Interesting observation. Float glass will have a thin coating of tin just on one side. Tinted glass could be just a surface coating or could be homogeneous throughout the glass I think.by dave3d - General
Ecky: I measured the temperature using the printer bed thermistor. I have previously used an IR gun to check the temp but it gave a low reading. It is due to the emmissivity of the aluminium surface. A highly polished surface will give a low reading. A matt black surface, a higher reading. krwynn: on/off control works fine. It overshot to 114 deg C initially then quickly settles down and cycby dave3d - Reprappers
A final follow up. I have now fitted the second 24v power supply unit to power just the bed. It is rated at 17 amps. I still use on/off control via a SSR. I adjusted the output voltage of the 24v PSU so it gives around 15 amps, just to allow a margin. It now heats up to 110 deg C in about 3 mins!by dave3d - Reprappers
Just to be clear. You plug the FlashAir card into the printer and it gets an ip address and can connect to a home network?by dave3d - Reprappers
Thanks for all the comments, some of which were over my head, but thanks anyway. After careful consideration I have decided to change to 24v for my aluminium bed. I have read that putting 24v through the 12v connections will heat the bed in 2 mins, which would be fantastic. Printing directly on the aluminium bed and doing away with the glass would also be an advantage. I found my existing 12v PSby dave3d - Reprappers
I have got an OrdBot that is made with Makerslide. There is a forum for Makerslide builders, laser engravers, not just the OrdBot: I know that a number of companies around the world make the Makerslide profile and I have heard of quality problems in the past with some of them. I am in the UK and I ordered my kit from ATI in the States.by dave3d - Reprappers
QuoteNophead wrote: If you put 24V on the 24V connections it wont get any hotter than 12V on the 12V connections (other than reducing the connection and MOSFET losses). It might heat more evenly though. You would need 30V to get the same heat as 15V on 12V connections. My aluminium bed has connections for a 12v supply and connections for a 24v supply. One would assume it is constructed with twoby dave3d - Reprappers
My aluminium bed is dual voltage and is designed for operating at both 12v and 24v. Connections are different depending on voltage chosen. It seems better to me to run it properly at 24v rather than putting 15v through 12v connections. digital dentist is right. If I got a 24v power supply, the 24v bed would take most of the current, leaving a much smaller current requirement for the Arduino/Rampby dave3d - Reprappers
It seems other people have had the same problem: There also appears to be different types of Mk3 heat bed. This is the one I have: and there is a Wiki which shows a slightly different one: On mine, both earth wires are joined for 12v. The one on the Wiki has the +12v joined together. Because the circuit is bonded or printed onto a solid aluminium base the temp should be even acrosby dave3d - Reprappers
dougal1957: under load from cold I I got 11.19v at the bed. At the SSR I measured 11.93v on supply side output terminal and 11.49v on the load (bed) side. Maybe I need to beef up the bed wiring.by dave3d - Reprappers
Thanks for all your replies. I will try and answer all the points raised. I have also done some further electrical tests. The power supply is a standard Reprap 12v 30A switching power supply that came with the printer kit, an OrdBot. To my knowledge the voltage is not adjustable, at least not from the outside. It maybe if I take it apart. I measured the no load voltage at the bed and it is 12.5vby dave3d - Reprappers
I have just changed my old reprap "printed circuit" type heat bed for an aluminium reprap type. It seems well made and a lot more rigid. Nice and flat. However it takes an age to heat up, like 30 mins+ to reach 110 deg C. Is this normal? I am using 12v on pin 1 and pins 2 and 3 are earthed together. I was thinking about recessing the hole for the thermistor so it fits in a bit better. The springby dave3d - Reprappers
The latest version of Repetier firmware has a lot of additional safety features. Have a look at the configuration web page.by dave3d - Safety & Best Practices
Use a digital voltmeter set on DC volts on a low range. I use a small metal jewellers screwdriver with a rotating end to which I attach a bulldog clip to the +ve side of the meter. I shrunk a bit of heat tubing over the screwdriver body to insulate it. As mentioned the -ve is connected to ground on the PSU. The adustment is very sensitive. I also check it when the motor is operating.by dave3d - Reprappers
Sounds like the PTFE liner is loose. The locknut needs to be tightened down with an allen key.by dave3d - Printing
My tuppence worth. My settings for ABS are: Hotend temp of 230 or max 235 deg C for ABS. No fan. Increase acceleration to get sharper corners. Set Slic3R on perimeters first, then infil. No lift on layer change. Retract on layer change, 2.5mm retraction. Seam position aligned. External perimeters first - leave this unticked, so most layer change blobs are on the inside.by dave3d - Printing
I am not sure what jhead you have. It looks similar to mine which is a Mk Vb, but not exactly the same. I suggest you check out the Wiki. I have looked at your pics. I can't see how the molten plastic could leak along the thread. Suggest you look closely to see if the peek bit is cracked. Could be a hairline crack. I overtightened mine and cracked it. should be finger tight or maybe a touch morby dave3d - Printing
I am in the UK. I have bought two Mk Vb Jheads from Hotends.com in the US. Delivery was very quick - less than 1 week. Yes, they are worth the money. Machining is superb. I previously struggled with a QU-BD extruder. I use 1.75mm ABS with 0.35 nozzle and a Wade extruder with a Bowden tube. Replacement parts are also available if any get damaged.by dave3d - General
It has been out for a while. I built my OrdBot Hadron using 3 sections of Makerslide and one normal Misumi section. It is a neat solution and makes for a nice rigid frame. The Makerslide sections bolt up to other industry standard fittings. I am surprised it is not more widely used. Availability has been mentioned as a reason.by dave3d - General
I have got two 1.75mm Mk Vb jheads from hotends.com. I have not run a 3mm version so cannot compare the two sizes. The 1.75mm size has a PTFE tube inside and I have replaced this with my own after it was damaged. I used a 1/4" PTFE rod cut to length and I drilled a 2mm hole down the middle, the Wiki says 1/8" I think. After screwing in the brass hot end (be careful or the peek will split, justby dave3d - Reprappers
Dilute the juice. I work at 50% of saturation and 110 deg C for the first layer then 100 deg C for the rest. Clean the kapton off with acetone first then coat with 50% juice. It leaves a thinner layer of ABS on the kapton after it evaporates.by dave3d - Printing
As I remember, you need to download all the files as a package and then they all need to be unzipped into the same folder. When you run the scad file it looks for the stl's in the same folder. If it does not find them it comes up with an error. Been a while since I have done it though.by dave3d - General
The test looks good, but if there is no infill then it must be the slicer I think. I am on XP/ repetier firmware/ repetier host/ slic3r. I would slice it then save the slicer gcode to SD card and run it from that to see if it solves the problem.by dave3d - Printing
You need to set your software so that it cannot extrude below a certain temperature. I just print with ABS and I have the cut off set at 190 deg C. It can be anything of course, depending on the plastic. This prevents it trying to force filament through a cold nozzle. Also adjust the pressure on the extruder hobbed bolt so it just "bites" and does not start to cut into the filament.by dave3d - Printing
If your bed is standard Reprap the same as mine it has 3 pins: 1. +ve 12v 2. & 3. need to be connected together to -ve 12v otherwise only half the bed is used.by dave3d - General
If it is the same bed as mine there are 3 pins: 1 is +ve 12v 2 & 3 need to be combined as -ve 12v otherwise only half the bed is used. It should say on it.by dave3d - Printing
0.3mm is a lot. It must be poor quality picture glass. Maybe imported from China. I print at 0.2mm layer height on top of 6mm float glass. Once the bed is levelled, the difference across the bed is not measureable using the sheet of paper test or a feeler gauge. In the past I have also used a large piece of thick float glass as a surface plate. With some grinding paste it is ideal for making surby dave3d - Reprappers
+1 DO NOT BUY THIS EXTRUDER I bought one for my Ordbot when I first started. It is cheap and nasty. It would jam and slip all the time. I wasted so much time trying to get it to work. I even drilled out the barrel and put a ptfe liner in. I binned it. I got a jhead hotend from hotends.com and a Greggs Wade extruder. Proven designs that have had many, many, small improvements overby dave3d - General
I bought a couple of jheads from hotends.com. 1.75mm filament and 0.35 nozzle. I extrude at 230 deg C and peek is fine. Spare parts for the jhead are no problem anyway.by dave3d - General
cosmicray: Thanks for the lesson on optics. I think you are splitting hairs. From your handle I assume you are a stargazer with precision optical equipment. For a Reprap printer like I (and most people) have got, the variation nozzle clearance across the bed with float glass is not detectable with a feeler gauge. It is less than 1 thou. inch. For all practical purposes for 3d printing it is flatby dave3d - Reprappers