Bridgeport Manual to CNC conversion...

Ok set speed for 2500 and acceleration for 400, moving right along - servo tuning.

Have done nothing on these apart from an auto-tune in CSMIO setup. I thought the results were ok, but having spent a few hours today scouring the 'net it seems they were pretty bad really. The first video here shows one axis after an auto-tune. Now, I have zero experience with servo's, being stepper builds up to this build, so I stand to be fully corrected but, i think the graph shows pretty bad over-shoot or oscillation?

https://youtu.be/IOAS4LMJzcg

So, throwing caution to the wind, i dived in and removed all of the "I" and "D" parameters as well as the "ff" or fudge-factor i think its called. That seemed to improve things so i started increasing the gain in steps of 1,000 and the graph seems better to my untrained eye?

The following error is lower, dead-band is reached faster and the dials on the machine no longer overshoot and slowly wind back to a stop - this was a concern as i could see it affecting cut quality etc.

This video was shot after my messing around...

https://youtu.be/Yr4joMqo61Q

Now, please feel free to rain on my parade, but does the last video look happier than the first?
Is there any issue running with zero "I". "D" & "ff" values?
I can't hear any grumbling from the motors, there is no visible 'hunting' at idle, following errors are down and the dials now stop on a dime as shown.

The Z axis would not tolerate as much gain and did go into permanent oscillation once so i backed off a fair bit but still no "I", "D" & "ff" values.

Suggestions?

Some short videos of the conversion in operation, 15mm Alu plate, full recommended speeds and feeds in use...

2d pocket clearing...
https://youtu.be/gpFq3sJfYVc

2d Adaptive clearing...
https://youtu.be/FBWLnouPMiA
I have massively increased the non-cut return speed since this video was taken :)

So far its working well.

Looking good Dave, always good to see chips flying!!!

Thanks, its good to watch:)

USB Issues?

I need USB in the control pendant, USB keyboard/trackball and USB socket for code loading.
Currently i have a cheap 4-way hub and extension but windows is not happy and i get multiple "new device found" chimes every time i start up or plug in a USB stick

Is it best to try a powered hub or run separate extensions to the PC??

The length needs to be 5m to reach.

Dave can you not transfer files over Ethernet

I don't really transfer, the code runs direct from the stick and the rest is just keyboard/trackball

USB Issues solved - it works well without the hub and just having two extensions, i have ordered another extension and some clip-on ferrite blocks to suppress any interference.

Also, at last - the adaptor I have mucking about with for the last couple of months is finally done :tranquillity: Admittedly it took so long as i was building the machine to make it and figuring out how to operate it but in the end, after ironing out all (so far) of the bugs in tooling, offsets, post-processing etc it really only took a couple of hours.

It's also the first part designed in Fusion 360, that was a learning curve!

It fits the mill snugly and as long as the high-speed spindle motor fits ok, should work beautifully, still got some jobs to clear before i can strip that down though.

Total cost in Z axis travel is 22mm - not bad i thought - that leaves me about 95mm to play with but on a small spindle with tiny tooling that should be ok i think.

Thanks for all help guys :wink::wink:

Attachment 19170

Attachment 19169

Attachment 19168

I have a tapping head, TapMatic SPD5 - http://www.tapmatic.co.uk/products/p_12.php

It's a self-reversing unit in mint condition.

But it was for a manual machine - you feed in to a quill depth stop, the thread pulls the tap down which disengages the clutch then you pull up which engages reverse and the tap screws out. You need to pull up slightly more than the thread pitch in order to keep reverse engaged.

Now, I don't have rigid tapping, probably never will on this machine, so is it possible to create the feeds/retracts to use this device in CNC or not?

Or, other options?

Quote:

---

Originally Posted by Davek0974

I have a tapping head, TapMatic SPD5 - http://www.tapmatic.co.uk/products/p_12.php

It's a self-reversing unit in mint condition.

But it was for a manual machine - you feed in to a quill depth stop, the thread pulls the tap down which disengages the clutch then you pull up which engages reverse and the tap screws out. You need to pull up slightly more than the thread pitch in order to keep reverse engaged.

Now, I don't have rigid tapping, probably never will on this machine, so is it possible to create the feeds/retracts to use this device in CNC or not?

Or, other options?

---

Yes you can, but you need to figure out the depth you are going to end with. I had trouble with Vertex job.

Personally I prefer the tread milling approach. Quicker and cleaner.

I have a lot of M6 holes to thread - can you thread-mill that small?

Quote:

---

Originally Posted by Davek0974

I have a lot of M6 holes to thread - can you thread-mill that small?

---

Cutwel list cutters down to M3, but you might need to sit down when reading the price.
The most basic 1mm pitch cutter has a list price of 60.66 (Order code - L1211310)

Yes it is possible.

I bought a single form one to do my grid of M12's from here: http://www.drill-service.co.uk/Produ...20000&Tool=799

You would use the 6mm one with a max cutting OD of 4.8 so you can get into the 5mm pilot holes.

If you want to go quicker, you can get the multipitch endmills that can make the thread in a single pass but they do become more expensive.

Have a look on NYCCNC's videos for how to set it all up in Fusion 360.

Regards

Ouch! thats a bit spendy for a thread :)

Just found a Torch video and they have a similar head to my Tapmatic - theirs is Procunier but the action is the same it seems.

The only benefit they have is that its all pre-programmed canned cycle stuff. I don't have that luxury but at least it proves it can work.

I will have a look at the specs on the head for tap-travel below the stop point and see if i can come up with a method of programming :) From memory it was 5mm below the stop point to where the feed disengaged so for a 10mm deep thread you would stop feeding at 5mm, wait for the clutch to disengage then feed out.

Hmm, thought i could get smart and do it in Fusion360 which comes up with this code...
(1)
(T1 D=6. CR=0. - ZMIN=-10. - RIGHT HAND TAP)
G90 G94 G91.1 G40 G49 G17
G21
G28 G91 Z0.
G90


(DRILL2)
M5
M9
T1 M6
S1000 M3
G54
M7
G0 X-5. Y0.
G43 Z15. H1
Z5.
M29 S1000
G98 G84 X-5. Y0. Z-10. R4. F1000.
G80
Z15.


M9
G28 G91 Z0.
M30

This should be a M6 thread 10mm deep with a 4 second pause, But it seems Mach3 does not recognise G84 so thats out, whatever G84 really is :)

ebay , 1 and 2 . I have been looking to grab a couple . 5$ instead of 50$. What you say? I think these are ideal for various inside threads

G84 is rigid tap cycle.

You should have bought one of these.

http://www.stevenson-engineers.co.uk...xis%20mill.jpg


£450 landed in UK.

No computer, no monitor, no windows license, no Mach licence, No CSIO box of tricks.

Does rigid tapping, tool changer, pendant, all built in.

These are going to be a game changer in the future.

Quote:

---

Originally Posted by John S

G84 is rigid tap cycle.

You should have bought one of these.




£450 landed in UK.

No computer, no monitor, no windows license, no Mach licence, No CSIO box of tricks.

Does rigid tapping, tool changer, pendant, all built in.

These are going to be a game changer in the future.

---

You are reading my mind, i have difficulty expressing how i feel about each one of the BOBs available now on market, or it would be expensive, or 5v,or not shielded, or will not do this or that correctly, or ...http://www.sherv.net/cm/emoticons/gu...oting-guns.gif

Ouch, nice box. Didn't know about it then though, I also like the more graphical nature of Mach3, tweaks, tricks, customisations etc :)

This might be getting there, treat it as a drill, chip-break operation, full retract, set peck depth to thread depth minus the 5mm for tapping clutch, pause before retract to allow clutch to disengage then retract.

I se for a 6mm x 1mm thread so i chose 500 rpm and 500mm/min feed should match the pitch rate of 1mm/rev ??

Only issue i see here is that it rapids out as G0, will look at that.

Code:

---

(1)(T10  D=6.1 CR=0. TAPER=118DEG - ZMIN=-5. - DRILL)
G90 G94 G91.1 G40 G49 G17
G21
G28 G91 Z0.
G90


(DRILL2)
M5
M9
T10 M6
S500 M3
G54
M7
G0 X0. Y0.
G43 Z16. H10
Z2.
G1 Z-5. F500.
G4 P4.
G0 Z6.
Z16.


M9
G28 G91 Z0.
M30

---

Sorted, the guys on the Fusion360 forum edited a post-processor so it can feed in, dwell and then feed out.

Should have it sorted nicely :)

Sub-table for the engraving spindle...

Attachment 19180

Holes A are for M10 or M12 CSK socket-head screws to bolt into the Bridgeport T-Slots, holes B are two locating dowels on the rear face to sit in the middle slot on the main table, keep it all square etc :)

25mm eco-cast tooling plate.

Dave, once setup drop a couple of shallow keyways in the plate both vertically and horizontally so you can drop a piece of key steel in to act as back and / or side stops to get parts square

Sub-table is coming along nicely, can just be seen in the bottom of the picture, just the matrix holes to drill & tap now...

Attachment 19237

The new spindle motor fitted my adaptor perfectly, got the VFD dialled in nicely, just the water cooling to sort out.

Job done, turned out very nice.

100 holes, spotted, drilled, countersunk, blind-tapped M6

Attachment 19282

Surface was parallel to within 0.03mm max so i'm not going to bother running a facing cut.

Quote:

---

Originally Posted by John S

G84 is rigid tap cycle.

You should have bought one of these.

http://www.stevenson-engineers.co.uk...xis%20mill.jpg


£450 landed in UK.

No computer, no monitor, no windows license, no Mach licence, No CSIO box of tricks.

Does rigid tapping, tool changer, pendant, all built in.

These are going to be a game changer in the future.

---

Is this going back to the old style controllers?
Are the inputs manual or autocad? Does it connect directly to servo drivers?
Thanks
Colin

Takes standard Fanuc G-code.

Plugs and sockets on the back to go direct to drivers, tool changer, VFD for spindle, encoder for threading or rigid tapping, probe and pendant.

Quote:

---

Originally Posted by Colin Barron

Is this going back to the old style controllers?
Are the inputs manual or autocad? Does it connect directly to servo drivers?
Thanks
Colin

---

I would not say old style controllers, I would say professional. There is an element of setup but not as much as you would think. You will also need to change your habits if you are used to Mach or EMC, for example: just zeroing your part may not actually write the current offest to G54.


Some standalones, like my GSK980MDc also allow you access to the ladder logic so you can tweak it to your hearts content. Been trying to learn this myself but it is proving a tad difficult since there is very little to go on except some cryptic manuals.

Another element I have seen is that some controllers will accept DXF file direct input for drilled holes. You set each hole size in a different coloured layer and do all the coding on the console.

What I really like is that it moves away from the classic argument of EMC vs Mach, parallel vs motion controller etc. It just sort of works.

To get back on track....

Have decided to replace the little Bridgeport motor and simple V/Hz VFD with a 3Hp inverter rated motor, sensorless-vector vfd, timing belt drive and encoder - this should give me usable torque and power from about 300rpm to 3000rpm and also semi-closed-loop speed regulation as Mach and the CSMIO controller will maintain the speed as load changes, up to the point of tripping the vfd :)

It means i can finally get rid of the clattering vari-speed pulleys and power-sapping drive and not have to mess with setting the speed manually. I also get actual speed display on-screen.

Also got the braking resistor so stopping time should be about 1s or less.

Told you ages ago you should have bought that step speed head with brand new 3Hp motor already fitted ( sigh )

Yeah i know, live and learn :)

I think this this will be a step ahead of even the step-pulley though as it will be timing belt drive and no step-pulleys at all ;)

Needs the timing belt as i'm mounting the encoder on the motor shaft at 1:1 drive

Any ideas for encoder mounting?

I was thinking of coming off the end of the motor shaft - there is an M10 threaded hole in it, then connecting the encoder to the shaft. I'm not sure if a rigid connection is a good idea though, is a coupling of some sort better here??

The other option is a 36t HTD5 pulley bored out to 35mm to fit the spindle shaft and mount this between the spindle drive pulley and the old lower vari-disk/brake disk in the head then mount the encoder out the front where the old speed control used to live using another 36t pulley. Not as cosmetic as the motor shaft idea but??

Any thoughts?

I remember when once was looking into that, that there were encoders that could count straight from the HTD pulley teeth. though there was some limit on the speed, but i think you are in. Though cant remember more for them right now

Probably, i already have the encoder though ;)

Read the installation requirements for the encoder.
Depending on the style of encoder, there are different installation requirements.

Thanks, was just looking for ideas - the encoder is a rugged little unit with self-supporting shaft capable of something like 15N radial loading which is pretty tight for a belt.

I'll try the motor shaft idea first as i have the bits for that, if i need pulleys i'll have to order some up.

You'll probably want some kind of flexible coupler for that style of encoder, as unless you can guarantee very accurate alignment, you'll likely kill the encoder pretty quickly.

An encoder with a separate disc/reading head would of been a better choice for mounting directly onto a shaft.

Thanks,

I have seen the actual encoder body mounted on a spring plate presumably to allow for small misalignment

I will get a flex coupling in there.

Well, the motor was fitted, the pulleys wouldn't turn so something was wrong, then i discovered the rib that was cast into the top housing cover was rubbing badly on the top of the belt edge :(

Off it all comes again, rib was duly altered with a grinder ;) all back together again and nice smooth movement this time, my measurements and belt length calculations were spot-on and the adjuster slot on the motor plate was mid-way when tight. :)

Lugging a 3Hp motor up top on a Bridgeport on your own with only a pair of steps is no fun, doing it twice was pushing the limits a bit ;)

Just got to fit the VFD, wire up and we should be good.

Something that rarely gets mentioned...Power required...

I have a 3ph 2.2kW spindle motor on a vfd, 700w X servo, 700w Y servo, 400w Z servo, maybe 100w for pc and controller on this machine.

How do i calculate the supply capacity allowing for diversity - it will not be running 100% flat out all the time :)

I know i need to uprate the MCB's and supply cables as the build was originally for the small 1.5hp spindle motor.

Adding up the maximum ratings for all drives gives a figure way more than i can supply :)

A quick mental calc, and I'd say 16A would cover you.
2200+700+700+400 = 4000.
Divide that by 220 gives 18A, or 250 gives 16A.

Power up surges of the drives are likely to give a bigger problem than too much current draw during use.