PeterE builds a 3d Printer

[PeterE]

picclock,
First of all, thank you very much for nice comments!

I will pick up your tip on both the 5V load resistor placing, and to fit a terminal block on the outside of the PSU housing, very good ideas both of them!

nrml,
The answer to the choice of a PC ATX PSU instead of a CCTV/LED unit  is simply that I didn't find one as I was looking around. The ones I did find cost way more than about 18£ here in Sweden and none was to find on flea bay currently, had I found one that would have been the choice.

On the other hand, using the PC ATX PSU I automatically solved the mains switch and power receptacle matter.

I wish all readers a happy new year with many interesting builds of all kinds!

BR

/Peter

[PeterE]

Happy new year to all! 

Starting out this year with a question ...

picclock; On your picture of the rear of the PSU I tried to compare your setup with what I understand from the description I use and my PSU. The white cable to the far right, what is that one used for?

For the rest it looks like you have (from left to right):
 - Ground
 - +12V
 - Ground
 - +12V
 - +5V
 - Ground
 - +3.3V
 - PSU On
 - Ground
 - ??????

Quite similar to my setup which turned out as below:

I made a small label strip beneath just as a reminder of which is which and I think you can see which will be which on mine. There are actually two different +12V outlets on my PSU at 20A each  so I don't have to divide one into two.

Furthermore, I will enter the cables from within the box to the topside of the terminal block so the consumers will be let out from below. I think that will make it easier to keep the cabling along the bottom of the machine later on. I will of course fit the cables for the consumers before fitting the complete PSU to the machine to simplify connections.

There is a difference between the two in that you have chosen to have a 3.3V connection point (orange cables) outside the box whereas the description I use does not include that. Is your choice just due to not wanting to leave the possibility out and that the mod is a general one, or anything else? Just curious to know before not including it myself.

BR

/Peter

[PeterE]

Well thinking long and hard and looking at what the manufacturer had chosen as suitable, I found that two strands/cables were judged to be enough for 12V 20A. A quick check with the 24VOLT.eu site told me that it was quite OK. So I could use that as template for the rest of the setup. The site turned out to be quite useful and the link is here: http://24volt.eu/kalkylator_kabelarea.php. Click the UK flag to change to English.

I also decided to include one single 3.3 V connection on the outside to be prepared for any circumstances appearing. Had therefore to change the label  so the rear of the PSU now looks as follows:

But it is not yet possible to put the lid back on - of course the load resistor for the +5V line was not in my store so have to buy it next week ...

While waiting for that to turn up, it is high time to try to understand the electronics setup and with the following walkthrough of the bits I hope to get some feedback if I am off track so to say.

The base is an Arduino Mega 2560:

It is fed using the USB connector to the left at loading and setting up time.

When done, the USB connection can be removed as the control board called RAMPS is to be fitted as a piggy-back board on top of the Arduino board. This contains the controls for stepper drivers, end stops, extruder heater, hotbed, etc.


The USB cable is not required as we connect the two +12V lines to the lower left for the two circuits.

Thereby the Arduino board below seems to be fed from the RAMPS board. at least it looked like that when inspecting the connections.

Then add the SMART-adapter for he display board on top of the RAMPS board to the right.


Now we can attach the display board with it function selector  in the SMART-adaptor connectors (quite short cables between those - hmmmm).


And finally, five small stepper driver boards is fitted on top of the RAMPS board. I placed one of the five in the upper row to the left.

This is supposed to be a job to be done with caution as if the stepper boards are turned the wrong way there is a risk for the  whole setup to blow, all the way from the Arduino and upwards!

So, this is what I can see from just looking at the parts, is this correct? Is there a way to ensure that the stepper drivers are fitted correctly, I mean something particular to note at assembly time?

Now back to think about the best place for the control display .....

/Peter

[picclock]

Hi Peter E

Happy new year to you to 

Your PSU looks very neat, certainly smarter than mine. I think the white lead is -12V, it was just put together as a general additional bench supply for various project testing.

I have been running running temperature rise tests on my stepper drivers and you really do need a fan for cooling them. I thought I might be able to get away without as I'm using 24v but it won't work for reliable operation. My chips trip at 150C and without a heatsink on top I was reaching just over 130C chip temp with an ambient of 11C (measured with infrared thermometer on chip surface at 75C). Worst thing is this is for a single driver at 1.4A. So very much on the edge. The twin driver z axis will likely dissipate 3x as much driving at 1.3A each so for continuous use good heatsinking needed. I have designed pcbs for the drivers you are using but they were never expected to dissipate so much. Problem is if one stepper shuts down for only a fraction of a second print is ruined. So to sum up, forced cooling essential if you want good reliability.

When you start testing, ensure that you have bed and head thermistors connected or Marlin will shut down with ERR MINTEMP but the screen will continue to show normal operation. I have flagged this as undesirable/misleading behaviour with Marlin who indicate that the message will be changed to show the system has halted.

Good luck with your testing and further progress. 

Best Regards

picclock

[chipenter]

This will test your steppers and drives , match the baud rate and they shoud turn , I can't get my software to see my shield says my encoders are wrong , but they turn so I know it's correct .

[PeterE]

picclock,
Thanks a lot! Ah, -12V, that one i did leave out this time.

Interesting findings about the temp issues for the stepper drivers. Must make sure I can arrange something useful for extra cooling. It also sounds that some sort of airflow guidance would be useful to ensure good cooling. Have to think about that.

Yes, I will have thermistors connected both to the heatbed and the extruder nozzle.

chipenter,
Thanks for the code! Must try that at starting-up time.


In the meantime and while waiting for bits I have made a mock-up from some styrene bits I had laying around. Thought I might make it presentable at least. I know I will not be able to print myself for some time yet and the display is needed before that. The top side looks like this: ...

... and the bottom side like this.

Nothing complicated but good enough to test both where the panel is best fitted and if there should be any extras like storage for SD cards or the like.

/Peter

[picclock]

Hi Peter E

If you are just waiting for the resistor to arrive for the 5v load, you can easily use a car light bulb. These give off a deep orange glow and can look cool !!  . Any light bulb will do (probably 10W minimum) though I'm not sure if the very small lower wattage interior lights would work. Because it will work off of 5v it should last forever (well, as long as the psu  ).

Marlin gives you the ability to check the motors. Just go to the prepare menu, select autohome (won't work without that - bug in marlin I think) then select move axis and the distance, and rotate the jog control to see the motor move. You can't check extruder or z axis with just Marlin (if so I've just not found it ). Using octoprint (octopi even) gives me complete wireless control of all the axis and the extruder, even from my phone (must get smaller fingers). 

I have had to do all the other stuff so I can work out where to drill the mounting holes in the granite base - so its all got a bit out of order for me. Still, nice to know it will all work Ok.

Good luck and good progress.

Best Regards

picclock

[PeterE]

Hi picclock,
Thanks for comments, very useful!

I looked at the light bulb idea but to my surprise found that it would be much more expensive than waiting for the resistor  so it will be a resistor.

Good to know that there are means to check the drives already in the program. Will do that when all is going. That about wireless control also seems very interesting! Must look further into that as well.

We are not meeting any particular deadlines I think, so if some steps take a little longer than intended I don't think it really matters. What matters much more is that it will be as intended and tought out in the end!

So, while waiting for bits I have made a mockup of the "box" for the display - yes, I know it looks horrible but it is a mockup!    Anyways, one thing to remember is that the slot for the SD memory is at the left side of the display and that have to be accessible with ease regardless of where the thing is placed.


So, now to where to place it? To me there are four possible positions on the machine, the question is which is the best one????

No 1 - At the upper left corner of the portal

This has the advantage of short distance to connect to the electronics, the downside is that I have to stretch across the machine even while it moves.

No 2 - At the baseplate to the left of the build board

This has the advantage of being easy to access and to handle SD-cards, the downside for me is that it is to the left as I normally use my right hand.

No 3 - At the center of the baseplate in front of the build board.

Advantage, easy access and easy to handle SD cards. Really a quite OK position. The possible downside would be if it is in the way of work when removing built items from the board?

No 4 - At the baseplate to the right of the build board.

This is the easiest place for me - I think - with easy access and easy handling of SD cards. But it have to be placed in front of the build board to avoid hiding the SD card access.

All four positions have their advantages and downsides. Many I have  seen are placed where can be done due to cable lengths I think, and others place it where seems fit and fixes the cables to suit. If placed on top of the portal I think it should be skewed a bit so the panel faces the user standing in the middle. If placed on the baseplate, the display should be tilted like in the images to be easy to read and avoid un-necessary light reflections.

I would like to get some input on this before I finally decide, I have an idea but don't want to bias any answers and thoughts. Just general comments are good as this is a small usability test.

BR

/Peter

[PeterE]

Still no thoughts??? Ah well let's carry on then ...

Today I made a smallish thing that needed special attention. Anyone tried to find M4x60 screws? Hard to find? at least they are in Sweden! It seems only a few companies stock them and sell over the net at insane prices 

Only one thing left to do = make your own! Two small bits of the leftovers of the 8mm smooth stainless rod was drilled, threaded M4, cut to length, and given a screwdriver slot thereby making up two screw heads. With a suitable piece of all-thread the sought-after screws are there to an immensly lower price and they get exactly as long as you want/need 

The all-thread is secured with a drop of Loctite and we have a screw. Now the extruder is in place:

Next is to fit the extruder head and the feed something that will include some more special bits as it seems.

/Peter

[Bluechip]

Have had some long metric screws from here :

http://www.a2stainless.co.uk/M4-x-0-70mm_B22V22.aspx

Even got M4 x 100mm

Just A2 cap screws. Only know a few places in UK that do long machine screws in similar lengths but they only do 100's 
as you say at insane prices. ( particularly if you only want a few ...)

Dave

[picclock]

Hi PeterE

Good to see your further info. The M4 screw looked very smart. Do you not have allthread/studding that you can use for long fasteners? just seems a lot less effort to use that. Loved the display case mockup. If you had a 3d printer you could print one of those   

Its a nuisance needing stuff to build the printer. I have bent up a rather poor fan shroud for cooling the drivers out of aluminium, all the while thinking what a waste of time as I will replace it with a printed one at the earliest opportunity (or when I get round to it  ).

Keep up the good project log.

Best Regards

picclock

[PeterE]

Bluechip,
So the same goes for you in UK. Odd sized = very expensive and few suppliers. In my case I only need two.

picclock,
The "stem" of the screws are made from pieces of a metre long M4 allthread even though it does not show on the blurry image, sorry.

The mockup of the display case is of course being targeted for a print later on, but now I need something for protection and to find out if any mods are desireable, swiveling or tilting  foot perhaps, or anything else that might come in handy.

Well nuisance or not I think the need for making things on the way as they are discovered is one of the temptations/challenges  to solve and also a part of the effort to develop a well functioning machine with precision from everyday bits.

A thing here and a bit there will make good results. The biggest difference so far I have found is that most of the fasteners were designed for imperial system as far as I can see. Re-designing for metric did show a few misses, like the long M4's for ex. Also there were countersinks for nuts at the back that were dimensioned for M3 nuts! In my opinion M3 would have been too thin for the application. I guess such differences comes from differently sized standard imperial measure components versus metric ones.

I'll be back as soon as I get some more done.

/Peter

[picclock]

Hi PeterE

If the nut recesses are M3 you can likely bodge it by placing an M4 nut over the opening and applying a soldering iron to the nut to melt the plastic, allowing a tight fit. The excess plastic can be trimmed after its cooled.

Keep up the good work

Best Regards

picclock

[PeterE]

Hi picclock,

Thanks for the idea, did not think of that, and while very useful I am a little reluctant to do it with the whole thing assembled and in place.

I solved it in another way. I opened up the through-hole to match the 4mm countersink and used that to broach the six-sided hole into a round one suiting the nut much better. Careful and slow work and it all went well. But I will keep it in mind for later bodges.

Thansk again!

/Peter

[tom37]

Peter  If you need a metal printer, You likely have on MIG printer (i.e. welder)
If you have 3axis cmc mill, a little scrap and you have trial printer.  Good luck  tom

[PeterE]

Hi tom37,

You are quite right about that. There are just a few but's and if's involved as well.

Using a MIG welder will require a good electrical and electromagnetical separation of the weld voltage and current, from the three-axis movement voltage and current. On top of that the MIG nozzle is quite stiff and heavy as it is adapted for hand movement, so the re-design would be very hefty, but yes, the functionality is there.

Converting a CNC mill to 3D-printing, well that is a lot easier as it more or less "just" requires an extruder head clamped on the mill Z-axis and that extruder can very well be a REPRAP one. The downside here is that I don't have a CNC mill - but yes, the functionality is there. I could even think of a solution to have a special attachment for the plastic extruder so that it can be mounted using the CNC mills normal tool fixing means, then change from mill to print is just a minutes job.

Well, we'll see where it goes. It is fun testing and trying new things. Thanks for your thoughts 

/Peter

[PK]

We use our CNC router for welding...

Here's the TIG head:

We also use it for stud welding, although I just realised that we don't have a video of that. Here's the welder when we first got it.

It did take a bit of sorting out to eliminate earth loops and capacitive coupling. But we use these setups commercially.

PK

[awemawson]

Great stuff 

Looking forward to the CNC stud welder - are you automating the loading into the collets?

I have this little hand held stud welder that works a treat:

http://madmodder.net/index.php/topic,10358.0.html

[PeterE]

PK, thanks for showing! As far as I could see, the TIG nozzle was mounted to the ordinary machine spindle. Is it clamped around the outside or held by a collet?

This looks very mucxh like you could also fit a similar attachment for 3D-printing using ABS or PLA, it is just the extruder part that needs fixing.

Really a multi-putpose machine!

/Peter

[DMIOM]

......This looks very mucxh like you could also fit a similar attachment for 3D-printing using ABS or PLA, it is just the extruder part that needs fixing.......

Peter - you could do it but the I think the slower traverse speeds and acceleration limitations in most CNC mills/routers would make it a very slow 3D printer.

Dave

[PeterE]

Hi DMIOM,
Yes, probably. There is a great speed difference in ball screw and toothed belt movements, not to say power differences.

But principally it should work of course.

/Peter

[PeterE]

A fiddly bit done at last.

I worked with the extruder a little more today and was looking over the bits prior to assembly. I got this extruder head and it has a PTFE tube connector in its top end. Unfortunately, that will foul with my extruder body so time to re-think this.

The PTFE tube connector was unscrewed to see more. It turns out that the thread is a 1/8"-27 NPT and not the more common M6x1. A quick look in my tapping dies drawer revealed a proper die. Good.

The hole in the extruder head is quite deep and if I don't put anything to guide the filament, I think I am in  for some problems. Some measurements gave a base for a small adapter to fit in place.

Without the PTFE-tube connector I also tested the extruder head collar fit in the base of the extruder body. Hmmmpf, the collar was a tad too large in diameter, but not more than a couple of strokes with a file couldn't correct.

A new test fit showed that the collar went in quite a bit, in fact a little over 1 mm more than its own height. New info for the adapter then.

So, the adapter need to compensate both for the removed PTFE Tube connector as well as creating a washer to make the extruder head stand proud of the extruder body about half a mm or so for clamping purposes. This is how it turned out:

The thin stem is entering the hole in the extruder body to further guide the filament to the extruder head from the feeder. The coned end is stuck into the extruder head and guides the filament properly down to the hot end so there should now be way less risk for filaments to mis-behave during printing. The adapter is screwed in place  using the 1/8-27 NPT but nothing more than finger tight is necessary since it will be pinched by the clamp.
And here we have the whole assembly before fitting to the X-carrier. It is easy to see that the extruder head is really clamped to the body and there will be no backlash or wobble anywhere in that setup as far as I can see.

With this the extruder is now complete apart from electrical connection(s). Starts looking quite OK now.

The the last bit to fix is to make a new fitting for the PTFE tube connector. It must be placed above the filament feed screw but there is not much meat to fit it.

I have ideas and will try them out.

I'll be back!

/Peter

[PeterE]

Evenin' All,

The load resistor finally showed up and was fitted. I put a paper below to show how I did. Solder close to the "body" and then a smallish piece of heat-shrink tubing to avoid un-necessary accidents.


Then to avoid having something bouncing around inside the box I tied the resistor to the mesh with a couple of tie-strps just like picclock showed earlier. Simple and effective and the resistor get some cooling air flow.


Then on with the lid and the fan and the PSU is done.


What is the proper place for this thing in or on the printer? My thought says put it on the left rear. That means that the electronics can be placed above the PSU and I can easily re-use the "left-overs" cables to suit.


The last picture also shows that the mains connection cable enters the PSU above the switch, which I think don't look very well from a usability perspective.

I am thinking like if I flip the PSU over and make a largish hole in the left triangle stiffener the cable and the switch have much more natural positions. That in turn would mean that I will not induce any un-necessaery cooling air streams around the build plate and thus limit the risk for bad prints.

Will think a bit more on that. To make a hole in the side will not geopardize the structural stability that much so it ought to work. Hmmm, a large hole or a grid with suitably sized holes? 

Any thoughts???


/Peter

[chipenter]

If you fit the wire fan cover over the hole or holes and use longer self tappers it will also fix the psu .

[PeterE]

Very good idea chipenter, many thanks for the input