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: Failed to get this digital clock kit working :(|
Probably the most sensible of all our rantings!
Doubt that R2 orientation is seen by the processor at all..
here is a crude representation of whats going on -
The processor drives open collector ( probably FETs, so open drain, but irrelevant here) transistor as shown. eight drive the A-G and D.P. segments of the displays.
4 drive the scan lines DS1-4
having looked more carefully at your schematic there is a qick test to see if the segment glow at all..will explain shortly.
So, assume VCC at pin 1 of the resistor network, ie, assume the network is inserted correctly..
Then current will flow down R1 (diagram below) through the 7 segment LED, IF the scan line transistor is on.
So, to turn on Segment 1 of display 1 ( say), as below, the A-G line transistor ( top one) must be OFF, and the scan line transistor ( bottom one) must be ON.
to turn a segment OFF, the processor will drive the top transistor ON, which pulls the the LED/R2 network pin to GND, so no current available to flow through the LED, so no glow.
Now, if you connected VCC to pin 9 instead of pin 1, then current still flows down R1, through the segment LED and the bottom transistor, BUT, it gets there via R8. Since R1 thru R8 are equal values ( 470ohm), half the current now will flow through the led, so half as bright. No other effects at all..
Now the test -
Remove the processor from the socket, power the board, and with a wire jumper, short one of the DS lines to GND. That should light up ALL the segment of one of the digits. Repeat for the others. You van see how that works - current can flow through all the segments since the top transistor is OFF ( missing), so shorting the DS1-4 line to GND provides the current flow path.
If NO segments glow, the display is faulty, or as I have had before, its a common anode instead of common cathode device...
It is reprogrammable FLASH chip - I am very familiar with it, extended Intel 8051 type device - did MANY projects with most of the 8051 variants , in assembler and C.. I have all the compliers and assemblers too...And the 'big advantage of the arduino platform' is no less complicated than any other method, until you know how...
But all that is moot, since unless someone can do it for Michael, I am sure he is not interested in getting down low with the code!
That will make a difference, but reversing the array only makes the segments glow at half brightness, and the decimal point will be messed - so it should still have shown something...You did check pin 1 of the processor..(Sorry Michael…
I do think you should try find a way to see if the oscillator is running at all..Borrow the neighbour's SW radio for 10 minutes.
Bit of a poor design inthe way it drives the led display, Michael. The processor sets up a 7 seg display code on the the lines A to G and then pulls one of the scan lines DS1 thru DS4 low. So, to show the figure 8 on display 1 ( left digits), lines A-G will be set HI . Line DS1 is then pulled low and all the segment LEDs will glow.. If DS2 is also pulled low, Display digit two will glow, etc.
What makes the design poor is that when powered from 5V, the 7seg leds will have about 4 to 4.5V across them, with a large current flow, all sourced by the processor output pins - not good for the processor at all!
I see when running from battery the supply V=3V, much better!
If the processor is not working , it will not be scanning the A-G lines at all. I presume you do not have an oscilloscope? If you do, check the A-G and DS1-DS4 lines - there should be pulse trains on them.
If no 'scope, just short one of the DS lines to ground - if the processor is scanning the A-G lines, a 7seg display will remain on during the short - this 'should' not damage the processor, as the DSx outputs are normally pulsed low and then go hi-impedance to not activate that display - They may however drive the output HI rather than hi impedance, so..
A neater way is to take a red led ( lower on voltage) and connect the cathode to ground, and the anode to each A-G line in turn - you should see it glow if the lines are being driven.
If not, there are two probable causes - The processor is not programmed, or the oscillator is not..To see if it is oscillating, first check carefully around the crystal, the two capacitors C2 and C3 ( are they really 30pf - can you see any markings?)
If visual is good, do you have a short wave radio? Set the dial to around 12MHz, and bring a wire from its antenna socket and touch the crystal metal can - tune around the 12MHz range till you detect the frequency - it should be very strong...
Let me know
|Thread: Sieg KX3 Y_Axis Skipped Stepper Steps😢|
G0 Z5. < Quickly.....
Many dozens of these in the Gcode file Nicola sent me...
Still think its a velocity/acceleration issue at high traverse rates, but I am normally wrong..
Actually, there are many rapids in X,Y and Z in your file , with the Y rapids the longest paths, so maybe there is still something there..
Do you know what the rapid traverse rate is set up for?
It is just a bit confusing from your descriptions though-
It's on the second passes that the penny suddenly dropped. The endmill is not touching the -Y side but cuts heavily into the opposite side, +Y. It can't now be workholding, maybe the steel is being stress relieved during milling?
Using a dial indicator before and after air cutting a job instead of the stock, it seems the Y axis is out by a massive 0.20 - 0.30mm.
Job finished. Y is off by -0.25mm.
JasonB, when the dial indicator I set up is indicating zero, the ball screw has returned to its mark. However, in Mach3 readout it's off by 0.25mm. To me that means the ball nut is fine, at least
I put this in a loop in a text file and ran it 200 times at F250. It didn't skip a single step, or didn't accumulate lost steps.
This implies that you don't lose steps, but that the machined parts is incorrect in Y, and when you don't loose steps the MACH3 DRO shows you are 0.25mm out....
It is not possible to move a fixed distance while not loosing steps ( Confirmed by DTI) but Mach3 DRO show 0.25mm still to go...so nothing sensible here...
Your G code file has X/Y moves in the 30mm range with many XY rapids - Maybe try John's file thus:
Set a round rod in the chuck - say 10m OD and place in table center - zero all axes,
Set the DTI on the table , up against the rod at the diagonal of the square in the MDI text below and zero DTI, then run the MDI text below ( Run the file first to be sure which direction to place the DTI so you don't crash it!)
G91 (sets incremental mode)
Run that say 10 times and see that the tool tip is back at zero, and that the DRO says 0
Very strange behaviour if none of those fixes sort it out! I suppose it could be a Stepper driver failure, but I doubt it.
Nicola, I am not sure I understand your axis direction - If the table is moving away from you, its the same as the table remaining still and the head moving toward you - that is Y -Ve direction, not +Ve...
Not really important here as it still has no bearing on the problem..
I doubt backlash comp has anything to do with this - backlash comp is a symmetrical function and would not create such asymmetry.
Nicola, if the G-Code file is not to big would you care to post it here?
Are you using MACH3 or UCCNC software with the UC300ETH?
Are the X and Y steppers the same type, ditto the stepper driver modules?
Are the two driver modules set up the same way, dip switches, if any, etc.
Some drivers can be set to go Half Current in the steppers during short pauses in moves, which when driven in microstepping mode can lose micro-step position within the native motor magnetic detent step - if that accumulates it can result in an accumulating step error. If your drivers have such capability, disable it.
I would also suggest checking the stepper pulse train definition setup in the software - MACH3 and UCCNS both have a section where you set up the dwell period between stepper direction control change and the beginning of the next step pulse train - if that is to short for your stepper driver, it can result in lost steps. Likewise, the minimum width of the stepper pulse train can be set up as well - I would make them not less than 5us, even go for 10us, for your kind of setup. At least make sure the Y axis setup is the same as the X Axis.
From your description is seems the Y axis is loosing steps in the -Y direction, biasing the cut to the +Y side. Does the part you are cutting have any rapid Y moves that are more in the -Y direction than +Y? If so , could be that the Y max acceleration ( or velocity) setting for the Y axis are to enthusiastic. X has to move only the X axis, vice and workpiece - Y axis moves include the whole X axis, vise and workpiece, and the Y axis mechanics.
|Thread: Magnetic swarf|
Irritatingly, I have had chuck jaws ( the hard type) become magnetic and then it's a pain clearing the fine swarf from the jaws when inserting the workpiece. Likewise tool steel lathe cutters, and some milling cutters and even the hard steel capscrews in the tool-holder. This only occurs in the hard steel bits on the lathe - I have never had issues with the lathe structure. I am not sure how, for example, the chuck jaws, become magnetic but they do so repeatedly. I demag all the bits with a homebrew demagnetiser, and all is well for a few weeks. There is that high-school science trick where you align a hard steel rod say North/South, hold it so and smack the one end with a hammer a dozen strokes - it becomes magnetic - maybe I should stop smacking the lathe so hard....
|Thread: Issues 303 stepper driven rotary table with hobbing capability|
This describes basic operation of a hobber WITH AUTOFEED capability. It is easily understood from this which modes are not applicable to the non-AutoFeed mode type...
The Rotary Switch selects the various modes.
Each Mode may require the setup of some parameters, such as continuous rotation RPM, angular step size, No of divisions in the circle, No of teeth on the blank gear, etc.
When a mode is selected, the JOG encoder is active and used to set the required parameter. The SET/ZERO switch enters the parameter as the active such as number of teeth in hobbing, angular step size, number of divisions to step, rotary table rotational RPM, etc
The JOG wheel increment size on the display can be increased by xN (N depends on your encoder PPM..) by pressing the MUL pushbutton and rotating the jog wheel. Useful when big increments are needed.
Your Hobber, rotary table, may have different gear ratios – these can be adjusted.
Rotary Switch selections:
5.1 BLANK JOG
The BLANK can be positioned as required by pressing and holding BLANK JOG, while jogging the blank with the JOG wheel.
5.2 FEED MODES
Since there is the option of Auto-feed of the cutter advance, the feed mode also needs to be set up ( Position, rates, auto/manual)
To position the cutter in relation to the blank, ie, almost touching, ready to cut, press FEED POSITION and use the JOG wheel to move the blank and cutter into the correct relationship.
5.2.2 FEED RATE
To set the feed rates ( in mm per blank rotation) press FEED RATE and use the jog wheel to set the value.
5.2.3 FEED MODE
The feed mode can be AUTO or MANUAL or NONE. This is selected by repeated presses of the FEED MODE button and will show on the display.
188.8.131.52 AUTO MODE
The feed will proceed in the selected mm per blank rotation and starts when the hob spindle starts running.
Pressing ANY other HOBBING mode button, eg, BLANK JOG, FEED POSITION or FEED RATE will immediately CLEAR the feed rate to NONE and if in AUTO-FEED, FEED will STOP – no AUTO feed will take place and the JOG encoder will not cause manual feed. Use FEED MODE to re-select the desired feed mode.
The FEED Mode can be changed on the fly, with the machine running or not. This allows manual take-over of feed, or AUTO from manual, or change of feed rate, and then back into auto, etc.
184.108.40.206 MANUAL MODE
In this mode the JOG encoder will drive the FEED axis Stepper. The JOG wheel is disconnected from ALL other functions and only generates FEED increments. Pressing ANY other HOBBING mode button, eg, BLANK JOG, FEED POSITION or FEED RATE will immediately CLEAR the feed rate to NONE, and the JOG encoder will not cause manual feed.
The FEED Mode can be changed on the fly, with the machine running or not. This allows manual take-over of feed, or AUTO from manual, or change of feed rate, and then back into auto, etc.
Gear Ratio Selection.
For those still awake, and interested, let me know what else you may need - greater detail etc is probably best by PM or emails.
This will take a few posts as I will be limited by number of characters/images per post at some point...
My previous postings on this subject relate to a 7 segment LED display array version of the front panel - this changed to the present version using an LCD ( as in the MEW article)
There are two versions of this setup - one is for rotary table controller type applications , including a hobbing function, and the second ( as done for Paul White) is more for a hobbing 'machine' in that it provides control of a stepper for the blank feed into the hob. This could be used for example on a mill, with the hob encoder fitted to the spindle, hob in the spindle, a stepper fitted to say the X axis for feed, and the rotary table placed on the mill bed feeding into the hob - ( see my photos and video in the previous posting to see the basic setup)
To re-iterate, the unit is based on an STM 32bit uP, using a NUCLEO module, similar to the Arduino type modules.
The right hand section is a USB based programmer for the main CPU, center/left. Open source ST-LINK programmer software from the STM site is used to program the module, on a windows PC.
The circuits follow - note that resolution is limited in the size image I can paste, so some areas are repeated , zoomed in, for better viewing.
Circuits for the Hobber WITH FEED controls:
The pushbuttons with blanked text at the bottom are repeated next , zoomed in.
Circuits for the Hobber WITHOUT FEED controls:
This is the Display Interface, common to both Hobber types:
This is a typical Power supply for the unit - no part numbers since you can easily make do with what may be available to you:
This is a sample front panel for a unit with Hobber AUTOFEED function
And this for a Hobber with MANUAL FEED function.
This shows the basic interconnection between items in the system: PSU, Hobber/Nucleo controller, Steppers, Spindle rotary encoder, etc
The un-modified rotary table at the start:
And the stepper fitted.
It is simple to change parameters in the software to cater for stepper pulse/rev, stepper to table gear ratios, table worm ratio, etc.
Next post, the basic operation...
What I can try is post some detail here - some circuits if they appear legible, wiring diagrams, etc, and some details on mechanical concepts.
I will also try to provide more detail on how it works, and maybe post the user manual in some form.
Interested folk can then maybe see if they wish to attempt this and then I can mail PDF's and source/binary code as needed.
Unless there are better ways of doing this, I will try do post some info in the coming day or two..
He saw and here he is...
Always a trade off with articles like that - to make it a DIY construction article would probably occupy two or three magazine editions and would perhaps tend to bore most folk. It's not really fair on subscribers to pay for the magazine and have heavy, possible uninteresting content, occupy many issue perhaps? I would not know..
Anyway, I don't really see the need for frustration - as Jason indicated I did do some posts which show in some detail what you would be letting yourself in for if you wished to build something like this, and I generally am around these forums and happy to assist any wishing to give it a try! Paul White, another UK forum member was actually the motivator for this - to build an electronic hobber, and so this was born and Paul did build and use it.
I can provide circuits, C source code if you wish to modify/roll your own, or binary code to you requirements ( within practical reason!) etc. My Wife is the software boffin behind all this. We do not use the Arduino development / compile, etc environment - it's to tacky for our way of working - so we use open source tools on a PC. The code runs on an STM32 microprocessor, on a NUCLEO module - very similar to the arduino type modules, but 32bit and much faster. So all interested let me know how you wish to go! All/most of the bits should be available from RS, Digikey and Mouser, and other favourites you may have.
The unit is not complex, but you need to be able to read a circuit, solder some electronics, deal with LCD character displays, etc, albeit at basic levels.
Can be via email, or on the forum, whatever works and very happy to help.
|Thread: CNC Lathe Scratch Build|
The 8mm teeth were just a modelling test - far to tall. What is the actual contact height ( axial height) of the teeth in your design? Around 3mm? - 4mm tooth height with what seems to be about 1mm between tooth crest and opposite trough?
What sort of milling cutter did you use? seems to be an angled cutter with a carbide insert?
The rotary table seems to be horizontal, so cutter is angled.
How did you do 'full pass' machining? Milling the flank of a tooth would require the cutter to be offset , say, to the left of the tooth flank, and then past the tooth, to the center of the disc, where the offset would need to be shifted to the right of the flank of the opposite tooth ( the tooth @ 180degrees).
I glibly thought to use my shaper to do full pass cuts - Not Possible!
Edit - text changes
Edited By Joseph Noci 1 on 26/04/2021 22:08:30
John, to be honest, no..
I did play around with a number of ideas, but there is still so much on the lathe's mechanical side to resolve ( and get on with!) that I was not fully applied in the experiments!
One idea which showed good promise I do wish to pursue - I took apart an old hand held Piezo gas igniter stick thingy - it had an obelisk of piezo in it - about 4mm square by 25mm long with a silvered cap at each long end. A scope attached showed a 8 to 15 volt spike, with the slab on a wooden surface and very gently tapped in the center of the slab using a tooth pick. I think this fitted into a contact probe for side and end touch detection has good promise!
Too many things on the go...Also busy upgrading the CNC mill, which I need to make the ATC tool plate, etc..!
I had approached it from the periphery rather that the flat face - drew the side view of the disc peripheral 'teeth' and wrapped it around the disc, but extruding it was a mess! your way worked a treat. here is a quick hack - as you say, now to juggle with teeth height and angles, etc. The teeth in this hack are very tall - would require 8mm movement to clear, but proved the extrusion technique.
The loads in my case are perhaps a little less since my stock size is limited to that of the 5C collet max opening.
Since loss of air pressure stops the job regardless, would it not be easier to reverse the role of the cylinder? Let the air pressure close the Hirth, and a lower effort spring push the Hirth open when the air pressure is released? I am contemplating a double acting cylinder to do both functions but maybe that's a road to hell...
Thanks again Ross - you have been most helpful!
Edit - added text
Edited By Joseph Noci 1 on 26/04/2021 09:35:53
I don't find a specific paper at that URL - it appears to just be a general search on Hirth using Bing? I have seen about all those items that appear on that search page while searching previously using google.
Most of the 'slightly' mathematical or more technical descriptions that I have found also describe the more conventional coupler, ie, where the teeth are fully formed triangles ( with tops slightly flattened for clearance).
I have not found any design detail on the type as in the images above from T.B / Ross.
Edit - there is a paper in there..I have seen that one - by a group of Italians - University Bologna - but lacks design info - focuses mainly of tooth shapes versus load bearing capability..
Edited By Joseph Noci 1 on 25/04/2021 07:38:09
T.B / Ross,
Why am I battling to model the Hirth coupler on CAD??!! It looks so simple! I have dug through all the Hirth sites I could find on internet, ifinding some pretty tools where you input the parameters ( no of teeth, angle of teeth, etc) and it generates a pretty 3D model, but have not found any sensible Mathematic or geometric explanation!
Have you some pointers for me?
I don't think its overcomplicated - perusing in some detail shows little room for simplification...I suppose the design could be flipped - place the stepper drive pulley inside the housing and the air cylinder on the right , outside - this may permit use of some variant of commercially available air cylinder? But that brings all sorts of other complications which brings you back to the same amount of effort anyway, in addition to the unit growing in width, etc!
Ross, the 5C spindle is a story on its own - I did cover its birth early on in my series of posts, but possible did not highlight the compromises I endured because of it!
First, its size was again limited by material availability - the spindle end up being machined out of a piece of Caterpillar side shaft...which was rather short...In addition the headstock was made from a chunk of aluminium on hand..which was rather narrow...So the space available for bearings, oil flingers, labyrinth seals, etc, was very limited. These combined bits were what drove the dimensions for the rest of the lathe in its entirety - sort of the tail wagging the dog..
There is no room in the headstock for a conventional oil bath/drain hole at bearing type design. I bored rebates for the bearings and then through for the spindle shaft, and made a trough or sorts feeding the oil drain oil to outside ( for oil changes). The idea was to have the bottom 10mm of the bearing in an oil 'bath' - this level being way below the external labyrinth seals, and hope for the best - turned out for the worst! Works well at high rpm, but below 200-300 rpm it leaks - the flingers are not effective there.
As posted previously -
1 + 6 (blue) Labyrinth seals.End seals.
2+5 Oil Flingers
7+8 Drive pulley preload nut and conical pulley lock
9 encoder pulley
10 5c collet closer
If you want detailed drawings I am happy to oblige - but perhaps more to show how NOT to do it..
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