We are going to order a stock of 20mm 80/20 t-slot before build season and we have a couple of questions: Have you ever used this material before, and what was your experience? We have, with good rseults. Where is the best place to buy 20mm t-slot extrusion? Where is the best place to buy the accompanying connectors and fasteners? Would it be acceptable to use #10-32 as the standard bolt on the robot even though the t-nuts will have a metric M5 thread (10-32 and M5 are very similar)?
80/20 is sold through distributors. Look on their web for ones in your area, The nuts are specialized so you need to by them from 80/20. The screw needs to match the nut. I would try to mix metric and inch sizes. Be sure to tell them you are a first team & ask for a discount.
We often use 10-32 hardware with M5 t-nuts. 10-32 doesn’t actually feel any looser in the threads to me, and if you gave somebody two M5 nuts with the two different screws, they might have a hard time telling which is the “right” one.
The diameter and threads per inch happen to be so close that it works fine. If you tried screwing a 10-32 into a deeper threaded hole, you’d start to cross thread it since the M5’s pitch is 31.75 threads/in. For the thickness of a T-nut, that difference doesn’t matter.
2186 has been using their 1-inch profile (10-series, I think?) since 2008, and the only problems we’ve had with it have been related to ship times. It seems to be the best off-the-shelf material running around that doesn’t need welding or other advanced techniques. One thing to note is that the cost is tilted heavily towards the fasteners, compared to the breakdown for other materials.
As far as buying it, they have distributors that you are supposed to order from. 80/20 offers a steep discount to FIRST teams, so you should make sure that your distributor is using that. The t-slot nuts, brackets, plates, etc. you probably want to order from the same place that you get the extrusion from, but any hardware store should have the bolts. You should order the generic fastener parts (90 degree gussets, 2-hole strips, 5-hole angle plates) at the same time as the extrusion, but leave the weirder brackets for a separate order. I’d recommend ordering as many of the slide-in nuts as you can; there’s nothing worse than losing a week of build season waiting on them, and you always underestimate how many you need. If you get more than you need this year, it just means you’ve got more to make for the ones you’ll lose. The drop-in nuts are also really important. They’re kinda pricy, but way better than taking apart the frame to add a single slider.
I wouldn’t plan on mixing thread types. They’ll probably fit, but are likely to cause more wear than using appropriately matched nuts and bolts. In an emergency, it would be better than nothing.
Do you have experience with 10-32 in an M5 nut to base this recommendation on? It works, and from our experience it doesn’t “cause more wear.” It makes sense to use 10-32 because they’re already commonly used in other places in FRC robots, they’re cheaper than M5, more sizes are available, and they’re easier to find.
AndyMark’s plastic omni wheels are held together with 10-32 screws and M5 nuts, by the way.
Edit: I thought the rest of the post was quite helpful.
The 10-32 thread and M-5 thread are similar, but not identical. The 10-32 bolts can work if you absolutely need to use them since the thread engagement with the T-nuts is small. However, if that thread engagement were to increase, you’d have issues with internal and external threads interfering.
We purchased all of our extrusions, brackets, bolts, nuts, etc from them last year.
They have a huge variety of stuff that’ll match 80/20 and will have anything you could possibly need, really.
The best part? They give 50% off to FRC Robotics Teams and offer FREE shipping once each month. When you’re ordering, like, 100 pounds of extrusions, brackets, and bolts… well… that’s a deal you can’t refuse.
Plus, we ordered $2,000 of stuff last year that pretty much did it for our robot - but wait, the 50% took it down to $1,000! So yeah, T-Slots is amazing.
Is this a deal for all FIRST teams or is that an assumption you’re extrapolating from the support that your team has received?
Additionally, how are they one shipping times? Our current supplier gives us a nice deal, but it takes then upwards of 2 weeks to get the materials to us.
Thanks,
Sunny G.
EDIT: Additionally, what distributor did you deal with? Or was it directly through TSlots?
It’s a phenomenal deal - available to all FIRST teams.
We deal directly with T-slots. I believe last year when we ordered them, they came the same week (if we ordered monday, we had them by the end of the week).
I work for an 80/20 distributor, I don’t think we can do 50% but we have done 40% before. My company’s name is Florida Motion and Control. I’m not sure if we can ship out of our area because of distributor territory, But as a tip to keep your orders quick the biggest time killer is machining and plastics. I am going to be using 80/20 this year and I will be tapping holes myself and getting lexan from other places to reduce that machine time.
At one time we used this type of extrusion in our designs but like many things in FRC it has its ups and downs.
On the up side, it allows rapid construction of framework and its very easy to make design changes. The T-slots allow mounting of various components in an infinate number of places. It’s easy to cut (chop saw) and machine.
On the down side, we found that things moved around a bit. During impacts with other robots and/or field elements, those t-nuts will slip no matter how much you tighten them. They also seem to work loose with vibration so check them fairly often. We also reached a point where we felt that the weight of this material was a little more than we wanted to budget for the frame so we moved on to a different custom solution.
I think this is wonderful stuff and a step up from many frame solutions utilized in FRC but beware of some of the pitfalls I mentioned.