So now I've set a threshold such that all values between 0 and 511 (>=10mm down to about 2mm) are analogue then all values from 512 and above give 1023 out (my PWM numbers are pretty much the same values reported by Duet). The G31 threshold is set to 522 to give a margin of 10 for noise. Seems to work well. However, for X homing I have an overshoot problem as the time-constant for my PWM filby Radian - Ormerod
OK, silly me. The probe wire wasn't connected to pin39 (AD12). Must have mis-counted. Now it should work!by Radian - Ormerod
I'm seeing something strange then. With my probe calibrated at two points to give a full Vdd swing on the blue wire at the 3-pin IR probe plug Z=0mm = 3.3V out, the web interface reads back 590 to 625 Z=10mm = 0V out, the web interface reads back 405 to 460 Edit: tried formatting it better with Tabs - which just posted it prematurely for some odd reasonby Radian - Ormerod
I'm having a hard time getting Z homing to reach a consistent height using an analogue voltage. I know the voltage I generate proportional to Z height is consistent and I know the analogue ground and general hash in the Duet is causing the reading to jitter as discussed before. So is there anything wrong with me simply thresholding my detection to produce a digital high or low as though Z was aby Radian - Ormerod
Quotedc42 I always use SMD components if I am making a PCB, however for a one-off, you could use through-hole components and assemble it on stripboard. Or solder SM parts to the underside of stripboard ;-) 0805 parts fit nicely between tracks, SOT23 parts straddle two tracks if you cut through the track between the two legs on the same track, SO8 chips with 0.05" pitch sit nicely on split traby Radian - Ormerod
Quoteshadow651 ...That's a nice test piece there, I might have to give it a try when I get AUX cooling set up. Still trying to figure out the best way to deal with the PWM signal.... /quote] What's the problem with the PWM?by Radian - Ormerod
Quoteormerod168 Quote.. perhaps a cylindrical co-axial duct surrounding the nozzle blowing thermoelectrically chilled air under closed-loop temperature control to cancel the thermal input from the hot-end ? Yes I have been thinking about that but there is too little space available under the original ormerod hotend, even a higher pressure (aquarium pump) one so I'm thinking about changing thatby Radian - Ormerod
Quotedmould The big advantage with Openscad is that if it hasn't got a particular function, you can simply create one by writing a module. I have two "rounded cube" and a "fillet" module that I just paste into a new design. They are all pretty simple. Thanks for sharing Dave. It's a new way of modelling for me but I'm getting to like it the more I use it.by Radian - Ormerod
Hi shadow651, you and Dave have both convinced me to design more "shapely" parts from now on I wish OpenSCAD had a simple "rounding" or "Fillet" parameter for cube edges. That would help with my cubist tendencies!by Radian - Ormerod
I hadn't realised that the layers would pull apart if the base remained stuck on the bed but that explains the mystery delamnation I had with this part: So in this case which direction would corrugations go to relieve the stress? From what you say I'm guessing vertical (90deg from the bed plane)by Radian - Ormerod
That all seems to make perfect sense Dave. I hadn't been considering the curl-up that happens on overhangs. But going back to warping on the base, while the first few layers start off well-stuck, I find it often only begins to lift (at any sharp corners) when the nozzle is several mm further up. This made me think that by then the body of the part had cooled to a lower temperature than the base.by Radian - Ormerod
I know this topic has moved on a bit but for Ormerods with the standard extruder drive assembly, I found that a bit of bent wire is all you need to hold the Bowden securing pin in place. It simply lifts out when you need to release the cable:by Radian - Ormerod
Quotedc42 Have you tried reducing the amount of cooling air flowing over the nozzle from the fan duct? The later Ormerod hot ends do not direct any of the air from the hot end fan over the nozzle. Well that's very interesting - has there been any explanation of why this was done? Quoteormerod168 ... until shrink-less filament is invented I see no other cure than to make sure the print sticks toby Radian - Ormerod
OK, I don't want to lead anyone astray so I will confess that today I tried printing with a 30C bed and had all kinds of warping. Seems I haven't nailed the true cause and effect yet. Taking a heat gun to one side of a room-temperature 80mm square by 3mm thick printed plate, contrary to my intuition, the hot side becomes concave such that the edges would be forced down if on a heated surface. Iby Radian - Ormerod
Quotedc42 There are some posts on other RepRap forums about using off-the-shelf inductive sensors for this purpose too. I guess I ought to take a look but I find it hard enough finding time to keep up with posts in this forum alone. Really I'm just playing around with the analog circuit and magnetics for the fun of it. Makes a nice change from coding all day. I read how you wanted to concentrateby Radian - Ormerod
Quotedmould I've read elsewhere that a coat of sugar water makes a great bed preparation - and what's more does not adhere to the print when the print is removed so does not need a re-coat after every print. I will try it out somewhen. Dave I can confirm this - and before needing a full re-coat just a wipe with a damp cloth works for print after print. Any sticky left on the part wipes off sooby Radian - Ormerod
I think you may be referring to a solenoid. The properties are pretty much the same as an inductor in that an electric current flowing in any conductor produces a magnetic field. The aim of this circuit is to create a rapidly alternating magnetic field which in turn produces an opposing field in the aluminum due to the induced AC current. A plain coil of wire would be the most the efficient (air-by Radian - Ormerod
Hi Treito, the inductor L1 is nothing special at all - it's an open bobbin type (fully shielded would not work at all) but apart from that, almost any similar sized part would do. I had this one in my parts box as well as a 68uH and that worked just as well - although of course the resonant frequency went up accord to: The capacitance value of C1 (which must also be the value used for C2) isby Radian - Ormerod
Quotedc42 QuoteRadian OK, thanks David, I'll give it a try - but I can't help thinking that the bottom of the printed part is too hot compared to the top - hence a greater thermal expansion factor. I thought the usual setting for a higher bed temperature for the first layer was so the freshly deposited plastic didn't cool too far and contract/come unstuck before the print got going. That was jusby Radian - Ormerod
Thanks for the prod, just got a bed on order - which I'd been meaning to get round to for ages!by Radian - Ormerod
Quotedmould Interesting. Do you get consistent values at the edges, corners and center of the bed? Dave Hi Dave, yes it's very consistent so long as the inductor is kept around 20mm from an edge. Just for giggles, the above photos show the test circuit I've lashed together. I've hacked in a fan control and white LED (SM edge lit device) that sits right next to the nozzle.by Radian - Ormerod
QuoteAagaard Also wiping with vinegar has has been a great success for my PLA prints on a 65 degree heat bed. How bad does it smell though ;-) Don't mind me - living in a Seaside town can produce an irrational dislike of vinegar!by Radian - Ormerod
Hi there appjaws1. It certainly is possible to extend the functionality in all those ways - lights are easy, however I think temperature compensation is really only practical with a small micro-controller. However, this isn't needed if Z homing and bed compensation are always done at room temperature as drift only becomes measurable above 30C or so. Already I can see that the inductive sensor isby Radian - Ormerod
Going back to Galactic Warehouse filament, I tried a few reels and I'm not too sure what to make of it... I had been having real problems with 3D Filaprint which was the first filament I'd tried other than the white stuff RS supplied with the Ormerod kit. Whereas the white stuff had a matt finish, the orange FilaPrint was exceedingly glossy (not just the bit in contact with the glass) and just diby Radian - Ormerod
So here I am again with yet another method for sensing Z height. To be honest, dc42 has probably nailed it with his dual IR hot-end board v2 but out of interest I'm developing an inductive sensor to see if it can out-perform my current probe which is my own capacitive design: As always, the motive is to replace the simple RepRap sensor which has improved by incorporating dc42's modulated detectby Radian - Ormerod
Thanks all for the tips. I tried a few "surface treatments" on the bed but in the end got the best adhesion by wiping the glass with some sugary concentrate (Bottle Green lemongrass & ginger). I'd noticed before when making drinks how sticky the stuff was! I especially like the fact that it's quick and easy to wipe on and off.by Radian - Ormerod
OK, thanks David, I'll give it a try - but I can't help thinking that the bottom of the printed part is too hot compared to the top - hence a greater thermal expansion factor. I thought the usual setting for a higher bed temperature for the first layer was so the freshly deposited plastic didn't cool too far and contract/come unstuck before the print got going. That was just my assumption at anyby Radian - Ormerod
I know this is a topic that comes up frequently with beginners but I felt that I'd got on top of this sort of problem ages ago. Not so it seems. I'm trying to print a rectangular enclosure (in PLA, direct on glass) for a PCB that's 110mm x 70mm x 25mm tall. The first layer goes down nicely and builds up perfectly flat for the first 10 layers or so, sticking well to the bed. This tells me that tby Radian - Ormerod
Thanks guys, I've now reduced the delay from 75 down to 20 seconds by using I=1.3 There is a small initial overshoot but it settles well before the printing gets underway. It seems to take a great deal of patience to get satisfactory PID settings so any "Auto tuner" would be most welcome indeed!by Radian - Ormerod
I'm wondering if I'm seeing expected behavior when the PID starts chopping the heater drive here: (75 Seconds of proportional control before the target temp is reached and printing starts) I've reverted to the default PID params after replacing the ATX PSU with a 13.8V 25A desktop unit which has increased the warm-up times considerably. The heater cartridge seems OK given the steep rise in teby Radian - Ormerod