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: Stainless steel boilers|
Obviously the Welders referred to are Coded..And so would know all the pitfalls re carbon precipitation which is less of an issue with low temp liquids contained within, but with steam and pressure, any carbon precipitation results in very rapid pinhole development and subsequent rusting, which would make a pressure vessel interesting after a little use..
Edited By Joseph Noci 1 on 27/01/2022 11:10:19
|Thread: Mach3 control loosing zero|
I use Mach3 on my router and Engraver, but cannot remember where the motor setups data is stored ( acceleration and max velocity settings) . Is it in the .DAT file? . Stalling is either binding slides/leadscrews or those motor speeds and accels data got corrupted - I think the latter is unlikely - I have never had Mach3 itself become corrupt, nor its setup files, not in 19 years of Mach3 use...
Going past the home position is most likely the home position sensor feedback is not happening - broken cable, microswitch, connector, etc? You can look in the Mach3 diag page at the switch sensors and jog the axis to the home position - you should see the sensor 'led' light up ( or go out, if sense is reversed..)
The cutter 'going walkabout' is difficult to comment on - that means little...
If a stepper looses steps during the machining cycle ( bad accel / velocity values, or binding as mentioned) then the cutter will be in the wrong place when sent off to do the next Gcode line, so may appear to be walking about...
There are checks you can do, but you do need to be familiar with how Mach3 works, how to enter MDI commands, how to view the diagnostic page, etc. Are you? If so I am happy to try assist you in checking your setup. If not, I am happy to try get you familiar with it all first!
|Thread: Single wire capacitive sensors.|
the first link ( schmitt trigger) falls in the category of the 'hum detector' except it detects any voltage transient level - most often your body with develop detectable levels of static electricity and that will trigger the schmitt. Removing finger contact will cause the capacitor in that circuit to discharge, removing the voltage on the schmitt input, and the output will then fall back to its inactive state.
That circuit will generate a 50Hz pulsing output if you are in proximity of a strong AC field and you touch the pad - that 50Hz signal will appear on the schmitt input an the output will pulse. How that signal is/can be used depends on the electronics in the control board.
That arduino implementation is more complex. A digital output pin generates a fixed pulse train. An input pin feeds a timer/counter. If the two pins are connected together, the timer will count a number of processor clocks, which equate to the time interval between the pulses on the output pin.
So if you vary the period of the output pin pulses, the counter value will vary as well.
Now connect the output pin to the input pin through a large value resistor, and place a capacitor ( the sense pad or foil) on the input pin. Now you have an RC network which delays the arrival of the pulse on the input pin, allowing the counter/timer to clock up a larger value. Add more capacitance ( your finger, a capacitive increase through your body to the air and ground) and the pulse is delayed further, and the count value increases more. That count is read and the finger contact detection computed...
The link John Haine attached is in the category of IC sensors I mentioned in my first post - there are many of that type available - However, I guess for your purpose you don't really want to start experimenting with other types as it may have influence on the interface with the controller board.
As a test, just connect a wire to one of the pads, and extend the wire say 200mm to another spot on the torso and add another foil pad to the wire end and try it - I am sure it will work.
Cannot be said definitively as there are dozens of ways of doing that..two most likely options are a 'mains-hum' detector - lots of AC mains 50hz noise about, picked up by our bodies, and when your hand is brought near the foil, a high gain amplifier with possibly a 50hz bandpass filter amplifies this hum, which is then detected ( diode type envelope detector, sort of like am AM radio audio demodulator).
2nd possibility is more complex and a bit more reliable - the wire and foil is part of an RF oscillator such that when you contact or come near the foil, the oscillator is de-tuned and either the change in frequency or amplitude is detected. More reliable since if the performances are given in a rural setting, maybe there is not enough AC hum 'in the air'...This along the line of the Therimin musical instruments.
The more modern technologies use many techniques - such as measuring capacitance change as you touch the sensor area - there are IC's that do all that in a small package - often used for touch sensitive keyboards, home appliance panel touch keys, etc.
As to moving the sensors and keeping the sensing result, I would suspect you have a good chance of success.
Try to make sure there is no metallic object behind the area you you wish to fit the foil - likewise, don't route the wire near metal bits, etc. Should be easy to test.
If you want to know more about what you have, try trace a little of the circuit from where the foil wires attach to the board - probably through a capacitor and then to either a transistor amplifier of op-amp amplifier I would think..I suspect this setup will be the mains hum detection type of setup.
|Thread: Can you recommend a "medium-speed" epoxy adhesive? (e.g. "30 minute" or "60 minute")|
+1 for ZAP epoxies - I use it extensively building these...Works very well
|Thread: Aluminium Composite Material|
What composition is the material in question? There seem to be so many core material types, from resin bonded fibreglass to PTFE, PE, PVC, a variety of foams of different densities, etc...
I did actually try make some panels from a PVC cored Ali substrate - was not a great success. The PVC was difficult to machine - did not work with high RPMs ( 1200rpm..) and would go gummy and tear the Ali surface. This was quite a few years ago, when I was still in SA, and then managed to find a single flute reverse spiral 4mm carbide mill which worked reasonably - around 800rpm if I remember well and quite aggressive feed rates. The reverse spiral help push everything down, had to use compressed air on the cut line to get swarf out and keep the cutter cool. The Ali still had a rough edge - was not really acceptable to me. I tried some of the HDPE Foam core as well - I never managed with that at all.
|Thread: CNC Lathe Scratch Build|
The KIPWARE mentioned was supposed to be a link to the site - I am sure I set it as a link - maybe mods killed it for me, or maybe I was just dreaming when I did it - here it is again....
If it turns un-linky again, then I blame the mods...
Next post with simulated brevity...
In a previous post I indicated I would use a neat oil 'coolant'/lubricant - That was not a success. The oil was great, very thin, and does is intended job well, but the mess is intolerable. An oil film sits on everything, and just sits there. It does not run off like the water soluble oil solutions do. It sits on the swarf and takes days to drain of, and even then , not so well. So I dug for a more modern soluble and found some excellent stuff - Ecocool 600-NBF, made by Fuchs. from 4:1 to 20:1 mix, and £45.00 for 20liters. When mixed, the solution is clear and has no detectable smell. Drains off quickly, and left pooled on a shiny machined clean mild steel plate over the Christmas/New year week, left not a mark.
The pumps is a 12V fuel injection pump - seems to be able to develop a good few bar pressure. It hangs in the coolant tank with an inlet sieve. The drain from the lathe goes through 2 further sieves on route before the coolant drops into the tank. We will see what the coolant mix does to the pumps gears/seals, etc. The pumps was inexpensive anyway!
Coolant spouts placement on a CNC lathe is a big deal..Normally on the CNC machines the coolant spouts from the tool holder onto the cutting edge, often out the cutter itself with special coolant channels in the cutters, drills, and tool changer. Since that is not possible on my setup, I opted for two spouts, one placed for surface and face cutting, and one for drilling and boring and with Live Tool spindle- the latter spout to the right of the workpiece, the former on the left.
(some suppliers are STILL on holiday, so the right spout locline has not yet been lengthened..)
The left spout is fixed, and will flood fully the workpiece from behind / under. The right spout moves with the carriage and is aimed at the workpiece center face.
Still some machine covers at powder coaters, and when that's done the machine is 'ready' to use...
On the software side, My good Wife has modified much about Linuxcnc's basic setup to make a really nice user interface, and with features that make the machine user friendly. I looked at the many 'available' screen MMI options out there for Linuxcnc - some very fancy looking ones, and after detailed investigation decided they are of little use. They tend to be flashy, many buttons and LEDs and options, dozens and dozens..There are 'nice' tools to allow the screens to be easily modified and changed, but likewise, I found that it took days to understand what the creator of that screen had done, what the buttons did, how they tied into Linuxcnc, etc, After writing up a spec of what I wanted on a display, info, buttons, etc, it was clear that these screens were a waste of time they were so much eye-candy, done because the creator could...I bet none of those creators actually ever used one of there creations in a working machine environment!
In addition, there are wonderful incompatibilities between the screens ( the language they are written in, Python2) and Linuxcnc Vers2.9, which ONLY works with Python3 addons, etc. Lcnc vers 2.8 is the current 'formal' release, but does not have any of the kinematics and features I need for the C axis / live tool on my lathe.
So, My good wife modified the vanilla Linuxcnc AXIS screen definition, down at Python3 level, and we have a very nice screen setup... As soon as the powder coated stuff is back, lathe assembled, etc, videos will happen!
On the CAM side, I found a package called KIPWARE :
Kipware CAM sofware
Which is a conversational CAM tool, works very well, can do my Live tool / C axis with little effort, and allows easy Gcode generation for all basic lathe machining operations. The Company is 'glitzy' and sort of sticks in my throat, the product presentation is also a little garish, but it works and the price is not bad..
That's it for now.
Progress on the lathe enclosure was somewhat hindered by the holidays - Powder coaters , Perspex suppliers, FESTO piping/stopcock suppliers, LocLine suppliers, etc, all insisted on closing for the holidays...
Some have opened, some have supplied and so some progress has been made. Getting close now...
The Splash.Swarf enclosure is complete. All the Metalwork is done, painted and together. I used 6mm perpsex for the window ( no sanely priced 'flexicrylic - the non-shatter stuff - available in Southern Africa - R4700.00 for 2.4Mx1.2M, the smallest available)
This required a 38degree bend in it, so I mad a supawood jig and heat-bent the perspex with a heat gun. That worked very well.
Heat gun heater..
The bent sheet.
Handles fitted and cover located on Enclosure window.
I have to split my post into 2 or 3 it says - 1450 words to many - WHAT??? Don't mind this forums software to much, but this gets me every time and it irks me - there are not even 1400 words in the total post...
|Thread: shaper cross feed|
And the not so big boys too...
|Thread: EMCO FB2 side milling issues|
YC indicates that a good finish is obtained in X so I would think that to a large degree eliminates feedrate issues, cutter type, etc. Kiwi Bloke's comments should be investigated methodically. Make sure the four bolts clamping the column mount to the XY table base are tight - likewise the two clamp bolts that close the split in the column mount.
I run my FB2 with the gibs perhaps a little tighter than most - grab the Y table at its ends and push one end, pull the other - there should be no deflection. As KiwiBloke said, the geometry is an indicator here - make sure the slide on the column is really tight - perhaps for testing, release the grub limiting screws on the column slide ( they assist in setting the 'gib' effect when removing play on the slide to column interface) and tighten the two bolts that close the slide split so that the head cannot move. See if the finish improves? Likewise lock off the quill so it cannot move.
|Thread: Milling collet choices|
I use ER collets. However, my mills are small so cutter sizes are limited. That said, I do occasionally use a shell end mill , abt 45mm diameter, that has a 14mm drive shaft - In Ali I really have to tighten the ER25 collets up on that shaft, I mean really tight, A good DOC sometimes would allow the shaft to slip in the collet. An ER32 collet would probably do better. The bridgeport is a much bigger mill, with more power, and I would think R8 collets would be the way to go. Cost more I suppose. ER collets have limited contact length, but are convenient for quick changes.
|Thread: EMCO FB2 side milling issues|
Says I need a Login to see your Photo's YC...
Perhaps you can put them in an album on this forum? I have three FB2's....although one has a J&S head. The other two are original, except for one being CNC'd.
I obtain very good finishes in Ali with with greater DOC than what you have attempted, so you should be able to do it easily.
What does it sound like when cutting? Just the normal load gearbox/ ( esp at 2000 rpm..) Have you tried lower rpm?
What happens when you vary the feed speed? How is the cutter held - ER collet, Morse taper shank cutter? I have an 'abused', now replaced, FP2 quill where the morse taper for about 25 to 30mm from the mouth was badly damaged, as though the previous dolt-owner had not pulled up the taper and so it slipped, or had crud embedded, etc. ( its a long story..) This resulted in a morse taper inserted showing some side wobble under load - how does your quill taper look?
The obvious things are taken care of? - cutter edge quality, workpiece stability, etc?
would like to see the photos..esp the vise type,height, X and Y construction, etc.
|Thread: XY Table, or XZ gantry?|
Makes for a concise and neat structure, and can be very rigid, but there are some non-trivial issues. Rotary table backlash is difficult to eradicate, and does not stay so for long - eliminating backlash in ball screws is easier. And then the software is not simple - you need good polar kinematics, with all the issues of the ArcTan near workpiece centre of rotation ( requiring very rapid - instant- rotations of the table as the cutter passes centre). I have just done this with a C axis / live tool implementation on a lathe, which IS simply an XZ mill with rotary table, on its side...It was painfull
I would not go that route for a 'simple' mill. Not to mention Linuxcnc...
An XZ gantry works well for such use.
My 'engraver' - very sturdy - table is a bit bigger than A4 size. Table moves in Y. Machine weighs around 36kg.
Peter - this looks interesting - the gantru appears bolted down so I assume this is the operating construction - interesting kinmatics here with a linear angle transform. All perpendicular cuts require angular transforms...
Edited By Joseph Noci 1 on 28/12/2021 06:26:04
Edited By Joseph Noci 1 on 28/12/2021 06:26:59
|Thread: CNC Lathe Scratch Build|
Thanks Baz - I am enjoying the building, but it does become a bit much sometimes...
I suspect my 'code' won't make it anywhere - its is not really universal - the C axis is very specific- using a powerful step/direction servo motor ( not stepper, and not true servo- it is closed loop servo, but closed internal to the motor, with its own servo driver, encoder, etc). The ATC is also unique/specific and so the polar interpolation mode integration is likewise somewhat specific - the math not so, but the glue is rather.
The C axis, ATC and a few other bits are Hal compile components, and will never be considered mainstream Linuxcnc code to be integrated into master. Also, a large proportion of the tricks is also all in the INI and HAL files...
So, probably not - just another one of those 'brilliant' glitches in life...
I admit to not having made progress with a probe setup.. I have only just got to grips with Lcnc's rather cryptic description of how to set up tool offsets...And as the ATC can host 8 tools, I use one master tool (facing roughing tool) , set its offsets accurately once ( painfully) and then set the othesr in reference to the master, also painfully.
I need to get the machine done so I can use it and discover how much of a pain it is with future tool setup..A threading, parting, facing/roughing/finishing and triangle tip should cover most simple work without changing tools - the others are drill bits, two fixed boring bars, center drill and live tool.
The Polar mode for your laser engraver is good - just be aware of the Atan issue near center - results in rapid rotations of the rotary axis, sometimes 'instantaneous'...Clock face periphery engraving is no problem!
There are many polar 3D printers, cheap too, that work like that - a rotary table/disc with a linear arm plus Y axis. Maybe get one of the better ones of that type and hack it?
|Thread: a gluing quandry|
As was mentioned, you wont get all the glue out from the joint no matter how hard you can clamp it - also, other effects then apply as well - think what happens when you wring two gauge blocks together - almost impossible to pull apart, and there's no glue..
|Thread: CNC Lathe Scratch Build|
Still No video of the lathe doing some Live Tool Stuff...
I had more than enough of LinuxCNC , and all things Linux, for a while....So am tackling some of the many bits still to be done on the lathe - Coolant pump and piping, Swarf/Splash guards, etc. Coolant is a bit of an issue on a CNC lathe like mine - The tool changer does not incorporate coolant feed pipes for each tool, like the big CNC machines do. I will have one spout, and that means the coolant is sometimes aimed at the wrong place. The spout can be set up reasonable well for most facing/turning/threading tool tips - they are more or less in the same place when selected, give or take 10mm or so. However, a drill bit, boring bar and the live tool center are not so simple. So the Spout has to be 'fixed', ie, does not travel with the carriage, but aims at the workpiece and must really flood it. I also intend to use a positive displacement coolant pump to have good pressure to blast swarf away...
Coolant will be neat cutting oil - Castrol Ilocut™ 510 MP, a chorine and heavy-metal free, multi-purpose neat cutting oil. It can also be used as a hydraulic oil confirming to ISO 6743/4 Type HM, so I wonder if using a thin hydraulic oil is also possible?
So while the design concepts for all that brew, I continued with the Splash guards. This encloses the lathe entirely, to be fitted with a perspex front panel for viewing. I cannot get the flexible acrylic matl in Southern Africa, so Perspex it is..
Also have to think a bit about lighting internally - IP66 lights don't exist here...
The Guards so far-
Edited By Joseph Noci 1 on 13/12/2021 20:56:05
As each hurdle is overcome, another looms large...
Polar Kinematics are fully ensconced in The Lathe's Linuxcnc controller and working very well,
I believe all the major Linuxcnc issues are at an end, with only a few minor things to still fiddle with.
My Good Wife has again proved to be a Star - She decided to work fully with the Linuxcnc source-code since we had some show-stopper issues in machining 'Polar' parts - She eventually found a bug in Linuxcnc, and the Developers agreed and fixed it! So we now have a fully working C axis Live Tool Lathe!
Tool offsets are all implemented and working. The fun started when I began to machine test pieces. I did a simple hexagon on the end of a 40mm OD plastic bar, and a U shape across the face of the same sized bar. The U shape is particularly challenging as the milling cutter approached the center of the bar - at that point there are small movements in X with large C axis Rotations.
The first result of the machined U ...
Around the centre the cut lines have a 0.2mm deviation - they are parallel, but offset.
This was due to tool height, 0.2mm below spindle centerline.
This photo shows the 8mm milling cutter cut a slot part way through the bar face, then withdrawn and then the bar rotated 180deg in the C axis and the cutter then brought in again.
The cutter cut 0.2mm low each time, hence the offset seen below.
The ATC was then raised with 0.18mm brass shim - still a tad low - and another U machined.
This shape made sense and showed that the Live Tool X offset ( G54) was in excess by 0.3mm / 2 ( since the Gcode for these modes are always in 'Diameter Mode'. This clearly shows that the left and right ends of the U are almost at the correct heights, since that is related to tool height and not to X position, while near the center, at the bulge, the C axis is almost at 90 deg, ie, the U sides are vertical, and so X offset plays a big role.
This error in X offset ( since all tools are referenced to the master tool in station 1) is due to an error in tool-1 X offset because of poor Homing repeatability and accuracy. I use Hall effect sensors, and extensive tests show no better than 0.2mm spread in detection. So the sensors have to be hugely improved.
Sorry about the crappy red text - it says the bulge is due to the X tool offset error of 0.2mm
I then machined the U again, but this time setting the Live tool offset AFTER Homing, ie, eliminating the Home deviation - this could be done each time the machine is switched on, then home would not matter, but that is a pain...Good Home sensors are imperative.
The left side of the U shape below is about perfect. The right side not so much... Further investigation reveals that it is actually the bottom right of that edge that bulges out - and that is due to not-so-good resolution on my C axis encoder - 4096edges which gives 0.08deg, with a servo deadband of 3 edges which is 0.24deg accuracy at best, with an additional 0.08deg on top of that for position repeatability. So, I need a much better encoder - 8000 edges or so..2000 pulses. The Hex is off course much better, and much easier to achieve good results - the C axis encoder contributes less error since the x deviation versus C angle change is never as disproportionate as when the cutter is near bar centre. The hex is actually very good within 0.02mm in dimensions which in plastic is not bad.
In polar/Live tool mode, every little error has to be fixed, any play, offset, etc is critical, and tool height is King...
Will try do a video of the lathe cutting stuff in Polar with the live tool.
EDIT _ get rid of grinning smiley's...
Edited By Joseph Noci 1 on 18/11/2021 17:17:26
|Thread: Feed trip electronic|
You don't need a second encoder - lets take a look at the basics of most ELS systems.
Using an ABZ encoder which has an A and B quadrature channel pair , and a Z or index channel is how most ELS systems do it.
The index is used by the ELS to sync the leadscrew stepper so the threading tool enters the workpiece at the same place each time. So it does not matter where the tool tip is placed in relation to the work piece - ideally it is position a few thread pitches from the thread start. But is does not have to be the same position each new threading pass. So you could set it say 10mm from the start, do a pass, then return and stop say 5mm from the start and it will still be OK. As long as the halfnuts are kept engaged, the ELS will wait for the index pulse, and then in the space leading to the thread start in the workpiece, it will accelerate the leadscrew stepper such that the leascrew is at the correct speed ( for the spindle speed and chosen thread pitch) and at the correct position when the tool tip enters the workpiece.
The AB channels ( you can get away with only A in you never thread in reverse..) are generally a high number or pulses per spindle rev - around 2000 to 4000 or so pulses. These pulses are used to generate the stepper pulses ( and pulse rate) via a divider or via Bresenham's given the desired thread pitch and spindle RPM, which is measured by means of said encoder. Likewise, it does not matter where the thread end is - you only need it to be in the same place each time , esp if threading to a shoulder.
In reality is is a simple task for the ELS to keep track of the thread end, thread start, threading in process and threading done mechanisms, so having hards stops, or any other form of stop is superfluous.
mine works as follows -
Set tool tip at thread start point, say 6mm from the shaft end. Press Thread_Start. Jog ( Via ELS button or handwheel) the tool tip to the thread end position, press thread end. An led lights up, indicating 'go to thread start' Press button to go to start - carriage rewinds to start. An led lights indicating ;Start Threading'.
Start the spindle, press 'Start Threading' button, with depth of cut set.
Tool reaches thread end, carriage halts. Retract tool, prees 'go to start' button, carriage returns to start position and repeat.
I use a jog wheel to set the start and end points and to select thread pitch etc..
Threading with ELS can become 'boring' - no more butt_clinching, so it needs to be simple to use, no complex settups, etc - all so you don't get sequences wrong cause you are thinking of other things..
ELS is long narrow panel below the DRO.
This is the same ELS system, fitted to my smaller EMCO lathe.
Do you mean a physical stop, ie, a forced hard stop? There is no technical reason you cannot just do that - most useful ELS's allow the user to set the thread start point and end point by various means - start and end by jogging to those point and indicting start and end, indicate start and number of threads, etc. The one I designed I jog to start, press start button, jog to end and press end and then go. But, I could set the start point, and then set the end point say 100mm down the shaft, while I only want a threaded section of 10mm long. I could then place a feed clamp on the bed at the 10mm position. When the carriage hits that, the stepper will stall and you stop the process, go back to start and repeat.
You do need to size the stepper and it's torque carefully though - it must stall gracefully and not wind up the leadscrew...
The system will always self-synchronize - it uses the index pulse on the spindle encoder to know where the carriage needs to be in relation to the thread start point.
The value of CNC'ing the lathe depends on your needs - most often, if it's your only lathe, it's then a pain as every job you do needs the computer turned on, you need to create the G code - for it to be quick and not an impediment to small off-hand jobs you should have a really good conversational CAM package to generate the Gcode. Also, if you don't use it that often, memory will make it more frustrating as well. Its not the same ease as chucking a piece of shafting, taking a cut and measuring till it's right...
You can fit electronic handwheels to X and Z, but I hate them - they do not have the same feel by far, offer no resistance to hand force by which you judge the cutting force, and by which you 'smooth' out the hand feed, etc.Just rubbish, those handwheel.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.