@DC42 Nice summary on pros and cons. I also prefer an absolute position switch and don't see a need for any actual position readings, except perhaps for helping with diagnosis should something not work quite right. Like most, I just want something simple and reliable, which for me may be your current modulated IR sensor, but what happens when I move to a different location (shed in sunny gardeby Treth - Ormerod
@DC42, If you go back to the push solenoid method then this solenoid is approx 12x11x20mm (coil frame) and a stroke around 5mm PLUS it has the return spring all for £5.10.by Treth - Ormerod
Another thought trying to get to low cost and robustness. This would be very cheap for hardware and is small. Thinking of the combined bed sensing and the need to retract the sensor, how about using a vibration motor as used in the iPhone etc. This would be used as a motor to move between sensing and parking positions and as a generator/sensor for contact with the bed. A sensing arm is mountedby Treth - Ormerod
Quotedc42 I've gone through a lot of solenoid catalogUes and listings looking for something suitable! Yes, I guessed you had! The spec's and extracted spec's are quite poor, so I appreciate your time and efforts. I like the Farnell part you selected, I guess you would have thought of this as well, but is there room to put a 'black' coating of some form along the protruding shaft and use a reflecby Treth - Ormerod
Just found this on Rapid Electronics Not ideal for the sensor end, but cheap and has both ends available and 2 to 3mm travel. Need to attach a small rod at the spring end to go through the opto slot or similar. CPC do these more expensive ones What about model railway track switching solenoids, I'm not into this area, but do they offer anything suitable? Just some thoughts. P.S. Couldn'tby Treth - Ormerod
Quotedc42 QuoteGregL Sensor fixed relative to nozzle - Z difference known. Fire the solenoid to extend the contact tip, and measure the extension. A bit of arithmetic to determine the exact height of the nozzle. That is exactly what I am looking at. I will measure the extension either using the variation in inductance of the solenoid, or with a separate optical sensor. We don't actually need toby Treth - Ormerod
This is the type of precision position switch we would like I haven't got pricing, but looking at other examples my guess is they are greater than £50 and probably over £100....... But it shows the type of switches available. The earlier post suggesting something like a ball point pen tip, that would be a great sensor! Metal ball (in plastic guide tube) sprung loaded to a tip metal ring, peby Treth - Ormerod
Quotebalidey I was thinking you could use the nozzle as the probe, not a separate one. Then no need to move anything or have additional hardware, just a feed to the print head, ground to the Kapton. I like this idea, but I think the Kapton Polyimide tape is a good insulator. Also any hot melt extrude at the tip will be an issue.by Treth - Ormerod
There used to a 'touch probe' for any material. RS sold a robust diamond tip switch in a small tubular housing that had repeatable micron switching accuracy. Basically a very robust accurate switch. Probably too expensive for us if they are still produced, but as with other techniques you need the 'move out the way' while printing and this must not impact on the accuracy. The simplest method Iby Treth - Ormerod
Quoteormerod168 150 x 45 x 40mm angle alu, a few holes, a bit of milling for the belt and y-micro switch, nothing to it really Erik Hi Erik, these look great, but "....,a few holes, a bit of milling for the.....", for those of us without the milling, I presume that this could be just drilled alu angle and a bit of filling (for slots)? Would not look nice like yours, but would be robust! Thankby Treth - Ormerod
Quotekwikius ... BTW Sincere apologies I havent done any work on this. I should do something rather than just talking about it! regards Andy It is these discussions that help us progress.... I talk too much...., but as long as we have some 'do-ers' we are a good team. Just to add, I have used these slotted-optos for position sensing many years ago (using a 6502 uP !!! that dates me.) and the pby Treth - Ormerod
Firstly very nice summary DC42. Quotedc42 Quotekwikius Anther option is to use a z-axis position detector like for the x and y axis, either a microswitch or an opto break beam system, ideally in a dark box regards Andy True, but that's only OK if the bed is level and very stable. If like me you use several different glass plates, then you really need to sense the height above the glass, not thby Treth - Ormerod
Quotejstck .... even when the desired material isn't directly printable, 3d printers are quite useful for making one-off molds for example. Yes, this is one of my desired uses for producing bespoke silver jewellery and will be exploring this in the summer, along with 'press forming' for thin sheets of malleable metal. So totally agree 3D printers can be a useful step in a process to a metal objecby Treth - Ormerod
While trying to find a similar post on hole sizes I found this thread that could be of interest. And just because it was interesting someone got improved prints (different printer) with a change to the nozzle cone shape Excuse the randomness of the above, but worth a look! and this one....by Treth - Ormerod
Could it be the layer thickness and the over extrusion into the open area, i.e. the hex nut profile?by Treth - Ormerod
QuoteRadian I'm greatly enjoying this thread - it's really switched me on to OpenSCAD and I'm also dreaming up ideas for projects involving parabolas. Treth, have you thought about printing in ABS and using the Acetone polishing method: ? Great idea about the acetone and ABS, I have seen this used with models and ornaments etc., but yes there could be a good 'engineering' use as well. At the moby Treth - Ormerod
QuotePointy Quoteonno. I assume RRP has its reasons for not including all changes and/or fixes, but I hope it doesn't discourage you from future development work where you deem that necessary. I can tell that your efforts are certainly appreciated. I second that! Quotedc42Now that I've reached z, it's probably time I gave up making firmware improvements anyway. You should only stop if you don'by Treth - Ormerod
@Andy, Dave and Kim, Thanks again for your help. @Kim sorry for any confusion, I want a parabolic dish to amplify ultrasound, I haven't yet defined the size, I expect it to be about 3cm diameter up to 10cm. I shall print off some and see what offers the required sensitivity. The mic insert I have selected is only 3mm diameter and with an even smaller aperture, so I require the parabolic shape fby Treth - Ormerod
Quotekwikius Quotebobtidey paraboloid maybe a good starting point I found a much more concise method of generating the parabolic section, though it requires you to enable OpenSCAD's concat function in preferences, but then you can create your polygon inline... Here is a view of the result: The code is a few lines only : /* parabolic reflector n.b need to enable concat in preferences */ /* pby Treth - Ormerod
QuoteKimBrown In FreeCad I first click file, then New to start a new project. I then placed a Sphere the size I wanted for the inside, To alter the Sphere sizes, first click on one of the Spheres...(If you right click it you can give it a name if you wish). Then in the panel on the left, at the bottom, you will see a tab with Data...... I suggest you look around their Helpful Videos.... The Engby Treth - Ormerod
@KimBrown, now that looks impressive! Thanks. I look forward to hearing about the performance as I'm hopefully going to do my BIG upgrade (aluminium bed, Daves IR sensor and other parts) in a couple of weeks, once 'real' work slows down! But then there is the garden and decorating.........by Treth - Ormerod
@GregL, Wow, what an amazingly clear explanation..... thank you I followed that step by step, great! I shall now investigate the commands in a bit more detail and look at the instruction flow in other programs. Way back in the 80's I did have and used Forth on a Sinclair Spectrum, that was fun and tricky at first, OK. But that was a long time ago! Thanks for taking the time to explain this.by Treth - Ormerod
QuoteKimBrown I did this in about a minute in FreeCad.. Kim @Kim, thanks for the post, hmmm a minute, probably will be more than that per line for me in OpenScad! So I'm new (very new) to FreeCad (in fact most mechanical CAD!) can you give a rough guide to the steps? Presumably you defined the parabolic curve via an equation, gave it some thickness to produce an area and rotate around the cenby Treth - Ormerod
QuoteGregL I have annotated the code I used in my earlier post above. It uses the Paraboloid code from elsewhere, with a bit of mycode to call it a couple of times. ... Greg Many thanks for this, I'm far from understanding the sequence...., but I'm starting to visualise the code functions. Quote3D-ES ....... Have you seen this PDF / presentation? No I had not seen that before and it is very heby Treth - Ormerod
Not related to the topic, so apologies, but Firefox (V28.0) consistently crashes if I click the "nozzle mount" in jstck link in above post! Just interested if anyone else see's this?by Treth - Ormerod
@everyone, many thanks great advice! OpenScad really does excel when you know how to use it! Seems to suite certain tasks such as this very well with so few lines of code, but wow the details in that code. I need to get by brain thinking with the correct sequence. Thanks.by Treth - Ormerod
QuoteRadian Hi Treth. The capacitive scheme has been working very well for me in the last couple of weeks, but I suspect changes in humidity are going to require more frequent recalibration than an inductive approach - which is probably the least affected by environmental variables. As things were moving surely, if a little slowly, with the other techniques I didn't want to get sidetracked by expby Treth - Ormerod
Quotekwikius From here the next logical step for the Z sensor has to be Sensor Fusion regards Andy Interesting. The first method mentioned in the link was "stereoscopic vision" which is another technique I was playing around (in my thoughts) with! This or a close range triangulation method 'fused' with the modulated IR beam and the.........., could be the solution! I still like the inductiveby Treth - Ormerod