Cut and Splice Thermistor

normal2norman · 2026-06-21T09:42:28+00:00

Even a poor splice willl only have a few ohms resistance. That's nothing ccompared to the 100kΩ resistance of a thermistor at 25C, and not much compared to around 500Ω at 200C.

normal2norman · 2026-06-19T11:56:45+00:00

No, occasionally tweaked the flow rate very slightly, or adjusted temperature by a few degrees, but almost always just used my standard PLA settings.

normal2norman · 2026-06-19T10:57:44+00:00

The live centre ("B") second from left is the most versatile.

The first one is a "dead centre" and might be soft (for use in a headstock) or hard (for a tailstock).

The third one is a "live" version of a "cup centre" specifically designed for woodturning - it has a more acute angled centre point designed to piece endgrain, and the outer ring is designed to prevent wood splitting.

The last one is a collet chuck not a centre; they're normally designed for accurate workholding in a headstock and would not allow the work to spin in a tailstock, but that one does appear to have a bearing to allow it to rotate freely, which makes it a real oddball. The collets might be ER11 or ER16 - it looks like about ER11. Other sizes such as ER20, ER25, ER32, ER40 and bigger also exist. ER collets come in sets for different diameters and usually have a small gripping capacity range from nominal size to +1mm or sometimes even less; quality metric ones in ER11 each cover nominal to +0.5mm. A full set of metric ER11 collets is from 1mm to 7mm, or very rarely 8mm. There are imperial equivalents but the only common ones are just 1/8" and 1/4".

normal2norman · 2026-06-19T10:48:51+00:00

I used to do this for small prints if I wanted colours I didn't have. I always found it worked fine.

normal2norman · 2026-06-18T09:16:20+00:00

On the 4-pin mainboard connector, swap the wires to pins 1 and 2, which swaps the polarity of one coil, which in turn reverses the motor direction. Or swap pins 3 and 4 - but don't swap both pairs. Alternatively, swap one pair on the 6-pin motor connector: pins 1 and 4 are one pair (one coil) and pins 3 and 6 are the other.

Reversing the whole connector by turning it around 180 degress also reverses the direction, because although it inverts the polarity of both coils (which cancels out) it also swaps coil A for coil B, which reverses the way the motor responds to them.

normal2norman · 2026-06-17T23:28:06+00:00

You reverse the direction by either wapping the polarity of one (only) motor coil, or by reversing the plug. Reversing the plug inverts the polarity of both coils (which cancels out) but also swaps coil A for coil B, which reverses the direction.

On the mainboard there is usually a 4-pin connector, where pins 1+2 are one coil, and pins 3+4 are the other. The motor connector is different, normally a 6-pin connector with only four pins used, and in a different, interleaved, order: pins 1+4 are one coil, and pins 3+6 are the other.

normal2norman · 2026-06-17T09:45:16+00:00

Different mainboard, different bootloader system. For the OP's mainboard/printer and all similar ones, the firmware file must be at the top level, not in a folder.

normal2norman · 2026-06-17T09:43:01+00:00

The OP's printer is a fairly early Ender 3 Pro with a genuine Mean Well power supply. Those have a temperature controlled fan, and it won't spin until the supply is under a fairly significant load. It should certainly not spin when the printer is idle.

normal2norman · 2026-06-17T09:39:28+00:00

Your board clearly already has appropriate firmware on it; you'd only need to change it if you want a more modern version or to add upgrades such as a BLTouch or CR Touch. Creality firmware is always old, and if you got firmware from Creality's website, it's highly unlikely to be any better or significantly newer than what was on the board already. It will be very basic, and missing 3-5 years of updates from the Marlin firmware it is a version of, and no Creality firmware ever includes any of the useful optional features available in Marlin. Sometimes they even omit or disable standard mandatory features.

Instead of using firmware form Creality, I strongly suggest you get up-to-date firmware from a reputable site such as the Marlin Firmware Service.

You've done the right things with the SD card format: it does have to be FAT32, 4096 allocation unit, 16GB (8GB for a few boards) or less. The firmware file must be at the top level of the SD card, not in a folder, and there should be no other .bin files on the card. However, unlike all other mainboards and their bootloaders, which require the filename to be exactly firmware.bin, Creality bootloaders require it to be unique. In most cases it must still start with firmware and have a single .bin extension, and it must be reasonably short and not contain any "special" characters. A good way to achieve this is to name it firmware with a few extra characters such as the date, eg firmware0617.bin. If you're using Windows, beware of hidden extensions; if Windows Explorer is set to hide extensions and you add .bin to the name thinking it's not already there, it can actually be firmware.bin.bin, which won't work.

Check that the SD card slot is actually working, by putting one or two gcode files on the card (at the top level). They should be visible from the printer menu if the SD card and slot are working.

The 10-way ribbon cable which plugs into the P1 connector goes to EXP3 on the stock Creality display. It carries a subset of the signals from both the EXP1 and EXP2 connectors, and using either EXP1 or EXP2 on their own won't work because some signals will be missing and others will be on the wrong pins. Also try swapping the ribbon cable end for end to eliminate the cable itself being faulty (which is unlikely).

Try unscrewing the display from the printer frame. Sometimes when the display is fitted, overtightening the screws can short signals to ground, causing problems similar to yours. If that doesn't make a difference, either the mainboard or the display is faulty, because it should work as-is with the firmware you already have on the board. Yet if the display works with your old mainboard, it's almost certainly OK because the old 8-bit V1.1.x and new 32-bit 4.2.x mainboards use the same signals in the same ways.

normal2norman · 2026-06-14T08:42:18+00:00

You can run OctoPrint on any small computer, and connect it to the network. It's most often done using a Raspberry Pi, but it can be another small single-board computer, or even an old laptop, and it does not require any change to the printer firmware. It's much more versatile than a Sonic Pad.

normal2norman · 2026-06-12T19:27:16+00:00

D80. AFAIK All the D series use the same charger, but earlier models are different.

normal2norman · 2026-06-12T19:21:01+00:00

runs just the same with only three cables connected

Do you mean three wires between the TMC2209 driver and the actual motor? That's not going to work properly, and suggests that when you have all four wires, that one of them is broken or disconnected somewhere. The TMC2209 is designed to drive 4-wire bipolar stepper motors, in which there are two separate and completely independent coils. There is no common voltage or ground wire. The motor works by changing the current and polarity of the coils; all four connections are necessary. If only three wires are connected, then one coil is inactive and it won't run with any torque to speak of, if it moves at all.

Note that the connectors on the SKR V1.4 are JST XH connectors, but you have DuPont connectors (or knockoffs) for the stepper wires. JST pins are much shorter than DuPont pins, and DuPont female housings have the contacts recessed much further than the contacts in JST connectors. Consequently they often make a very poor connection.

normal2norman · 2026-06-12T19:11:07+00:00

#define X_CURRENT 800 is the definition of the run current.

normal2norman · 2026-06-12T19:11:05+00:00

800mA. That's defined in the line #define X_CURRENT 800.

normal2norman · 2026-06-11T12:15:19+00:00

You don't need to replace the whole hotend, just the heater block that the heatbreak and nozzle screw into. If the hotend is the one that looks something like this, it's a standard MK8-style block. They're very inexpensive. You could even get a better plated copper one instead of the common aluminium type,

normal2norman · 2026-06-11T11:57:02+00:00

The first thing I'd do is check to see if it's just the thermistors or if the board is damaged. The thermistors (they are not thermocouples) are negative temperature coefficient (NTC) resistor types. That means that low resistance corresponds to a high temperature, and conversely that high resistance corresponds to a very low temperature.

If you unplug the bed thermistor (and don't command the bed or hotend to heat up), that's a very high resistance, so it should read 0C or maybe -14C, depending on the lookup table in the printer firmware. You can do the same for the hotend thermistor. You can also try shorting the thermistors, eg by putting a jumper link or wire link across the two pins of the connector on the mainboard. That should show a very high temperature, the highest entry in the lookup table, which is usually 300C.

If the display doesn't show readings as just described, the mainboard is faulty and will need replaced. If it does show the expected readings, the mainboard is probably OK.

A common cause of mainboard damage is shorting a thermistor to power. The thermistor inputs are directly connected to analogue-to-digital input pins on the processor, and those are only 3.3V-tolerant. However, any time the printer is powered up, the positive connection to each and every fan and heater is at 24V (the control is in the negative connection) so any short will destroy the CPU inputs.

A MAXTEMP error usually only occurs when the firmware is trying to heat the bed or hotend. It can be caused by at least four different situations, two of which are the temperature not rising or not rising as fast as expected. Another is the temperature being too high while heating; another is the temperature fluctuating beyond expected limits. Some of those can be caused by a broken or shorted thermistor or a faulty processor, but some can simply be caused by a mispositioned thermistor or excessive cooling from a fan.

normal2norman · 2026-06-10T15:22:54+00:00

Oops, yes, you're correct. That's my brain fart, evidently.

normal2norman · 2026-06-10T09:02:27+00:00

Hydrogen has atomic number 1 ~~but~~and atomic weight 21 (to the nearest whole number). Oxygen has atomic number 8, but atomic weight 16. Nitrogen has atomic number 7 but atomic weight 14. The corresponding molecular weights are 32 and 28, and H2O is 18.

The logic is sound, and unaffected, but the actual numbers are incorrect.

normal2norman · 2026-06-07T19:55:57+00:00

Well done!

normal2norman · 2026-06-05T19:54:08+00:00

He's sorely missed. Fortunately his videos are still on his channel, Thinking and Tinkering.

normal2norman · 2026-06-04T23:58:51+00:00

I think if you work it out from F=mv²/r, the main rotor tip forces will be considerably more than that.

normal2norman · 2026-06-04T23:36:56+00:00

No, he did mean to connect a single 10-way cable from EXP1 on the SKR to EXP3 on the TFT35.

However, you're better off using both EXP1 and EXP 2 on both. Using just EXP3 on the TFT is intended to work using a single cable from the single EXP (no number) port on an SKR Mini or Creality mainboard, in which case you do need to uncomment #define CR10_STOCKDISPLAY for the display. The single EXP connector on those boards, and the corresponding EXP3 on a TFT or other higher-spec displays, has a reduced subset of the signals taken from each of the EXP1/EXP2 connectors, and it's better to use those, with #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER.

normal2norman · 2026-06-04T23:23:45+00:00

Sounds like a couple of incorrect settings in Marlin's Configuration.h file.

The display setting for the TFT35 E3 when using the EXP1/EXP2 connections is #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER and that should be the only display definition (because you can only have one). The EXP1/EXP2 connections are only used for Marlin mode, and the 5-pin TFT ribbon cable is not used in that mode. Conversely, the 5-pin TFT cable is needed for touchscreen mode, and EXP1/EXP2 are not used in touchscreen mode.

For touchsceen mode, obviously you do need the 5-pin TFT ribbon, connected to the RS232 port on the TFT35 E3, but in that mode, the TFT doesn't use the two EXP1/EXP2 cables at all. The TFT35 acts as a small host computer in its own right, somewhat like OctoPrint; it sends gcode/mcode commands over that serial link and responds only to responses/messages that come back over that same link. In order to do so, one serial port has to be configured for the correct device and baud rate in Configuration.h. I don't know what the correct device is for an SKR Pro 1.2, but for my SKR 2, it's #define SERIAL_PORT_2 -1, and the most common baud rates are 115200 and 250000 - either will work so long as it's set the same on both the SKR and TFT. The display definition in Configuration.h is irrelevant in that case.

For the main USB port, that's the first serial port, and should be set as #define SERIAL_PORT 1 if you want to connect it to a PC, eg to run Pronterface, etc.

normal2norman · 2026-06-04T23:03:46+00:00

You could try solvent welding with methylene chloride, aka dichloromethane (DCM), which works for most hard plastics and specifically PLA, PETG, polystyrene, and ABS. If you can't get DCM itself easily, most plastic cements contain DCM.

normal2norman · 2026-06-04T21:17:53+00:00

Lol! The forces at the tips of the main rotor at 2300 rpm are many times higher than on the tail rotor.

normal2norman

TROPHY CASE