The MegaRail family of profiles starts with two 
members:
- MegaRail 80, shown here, is a large beam with running surfaces for V-groove wheels on all four corners.
- MegaRail Z, a much smaller profile with a single running surface, is designed to be attached, in pairs, to a flat surface, for a much wider wheel span than is practical with a single profile.
MegaRail 80
The drawing of the MegaRail 80 profile can be found at GitHub. The overall dimensions are 46.4 mm by 87 mm (not including the slightly protruding ribbing). Walls are generally 4 mm thick, although four small sections are 5 mm thick to provide more “bite” for tapping holes. The four screw ports are M6 at 32 mm × 64 mm centers. The running surfaces are wide enough for both RM1 and RM2 steel V-groove bearings (although it’s not a good idea to run steel wheels on it unless it’s hard anodized). The standard MakerSlide V-wheels work, of course. With these, the wheel span is 104.6 mm centers, the same as for OpenRail on Misumi HFS5-4080 profile, or exactly 40 mm wider than for MakerSlide. The parallel running surfaces are centered exactly 40 mm apart.
For extra strength, two MegaRail 80 profiles can be bolted together. The groove pattern on one side nests into that on the opposite side, for perfect alignment.
The profile is extruded out of 6005A aluminium alloy (to be confirmed), and weighs about 3.2 kg per meter (MakerSlide is 0.9 kg per meter). MegaRail 80 has area moments of inertia (a measure correlated with rigidity) about 18 times larger than MakerSlide in the wider direction, and 25 times in the narrower one. It is about three times more rigid in the wide direction than in the narrow one. I don’t have numbers for torsional rigidity, but I expect an even larger improvement, because of the unbroken outer wall.
MegaRail Z
I have several candidate designs. I’m still pondering which is the best combination of features. MegaRail Z can be used, as the name suggests, as the Z axis of a gantry-style CNC milling machine, but also as the Y axis of a moving-bed machine. There are several different arrangements for the Z axis, each with advantages and disadvantages, and each favours different features (and dimensions) of the profile.
Timeline
No idea yet. I am sending the MegaRail 80 drawing to the extruder/fabricator tomorrow. They will give me an ETA, which I’ll take with a small boulder of salt.
Hello
It may be too late but…
You should have added one or two sliders inside that would be able to hold PCBs (1.6 mm thickness), so this rail can *also* be used as electronic device housing when cut in short sections (5-10 cm).
That’s a marvelous idea! I don’t think it adds anything to the cost, and no, it’s not too late.
I should make the next control electronics board fit that space exactly, and not say anything, and see if anyone discovers the feature and decides to hide the electronics inside the rail (not the smartest idea, but cool).
Wohooo! If you do that, and the price is fair (I believe it will be), i’m a buyer ! Whatever the order delay! You can also sell endplates.
See here some examples:
http://www.lincolnbinns.com/category/e-case/
http://ru.aliexpress.com/store/product/Free-shipping-aluminum-case-for-aluminium-extrusion-enclosure-95-76-35mm-3-74-2-99-1/131407_1494335276.html
From the image you posted you could probably fit 3 or 5 PCB slots.
A standard PCB is 1.6mm thick, I don’t know which tolerance is OK for easy insertion without too much play. 2mm slots are certainly fine; 1.8mm seems perfect but maybe not wide enough.
2mm slot depth seems to be enough to keep the PCBs in place without eating too much board space.
I sent a version of the profile with one PCB slot to the fabricator for a quote. I don’t want to add more slots, because they can get in the way when the profile is used for its primary purpose.
Hello,
Is that the original profile? http://amberspyglass.co.uk/resources/parts/pdf/MegaRail.pdf
So where did you add the slot? In the center of widest part?
This is the profile without the slot: http://amberspyglass.co.uk/resources/parts/pdf/MegaRail-rev-2.pdf
This is it with the slot:
http://amberspyglass.co.uk/resources/parts/pdf/MegaRail-rev-2a.pdf
There’s 3 mm of clearance between the bottom of the PCB and the screw ports — I would guess that would be enough for most soldering, but I can move the slot a bit toward the center line to avoid any problems.
This looks perfect !