University low budget project, please help!

[neotko 1,417]

About checking with Ultimaker just drop a msg on support.ultimaker.com and post a ticket to sales, they will quote the price.

[UniProject 0]

About checking with Ultimaker just drop a msg on support.ultimaker.com and post a ticket to sales, they will quote the price.

 

And they will sell it just to you? This would be an option.

@all

Anyways guys you are so helpful here

I just got the last questions here:

Its about the UM V1.5.7. It can handle more types of Sensors including PT100?

The heater output is 18V? This would be go up to 24V if I would mod it to 24V PSU!?

[neotko 1,417]

No, they will sell it to you. At least they should I think...

[jonnybischof 60]

...

@jonnybischof

From what I understood is, that the guy on youtube is actually changing this linear regulator and he did a bunch of videos with his UM after that, so maybe this would be a good solution.

Going to the relay/transitor thing: Well I do not understand why the source of this hack is telling me to buy a 300W PSU for a 200W Heatbet. A relay or a transistor should not consume so much power. Anyways I do not really understand what you mean "100 times better"!? Afaik they do the same.

...

 

This is a very common question that most people don't know. But the idea is very simple:

A 300W switching power supply unit can deliver up to 300 Watts of power. But it will only deliver as much power as the "load" draws. So, you can connect a 200W heatbed (generally speaking: a 200W electrical load) to a 300W power supply unit which will then deliver the 200W drawn by the load.

Now, every power supply unit has an efficiency rating (e.g. 85%), so the power supply will draw a little more from the mains socket than it will effectively deliver at it's output. But the power rating counts for the output - so don't worry about that.

So, why would you want to use a 300W PSU for a 200W load?

1. Some cheap power supplies will not actually be able to deliver the full rated load continuously. They may become unstable or die after a few months of use.

2. The closer you are to the maximum rating of any electrical device, the more "stress" you put on it. It will run hotter and generally wear out sooner.

3. You don't lose anything in terms of power. On the contrary: Most power supply units have their optimum efficiency at around 50 - 75 % of their rated load.

The only downside is that a 300W PSU costs more than a 200W one.

--> You should generally dimension your power supply units to be able to deliver around 30% more power than what your application actually draws. That is a rule of thumb, not a mandate. But it has it's reasons.

About the relay vs transistor: the "switch" (relay or mosfet) is put in series to the load (heatbed). The switch has a certain electrical resistance, which means it will actually "steal" a small portion of power from the heatbed.

Simply put: A mosfet has a much lower resistance than a mechanical relay. The one that I use in my hack is virtually invisible (practically 0 ohms). Now, if you compare the datasheet values, you will find that the contact resistance of a 10A is around 30 mOhms (0.03 Ohms).

My mosfet is around 3 mOhms, which is only a factor of 10 better, not 100.

But there are several other factors that make the mosfet better:

Relay contacts are generally NOT intended to switch DC, but AC. You can see that beautifully in the picture neotko showed above: It says "10A 277 VAC". The thing about alternative current (AC) is, that it alternates between a positive and a negative voltage in a sine form. That means, the current will periodically hit 0 every time it alternates from positive to negative or back.

Direct current (DC) doesn't do that. You have 12V at all times, period.

Now, if you switch a mechanical relay contact while there is a voltage present, there will be a spark between the contacts. An alternating current will always extinguish that spark when it hits 0V (which is 100 times per second on a 50Hz signal). A DC however never hits that 0V mark, so the spark won't be extinguished.

Of course the spark disappears by itself at some point, BUT as a matter of fact, running a mechanical relay on DC will lead to burnt out contacts eventually (much sooner than AC). And, a "10A AC" rating means NOT that you can run it at 10A DC reliably and for a long time.

Now, a mosfet doesn't have that problem, because there is no mechanical contact "opening" but a semiconductor "switch" that changes its resistance. No spark - no problems!

So, what does "contact burn" mean on a mechanical relay? Simply put: It means that over time, the contact resistance will increase (and therefore steal an increasing amount of power from your heatbed)! The bad thing about this: The more it increases, the faster it will continue to increase.

This is why many manufacturers write "initial contact resistance" in their datasheets. Note that a mosfet doesn't have that problem, either.

Now I've used a lot of time for writing... gotta get back to work o.O

Edited October 29, 2015 by Guest

[UniProject 0]

Hello guys, it has been a while since the last time I was here.

We ordered parts now and this Sainsmart UM Pack (with that V1.5.7) arrived.

So this Board came and there where several connectors missings so I had to fix that first.

Anyways, as normal for that V1.5.7 Board the thermo connectors have three pins for that Thermocouple thing. The UM+ and the UM2 do have just two pins. So can anybody tell me how to connect a simple PT100 to that Board?

[neotko 1,417]

For that you might need a pt100 amplifier board from E3D.

http://e3d-online.com/PT100-Amplifier-Board

Read also their wiki:

http://wiki.e3d-online.com/wiki/E3D_PT100_Amplifier_Documentation

[neotko 1,417]

Also you could ask @ataraxis who asked the same but for the real ultimaker original board

https://ultimaker.com/en/community/view/17383-idea-question-pt100-sensor-on-umo

[UniProject 0]

@neotko

I wrote him, but it seems we need that thermocouple thing twice, this is sad.

Anyone else an idea.

[ataraxis 51]

I wasn't online for a while, sorry! I wrote back

[UniProject 0]

@ataraxis

I wasn't online here a while too.

I will read you pm's just after that post.

@all

The green China UM2 Board arrived and I did a dry test with it.

There seem to work all axisses excepr the Y axis.

Any suggestions? May the default firmware on this have an error.

The stepper is under voltage because I can't turn it with my fingers until I tun off the board.

[UniProject 0]

I just gonna give you guys an update here.

We have almost finished the first printer and the second one is not going to be finished by us.

I wasn't able to get that China Board V2.1.1. to run correctly because there was obviosly something damaged.

So the first printer has to run with the Arduino Mega 2560 and the UM Board V1.5.7. by Sainsmart.

We got the thermistors (PTC 100K and PT100) running without any thermocouple.

There was also a lot of work with that Board and a lot of trouble with that Set:

-Stepper Drivers 3 of 5 not working at all, one exploded due misfunction and the last one was the only one working in that set.

-The Arduino Mega has lost its flashability after the first flash, we had to replace it, no chance.

-The steppers they sold us were Nema 15 instead of Nema 17 and they had no plugs.

-Half ready to go solder Job. Looks like drunken chinese kids did that (Made in USA).

So now we are almost finished and I just wanna tell you guys, especially those who wanna rebuilt an Ultimaker from drifferent sources for parts: Just get another Mainboard. If I had the chance to redo the project, I would defenetly buy a Rumba Board or somethin' like that. This brand is so expensive and you are able to get the same results much cheaper. This was all I wanted to say right here. I just regret, that I didn't knew it better.

[neotko 1,417]

Well your experience with Ultimaker boards, are with 'non-made-by-ultimaker' boards... So yes, cheap stuff goes wrong, just as we told you. Also you could have use a Smoothieboard, Rambo, Rumba, Megatronics, and a long etc of Reprap boards made in Europe/USA.

[niyoki 21]

UniProject hier finden Sie Ultimaker Baugleiche Vertex 3d von Velleman ist auch ein Open Source 3D Drucker mit alle dafür nötige Zeichnungen. https://github.com/Velleman/Vertex

oder K8200 oder 3drag http://reprap.org/wiki/3drag

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Gruss