3hp induction/encoder setup i think.

Was a nice thought but just not worth more cost than the little servo i was looking at.

1086

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 27, 2016, 08:18:28 AM »

Nice,

Been messing with my speed/feed calculator, looking at all the figures i usually ignore

Mild steel,
50mm facemill with 5 tips, full-width cut, 1.6mm deep = 420rpm, 201mm/min, 0.4kW 9.24Nm
20mm endmill 4 flute, 35mm DOC, 5.4mm engagement = 650rpm, 204mm.min, 0.81kW 12.12Nm
15mm drill = 650rpm, 111mm/min, 0.37kW 5.5Nm

So using your quote of 0.3kw at 450rpm the answer is NO it will probably stall on a 15mm drill and a 20mm endmill but be ok with the facemill.

Yes, I *could* enter the actual power curve into the calculator and it WILL give me a solution BUT I think going lower power than a 1.5hp Bridgeport is a little pointless.

That clears that up then I think, forget the servo, if anything IS to be done it will be a 3Hp AC motor, sensorless-vector drive, braking resistor and encoder I think.

Thanks all for the patience

1087

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 27, 2016, 07:25:22 AM »

Trying to get the lightbulb to come on....

If i have a tool that takes 20Nm to rotate it and a motor that can provide 20Nm torque but zero Hp - would that mean the tool just stands still?

Then if i want to propel that tool forwards into something (my head probably) at say 100mm/min I need to increase Hp above zero to some positive figure that i have no doubt can be calculated?

So my theoretical tool might need 20Nm and 5Hp to make it move at 100mm/min

Probably still in cloud cuckoo land....

1088

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 27, 2016, 06:58:31 AM »

Yes, i do recall, but still confused

And to muddy the waters a bit more, I do have the motor on a VFD at present, to get my speed range semi-adjustable from MAch3  I am running the mechanical controller only in one of two positions - 700rpm and 2200rpm, the rest of the variation in speeds from 450 to 3000 is covered by the VFD running from 25Hz to 75Hz.

It sort of works reasonably well, Mach gets its knickers in a twist at times but mostly all good so far.

Now, I have no idea as to what this is doing to the power from the AC motor but I guess its not all good, thats why i limited the range from 25 to 75Hz only, its an old motor and not made for inverters so did not sound too sweet at 100Hz and was useless below 25Hz

Also throw in the serious power losses from the vari speed drive - i did read a paper somewhere that listed 75% efficient so thats a pretty big loss.

Any of that help me - i doubt it

1089

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 27, 2016, 05:11:55 AM »

Is it possible for some kind soul to say one way or the other if a 1.8kW AC servo is just too weedy to replace the 1.5Hp7Nm AC motor i have already??

My views are restricted by knowledge and muddied by confusion

The original motor has about 7Nm - with the mechanical vari-speed probably about 15Nm at bottom speed 450Rpm but only about 2.5Nm at top speed 3000rpm

The servo has 6Nm continuous and 18Nm peak - now I have no idea what "peak" is or how long it can maintain it before going Chernobyl on me

This is where my knowledge runs out.

Simple question, forget cost, will the servo work or will it stall out at low speed ?

Bearing in mind this is a Bridgeport and not a metal hogging monster so heavy cuts are intermittent.

Knowing this would simplify my choices by narrowing things down a bit .

1090

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: September 27, 2016, 04:54:20 AM »

Thanks

the cost between a new 3Hp motor/vfd/encoder and a servo is about the same

BUT

I cannot get the servo to match both speed AND power it seems - this means running a far bigger slower servo and gearing up.

The 3Hp AC motor has plenty of torque down to silly speeds according to the specs - something like 15Nm at 146rpm all the way up to 8Nm at 2900rpm

The servo seems only affordable at 1.8kW /6Nm & 18Nm peak 3000rpm. Any bigger and cost goes silly.

It does seem the CSMIO is geared towards servos.