3D Printed Versa Blocks

FIRST General Forum
#1

Hello everyone. Recently, my team (6897) and I have come across a huge opportunity for saving weight, money, and time. That opportunity is 3D printed versa bearing blocks.

Some backstory: I have an Ender 3 pro and have 3D printed minor things, like spacers, in the past for team 6897. Over the summer into fall, I decided that despite our mentors’ and president’s hesitation towards 3D printing major components, I would prototype them on my own. It started with me thinking, “what is the most used, heaviest part on our robot?”. My answer was the versa block.

Versas weigh about 0.1 pounds each. So, for a single shaft to be mounted, it would need close to half a pound of hardware. Our design for 2019, 2020, and 2021 consisted of a lot of shafts. This year, we are using over 30 pairs of versas. That’s nearly 7 pounds worth. The 3D printed versas weigh a little over 15 grams each. That means that instead of 7 pounds, it would only be around 2, saving us over 5 pounds.

Ok, so we’ve covered the weight aspect. What about the price? Well, a 3D printer costs a couple hundred bucks. Ideally, teams would already have one. If they don’t, they can be used for a lot of stuff around the shop and on the bot and are worth a buy. Or, maybe a team member has one (which is our situation). Because of this, I am going to disregard the cost of the printer in my price breakdown. So, a set of V2 versas cost $30. That means that if we didn’t already have the versas, we would be spending over $1000. To print all of our versas, we ordered 2 rolls of filament. My favorite is black Hatchbox off amazon. It costs $23/roll. So for less than $50, we have enough filament to print all of our versas and other things, like spacers and continued experiments. That’s a savings of over $950.

That’s great, but why did I mention saving time? Well, unless you want to pay around $100 for 2-day shipping or live by Vex’s warehouse in Texas, you’ll be waiting a while for them to ship. 9 versas, the max that will fit on my ender 3 pro, print in under 15 hours. So, you can calculate how many versas you want based on that. Odds are it will print way sooner than Vex can get them to you.

So, there you have it. 3D printed versas can and will save you weight, money, and time. I’m not going to give out specifics as there was a lot of time spent testing to make it fit our needs, but normal PLA is strong enough, and I print these at 50% infill with 5 layers of walls. Below is a link to a video of them in use:

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#2

How are you threading the bolts through the printed versablocks? It looks like you just threaded it directly into the plastic. Has this held up with repeated use and repeated assembly/disassembly? It might be worth considering switching to threaded inserts that you can put in the printed hole. I suspect inserts will give you more reliability and repeatability. My team has used these in the past and been very happy with them. I have also heard of other teams using heat set inserts. Very cool project, definitely has a lot of advantages when you use a lot of versablocks.

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#3

This is a very good point that I omitted in the initial post. Eventually, the plastic will let go and you cant use the versas as we did in the video. In this case, just using a nut at the end of the bolt works well. To add inserts we would need to edit the cad, and then put them in during printing, and it would be a lot more work than it is worth. Not to mention that while the versas are strong, they will need to be replaced more often than normal versas and it wouldn’t be worth using the inserts.

#4

You don’t really need fancy threaded inserts. A common technique is to add a hexagonal recess and press-fit a nut into it. This can be done after the part comes off the printer. The only advantage of doing this over just adding an external nut, as you describe, is that the nut is captive, which can make dis/reassembly go much faster.

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#5

Neither of the inserts I linked need to be added during the print, both are added after. The only CAD you would need to modify is to change the size of the hole to the size that the insert requires. In low load situations like the one you showed in the video you shouldn’t need to be replacing those blocks very often, definitely less often than the plastic will give up on the threads. Also it is very quick and easy to use the screw-to-expand inserts I linked in my first post, you simply press them into the hole and then put a bolt in. If you are very against inserts I will also second the suggestion of an inset nut like @veg said, you might need to increase the thickness of the block to fit a nut in, but that is not necessarily a bad thing.

#6

When I said the cad would need to be modified I meant the overall size of the block. Right now if there was an insert put into the hole, the plastic between the outer edge of the versa and the insert would be thin and break easily, which means we would need to make it thicker, which would possibly affect clearance of other parts or not. Ill look into inserts further, thank you.

#7

I will look into this thank you.

#8

The big downside of printed versablocks is that they are far weaker than their aluminum cousins. Good for intakes, conveyors, and idlers maybe. Not so good for shooter wheels, drivetrains, or arms.

We made smaller 1x1 bearing blocks with screw-to-expand inserts for a hopper. Worked well. Heat set and screw to expand both seem reasonable for these - I wouldn’t want to do bare plastic if it could be avoided.

Is your Ender 3 tuned at all? How much did you have to oversize things to fit?

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#9

While they are weaker, yes, with the CURA settings I have now they are as strong as they need to be. I would never mount a motor onto them, but I wouldn’t put shooter setups and arms past their abilities. Bare PLA works well for these. Maybe you could acetone vapor smooth some abs but that would only help with durability over time. However, it’d probably be easier to just replace them. I’ve got a mildly upgraded Ender 3. All metal feeder assembly, upgraded bowden tubing, a bltouch, glass bed, and an enhanced cooler. Sizing varies but I’ve found that printing the stock V2 versa with the large rectangle-like holes filled in at 100.5% with a 0.8 nozzle fits the tube stock just like the ones that come from Vex do. The upgrades I have help with accuracy but it’s not like these couldn’t be printed with a stock Ender 3. It’d just take a little more time to get it dialed in.

#10

I would be concerned about these applications especially in pla.

Pla is a brittle material and arms tend to have shock loads applied to them. While it may be fine if you’re gentle I’d expect fracturing if you ran into walls or such.

I’d also be very curious the impact that the vibrations of a typical wheeled shooter have on the parts over time. Doubly so in PLA.

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#11

When I spoke about the shooters and arms, I was more talking about things that would fold down with a hex hub. If the system was pushed down with pneumatics or gravity, I would also be concerned although testing may show success in ASA or ABS. I wouldn’t be as concerned with high rpm parts of a shooter though.

#12

I’m with Andrew here. At work, we do NOT use PLA–from experience, it breaks way too easily for our (generally somewhat high-load) applications. It’s ABS all the way for us. Don’t usually bother with acetone vapor smoothing (though when something needs to be smooth it’ll be sanded then sprayed with acetone).

+1 on the insert method–actually for a VersaBlock I’d use these–as it works. Though you do need to account for their size it’s a bit less of an impact IMO.

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#13

In our uses, which is just for belt and wheel spinning, pla has held up well. I have some experience with ABS but unfortunately my current setup is not equipped to print with it.

#14

We’ve used 3d printed versas on last year’s build for to make the intake as light as it could be. So far it’s held up all year without issues. :rofl:

#15

I would want to see testing done on this. Shooters are extremely high vibration areas and I could see the bearing block deforming relatively rapidly.

#16

Can you provide the math or empirical testing you’ve performed to back up this statement?

#18

Don’t use PLA except for maybe light brackets like limit switches etc. PETG, ABS, HIPS, Nylon are better. For some of those you might have to upgrade your Ender a little. I would get an all metal hotend as even PETG for good layer adhesion likes 235-250 and that is pushing it with a PTFE lined hotend. ABS, HIPS, NYlon - depending on type might need higher temps and an enclosure plus a print dry which you can build out of a food dehydrator if you want to safe some money. But you can print all kinds of things

#19

I hit it with a hammer like a monkey and it didnt break

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#20

An all metal hotend is on my list, but at that point I would go with carbon fiber fills and more exotic filaments. PLA is cheap and easy, I agree it isn’t the best but it works. I print often enough that I don’t need to worry about keeping filament dry but if I do turn to the aforementioned filaments it’ll definitely be obtained.

#21

Carbon fiber fill has its purposes if you are looking for stiffness and abrasion resistance if you looking for strength go with a filament that has no fill.