Very Strange here.. temp holds great for first layer.. then drops like a rock  

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

I had same problem. Dont waste time and filament (like me) and just buy new heating cartridge and install back original orange fan duct ;). Or better - contact customer support and I am quite sure, they will send you replacement (your cartridge is obviously faulty/weak and they are aware of this problem). PR started using 40W instead of 30W btw.

Adjusting fan speed may solve the problem with temperature, but print quality can suffer in some cases.

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

True, I had the exact same problem solution is 40W cartridge , No problems from that point. Prints are beautiful. And probably heats up faster.

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

True, I had the exact same problem solution is 40W cartridge , No problems from that point. Prints are beautiful. And probably heats up faster.
While that is surely fixing the current problem, using a higher rated cartridge will increase the risk that your fuses pop, or even worse, your heater connection on the controller will melt (has happened to many people).

There has been numerous posts these last few months concerning this, and the conclusion is that E3D cartridge was manufactured with tolerances far beyond what was specified (I got one too), which resulted in many cartridges being shipped with a far less Wattage than what the printer needs. Just contact the support here and they'll help you out.

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Sascha

Unfortunately, others see a 40W heater cartridge as a "solution". It is not. A solution is something which solves a problem. This is simply a work-around for at least 4 problems with the hot-end.

You are absolutely correct with your comments regarding the 40W heater. In addition, in e-mail correspondence, E3D have stated the following:

"We send 12V 30W heater cartridges as standard with all of our HotEnds, we do send 25W but only in our 24V specific kits and we only send 40W cartridges if specifically requested by a customer"

and

"40w heater cartridges' also need a lot more supervision compared to 25w or 30w cartridges"

I do have some information which states that about 20% of the 30W heater cartridges supplied be E3D actually produced less than 27W of heat.

There are also various posts around the internet stating that 40W heater cartridges are more subject to "thermal runaway", hence the last quote from E3D above.

And as user "Marcin" has discovered, installing a 40W heater can result in the blowing of fuses with only about a 10% headroom on the relevant 5 Amp fuse (there may however, be other issues with his printer).

I do not believe that the RAMBo mini was designed to work with a 40W heater cartridge. If it was, then more overhead would have been designed into the board with regards to that particular fuse.

Also there is the additional cost of running a 40W heater with a fan housing which over-cools the heater block. Yes, that only works out to a few pennies/cents/whatever every week, but over a year and with many hundred of printers in this configuration, the amount of energy wasted is significant.

So, what is better? Well, in my opinion, the best solution is to fix the other problems and to install a 30W heater cartridge. One which is actually 30W. The cartridge I am using (with the amended fan housing) is generating about 28W and I have no problems with that at all.

Ideally Prusa Research will soon be in a position to provide an actual solution to this problem rather than employing workarounds.

Peter

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

I will just pick up a new v6 lite hotend. They are cheap enough. Just don't know which one due to there being the 12v, 24v, direct drive, boden, thermister...
Ahhh confusing.
https://printedsolid.com/collections/accessories-and-upgrades/products/lite6
I should get the one with the Stud Thermistor right?

Will check in a bit too about the resistance at the terminal.. in a pathfinder game atm using Fantasy Grounds...

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

I believe that was about heatbed connector, not heater 😉 (heater and hotbed connectors are same, so heater connector shouldnt be problem at all)

will increase the risk that your fuses pop, or even worse, your heater connection on the controller will melt (has happened to many people).

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Roman

That is correct, but as you reduce the resistance/increase the current of the heater cartridge, you increase the possibility of heat in any "high resistance" connectors. As there are two mechanical only joints in the connector system and because you don't need very much power dissipated in either of those joints to create significant heat, there is an increase in the possibility of heat damage in that connector.

Peter

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

If i measured correctly with the machine off and between the leads of the heater... 5.7
Sounds wrong to me...

Well replacement heater is on the way! Dan was great going through the support with me.

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Scott

5.7 Ohms @ 12 Volts = 25.26 Watts (P = V^2 / R), but the actual voltage is around 11.2V, so power in use = 22 Watts which is significantly lower than the 30W required.

But it depends on how good your meter is; if you also measure the leads by touching the probes together, then subtract the reading from the 5.7 measured, that will give a more accurate figure.

As it is it would appear that you ore one of the many with an underpowered heater.

Peter

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Just an update.
I was finally able to get around to replacing the heater cable.
Well it is working great. Replaced it a little bit ago.
Thanks.. awesome customer service at Prusa!

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Sascha

Unfortunately, others see a 40W heater cartridge as a "solution". It is not. A solution is something which solves a problem. This is simply a work-around for at least 4 problems with the hot-end.

Peter

Does it solve the problem with staying on right temp ? Yes

Does it use more electricity ? No. Why would it ? It is regulated by Rambo wich is controling temp. So it is the same , maybe even less because You are not waiting longer for printer to get ready.

It may use more current in the begging then standard one, but heatbed uses much more current then hot-end so why are you worried about that ? Its on 130 € rambo board which was made for the this task. Not like 5 dollar Ramps that will probably fail due to bad components. The ones that get burnt connectors are just incorectly tighten screws or loose attachment of connectors.

The solution really is just more powerfull heater, thats it.

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Jozef

Sorry, but I don't think you are quite grasping either the issue or the maths in this situation. I don't want to get into a lengthy discussion to demonstrate why some of your comments are quite incorrect, but I will explain in detail should you so desire.

Peter

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

The solution really is just more powerfull heater, thats it.
If that's the case than you should be able to install a 100W cartridge and have even better performance and less issues, but that's not how electronics work.

I would just as Peter like to explain it in detail, but you have kind of shown with your attitude that you're not ready to be humble and learn from others.

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

my thoughts about this:

1) I agree, that original fan duct design needs to be slightly reworked or heating block insulated. I have second printer with 30W heater and there are no problems with temps even with high power fans. (but for the moment 40W heater is easy solution, along with some heater block insulation - for example with kapton tape).

2) I believe 40W heaters are quite common, propably much more common than 30W heaters. I know, that E3D now uses 30W as standard and it should be more than sufficient. I dont think, that Rambo isnt ready for 40W heater though (40W is IMHO more often used, than 30W).

3) Ramps 1.4 uses 5A fuse for extruder heater (and it supports two heaters for dual extrusion configurations).

4) you can adjust maximum power to heater via firmware (range 0-255).

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

I dont mean to dishonest someone. I just like when there is a clear solution that fixes things rather then speculating 3 months about something. Im a simple man - I see problem and I try to find solution. Sorry if I offend you. I dont like arguing. I like facts. Someone already put effort in designing this. But it was designed with 30 W heater. By printing another design of cooling fan you are actualy "working-around " like you are saying.

Limitation of heater used is only what can tranzistor in Rambo take (probably the fuse will blow up if its only 5 amp) . Of course.

The problem is that heater used (claimed to be 30W clearly engraved on heater cartrige) was not 30W . There for you need better one.

When the fan kicks in 100% its colling heater block , wich means this breeze throws off the equilibrium of power needed and power that can be put in , But the heater is probably going 100% already so there is no reserve to accomodate that. I believe that Rambo uses PWM to control this so it really should not be problem to limit the output. Therefor The system will remain the same , but you would have that reserve of few watts more when it is needed. Here is just one fan to cool. What if there are going to be 2 fans ? or 3 ? that will get better performace in cooling ?

In this case its not really a math issue. If it is , it would be fixed already by code.

Solution : 30W (really 30W not less) or more powerfull heater.

Do you agree with this solution, if not why ?

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Jozef

As I mentioned previously, there are at least 4 issues which contribute to a drop in extrusion temperature whilst printing and when using the part fan at lower levels.

Three of the issues are design faults and one is out of specification component. Yes, the problem can be worked-around by installing a more powerful heater, but that comes with potential costs.

For the design issues, there are 2 which relate to the printer design: the part fan nozzle and the orientation of the heater block (if you hadn't noticed it is upside down).

The third design issue is that the hole in the heater block where the heater cartridge fits is slightly too large.

The above three faults all contribute to inefficiency of the heater cartridge and contribute to wasted energy (money); although they may be overcome by the install of a 40W heater cartridge, the end result is still (more) wasted energy.

The fourth issue is that of out-of-tolerance heater cartridge. The nominal 30W heater cartridge will generate about 28 to 29W of heat in this printer (the 12 Volts being reduced slightly due to the voltage drops across the components). This in itself does not cause an issue and in fact I have a heater cartridge which generates a nominal 27W and this too works well (with an amended fan nozzle).

However, some of the supplied heater cartridges have measured as low as 22W output, and these do have issues with temperature drop - these have mostly been replaced by PR.

Now, the problem I have is that we only get to hear about heater cartridges which have higher resistance than they should have. One has to assume that the shipped 30W heater cartridges have an actual range of about 24 to 36 Watts. Therefore the same would be true of a 40W heater cartridge (ie a range of 32 to 48 Watts).

When designing electronic circuits, allowances must be made for worst-case operational tolerances. In this instance we are looking at a fuse which protects the extruder heater, the fans and the electronics.

We have already seen that a 40W heater cartridge can consume up to 4 Amps of current which only leaves an overhead of 1 Amp for the electronics and fans.

Fans use electric motors which have a stall current significantly higher than normal operation current.

The electronics (5Volts) are powered vial a Buck regulator, capable of handling up to 2 Amps of output. Fortunately Buck regulators work by reducing the voltage and amplifying the current; however, they are only about 90% efficient.

A simple estimation of current draw with a 40W heater based on the above should give an indication that this RAMBo 5A fuse potentially on some printers does not have sufficient (if any) overhead.

For what it's worth here's a photo of my re-worked extruder:

Note that this overcomes two of the design faults mentioned previously. I also note that E3D are now selling a revised extruder (along similar lines) with a 30W heater cartridge as an "original" i3 upgrade kit.

However, I do believe that all this is becoming somewhat academic; I am certain that Josef et al are not sitting around scratching their butts all day and that very soon we will get to know what they have been up to over the last few months.

Peter

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Fan looks good. Its compact. But now you need that channel that holds the cables right ? Where is it attached ?

I did noticed the flipped heater block. But It puts the heat closer to nozzle so it shouldnt make it worse if flipped around. Termistor is closer to the end too. Although aluminium has great heat transfer anyway. Maybe insulating would work too.

Well it is wasted energy but is such a small amount.

I do understand all the electronic part. And I do understand that they move around 40 W. And that gives you higher possibility that you have enough, rather then underpowered 30W . wich is not enough. So the replacement is really a solution for this problem.

I just wanted to make it really clear for others. So we can stamp this thread with label SOLVED 😀

Yes Im curious if they come up with something new 😀 .

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Jozef

When asked, E3D had this to say about using the heater block downside-up:

"The issue with mounting the heater block upside down is that the plastic can cool slightly before it leaves the nozzle due to the distance away from the heater cartridge.

"This could potentially cause jamming or de-lamination issues once you start printing.

"We always suggest that you mount the heater cartridge lowermost."

In other words, the ideal situation would be to have the heater in the nozzle itself such that the temperature lowers gradually all the way up the extruder. The further away from the nozzle that the heater and thermistor are located, the hotter the required printing temperature and again, bye-bye Pennies/Cents/Haléru.

My Chinese clone will happily print PLA at 180 degrees; the bottom limit on the PR is 190. There does have to be a reason for this...

Unlike some people, I have limited resources and I really cannot afford to waste any money. I would much rather spend my hard-earned cash on filament than just throw it out the window.

Please believe me when I tell you that a 27 Watt heater cartridge is working for me. It is plenty of power and is much less likely to have a "thermal runaway" than a 40W heater. I do overnight prints, and I really don't want my house burning down, thank you! (And yes, I do have a smoke alarm above the printer.)

Please also bare in mind that as mentioned above, a 30 Watt heater is is being shipped by E3D in their upgrade kit. Does that not convince you? If not, then I really do give up!

Peter

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Fan looks good. Its compact. But now you need that channel that holds the cables right ? Where is it attached ?

Jozef

There is a cable guide (a small trough) going off to the left from the bottom of the extruder fan, with a couple of ridges for cable ties.

Peter

Re: Very Strange here.. temp holds great for first layer.. then drops like a rock

Yes Im curious if they come up with something new 😀 .

I think you will be quite impressed... (not that I have any information, but based on developments elsewhere in the industry).

Peter