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|
Now that is neat, and the diagram is worth a thousand words. All the other posters 'hinted' at the concept but though I seem to be 'good' at what I am doing here, sometimes 'concepts' remain simply that in my head! Thanks for the info.
John, I seem to recall we conversed some time ago - maybe on the making/grinding of a shop made dovetail cutter?? Or maybe I am just blowing smoke again..The photo of the grinder seems to have triggered that memory.
So many diversions on this project..
Waiting for materials to arrive also delays things! The Bellville springs arrived - I installed and did a spring-load test which was fine. So now I wait for the steel shafting to arrive so I can make the need ATC main shaft with the through hole for the live spindle drive shaft.
And while on that subject, I started on the BLDC speed controller for the live spindle drive.
This is based on a small development board from ST - the board is about 70mmx30mmx12mm and can take a 45v supply and deliver up to 16amps to the motor.
Managed, with my Good Wife's help, to get a sensored, FOC control software suite running, and the motor runs so sweetly. A leather gloved hand was used to load the motor in tests...
At 500RPM, with 40VDC supply and 12amps the motor speed slows by 40rpm. Releasing the load ( take my hand away..) and the speed momentarily jumps by 70RPM and settles back at 500rpm - the jumps lasts about 300ms.
At 2000RPM, its a little hairier...40VDC and 14amps, the motor speed drops by 30RPM, and jumps by 45RPM when releasing the load - takes 380ms to settle. The PID is nice and tight.. Tests are very quick and time spaced - 40V/14A is over 1/2KW, so the glove, motor casing etc heats up fast when applying load by friction!
A few additions to the code still - a ON/OF control for the motor, so failure detection ( hall sensor failure, motor stalled, etc) so the LinuxCNC can know to not run the milling cutter into a workpiece while not spinning..
The controller underside:
One of three hall sensors fitted - 120Mechanical degrees apart, which works out to one sensor spaced four motor slots apart in the 12slot motor. The motor is 14poles, ie, 7pole pairs, so the 120 mechanical degrees equates to 17.1 electrical degrees. Sensors will be epoxied in place next.
Test setup...The Nucleo processor board lower left is just being used for the programmer part of it, to load the code into the BLDC controller.
The project certainly covers all bases!
Edited By Joseph Noci 1 on 16/08/2021 21:23:52
|Thread: Hole diameters for single point threading|
Thanks to all for the comments and advice. The cutter I am using is an 16IR-A60 carbide insert. The tip radius appears very small under the microscope - maybe 0.1mm ? Low slop was a poor descriptor to use for what I am trying to achieve and strength is not the concern, but good coaxial alignment is the main aim. I will make one or two test rings and thread for best fit...
I have tried to find methods of defining the hole size for a particular thread to be single point cut in the lathe.
This appears to always be based on thread engagement, which is influenced by the material being threaded, and the focus is strongly on tap life. So the hole is larger for aluminium than for a tough steel, etc.
However, tap longevity is not really directly applicable to single point threading, so does this engagement issue still apply unmodified?.
I am internal threading a mating part that screws onto a M1.25 threaded stub, 34.5mm OD. The OD is the OD of the thread on that stub. The mating thread will be in EN8. The thread section on the stub is 30mm long. There is not a great load on the thread when assembled, but slop needs to be as low as possible.
I would presume that I should therefore try to get as high a thread engagement as is possible. 80%? More maybe? I would assume that 80% or more should be easily achieved when single point threading? So do I just use 'ordinary' tapping tables and select 80% or better?
Most tables don't list a 34mmxM1.25 size, but there calculators that do the job - So one could just faff about till the part threads on in a good enough fashion but I don't particularly like that approach - some science (or engineering) is applicable! What engagement should I start with for the 'best' fit possible, including a little faffing?
|Thread: What Type/Gauge wire is best for soldering onto Arduino shields|
If its for signals rather than power, I use 22 or 24AWG 7 to 9 strands PVC insulation 'hookup' wire. 1mm I feel is far too large and in-flexible. Nothing more frustrating than trying to debug the project where wires break off because they are too stiff at the solder joint. Same reason I would not propose ethernet wire - they have only 4 or 5 thickish copper strands and break easily at the solder joint after some flexing. If you are sure of your wiring, and the board won't be manipulated, then I suppose stiffer wiring is OK, but that's tempting Murphy..
Duncan, here in Namibia, 'phone cable is single solid strand - I would not recommend that!
|Thread: Problems in bending sheet aluminium to a 90 deg angle|
If you have not machined flats on the edges of the angle, ie, the edges now holding down on the bend-sheet then you are going to get a large bend radius on the material and that radius is rather uncontrolled. Makes it difficult to work out any bend allowance and setback.. In addition, your setup won't easily allow for sheet thickness compensation - I suppose the big holes around the capscrews will have enough slop to move the angle about a bit to aid that.
Put those flats on and elongate the capscrew holes and use a thick (6mm?) steel washer under the capscrew head..
But I guess your bend job is already done!
|Thread: Accurate Clamping|
Actually, only one, and it was not running - doing its best to hide from us. Wildlife very scarce at the moment, after 5 years of drought. In 10 days we saw only the one herd of Springbuck, over 1000km of travel in the North West regions, two Gemsbok ( of the Oryx family), where 5-6 years ago a trip like this would yield 2000-3000 Springbuck, a few hundred Gemsbuck. etc...and the Lions are suffering - many have died from starvation.. terrible situation the Wildlife are in here..
|Thread: CNC Lathe Scratch Build|
Ok, back to work...
Duncan, I think I follow your idea - makes sense and I will see down what road that all takes me..
This thing is certainly taking me down many a painfull track!
Still fighting the tool changer - still have not receive the Bellville springs from SA..
So I started think about the live tooling or milling spindle. The ATC is small, so not easy to incorporate conventional live tooling. I would like to have a radial and axial milling capability, but that means swinging the milling spindle around, and doing that servo-ed is not really feasible on the cross slide, space, etc. Manual swiveling is ok, since milling on the C axis is not done often. I considered 2 milling heads, at 90deg - the axial head can remain in place and will ( should..) not crash, but the radial head must be removed at times..all together a pain in the butt!
Then I thought if I made the axial spindle coaxial with the ATC main shaft, it would free up space in front of the ATC and allow the radial spindle to be fitted there somewhere.
And so the hack began...
The 9th toolstation was the ER20 Chuck in the ATC toolplate center ( see previous pics..) - the idea was to remove that, and fit bearings carrying an ER16 chuck, with the chuck drive shaft through the ATC main shaft, out the rear and driven by a BLDC motor at the rear.
The RED parts are the milling spindle and spin together. The Lilac parts are the ATC main shaft and are static, except when changing tools - they then rotate to new tool position, and slide left to clear the HIRTH coupler before rotating. On the right is the BLDC motor Bell housing ( contains the motor magnets) which is pinned to the 8mm spindle drive shaft. It is supported by the Bell Support Bearings ( Lilac). The Orange parts on the right are the BLDC motor Windings and rotor(?) core, on bearings, on the 8mm drive shaft. This orange section is constrained from rotating, by a sliding retainer ( not shown) fixed the ATC housing. The orange section, Red and Lilac sections are slide left to clear the Hirth coupler during a tool change.
The 8mm drive shaft has a free length of 132mm.
I have been trying to model what sort of torsional mode will arise in that section when milling - vibration, resonance, etc, but have given up! Very difficult to find data on milling cutter energy needed for an milling edge to cut say mild steel, given DOC, RPM, etc, etc..and then the resulting twist in the drive shaft, and release of that wind-up when the cutting edge clears, etc..
I cannot go larger than 8mm on that drive shaft - increasing means increasing the through hole in the pneumatic piston for the Bellville spring compression. That means less piston surface area and more air pressure needed. I am trying to stick below 110PSI - if you followed the discussion previously in my posts you will know the reasons behind said pressures..
The milling process is low key - not high rate of metal removal, etc.
The BLDC motor is a 400watt motor- 400watts for 60sec it says.. 250watts cont. The largest milling cutter would be 8mm, probably 6mm. The lowest useful spindle RPM would be 300rpm and the highest around 5000rpm. The BLDC motor is capable of 5000rpm at 45VDC supply.
Am I wasting my time???
Forgive my late response - I became a bit despondent with the project and gave it a rest - decided to go and play with the Pussy cats in the desert..Some pics..
I think I have the idea...The moving bits are the tool changer and then the X axis plate and slide bearings - the Tool changer is approx 6.4kg fully loaded with cutting tools, the X axis plate, etc, is another 1.4Kg, so a total of 8 to 9kg max.
Not a lot, so probably not worth the effort..
The ballscrew nuts are dual, adjustable for nill/low backlash. The Z axis is a 16mm screw, while the X is 12mm so I guess the aim would be to remove the constant load on the smaller balls in the nut on the X screw. It is probably academic as the lathe is the project, not what it will make..The lathe won't have a busy life so the X screw and balls probably won't wear much in the next 10 years!
However, as the project is so OTT, why not keep going.
Perhaps Hirth is a misnomer in this application? Certainly this coupler is flat, no cone involved - the convergence to a central point is the common line passing through that tooth flank slope midpoint. Likewise, the center of each tooth, on the disc's periphery, all pass through the disc midpoint, so all is aligned..And as certain, my English fails me hopelessly in my description attempts!
The best way to imagine it is perhaps to take one disc as a given, and press it into a flat slab of plasticine - both mate perfectly, both are flat, self centering, etc. How to describe the given disc...
The piston counterweight concept does look neat and appears quite simple. I have just done a pneumatic cylinder - the one inside the ATC body, and that was a lot of work! Also, as usual, finding seals and such is complicated here. I see some solutions in the Parker / FESTO catalogues, but I am sure they want both my legs for one..
We will see where this goes!
Thanks for the ideas.
Going to read all about air tank.cylinder pressure based counterweights - new to me, and seems that it will be complicated..
Ady1, I fear you have lost me..not sure what you referring to..
It is an optical issue - Here is a drawing showing the cut lines for the teeth - the sides are at a 60deg angle and the two par orange lines show the upper and lower part of the tooth flank - they do not pass through the disc center. The single orange line passing through the disc center is aligned with the midslope of the tooth flank. This thing was complex to make, and even worse to describe..
Still a few bits and pieces to be done on the ATC, swarf guards, etc, but most of the major effort is over. STILL waiting for the Bellville springs - seems I have to wait another 7-10 days, and pay some or other new tax...I am considering ordering from the UK - Will cost a little more, but at least I will get the goods! SA is done...
I have rough drilled out the axial tool holder locations to 19mm after centering in situ in the lathe. That turned out nicely. I will bore them out to final 20mm with a boring bar in the lathe chuck, but I need the Bellville springs in the ATC for proper location and rigidity.
Covers are made for the ATC drive belt and the lathe spindle drive belt - to be powder coated now.
The ATC weighs around 7kg. That is quite a lot of weight at a 45deg slope on the X axis. I am looking for some way to counterweight the X axis. A counter weight and pulley arrangement won't work as the weight would have to move with the Z axis and so flail about...I am looking at the possibility of a gas strut mounted in the plane of the yellow line in the image below - Anyone had any experience with such an implementation? Or any other ideas?
Edited By Joseph Noci 1 on 17/07/2021 20:54:03
|Thread: What Did You Do Today 2021|
Mmm, not true....Iroko is also known as African Teak or Nigerian Teak, definitely not Ironwood - in fact, there is no such thing as Ironwood, or an Ironwood tree...Poor usage of the term has resulted in any wood heavier than water being termed Ironwood, but there is no botanical wood named such. Iroko is native to the North African West coast and only resembles Teak - it is not Teak...
And, Iroko floats on water..
Dad was a Master Cabinet Maker, so I have saw dust in my Blood..
|Thread: Can auto darkening welding helmet capsule be restored.|
As Andrew said, probably the batteries, and most of these cheap helmets don't allow easy battery replacement - I had two such and did cut open the module - there were two lithium cells, in series, with the center tap also connected so seems like it used a split supply. Did that about 7 months ago, and this weekend the helmet is playing up again..
This helmet also has small PV panels, but as I don't do much welding, the helmet sits in a box so no sunlight and no welding UV and it appears the quiescent current is not insignificant.
I again replaced the batteries, but with two D Cells, duct taped to the top of the helmet..
|Thread: Amazing Active geared ball joint|
This is amazing!
|Thread: carbide insert tooling|
I presume that the implication is that these 'rubbish and fake bits' you refer to are of Chinese source or similar?
I must say that I cannot agree with a statement so general in nature..
I have purchased a small handful of those 'sets' - some of the 10mm. some 12mm and some 16mm square tooling. I have found sets with left and right hand complements, in cutting tool and single point threading tools. I have purchased from Banggood, Ali-Express, and one or two other Chinese sources as well, and I have not been disappointed with any of the tools at all. Perhaps there may be one or two types here and there that are dicey, but I have maybe 40 or so different tools and none are bad. I modify them to suit special applications as well - for my small CNC lathe the ATC requires the tool body to be 50mm max in length, so I cut them down as required. And the steel used is very good! A hacksaw feels like it cuts the tool body the first stroke very nicely, but thats because the tool just removed all the sharp peaks of the teeth from the hacksaw blade.. The steel is hard through, not just case hardened.
I would not be too quick to speak disparagingly of these tools and suppliers..
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