Installing e3d Hotend

For those who have installed a e3d hotend on your Mendel90 I was wondering if you could point me to a tutorial/guide on what I would need to do. Would I need to upgrade the thermiristor tables? and how do you wire the hotend fan? For what it is worth I have the kit supplied by nophead.

The thermistor supplied needs the line in configuration.h to read

#define TEMP_SENSOR_0 5

The hotend fan can be wired to the left probe pin (gnd) and the left heater wire on the small pcb (+12 volts). Wired in that fashion it is on all the time. I used a larger fan mounted on the carriage.
I printed a new X-carriage for the mounting. Details at
[www.thingiverse.com]


The E3D is longer so the Z_HOME_POS needs recalibrating as in the original instructions with the kit.
Mine now reads:
#define Z_HOME_POS (179.6)

The print cooling fan need a different mounting due to the size change. My modified version is at
[www.thingiverse.com]


Edited 1 time(s). Last edit at 05/09/2014 07:09AM by Ralph.Hilton.

Thanks, hopefully I can get some time this weekend to install it.

I have been printing only 2 weeks and destroyed my peek Jhead when the thermistor fell out.
Today I received this hotend from E3D and it looks fantasticly well build.

Thnx very much Ralph Hilton to give all I need to configure the hotend.
It took quite some time to prepare the hotend and install this in my Mendel.

Issues I encountered:

When putting the top of the heatsink into the bottom of the wades block I noticed 1 side goes deeper and the washer is not touching and holding up the heatsink firmly on one side. I fixed it by bending the washer a bit so it makes contact with the heatsink.

I followed the manual on ebay and so I installed the fan allready before putting it onto the x-carriage. Only solution was to take the fan off again and put the hotend on the x-carriage first. Screwing the fan back on sideways makes installing this hotend a challenge.

Because of the fanholder I had no room anymore to put on the wingnut on the left side of the x-carriage. Turning the fanholder is not possible.
I fixed it by screwing on a normal nut instead.

Quote
Ralph.Hilton
The print cooling fan need a different mounting due to the size change. My modified version is at
[www.thingiverse.com]

s1361.photobucket.com

thanks for sharing the fan setup! i'm currently trying to modify a E3D 1.75mm direct drive setup (http://www.thingiverse.com/thing:147705) for the Mendel90. The one item I hadn't figured out yet was the cooling fan.

Just installed the E3D-v5 on my mendel90.
But we cant seem to get it to work good.
See the attached image.

3mm PLA
195 degreeC
5 mm extruded @ 50 mm/m

The extruded PLA just curles back onto the nozzle. What could be the reason for this?

PLA often curles when extruded into mid air. It is of no consequence once the nozzle is close enough to the bed.

---

[www.hydraraptor.blogspot.com]

Thanks for a fast answer!

After a bit of adjustments of settings our Mendel90 now prints nice with its new hotend.
Now its time to try some more exotic filaments :-)

From the picture I can't tell whether or not there is a gap between the nozzle and the block. Without a gap the nozzle may not tighten fully against the air gap screw causing leakage.

There is a small gap. The instructions where very clear on this point.

I am not quote sure I get correct readings from the thermistor.
If I should measure the temperature of the hot end where should I put the thermocouple?
Should I just hold it against the nozzle tip from the outside?
Should I stick i down the same way as the filament an measure the nozzle from the inside?

It needs to be on the inside to read an accurate value. It definitely won't work pressed against the outside, it tends to read much lower.

To measure accurately from the outside it would need to be embedded into the heater block like the thermistor is.

---

[www.hydraraptor.blogspot.com]

Since asking these questions I got the printer running well with PLA and did not bother with the temperature difference.
But I have now been trying ABS and I now again notice the incorrect readings of temp.

So now its time to measure the temp inside the extruder.

But then I have a new question. If I plot my measured values vs. thermistor readings in pronterface how do I correct the difference?

Cheers

You need to make a new table for the thermistor. See [hydraraptor.blogspot.co.uk]

---

[www.hydraraptor.blogspot.com]

OK, reading thruu the page you linked to I think I understand what I need to do.
Based on this:

"If you set the temperature to a value in an existing table and let it settle and then measure it with a thermocouple you know that the ADC value for the measured temperature is the value in the table for the set temperature. You can then produce a new more accurate table."

I set the temp to a value at the time in the table. Let it settle and then take a measurment with my thermocuple inside the hotend. The measured value is then inserted at that point in the table. If I do this for all points in the table I have corrected it.

Am I right in my assumption?

Regards
Amr_dwarf

You could do that but you only need three points: room temp, one at extrusion temp and one in the middle. The Python script will then calculate the rest of the table for you.

---

[www.hydraraptor.blogspot.com]

Guess I need to learn how to run Python-scripts :-)

But the point at extrution temp, I use at least three different temps for different materials.
Should I try a average?

Just use the highest. I think the Steinhart-Hart equation is accurate to less than a degree over the full range with just three accurate widely spaced points.

---

[www.hydraraptor.blogspot.com]

Do the scripts mentioned in your blog post a couple years ago produce tables as are reflected in the current Marlin tables .. the look a bit different.

Yes, the table format hasn't changed.

---

[www.hydraraptor.blogspot.com]

How do I measure the thermistor resistance when it is also connected to the controller board? I tried to measure on the screw terminals of the connector on the board (it is a Melzi board .. all the connectors are screw connectors which are very nice), and that does not work.

You can't measure the resistance directly without disconnecting it. But the method I described and my python script can use inferred ADC values to calculate the table.

E.g. if you set it to say 240C with an existing table you know when it has stabilised the ADC value must equal the value for 240C in that table. If you measure it as say 245C then you know the ADC value at 245C is what is in the table for 240C. My script can then work out the resistance from the ADC values.

---

[www.hydraraptor.blogspot.com]

Which script specifically has the inferred ADC value calculations?

This one does: [github.com]

---

[www.hydraraptor.blogspot.com]

So here is what I did .. Took a real T0 .. room t0=20 and r0=120700

For the t1 in the script the resistance was 94 and t2 was 256 with resistance 42

When I set the host to 209 .. the real temperature via a thermocouple was 178.3, and at 256 .. it was 218.5

So .. I put t1=178.3 and t2=218.5 leaving the resistance alone and generated the script ...

Is that the idea??

Thanks!

It would only be correct if you started with my table. If you are starting with a different table you don't have the resistance values so you need to use ADC values from that table instead.

---

[www.hydraraptor.blogspot.com]

Which table is your table? I hate temperature!!! So confusing

In my fork of Marlin for Mendel90 I added two Steinhart-Hart tables for the two Epcos thermistors that I use as tables 8 and 9.

Table 8 corresponds to the default values in the script but 92 and 42 are not resistances, they are ADC values from which resistances are calculated. It is also the same table shown on my blog.

More than likely you are using a different table to start with as I assume you are using a different thermistor. If so you need to use two temperatures that are actually in your table and the ADC values that correspond to those. Then you know your measured temperatures correspond to those ADC values. You input those into the script and it converts the ADC values to resistances and makes a new table.

---

[www.hydraraptor.blogspot.com]

Sorry being so dense .. I do not have the table that corresponds to this thermistor. All I have is 100K with a Beta of 3950 .. how do I build a table for that?

Because I can't measure resistance as the thermistor is used, I can't take data points when the hot end is at a stable temp.

If you are able to run it at a stable temperature you must be using a table. It might not be right for your thermistor but it doesn't matter as long as you are able to run it at representative temperatures and it is stable.

You don't need to know the resistance because you can get the ADC value from that table and my script will calculate the resistance. You do have to know which table you have selected and you need to pick temperatures that have entries in that table with corresponding ADC values. You then measure the actual temperature and you have a tn, adcn pair.

---

[www.hydraraptor.blogspot.com]