NickJ

Solder in a crimp connector? Some parts of the internet claim you will die of syphilis for such activities

Didn't @ajg193 make a steam lawnmower?

Bit of a Barry fix innit? There is corrosion allowance in the tank design based on whatever standard it is built to, so not really a big issue if you keep on top of draining and retire the tank when expired as written in the manual.....

0.9 is terrible for panel work, you need way more heat than 0.6 to get a decent weld which puts you right on the edge of burning through. ER70S6 is standard mig wire spec for steel.

Yeah definitely, while I don't want to spend my weekends shuffling jobs through, if its gunna take up half my shed it needs to be productive.

I use a diamond wheel on my dremel for tungsten if budget is the driver?

Saw that up at ashburton lakes a few years ago, dude driving had a massive smile on his face tackling a gravel road turn around. Looked massively bloated but impressive build for such a small chassis

Mate called asking if he could borrow a jigsaw to knock up some decoys. Jigsaw? Pffft, bring the corflute over.

Good point, i'm still basking in the glory of getting onto a 5 year standing DIY job, I shall remind her of the costs savings at once!

Making stuff! Last weekend I poked a pretty nasty scab The lower part of the frame lifted out in a soggy heap once the glass was out. The usual way to profile the required timber is to run it through a table saw only my table saw doesn't angle the blade and its in storage. But I have a CNC! Step 1) Take a picture Step 2) Draw around it using real measurements to calibrate Step 3) Assign toolpaths And munch So what could have been achieved in 30min actually took most of Sunday, what kicked hard was the clearance of the sub spindles, at full cut depth on the tool, there was barely 1mm clearance on the part, with the tool at full retract I had less than 2mm of travel left, this lead to some dubious manual code changes and many errors as the controller informed me the next move would hit the limit switches. While I have the new profile ready, the window is still boarded up. Also fired some ali through to make spaces for another project, it really showed up the play in the spindle retract mechanism, while its really nice having 3 different clearance heights, I will probably have to fix the spindle to gain more rigidity.

Cheap guns only have one emissivity setting so can vary wildly depending on surface, a cold black item can read higher than hot polished stainless etc. Expensive guns have full emissivity control but you can never be bothered to change it -Hold down 2 buttons in a sequence you can never find the instructions to remember. Easy way to get around this is buy a cheapish option and just place a small square of masking tape on the surface as a target, i've found it to be as accurate as you'd look for in such a device.

Servo tuning time.... So, how does a machine get from A to B? well, in basic terms you say hey, go to this location. In greater detail, imagine you have a tennis ball in your hand and want to get it onto a shelf 10m up, in order to get in nicely, the ball will need to go slightly above and come back down, this is called overshoot, not really a problem until you want to machine an internal corner, that overshoot will eat into the corner and not leave a sharp edge. The ideal path is to just make it onto the shelf and stop. There is an additional problem, in order to perfectly land on the shelf and minimise the overshoot, the max acceleration of the ball will be finite, limiting how quick you can get there. If we add brakes to the ball, then we can throw it much harder, bringing the ball to a stop in just the right place, hit the brakes too hard and you'll need a harder throw, get it just right will minimise input energy which is an obvious goal for machine life etc. For a machine, all these values are fixed in code so in order to find them we can either do really complex maths (which also needs many precise inputs) or we can force an input and look at the raw path it took to get there, iterating on initial acceleration and braking force until the error of reaching the desired position is minimised. -Now before I get much further one can go way further down this path, the above is a simple explanation and my methods are not exact, but get the machine working to a level that the residual error is less than other errors, ie no need to roll in too much glitter. How does the machine know where it is you ask? On the back of the servo motors that drive each axis is a rotary encoder that sends a signal back to the computer informing distance and direction, in this case, 8192 pulses per revolution, or one pulse for ever 2.5 micron of travel. The inputs I will look at are the position error "joint.0.f-error" in halscope, a handy tool in linux cnc to look at raw inputs, this output provides us with a simple calculation of position expected minus position actual, if we adjust the input acceleration and braking forces, we can iterate around to get this to a minimum. Starting values are hard to guess, thankfully I had the factory settings which where actually on the money for a conservative start. Round one, request a 5mm movement: That squiggly line is telling us we're close, but can it get better? Adding some numbers, in real rough terms, P = the initial throw, D = the braking, I = A helping hand to hold you on the shelf FF0, FF1, FF2 are new to me but I was advised to leave I, D and FF0 alone, add small amounts of FF1 and even smaller amounts of FF2 which should get us there quick. Before FF1 and FF2 are added, the value of P was increased until the drive went into oscillation then backed off to stability. After some iteration where I double or half the input and react about that these are the numbers I settled on for the X axis, once the changes are in orders of magnitude I accept good is good, hence round numbers. The result: The output is now scaled 100x larger and the error is now visible in relation to each stepcount coming back from the encoders, if we view the square pulse as 2.5 micron, the overall error is in the order of 0.01mm, on a woodworking machine, no worries. This was then repeated on the Y and Z axis to even better results: Y axis: Z axis was a bit weird, but I also had issues with the pneumatic counterbalance as it adjusted to grease in the raceways for the first time in 20 years, if it shows up in machining I may look at these again, i'm betting its not going to..... All the above tuning took me less than an hour, by far the hardest part was finding the correct inputs for the scope, searching google for information is a nightmare, so many Barries harping on for 45min+ on youtube but not distilling the required 2min of info or reams of data sheets written by software engineers (fuck know what methods they communicate in). Once the inputs were confirmed (Cheers Andrew, again) I could dial in on the signal, getting gain/zoom correct, moving forward.

Really wish half the "Engineers" I come across would spend a week with you (but you don't want this) What you achieve with basic tooling they spend weeks trying to draw with every CNC under the sun at their disposal. Very simple work holding and robust strategies, such a pleasure to read and follow.

Ooh, which model? Pics? Andrew has been a massive help with mine (Author 503) getting me up to speed with linux and the Mesa boards, its all up and running now but I still expect fine tuning on the axis scales as i've only calibrated them with a tape measure.

Nah not me there sorry, but I do have access to machines that build such fun things if you have an overly excessive budget.

I am greatly impressed by your perseverance and those subframe bolts are a thing of beauty!

As per previous post (and my partner's disgust) I have successfully carved the official OSCNC test pattern: This brought forward many answers, firstly the original machine coordinate system puts Z+ as moving down, this is a right pain so needed a swap on both Y and Z axis direction to get everything happy. Also found the air blast works really well at scattering chip around the workshop, once things progress further i'll re-install the vacuum hoods. And not so fun, while cleaning out the X axis pulley housing I found cable ties holding the drive cable plug, uh-oh Seems this has had quite a crash at some stage, busting both plugs, replacement cost hurts but have a pair on the way, really don't need that shorting out. for now its carefully back together with additional zipties until parts arrive. And it turned even worse after that, in an effort to clean up the housing better I pulled the ballscrew out, turns out it should not have been pulled out in one piece, the smaller diameter is meant to go out the other side, this took most of Saturday morning to rectify, but everything is clean and back together. Belt is pretty standard AT-10, pic here for reference if needed.... And to finish on good news, walked the dog past Anton's house this morning for a catch up and he lent me this wee toy Beautiful Soviet era tachometer, this confirmed my speed was out by a factor of 1.2, after some digging, I found LinuxCNC is limiting max speed to 10,000rpm, so far I have no idea why, but have scaled back the output voltage to 8.33V@10,000rpm which when asking for 2500rpm gave 2500 on the dial, awesome

Whats backlash? Spent the day digging further into the greasing issues, pretty sure its now getting everywhere, lots of black gunk spewing out onto the rails and its much, much quieter! still have quite a list to do before full operation, but yeah, could start smashing out cabinets if the will to CAD them existed.

Oh my……

According to the spec sheet for the machine 18,000 rpm, one explanation i’ve been given is 12,000rpm full load and 18,000rpm at reduced capacity.

Continuation of roadside sharns sounds like a good idea, i'll get in touch later this week.

This is the nameplate: That aligns with our best guess of 2 pole. 4 pole would put everything out by a factor of two right?

VFD - Settings confirmed as all wrong, but not terribly so, but with "better" numbers the external tach is now all wrong, while I didn't get my head around the external output settings that feed it, for now I'll let it be until I can get my hands on a hand held tach, unless someone has a fancypants way to work out the number of poles if its not on the nameplate? Currently set at 2 because thats what it was and it turns........ Managed to spin up all axes again and get each one to home on the limit switches, good learning here, setting home as zero throws errors cos it trips the switch, moving home position to a nominal offset cured that. Also found a few of the limit switches not quite in position, so fixed them too. All Green! If I was so keen, the controller would accept and run a program In reality this puts me servo tuning away from using the machine, in true procrastination form I dug into the pneumatics... Spilling the wires and tubes out from the head I set up a test manifold to find out which solenoids worked and which were NFG. Expected result, more bits dumped in the bin Thankfully I was left with 7 operational 5/2 solenoids, a few other shuttle valves and a mountain of various fittings &hose, these were set up on a manifold and re-installed to work the tool change on the main spindle. All of this^ is now this: Not being one to leave a chance to test, a quick switchboard was thrown together linking the above solenoids In what I can only amount to a miracle, I somehow managed to get the polarity of the air lines correct allowing removal and insertion of a tool holder first time, while it was only manual, it gives me hope that if I can sit down with the ladder logic side, I should get tool changing on the functional list (Of course its not this easy, there are many interlock switches to monitor making sure everything is correct ie tool correctly loaded before 10,000rpm etc) The tool change was also horrifically violent, must re-adjust the needle valves. So, limit switches, homing and tool change. Time to sculpt? No, theres still more distractions! Enter the auto-greaser.... I personally hate these things, experience tarred from older, mistreated farm machinery where blockages cause dry joints and days disappear in feeble attempts to unblock lines or work out which orifice plate goes to which port. But, when they work, life is pretty darn peachy. Using the valves assembled for the above air tests, I soon found the pump wasn't building pressure, a quick loosening of fittings and air purge had that raised to a healthy 200bar grease pressure (safety glasses on) Cracking the furthest distribution block I soon had grease pouring out then followed by a MDF/grease goo flowing from the linear rails and ball screws. While the flow is pretty uneven, i'll give it a few cycles a day in the hope everything will even out, worst case the lines can be swapped for nipples. Ok, so large phallic engravings now or what? Nope, in the adventure of chasing the grease lines I found the X axis drive cover was actually split and therefore working out the actual reduction ratio is possible. Cover off locates, well, more grease. Grabbing the nearest doggy bag the goo was disposed of and wiped up Fairly certain its just grease, the belt appears healthy but I might try locate a new one and replace it if the price is palatable. And yes, this whole post has been a tease, I never managed to run a program, having a go at tuning the servos I realised I have no idea how to run the internal oscilloscope, back to the school of YouTube then I promise to cut something worthy.

Hmmm it just gets more interesting..... Had a good read of the VFD manual, Power Electronics SD50, from that I identified the most likely settings which were in need of a check up- Control input, remote operation, min/max speed, control input type etc etc. Well, before getting to the inputs it turns out the basic characteristics are all wrong, input voltage, motor power etc so quickly dragged them to range, then moving to the control side I found it was set to remote operation, local speed control, set speed 400Hz or ~8000rpm. A quick reassignment of inputs and she's all happiness, typing GCode into Linux activated the VFD and spun up to speed, even the tacho now reads a reasonable value when asked for 3000rpm, no doubt confirming parameters will get things inline. Its a pretty big win in the overall process, but mindful that there may be some more bad settings I shut down and tomorrow will dig through the entire VFD menu and confirm each and every setting, yuck.

Is that a legit move to avoid cert? Turning the tops off and threading for an insert and cap is straight forward machining, not having a stub makes it a bit more palatable too.