Metal Frame Design

[DeltaCon]

I don't mean to advertise other brands, but I just bumped into this picture. I have taken a look at the website and forum and it is really not as professional and elaborate is what I am used to here But the idea of the out of steelsheet manufactured top and bottom pieces looks very slick and simple, and promises a lot of stability. The motors are very nicely integrated too. Does anyone have experience with constructions like this? What are your thoughts?

[IMBoring25]

I'd disagree that it inherently "promises a lot of stability." There are a lot of kinds of "steel," some of which are quite ductile.

Stability also requires interaction between material and shape. The Rostock top and bottom sections are essentially built-up torque boxes. That looks like a very thin-section sheet, which may only have good resistance against forces that tend to directly pull the top and bottom of the towers apart.

[DeltaCon]

@IMBoring25
Yes I understand what you are saying. I can only assume that they would use a steel alloy that is suited for the job. I don't think that the sheet looks very thin. I can't find it this instance, but one of the other pictures I saw made me estimate a thickness of 3 mm and I don't think that will bend a lot on the forces of a 3d printer (given the use of the right alloy). In fact most cartesians are built with very much thinner sheets. Also the real stiffness comes from the 90 degrees bended edges and not from the thickness of the sheet. The only con I can think of is that the fitting of the extrusions is less accurate than machined ones.

Besides all that it is not especially about THIS picture, but about the idea of the steel sections that in my opinion would make assembly a lot easier and probably stiffer. TrickLaser has a nice solution for that, but this one is probably also worth discussing.

[Xenocrates]

@IMBoring25
Yes I understand what you are saying. I can only assume that they would use a steel alloy that is suited for the job. I don't think that the sheet looks very thin. I can't find it this instance, but one of the other pictures I saw made me estimate a thickness of 3 mm and I don't think that will bend a lot on the forces of a 3d printer (given the use of the right alloy). In fact most cartesians are built with very much thinner sheets. Also the real stiffness comes from the 90 degrees bended edges and not from the thickness of the sheet. The only con I can think of is that the fitting of the extrusions is less accurate than machined ones.

It is in fact 3MM hot rolled steel, which is laser cut and bent to shape. My major issue with it is that the center of those spars don't have the bends which as you noted, give it rigidity. I'm less concerned by printing loads warping it than I am by transportation and picking the thing up. Beyond that, their dual extrusion hotend is very interesting, as it seems to have the filament paths merge in the heatsink. I don't think it's a great design. They also have things like Geckotek, which if I recall correctly, is largely a disappointment, and the MKS Base, which is a closed source smoothie rip-off (As Arthur Wolf stated, they are taking community work and open source code and turning a profit on it without contributing, and it seems like there's very little information besides a pair of posters who seem to be the Ebay sellers or similar.)

So over all, it seems like a solid base design (Or at least mostly. I don't like that there's not really any enclosed space for mechanics or wiring), with some extra cost options that are dubious value adds. I would have liked to see cross bracing at the towers as well, so that it would be easier to enclose the printer and make it more stable though.

[Polygonhell]

I have one of these arriving tomorrow, I'm interested in how it goes together.
It'll be interesting to see how easy it is to get the towers aligned correctly and how much error there is in the extrusion lengths, but the build is supposed to be extremely simple.
The top and bottom plates are cast aluminum rather than steel.

[img]http://www.3ders.org/images2016/billy-z ... -500-1.jpg[/img]

[Qdeathstar]

I think that the arms look pretty easy to bend meaning misalignment of the towers... If it was 1/2 the cost of a max metal it might be worth it

[Polygonhell]

The arms are CF rods, I would imagine they flex considerably less than the nylon Max arms.
It also is <1/2 the price of a Metal Max, though that didn't really factor into my purchase decision. I know the designer through interactions on the RepRap forums, and I respect his work so I thought I'd support it.
It's not a "full Kit" and he only made 30 of them, so it's not really comparable or competitive with the Max.
I do however appreciate the simplicity, I just have to wonder how that translates to aligning the towers during construction.

[Qdeathstar]

I was referring to the "arms" of the frame And the "cost" to the cost of Tricklaser's frame which is around $300... Let us know your impressions

[Qdeathstar]

Your picture has 2040? extrusions instead of the first pictures 2020 extrusions? Can the frame be adjusted to accommodate a larger extrusion?

[Polygonhell]

I think they are 20x60 which is probably total overkill, the printers smaller than a Max 10 inch build plate and I think 12 inch build height.
You could certainly use taller extrusions, I have no idea what brand he's using (if I had to guess I'd guess Misumi), I haven't seen it in the flesh yet, but you'd have to have them cut pretty accurately to length.

I was referring to the "arms" of the frame

I guess I don't see how a shorter 20x60 extrusion can be more likely to bend than the longer 25x25 on the Max/Metal Max.
The mounting via screws though the plate into the ends is not really an issue IF the extrusions are cut straight and the tolerances are tight. There are several consumer level router designs that do this for the X axis which is under far greater load.

I probably won't get a chance to build it for a couple of weeks, but I'll post my impressions when I get around to it.
I have no idea if he's going to make and sell more, so it may be no more than a curiosity for everyone else.
The Kick Starter price was $500 for the entire printer not including electronics and heated bed.

I'll build mine with an AL heated bed and a Duet I have lying around.

[Qdeathstar]

ugh... I mean the arms on the top and bottom plate...

but, I agree if you use 2060 extrusions they themselves are going to add a lot to the rigidity of the frame... does it come with those? In the op's photo it shows 2020 extrusions.... in yours it shows 2060s.... which comes with it?

[KAS]

does it come with those? In the op's photo it shows 2020 extrusions.... in yours it shows 2060s.... which comes with it?

They are different printers. The Polygon is 2060

http://www.polygonrobotics.com/

http://www.blueeaglelabs.com/

[Qdeathstar]

oh...........

[DeltaCon]

I have one of these arriving tomorrow, I'm interested in how it goes together.
It'll be interesting to see how easy it is to get the towers aligned correctly and how much error there is in the extrusion lengths, but the build is supposed to be extremely simple. The top and bottom plates are cast aluminum rather than steel.

Well that one looks really simple indeed. I think the Alu top and bottom plate can make it extremely rigid. If the screw-holes are machined accurately there will not be a lot of play for misalignment I guess. Thing to consider is that if Alu bends, it has the tendency to keep the new form instead of bending back when stress is relieved. That could be a problem for folks that like to print wherever they lay their hat

I am looking forward to your buildthread!