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Member postings for Joseph Noci 1

Here is a list of all the postings Joseph Noci 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: CNC Lathe Scratch Build
27/09/2021 16:12:27
Posted by blowlamp on 27/09/2021 14:28:16:

It looks like Centroid make a C-Axis controller, but at a price. You'd be looking at around $2300 for the board & software.

Martin.

Yes, they do. Centroid was my first port of call, with a near_purchase...It does implement a C axis and was told it would do what I want, but turns out that was not so - It does exactly what my LCNC setup as at present does - NO Polar Interpolation, no G12.1/G13.1. As with mine, it can only do C axis Indexing and coordinated moves. So you can drill holes on the face of a part at any angle, using the live spindle, etc, but no polar stuff..I searched for a controller or software to do this...Considering the pain en-route to what I have, I would have happily paid $3K for an of-the shelf option!

Joe

27/09/2021 12:16:23

Hi John,

Here is where one has to get you mind wrapped around the issue ( or the axis)...Also why I am only discovering the issue now, since as I mentioned before, you really only learn when you need to, not in passing..!

Anyway - The motion you speak of is essentially still just linear.

In other words, when you issue G01 X10.00 A10.00the two axes will move to 10mm and 10deg coordinated. So when A has move 1deg, X has moved 1mm, etc. The two axes will accelerated together, travel together and both decel to the 10mm/10deg finish line together. That's coordinated, not interpolated in the true sense.

This works identically in the C axis lathe - A G01 X10 C10.00 will do as your mill did.

Now Imagine cutting a square head on the end of a shaft in a Caxis/live tool lathe - It is educational to visualise the actual C axis / X axis movement relationships in travel as the path is cut - the path is non-linear, sort of Hyperbolic.

If the CAM packagedid the interpolation and then generated Gcode that was simple coordinated 'linear' moves, ie, many short G01 Xxx Cyy moves, then each move would be coordinated and the actual cut path alone one side of the square would be done by hundreds of such G01 moves - Caxis would rotate a tiny bit and X would likewise move a tiny bit, etc.

But CAM packages that are capable of C axis/live tool lathe camming tend NOT to generate such piece-wise code - they use 'interpolated modes' - They issue a G12.1 (or similar) which places the controller in polar mode. Then the issues Gcode are a specific notation of X and C axis moves, which if the G12.1 were not active, would make the two axes simply move in coordinated motion as the examples above - the path followed would not be along the side of the square at all! The G12.1 makes the controller looks at the X/C move command and do a linear to polar conversion to establish the path, and back to cartesian coordinates to then move each axis in normal coordinated mode, in very tiny increments, many thousands, compared to the hundred in the example above.

A long story...!

Hope that explains a little?

26/09/2021 20:04:16
Posted by blowlamp on 26/09/2021 15:58:05:

This is from the PlanetCNC gcode reference - I don't know if it's of any help, I'm just posting if you weren't aware.

Martin.

G15 - Polar Coordinate Cancel
Usage: G15
Cancel polar mode coordinate positioning.
Parameters:
#<_polarmode> - (RW) current polar mode
G16 - Polar Coordinate Enable
Usage: G16
Enable polar mode coordinate positioning. In the polar coordinate mode movement end points are
specified as a radius and angle. Origin is determined by the absolute/incremental position mode
setting.
The current plane setting determines which word is radius and which is angle.
G17 – XY Plane – X is radius, Y is angle
G18 – ZX Plane – Z is radius, X is angle
G19 – YZ Plane – Y is radius, Z is angle
Parameters:
#<_polarmode> - (RW) current polar mode
Example:
(square with corners -30,-30 and 30,30)
G0 X0 Y0
G16
G00 X42.4264 Y225
G01 X42.4264 Y135
G01 X42.4264 Y45
G01 X42.4264 Y315
G01 X42.4264 Y225
G15

Hi Martin. Unfortunately , not really.. G16 initiates Polar mode but in XY plain, and so intended mainly for XYZ axis machines such a mills. What G12.1 does on a Polar modes equipped lathe is take the polar Y modes of the XYZ machine and convert the motion to X linear and C axis rotation, wrapping what was Y axis linear around the C axis.

The key lies in your last bits of the post -

G00 X42.4264 Y 225
G01 X42.4264 Y 135
G01 X42.4264 Y 45
G01 X42.4264 Y 315
G01 X42.4264 Y 225

Still all linear moves, just computing the XY position in polar form...

The only way forward I see is for me to write my own full Polar Interpolation kinematics.

 

 

Edited By Joseph Noci 1 on 26/09/2021 20:07:36

26/09/2021 19:56:12
Posted by John Haine on 26/09/2021 14:32:29:

By polar code, do you mean using the spindle as an A axis? Could you not adapt a milling profile for when you want to do this?

John, the spindle is actually the C axis in a lathe, but the principle is similar. And no, you can't adapt a milling profile - or I suppose you can, but you have to unwrap the c axis required motion into a Y axis linear motion and convert that to C axis motion coordinated with X...! So no, not really..

26/09/2021 13:30:04

Well, nothing useful to report, other than that I am feeling somewhat like a piece of threaded rod at the moment...

It turns out that when I started this project, the future dilemma would, and did, lie in the fact that success was 'doomed' as I did not know what I did not know. And to discover what you don't know only seems to come about when the task in front of you demands that you dig deep and research a lot, for days...

I was searching for a machine controller that could do lathe C axis with live tooling, and did not realised what I should have asked was - C axis with live tooling AND polar interpolation...

Many climbed in and said to persevere with LinuxCNC as it 'can do anything' - but if you search ( exhaustively!) you find NO one has actually done this with LinuxCNC...

Bottom line is that LinuxCNC CANNOT do Polar modes - it lacks the kinetics, and so lathe polar work is not possible with Polar style Gcodes. And Polar Gcodes are what is generated by ALL the CAM packages I have looked at, tried, trialled and cried over.

All CAM packages that deal with Caxis/live tool lathes generate a G12.1 code which sets a suitable controller into polar mode and which then does the Cartesian/polar math. For this to work with LinuxCNC the CAM package would have to convert all coordinated Caxis/Xaxis polar moves to small line increments of angle and x Axis move commands. I have not found any package that can do it! 'Someone' siad F360 can, but did not have the time to test a simple case for me...I also understand that F360 Lathe post-processor has 'warts'...?

I had a few CAM companies looking at the issue - it took some doing to get them to understand the issue - they could not get past the disbelief initially that a lathe CNC controller could not do Polar motion...These are companies whose CAM costs between $2000.00 and $4500.00 per seat..Out of 5 companies, 2 were very helpful they even phoned me here in Namibia a few times for more details - I was so frustrated that I was 'sort of' considering paying such a price for something that would work and explained such. They went away and came with a proposal to add the non-polar piece wise Gcode stream - cost to add would be around $2500.00 plus some TBD cost to adapt a postprocessor for the lathe...

So I thanked them for their time, and thats that!

I do not like F360 - it is to complex to live with - if you don't use it for a few months, it takes a day to get back into it, re-learn the syntax and commands, etc - and they keep changing it - also dislike very much the user use-case and cloud base nonsense...So if someone who knows F360 well is prepared to do a small test code for me, I would be most appreciative - if it works maybe i'll purchase a license...- this may be my only solution bar one - this being that I write my own polar kinematics for linuxcnc and somehow integrate it with some new Gcodes (G12.1/G13.1), etc. That is such a mission - it was supposed to be a user adaptable tool, not a project unto itself!

Bah!

At least the mechanics are successful - the ATC works well and the whole thing works well as a 2 axis lathe!

Thread: Ideas on how to make up a G-Clamp Swivel Foot
19/09/2021 12:19:00
Posted by Nicholas Wheeler 1 on 19/09/2021 11:35:30:
Posted by Joseph Noci 1 on 19/09/2021 08:41:25:

Surely the foot is simple - I would think the ball on the screw end is more problematic since it was asked how to make that as well- for those without ball-turning jigs..

It's only for a clamp; by the time you've setup a ball turner you could have roughed out and filed a perfectly adequate ball.

True...

19/09/2021 08:41:25

Surely the foot is simple - I would think the ball on the screw end is more problematic since it was asked how to make that as well- for those without ball-turning jigs..

 

Edited By Joseph Noci 1 on 19/09/2021 08:42:11

Thread: CNC Lathe Scratch Build
17/09/2021 08:36:58

Thank You Pete. This is not most folk's cup of tea and it is good to receive some comment! Not this forum's idea of 'Model Engineering', and I am considered somewhat anal and excessively fastidious by some....

On top of that, this project has been, and still is, a challenge. It's scope grew beyond my intentions and the basic capability of most of my machines and challenged me to the point of almost giving up - a few times...Here in Namibia there are NO other folk dabbling in this stuff at all, so cannot even go see someone and lament over a cup of tea, or a barrel of beer!

Thanks for the encouragement.

Joe

16/09/2021 16:26:41

The ATC is 'complete' - all parts are done and the thing is assembled. I have tested it using a Nucleo with some test code - The Hirth coupling disengages @ 105psi and the stepper turns the tool plate just fine. The live spindle drive also works very well, so all in all I am happy.

View of the Bellville springs under preload.

bellville preload.jpg

Piston travel limiter installed.

piston travel limter.jpg

Piston fitted into the cylinder body.

piston in cylinder body.jpg

Mating all parts together

mating parts.jpg

Live spindle drive shaft installed

live spindle driveshaft.jpg

Spindle motor and drive electronics fitted

spindle motor electronics.jpg

Main cover fitted

main cover on.jpg

All covers on, ready to fit to lathe

atc closed.jpg

Views on the lathe

atc on lathe1.jpg

atc on lathe2.jpg

Now the big deal is to get LinuxCNC to talk to the ATC, so I am bum on chair and head buried in the mess of LinuxCNC, HAL and that cryptic world!

Last post on this lathe will hopefully be a video of it working..

Joe

Thread: Multimeter recommendations
08/09/2021 07:56:08

All the meters I have used have separate inputs for current, so must be a real lapse in focus to measure volts with the meter set so..

I think the 'cheap' meters are still pretty good value for money, if the intended use is around the house, shop and car.

WRT safety, even the cheapies don't appear too bad - certainly the high current ranges - 10amps plus etc, may be a bit suspect - pcb tracks are in some cases a little narrow for prolonged use at higher currents. Voltage separation of tracks in the cheapies I have seems quite adequate - nothing less than 6mm gaps that I found.

If the use is more professional, then accuracy may be more important, and very specific needs would then dictate a better instrument.

The two left meters are MusTool left was $9.00, 2nd from left was $18.00

Both work very well, I use them in the workshop, on 4x4 trips, etc. third from left is the venerable FLuke 87, this one now 26 years old and working as new. Next was my gift to me to replace the Fluke 87, a Keysight 5-1/2 digit meter - Very good at measuring, can record to a PC, etc - was $604.00 (!).

However, this was a bad buy -the Keysight display is crappy, not clear, hard to read in day without the backlight on(!!), the knob has a very uncomfortable rotational backlash which results in one not being sure if the required selection in made or not.. I use it for the more exacting tasks - measuring and computing ampere-hours for very low power wildlife tracking collars and so on. The Fluke and the Keysight unit are in the electronics lab all the time, and nine out of ten times I'll go for the Fluke. I could not physically view the Keysight unit when I purchased, went on reviews and made a mistake in purchasing it. I should have gone for the later Flukes (s). So price is not all - The only downside I found to the two cheapies shown here is the display update time is long - maybe 1 to 2 sec, and autorange time is irritatingly long - up to 4 seconds...The Fluke is less than 1 sec, the Keysight not noticeable.

Measuring +12V on each unit showed ( left to right) 11.88v , 11.9v, 12.01v, 12,002v

Current measurements showed:

0.5amps: left to right - 0.25A , 0.48A, 0.511A, 0.505, 0.5007A

1Amps : 0.98A , 0.97A, 0.99A, 1.0008A

10Amps : 9.77A, 9.89A, 9.98A, 9.9997A

So I think The Cheapies are just fine, except for the sub 0.5A anomaly of the left meter..

 

multimeters.jpg

Fuse setup of the cheapest versus the costly meter..

meterfuses.jpg

Given the lesson, and what Fluke has done for me over the last 1/3 of a lifetime, I would try find a FLuke...

Joe

 

Edited By Joseph Noci 1 on 08/09/2021 07:58:57

Edited By Joseph Noci 1 on 08/09/2021 08:00:19

Thread: Dynamic Balancing a BLDC motor rotor.
06/09/2021 21:52:38

Software is DynamsPro - from Miklos Koncz in Hungary.

Joe V51JN

06/09/2021 20:20:51

Hello Werner,

The RPM sensor is also used to reference the angular position. The RPM sensor is ringed in orange in the image below, the top left part. The Reference mark on the motor rotor is ringed in red in the same image.

A reference calibration is done to start - A small mass, maybe 1 gram or less, is attached at the reference mark position ( the one ringed in red) and the rotor is spun up. The accelerometer then detects this imbalance, and it should coincide with the optical detection of the reference mark. Once calibrated, the software knows that the reference mark is 0 degrees. The reference mas is then removed, and when the rotor is spun up again, any imbalance is detected by the accelerometer, and the angle computed with reference to the optical reference mark.

Hope that makes sense..

Joe

balance jig viewsrefsense.jpg

04/09/2021 15:25:58

The CNC Lathe I am building has  live tooling  requiring a drive motor. I used a BLDC motor , with modifications to the motor rotor housing, to be able to fit into/onto the ATC mechanism.

The  motor is an 'outrunner' where the outer housing, the rotor, spins. I modified this housing to fit into a new housing which has a bearing spigot to take rotational loads in the ATC. These modification require that rotor be balanced again. Very little mass had to be removed, I guess thanks to good setup in the CNC mill during machining.

rotor aircooling1.jpg

The existing motor rotor bell end was removed and the rotor pressed into the new housing - photo above.

The yellow part to be cut off/out-

bell end to cut off.jpg

End removed and rotor cleaned up.

cutting out bell end.jpg

And pressed into the new Rotor housing.

motor magnet rotor in housing.jpg

A balance jig  allows the rotor to float easily front and back, with accelerometers ( left and right) attached in the same plane.

Views below show;

TOP LEFT = Front View - the lower right is an optical detector detecting the start of the black line on the rotor. This measures RPM and the jig is calibrated by attaching a weight at the rotor reference position which coincides with that detection edge. The rotor is spun up and the referenced This calculates the zero deg angle for weight placement reference. The test weight is then removed.

TOP RIGHT = Rear View, showing the two accelerometers, magnetically attached. Two accelerometers are used,  since I need to do two plane dynamic balancing.

BOTTOM LEFT and RIGHT = side and side/rear views.

balance jig views.jpg

The Upper image of below shows the bearing housings on the test jig, the Lower image shows the air spout used to spin the rotor up.

air spinning and bearing housings.jpg

One of the accelerometers - magnets on the Z and Y axes allow quick attachments and removal.

accelorometer.jpg

The accelerometers, RPM sensor, all come to this interface box, where the correct planes can be selected. The signals go from here to the sound card in the PC, and the software does the rest..

balancer interface box.jpg

balancing software display.jpg

Did not realise the camera focused on the bearing instead of the mass positions..The + signs show where the balance weights are added inside the rotor. The - signs show where to remove mass to balance. The two small weights were then removed and weighed.

balance weight positions.jpg

A 10gram scale (0.001g 'resolution..) was used -  not accurate, but fine for comparative measurements.

10gram scale.jpg

The two weights were removed  and weighed. To get a feel for how big a hole to drill on the rotor inner to remove similar weight, an M3x5mm grub screw was weighed.

The two little tackytape weights seen here:

two balance weights.jpg

The two weigh near 0.085g, the grub screw 0.156g, so need to remove 1/2 grub screw size, spread over the two balance positions.

balnce weight mass.jpg

The two holes are 4mm diameter, 1mm deep each. I started with 3mm x 0.5mm deep. Then 4mm x 0.5mm deep, and repeat deeper till done.

final balance holes.jpg

This was all repeated for the right side of the housing , while verifying effects to the opposite sides regularly

 

Edited By Joseph Noci 1 on 04

Thread: CNC Lathe Scratch Build
04/09/2021 14:51:58

The motor Rotor/Housing is complete - just finished dynamic balancing of it at 8000RPM - worked out nicely. Have created a separate post on the balancing - this post is becoming a bit of a saga..

air spinning and bearing housings.jpg

final balance holes.jpg

Joe

Thread: Hole diameters for single point threading
04/09/2021 14:48:38

I seem to have managed...old and new shafts.jpg

Joe

Thread: CNC Lathe Scratch Build
01/09/2021 17:01:39

CNC'ed the air cooling holes into the magnet Rotor housing this morning, and fitted the locking grubscrews. rotor aircooling1.jpg

rotor aircooling2.jpg

Getting there...

31/08/2021 18:56:46

The last two weeks have been have been spread over 'wildlife' issues, with not too much time available to work on the lathe - did manage some over the last two days though..

The ATC's co-axial live spindle requires the remake of a number of items, with design changes - I have made most of the parts and a trial fit shows promise..One of my concerns was the effect of tolerance build-up in the linear mode of the assembly. I ended up with 0.13mm 'elongation' beyond my drawing tolerances, and had allowed for 0.3mm in 'adjustments' so all is well!

As a reference for parts, i have included the block diagram again:

live spindle sketch.jpg

This is a trial assembly of the important parts - the motor fitting still in progress

trial assy.jpg

The main new item was a replacement central shaft, with through hole for the live spindle drive shaft -

here is the shaft being threaded for the toolplate, central pre-load nuts and motor mount.

threading.jpg

Toolplate thread test fit:

toolplate thread fit.jpg

The collet and bearings fitted - test spin by hand..Face pre-load nut still to be made.

collet spinning.jpg

Spindel dive motor and halls sensors fitted:

The left section is the magnetic rotor .

motor and hall sensors.jpg

The orange part of the rotor will be machined off, as the rotor fits into the new motor housing below:

magnet end to machine.jpg

Motor stator inside motor housing

motor assy.jpg

Motor Rotor slid into motor housing - own shaft still to be pressed out and the orange part machined off.

motor magnet rotor in housing.jpg

As usual, more to come.

Joe

Thread: automating a coil winder
31/08/2021 12:56:54

Andrew,

I built a coil winder similar to what you are after - long, long ago.. - I used two stepper motors, one for the coil and one driving an M8 leadscrew carrying the yoke though which the wire is fed. Unlike screwcutting, this application never requires that you need to unhitch the carriage, or rewind to the thread start to restart. You always wind one direction, N turns, then the carriage reverses laying down the next layer of N turns at the same pitch, so much simpler, and quite different from an ELS - The typical ELS systems doing the rounds will in fact not work for this at all - will not allow the reverse pass layer to be wound..

My winder is so old - made it about 20 years ago Simple LCD with up/dn buttons to set number or turns per layer, number of turns total and wire thickness. I won't offer you my solution... - no Arduino back then and I used an Intel 8051 uP, and wrote the thing in assembler...

Are you arduino and/or software adept?

Joe

Thread: Small dc brushed motors
23/08/2021 11:04:24
Posted by Bob Mc on 23/08/2021 08:08:04:

Hi All...

am in the process of making an r/c boat, I need to find out which motor to use, I have already used a '400' type motor but have no idea what this means ... I will require a larger motor for the next build so need to know volts/amps/rpm/mechanical size etc.... is there a chart for all this?

will be grateful for any information....Bob.

Edited By Bob Mc on 23/08/2021 08:09:09

Hi Bob.

The term '400 type motor' ( called Speed 400 back then..) dates back a while, and very loosely referred to a motor around near 38mm long, a 500 motor was near 55 or 56mm long, etc. The old 400 DC motors were around 100watts max or so, 10 to 12 amps typically. If I recall, the Speed 400 was around 30mm in diameter.

Are you set on a DC motor? Do you already have the DC PWM RC speed controller? If so that would set some limits on the motor amps/volts choice I guess.

If you are not set on DC, the RC brushless DC motors are a good option. Much more efficient and more power in smaller packages compared to the somewhat dated construction of the cheap Speed series DC motors.

A visit to your local RC hobby shop will deliver..

Eg:

Howes Models UK

E-Flight Park 400

Example E-FLight motor chart

Joe

Thread: CNC Lathe Scratch Build
17/08/2021 11:10:16

Thanks for the reminder John!

I guess once the lathe is together I will be able to evaluate better what might be needed and may just reach out to you again..

Joe

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