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Currently the build volume is 200x200x220mm
Making the platform higher will instantly increase vertical build size, but comes at the expense of longer drive shafts, lead screw, smooth rods, and a slight loss of stability, unless you enlarge the machine footprint as well.
There is a 300x300x300 version planned that should be printable on a standard Morgan, or Mendel reprap.
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Nice! I actually like the idea of making a half round build area.
My link didn’t post before, but this bed looks great, even though it would need its own power supply: http://goo.gl/emcr2a
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Also, I know someone at the local hackerspace who says it’s not that hard to etch heatbeds yourself. The problem is, that would raise costs because you’d have to pay for the etchants.
He also said you can pretty much make heatbeds of unlimited size because you can etch smaller boards and tape/solder them together.
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And another remark on etching bigger heated beds: Even the normal size is difficult to handle with the toner transfer method, because it can’t be printed on a legal size (DIN A4) printer in one piece.
And finally it is very cheap to use normal insulated wire for the job. If the “bed of nails”, the wire is formed with, is used for several wire-films for several heated beds, it should not only be faster but also cheaper than etching.
Anyway: The thickness of the wire is far more precise over the length, than the best etching could ever achieve.
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It looks very good. How I wish i could get my hands on inventor without breaking the bank…
One suggestion, the current headbead i use has a small gap in the center for the placement of a thermistor. How about adding a thermistor into the film? I use the more afforable DO-35 100k thermistor from RS in stead of the EPCOS bead type used in the hotends
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I would place the thermistor in a small notch in the underside of the building platform (my one is made of aluminum though), sticking its connectors through the film. This way the homogeneity of the heating wire layout could stay undisturbed.
I’m already using a thermal conductive adhesive (arctic silver) to glue the thermistor into a notch in the platform. Works like charm.
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Instead of playing with lacquer and screws to adhere the copper, what about just sticking them down with a large sheet of Kapton/Polyimide tape? I just purchased a 33m roll of 200mm wide tape for $20AUD – and that means it can stand temperatures up to 280 degrees Celsius. I guess you could probably use smaller width tape (say 20 or 50mm) and knock the price of the tape down to $5 + postage. The advantage of the screws is that it would make is easy to keep the wire in a neat arrangement while you stick it down but I think it could be done without the screws by keeping the wire in-place with a small amount of tape as you do each bend.
I admit I have no experience with the tape, so I won’t be surprised if I am totally wrong.
Slicer software generally expects a rectangular build area. Is the solution to simply set the build area to be a rectangle which is the same width and depth as the semi-circle and be careful not to place parts in ways that would put them over the edge? I’d probably just stick to a rectangular build platform to deal with this problem. Besides, cutting the plate in a nice semi-circle may be more trouble than it’s worth (but it looks awesome!).
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@DDevine:
You will somehow have to arrange the wire with equal distances between the loops. Doing that “freehand” seems quite impossible to me, esp. because there are app.80 loops required to cover the building area.
I don’t know how good the glue on the Kapton-tape is, but I think it will be difficult to keep the tracks apart, because only a small part of the wire surface would have contact to the tape (tape -> flat, wire -> round) and this small contact might not be strong enough to keep the wire in place. The tape would also have to keep the wire in contact with the building platform, but on one hand the gaps between the wire-loops are too small and the tape would have to be bended many times over the whole surface (between every loop) to glue the wire to the platform (an air gap between wire an surface would lead to less heated areas on the platform). I don’t think this can be done because Kapton-tape is not flexible.Temperature is not important here, because the platform will not be heated significantly above 100°C.
About size and form:
Correct. One would use overall width and length of the platform for slicing and avoid the Morgan-unreachabe regions when placing the objects.
Cutting the platform to the circular form is no problem. I’m using a standard jigsaw with blades for aluminum. Works like a charm.I use the toner transfer method to mark the profile and the drill positions onto the aluminum.
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Enjoying your conversation.
Looks great Robert regarding the heated bed. Am I correct that the wire is insulated? I’d thought it’d be bare. I may have missed in prior conversation, what diameter wire are you using? What’s the total length of wire used to cover the entire area? Makes wonder how my end-stops would perform. Haven’t compared wheel movement to arm movement directly.
With the larger build envelope, couldn’t it be used for PLA w/o the heatbed?
That would be a tremendous build area, just have to keep the models inside the playground. Have to define the larger area to see.
Nice pictures too. -
Update on the method to fix the wire to the platform:
If the temperature stays below 100°C a good hot glue will do the job. The glued wire can easily be lifted off the “bed of nails” (e.g. after removing the screws, that marked the distances and loops) and then be glued to the building platform.… trying to keep things simple …
First try will take place next weekend. I have to order some additional aluminum first.
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@ate:
You can find a complete model over here too:
http://reprap.org/wiki/RepRap_Morgan_extended_BOM
There’s an archive with all Inventor-Files and another one with all STL-Files as well.
You may use the (free) student version of Autodesk Inventor to use the Inventor files.
You can download several drawings with assembling instructions over there too.Just a comment on your plan to expand the building height:
There is almost no limit, as long as you take the stability of your build in mind. The molten plastic that is placed on a layer may apply only minimal forces to the model, but at that height even that may cause the model to bend. But adding stabilizing structures to the model can surely compensate that.Greetings
Robert -
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@Robert Kuhlman; Thanks for the link (although that website is still puzzling me a bit).
Your concern about the structural stability of the prints is exactly why I’m building the printer, ie to look into stability issues of tall structures.
My main concern is the potential warping of the print material due to uneven cooling rates etc along the height of the of the printed model. -
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I’m thinking of a bigger building platform too. Having just finished a new building platform with a new PCB heated bed design, I was thinking about how to heat a bigger platform effectively.
After my experiences with PCB layout and etching for heated beds I came to the conclusion, that PCB is not effective for bigger platforms. It would be easier to use copper-wire instead. The only challenge would be to ensure euqal distances between the wire-loops.
I think I will make a kind of bed of nails and tense the copper-wire between the nails. The bed of nails could be made of aluminum and the “nails” should be e.g. M3 screws. The sections that have to be connected in parallel to achieve the requested electrical resistance, can be calculated by the wire-length used.
After tensioning the wire between the screws and flat on the bed, it can be fixed with Urethane lacquer:
It is stable up to 130°C, very insulating (>80kV/mm) and clear.
The first layer of Urethane lacquer will fix the position of the wire loops. After removing the screws, another two or three layers will form a film with the wire loops in it, that can be aluminum bed. One layer of lacquer on the backside of the film will be the insulation to the building platform onto which it can be glued with a fresh layer of the same lacquer.I’ll test this within the next few days. Should be much easier to realize odd forms and sizes of heated beds with this technique.
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Like ever I’ve had more time to construct the new idea, than to realize it first:
I’ve constructed the wiring for a maximum building platform for the Morgan. In this example, the copper is 0,75mm thick. The screw is 2.5mm by 5mm and the plate is 3mm thick. The distance between the loops is 2.45mm, so I placed a 2.5mm screw as an example for a “nail” to form the loops.
This version will have a resistance of 1.45Ohm, using 38 meters of 0,44mm² insulated copper wire (38.080055m to be precise).
The Inventor file was intended to let me test several wires just by typing there diameter, but something went wrong. But for a first try it’s good enough.
Here are the dimensions of the maximum building platform for the Morgan, all this was constructed for:
And here an overview over the complete platform wiring (so you can see it is completely constructed already):
The measurement of the wire-length was done on this basis.
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On the first page Robert said that the first version was using copper that had a diameter of 0.75mm, and that the second version (?) was using copper with a cross-sectional area of 0.44mm²… which Wolfram tells me is basically the same diameter.
This version will have a resistance of 1.45Ohm, using 38 meters of 0,44mm² insulated copper wire (38.080055m to be precise).
The copper wire *must* be insulated, else the current would flow through the path of least resistance (the platform itself) and without resistance, no heat would be generated. Insulated copper wire can look like normal uninsulated copper but in fact it just has a transparent insulating coat on the outside. If you look inside a motor or electro-magnet you will see coils of insulated copper wire.
Mathematically (it’s really simple) the resistance is calculated as shown here in this link and you can tell the amount of power dissipated (heat produced) by using the equation for Power (in watts)… (P = I*V = I²*R = V²/R).
You bring up an interesting point about the end-stops. I am sure that they would be fine, but I can’t say for sure since I don’t have a Morgan of my own yet to observe. There are some videos on Youtube which may shed some light on this.
Although I don’t have experience printing with PLA, I know that PLA does warp on large parts. So if you print lots of small parts in the area you don’t need the heated bed, but if you print a large part it will have to be heated because over the total length of the part it will shrink and warp.
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The correct wire thickness for a single section should be 0.75mm diameter (0.44mm²) for 38m length (and that’s almost the actual length; could be 37.xm as well).
I used nails to form the loops. I’ve drilled holes for the nails before pressing them into the wood (I have a small handpress for that, bit you can hammer them in as well). The I but the nails off with a saw. This lets me form the loops, stabilize them with some tape and lift them off the bed of nails to place them on the downside of the building platform, which is made of 3mm aluminum plate. It doesn’t bend with this thickness and the required width of 627mm but I still can use a standard jigsaw to cut the pieces I need and it still is not too heavy for Morgan’s z-axis mechanic.
I’ve tested the platform yesterday and it easily heats up to 110°C, but of course this needs a bit time (didn’t stop it, but app. 10 min. I guess). But I’ll have to use a different adhesive, because the hit glue I used doesn’t meet its specifications and begins to melt at app. 80°C (instead of 160°C).
But that’s no problem. I just need a different glue that withstands 110°C.
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ag fok I found it myself almost right away. Just in case the question is relevant to some one else:
http://sketchup.google.com/3dwarehouse/details?mid=cb498d810dfd31e885aaccba6f96ca0c(model by dr K )
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