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Posted · Ultimaker - Black Edition

3 mm is already a huge wall thickness for steel :) Most machines I know from the workshop have 1, maybe 2 millimeter shells. Only heavy equipment seems to have more, but most strength comes from smart braces, folding or boxing the material, not pure wall thickness. I can imagine that a 3 mm Ultimaker is way too heavy and although I did not do the math, my gut tells me you can get away with less, since the surface area of an Ultimaker is actually quite small compared to other machines.

The sandwich idea is interesting, but I am a bit worried how the materials behave together, since they are not properly bonded. Vibrations might become a problem and any gaps will eat away strength. Do you have a plan how you are going to execute those panels?

 

 

I think the issue is with the nuts not having a broad enough surface to balance against.

...

 

That... The Ultimaker frame needs a certain minimum wall thickness - regardless to how strong the material actually is at that thickness. It's just necessary to be able to join (and hold) the parts together.

Bending (near-)perfect 90° angles is pretty much impossible. You'd never get a satisfactory grade of accuracy. Bending thin steel sheets just for increased strenght works great, but it's a rather expensive process (that you can't do well on your own).

And again - thin sheets can't be joined "the Ultimaker way".

So, the ideal material would be something that usually comes in thicknesses around 5-10mm. And again - thermal elongation as well as thermal insulation are important factors to consider (aluminum has dire weaknesses in both these aspects).

HPL on the other side is the perfect material for the task. Trespa HPL plates for example have all the nice properties. The only problem is getting the stuff cut.

Once I'm happy with my prototype, I will clean up the design files and get a quote from a nearby waterjet company. I want waterjet cut HPL frame plates :)

About the composite material: Because you need a thick material, composite would be the best choice when working with metal. But it's a lot of work to join (glue) two thin metal sheets to a plywood panel (6 times). I decided to spare me that work after all, and ordered my prototype with 5mm aluminum sheets now. It's not a good solution imho, but it will make a good, cost-effective and easily done prototype.

 

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Posted · Ultimaker - Black Edition

Hmmm. Looked up the thermal expansion coefficients of steel and Al and they aren't horrifically different. Al is only double that of steel. Both are the order of 10^-5/K. Even if the frame is heated to 100 degrees above room temperature, the expansion is only 0.01%. Besides, even if the frame doesn't expand, the z axis lead screw still will.

As for thermal conductivity, I have some real doubts a about how much if a difference that actually makes and could be accounted for by blanketing the interior with felt or something like that. It might decrease system energy consumption and warm up time, but probably not a huge impact on performance.

Obviously much of the specifics depend on the precise steel or Al alloy.

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Posted · Ultimaker - Black Edition

Bending (near-)perfect 90° angles is pretty much impossible. You'd never get a satisfactory grade of accuracy. Bending thin steel sheets just for increased strenght works great, but it's a rather expensive process (that you can't do well on your own).

And again - thin sheets can't be joined "the Ultimaker way".

 

It makes me wonder, do you really need the Ultimaker way? Just a simple sheet metal brake and using other squarely cut panels as guides and attachment points might be enough to make the frame square enough to function properly and to fold the sheets enough to make things rigid. You could just bolt flat segment to flat sheet, not at right angles, eliminating the nut trap issues.

Trespa seems an incredibly interesting option, but like you say, cutting it properly is the issue. Even if I were to find an affordable way of cutting the stuff, not having the option to make replacement panels with some ease bugs me. I know I will upgrade the printer in the future and cheaply cutting updated panels is a major pro for me.

Trespa is obviously superior to birch ply, but I doubt whether you will actually notice a huge amount of different in every day use. Tropical areas possibly excepted. Why can't water jets be cheap and readily available? :D

 

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Posted · Ultimaker - Black Edition

Hmmm. Looked up the thermal expansion coefficients of steel and Al and they aren't horrifically different. Al is only double that of steel. Both are the order of 10^-5/K. Even if the frame is heated to 100 degrees above room temperature, the expansion is only 0.01%. Besides, even if the frame doesn't expand, the z axis lead screw still will.

 

Since most mechanical parts are made of steel I think coherent expansion is a bonus. However, I see most benefits in the strength steel provides when compared to aluminium. The latter is a bit more fragile when it comes to taps and dies, taking knocks and such.

 

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Posted · Ultimaker - Black Edition

That is true, but some aluminum alloys are better than others at bouncing back into form. Consider for example how well the aluminum unibody laptops and tablets hold up. I imagine they see far worse than a desktop 3d printer, unless you drop it.

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Posted · Ultimaker - Black Edition

That is true, but some aluminum alloys are better than others at bouncing back into form. Consider for example how well the aluminum unibody laptops and tablets hold up. I imagine they see far worse than a desktop 3d printer, unless you drop it.

 

True, BUT usually you don't get that kind of aluminum. Also, these laptop bodies are treated (anodized, maybe other hardening treatments as well) and hardened after machining.

My lasercut aluminum panels are "AlMg3" which is one of the softer, easily machineable alloys. This is worlds apart from 7075 T6 aluminum alloy.

"The Ultimaker way" frame panels have one huge advantage: The assembly is idiot proof - you don't have to worry about correct angles, tolerances, warping or anything else when assembling them. Just bolt them together and they will be fine.

If you can get to the same result using another technique, please show me :)

I'm currently putting my aluminum extrusion profile frame together. I've been at it for several hours and haven't even completed the profile skeleton yet. You have to carefully tighten one corner at a time, minding all the 90° angles and I didn't even get to the point where the gantry is supposed to fit in there at (nearly) perfect 90° angles...

 

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Posted · Ultimaker - Black Edition

True, BUT usually you don't get that kind of aluminum. Also, these laptop bodies are treated (anodized, maybe other hardening treatments as well) and hardened after machining.

 

My lasercut aluminum panels are "AlMg3" which is one of the softer, easily machineable alloys. This is worlds apart from 7075 T6 aluminum alloy.

 

 

True, but your panels will be thicker than the entirety of some of those devices. As long as you don't drop a panel, it will likely be fine.

I mostly agree regarding construction, accept that I have seen Al extrusion used with relatively good precision in a number of devices. I think there is a trick to designing corner pieces that force everything to line up correctly and perhaps getting precision cut Al stock.

I think a lot of the decision has to do with what manufacturing resources are available. The "Ultimaker way" seems to be less of a burden in that regard (unless the end user is happy to go through the effort that you are with those extrusions.)

BTW, will you plan to use cut outs in the side panels to form other parts, like the UMO design?

One thing I didn't realize is that the additives in Al alloys will begin to pericpitate at temperatures above 230 C. Not a big deal, unless one trys to make an Al hot end.

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Posted · Ultimaker - Black Edition

Thicker, yes. Still you can bend 5mm aluminum by hand, and as alu is not an elastic metal it will stay like that instead of returning to it's flat state.

The full panels (rear, bottom) are by far strong enough, but the windowed panels are weaker than you'd think.

Of course, when you handle the panels properly all of the time, there won't be any problems.

 

...

BTW, will you plan to use cut outs in the side panels to form other parts, like the UMO design?

...

 

Not sure I understand what you mean. Do you mean if I put small parts into the space where the window cutouts are?

That doesn't work when you get the stuff professionally made - 1 part per drawing...

 

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Posted · Ultimaker - Black Edition

Yeah, I was assuming that you just gave them a dxf or something with the pattern for the water jet.

 

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Posted · Ultimaker - Black Edition

I'm still preparing these dfx drawings. They'll need drawings with some measurements and indications for material, thickness, surface quality / treatment and so on.

I'll have a talk with the waterjet people when I ask them for a quote. If that works (using the window space for small parts), then I have some ideas for suitable small parts. But especially for smaller / thin parts, steel is perfectly suitable. And small parts (in quantities from 10 pieces and above) are quite cheap (cheaper than printed parts). Trowalised (tumbled?) chrome steel also looks very nice.

The mailman disappointed me again today - my metal panels should have arrived, but they didn't :(

 

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Posted · Ultimaker - Black Edition

Hi @Jonnybischof

Can I bother you with a question related to the shafts you comment on page 10-14. I was about to buy some shafts from misumi for my x3 ultimakers, I loved the idea of having 'black' shafts and also I really want true quality shafts. You comment that you where going to get h5-g6 fit tolerance. I really don't know much about many stuff, but for what it's said on that pages seems that g6 it's the way to go to avoid problems with the bearings and the copper bushes. What was your experience with the shafts from misumi and the black coating?

Thanks!

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Posted (edited) · Ultimaker - Black Edition

Hi @neotko

You are right that g6 is the tolerance grade you want, IF you also buy Misumi bushings (#SHBR). It depends on the type of bushing. Misumi ones are made for "g6 or f8" shafts (it says so on the pdf page). I'm sure you can get other bushings that are made for h6 or other shafts.

I wouldn't recommend the black LTBC coated shafts together with bronze bushings, because the coating quickly wears off. I'd take the hardened steel shafts (not stainless) with hard chrome plating. Those are really awesome. Misumi part number: PSFJ.

Not sure what the LTBC is really suitable for. Maybe linear bearings?

You should order a Misumi Webindex catalogue, there's a ton of additional information, and explanations about tolerances and so on (it has 185 pages of technical information).

Also, if you download the complete catalogue, you will find additional information about their parts at the beginning of the chapters.

//edit

By the way: Why was there no news here for half a year? I've decided to go all-in making a new 3D printer electronics platform, which is taking a lot of time and stalling my printer projects.

Some time in between I'll finish the UM black edition, but you know how it goes...

Edited by Guest
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Posted (edited) · Ultimaker - Black Edition

I also noticed the discoloration of the black coating, but I was attributing it to some of the bronze wearing off on the rods. The same thing probably happens with the standard rods, but it isn't as obvious on the shiny chrome or steal.

Either way, they don't stay that pretty mat black very long.

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Posted · Ultimaker - Black Edition

For a while now, I have been thinking about doing a scratch build. I cannot really decide between doing an Ultimaker clone, a Trespa Ultimaker clone or building something out of aluminium trusses and parts. The latter seems to be a bit like the Ultimaker Black. Could you tell us something about the problems you face with this solution, such as squaring things up?

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Posted · Ultimaker - Black Edition

Well, Trespa is a very nice material. But it proved impossible for me to machine on our local FabLab's CNC router. I bought expensive, and (seemingly) well-suited mill-tools, but they all broke after just a few minutes of use.

I suppose that router was just too crappy (vibrations, or maybe just the unbelievably stupid router settings that couldn't really be changed).

Aluminum extrusions plus brackets is awesome on paper, but a real PITA to get squared in real life. I would never ever do such a thing again. Took my prototype apart before I had even tightened the last bracket. It was obviously never going to work the way I wanted it to.

My latest attempt uses Misumi extrusions with the right mounting options. This works really well and I now have a frame that is built like a tank. See this thread:

https://ultimaker.com/en/community/16123-aluminum-extrusion-2020-um2-printer?page=1#reply-131852

Btw, the UM black edition is on ice for now. I'm trying out a different gantry style, and overall a different concept entirely so it wouldn't make sense to call it an Ultimaker clone.

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Posted · Ultimaker - Black Edition

Hi, now I'm thinking of doing my own UM black edition :)

Will be trying to find out if there's anybody around LDN or UK or EU willing to waterjet Trespa for me :) Will report here if anything comes out of it. Meanwhile: how did it go for you with your own Z-axis? Did you end up building better/cheaper than HBK? Did you try to make the bed wider? (I think it would be nice for me to make it say 23cm wide not 20cm - for the particular types of designs that I need).

On a different topic - I heard you're working on electric/electronic part. Did you look into Spanish SAV MKI ? Is it really better than Arduino Mega + RAMPS? I'm asking because I would need all that for my UM - so need to choose.. Or is your hardware going to be ready soon? :)

The same source that mentioned SAV MKI also mentioned replacing 1Amp A4988 drivers with 1.5Amp DRV8825. Does it make sense?

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Posted · Ultimaker - Black Edition

Aluminum extrusions plus brackets is awesome on paper, but a real PITA to get squared in real life. I would never ever do such a thing again. Took my prototype apart before I had even tightened the last bracket. It was obviously never going to work the way I wanted it to.

 

I was thinking about sort of a hybrid solution, where aluminium or steel parts are aligned according to machined or laser cut parts. Think of something along the lines of plates that cover the different sides, with holes to mount the extrusions to. That way the lining up and squaring should be minimized. Do you feel that would help anything?

 

Will be trying to find out if there's anybody around LDN or UK or EU willing to waterjet Trespa for me :)

 

Do keep me posted. I would be interested in that too.

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Posted · Ultimaker - Black Edition

It depends on how you mount the extrusions to that plate. Note that the usual profile nuts have a huge amount of play. I didn't find a way to reliably mount my (large, 2mm steel) brackets to the profiles without manually aligning them while tightening several screws at the same time.

If you can hire a few extra hands to help, then it works. Also, a large 90° angle tool helps a lot. But it's really not cool if you have to do it alone..

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Posted (edited) · Ultimaker - Black Edition

There is an aluminum extrusion company Maytec, which is base in Germany I think.  They have connecting hardware that utilizes cross drilled holes on the ends of the extrusion and innovative fasteners that pull the pieces together.  This results in very rigid and square (as square as the cuts allow)  connections.  If I were to build a printer frame from extrusions, I would look into this style fastening system.

 

Edited by Guest

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Posted · Ultimaker - Black Edition

That is really a nice system!

I bet it's not cheap though..

The way I described above is pretty much the same, except it works using only M8 screws instead of the connector. It is less flexible because you need pre-drilled holes in the profiles positioned where you want the profiles to connect. And there's only 90° angles, nothing more advanced like this Maytec system offers.

Would be interesting to get a full price comparison for an UM frame made with the Maytec system.

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