I have used 80/20, Bosch, ITEM, Microrax, and probably a few others over the years and I have loved them and hated them at the same time. They made building and prototyping really easy, but all of them follow the Razer + Blades business model of selling the profile for a reasonable price, but all of the hardware and accessories are expensive. Since you are already in their system you are stuck. This problem is one of the 2 major driving factors in the design of our system.
standard hardware decreases the cost of every attachment point from $.40 per nut (.20 if you are lucky) down to .02 by using standard hardware. This gives you the build experience that is so awesome at a much more cost effective price for schools and teams.
Linear motion is normally hard or expensive. Over the past 13 seasons I have been involved in FIRST there have been many amazing products which have changed the game (things like the shifting transmission, systems of gearboxes, sprockets, and wheels that just work together). The one thing that has remained hard for teams is linear motion. There are low cost options like drawer slides and more pricey solutions like ground rods and linear bearings but up to this point nothing that was designed with building a robotics elevator in mind. The V groove bearings and integrated features in the 1 inch profile allow for super easy integration anywhere in your mechanism.
Oh I forgot to mention this on Facebook, but you can also use a NYLOCK nut in our channel for added security.
As for the corners there are a few reasons (some more obvious than others).
When you design a part to be aluminum extruded it is in your best interest to keep a constant wall thickness through your part, this helps with the flow of the aluminum (similar things come into play when designing plastic parts also). Secondly the amount of closed profiles in your extrusion makes the dies more expensive and harder to get consistent results. Specifically speaking to the 15 mm profile it would have been almost impossible to do a closed hole in the corner.
As mentioned above all 5 of the holes can be tapped with allows for some interesting applications, one of which is mounting a hub to the end and driving it with a motor to turn our extrusions into a shaft that could be used for a pickup. Along that same lines the slot in the corner is specifically sized to accept a 1/6" piece of flat stock (lexan or other), I am sure you can probably think of a few times this would be useful
It seems to me that the x shape and the very thin material that allow for the nut pockets on all four sides make this extrusion very susceptible to twisting loads. I noticed above you advocated using this for an elevator. Currently, many teams prefer 2x1 rectangular tubing for an FRC-type elevator because (among other reasons) its resistance to twisting is highly desirable to prevent binding. While it is probably serviceable in shorter/low loading situations, in a game such as 2011 Logomotion where elevators where the full 60" tall I don’t think this extrusion would function very well in place of 2x1.
I do think that this is a really cool addition to teams’ resources though. With the sliding nuts on each side it could especially have FRC applications in rapid prototyping.
Generally, with this type of profile available from other manufacturers, the purpose of the T-nut is to drop it in anywhere on the profile, and then it rotates into place before tightening. This allows for easy additions of brackets to the middle section of the beam, even if the end sections already have brackets and hardware installed.
How would this be accomplished with normal hexagonal nuts? Would you pre-load the profile with any and all hex nuts you ever intend on using, and let them float free until you do? Or would you need to disassemble bracketry on one end to add something more to the middle?
The profile is actually much stiffer in torsion than what you would expect, but yes a 2x1 would be be stronger. You nailed it, as the implementation of the system is game specific, as some time a bit of twisting is acceptable (light game objects such as 2011). If people wanted to use this with heavier or more stout assemblies you can do a braced 2 post lift style (which I think is actually more common) and where the twisting on the individual member is less of a factor.
I agree about the prototyping, there have been many years when even if our extrusions don’t end up on the robot the flexibility to prototype with them is huge.
Generally speaking you would load the rails from either side with nuts, but another method I have tested is to cut a clearance hole (just over 3/8) in the channel where you just remove just the retaining flange and then you can drop them in. This almost has no strength loss (bending) and is easy to do with a cordless drill.
I have tested a bunch of t-nuts with the system and some work and some don’t. Most 1" profiles use 1/4-20 hardware, where this system uses 10-32 (or 24) so the nuts are bigger than the channel due to the corner holes in the profile. There are some smaller t-nuts designed for smaller profiles that do work with the system. We are not planning on selling t-nuts but if teams find ones that work we will be sure to link them from our product pages so a team can use them if they want that feature. In the future if people really want a drop in t-nut we can investigate making one specifically for this profile.
I love all of these questions! Right now REV is just a small start-up who wants to bring value products to the community. We will always be open to feedback from you all to help make our products better.
I know details are coming “very soon” but would you be willing to share the material, MOI, weight per foot and (approx) cost per foot of the two extrusion profiles now? I am sure there are lots of fancy add on plates and connectors that we will see soon on AM.
Very happy to see something for FRC in linear rail. We’ve used some openbuild rails before with a V-Groove channel. Great stuff to work with. Easy to use. AFFORDABLE and not like 80/20 or Item, especially the PRICE. We live 20 miles from 80/20 and it still cost us alot of money to purchase 80/20 direct from them. We had over $1000 in 80/20 for our pit organizer “general store” we call it. Most of the time we try to have Neff Engineering donate what we need.
But for parts on the robot a v-slot linear rail like this is awesome to see, especially if it will be tailored toward FRC. Here is a sample of openbuild v-slot we’ve been toying with.
Our team has recently looked into OpenBeam after having it recommended to us by a nearby team. OB also claims to be interfacable with common hardware and not specialized stuff, though it doesn’t seem the have a good V channel like some others. Can’t quite tell whether your offering is better just yet, though the fact that you are advertising it on CD is certainly a good sign.