Looking to try out shoulder screws

Hello everyone,
I have decided that I would like to try out shoulder screws. If I do like them, I plan to buy the large color coded variety pack. However, I don’t want to buy the large set yet, because It would be a waste to buy them and find them unnecessary, and that my team doesn’t use them. Right now, I plan to buy the orange 0.375" screws that have a 0.12" shoulder, with the orange heads so I can easily tell them apart from normal screws. I also plan to buy the Large steel washer pack, so I can use these for things like standoffs too. do you guys think that this is a good purchase to make, and do you recommend the robosource shoulder screws? And, should I get that type of screw?

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I haven’t yet used any of these shoulder screws, but I do not doubt their worth as a purchase in the slightest. The main advantage they have is a massive decrease in the slop a screw has inside a vex hole, and seeing as how this is the main source of problems when it comes to mounting points not being perfectly squared, I think purchasing shoulder screws is a great idea and I plan to do so for this season.

personally I would just buy the large pack, because I don’t see why you wouldn’t like them and it’d be cheaper and quicker than buying a smaller quantity to use as a test.


The colored screws are wonderful, roboteers can now get more screws out of the inventory by color than by just guessing the lengths. Plus at resort time at the end of the year when the robots come apart it’s just magical.

@Xenon27 has it, just buy the indecision package and your screws. Add in some of the thin nylocks, they are worth it.


Our organization buys all our screws from robosource.net. The only screws we have from VEX are what comes in V5 competition super kits. We get the color-coded shoulder screws, while regular screws are either plain or black. This helps keep shoulder screws differentiated from plain screws.


I should probably have clarified- the other reason I didn’t want to buy the big pack was because we weren’t buying these off of the school budget, and would rather do that later, when we do have money from the school, and $9 is cheaper than $70. I did already order some of the orange 0.375" screws with the 0.12" shoulder, and am waiting for them to arrive. Thanks for the insight.


Robosource’s shoulder screws are one of the best things to happen to vex. for their cost of manufacturing, they’re incredibly cheap (considering how niche their application is), and yet very high quality (better grade of steel and tighter tolerances than the stainless vex ones)- not to mention the fact that they make building a lot faster and more precise. i highly recommend them


I 100% recommend these. We purchased a 100-pack of the 1/2 inch with the 0.04" shoulder out of our own pocket and really found them helpful. Since we are only on hex drive screws the star drive heads on these screws have been pretty good at keeping things tight without stripping them during removal (star drive is pretty hard to strip).

We only use them on motors however when we first bought them we tried it out on some c-channel to see how much the play reduced, and even with the 0.04" shoulder on these screws it really improved a lot.

I can’t really comment on the colour coding of the heads except it makes it super easy to identify the shoulder screws Vs standard screws. As others have said I’m sure it would make finding the sizes of screws a lot quicker.

If you do buy them I’m sure you won’t regret it :slightly_smiling_face:


so with a soulder screw do you just put it all the way through the channels and then wrench tighten the nut on?
If its what im thinking it is it cant turn in the hole once its down enough right?

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You use it like you would a normal screw


The point of the shoulder screw is that the clearance in the square hole is very tight at the shoulder, therefore making a joint that has minimal slop when the screws are tight. You choose the length of the shoulder (or tenon, as it’s often called an industry) to match the thickness of the material being joined. Sometimes you might need to add a washer under the nut to ensure the nut can be tightened all the way without running out of threads. In some cases, the shoulder screw could be left slightly loose, and combination with a nylock lock nut, to make a basic pivot joint. A joint made this way without a bearing, however, should not be used except for a very light duty or low-cycle mechanism (for example, a mechanism used once per match at the most).


Here is a Fusion image of how the shoulder screw would work.
The one on the left has a shoulder screw, the one on the right is not. The shoulder is in orange for visibility. As you can see, the shoulder screw has no room around the outside, compared to the non-shoulder screw, which has some room.
As you can see here, the shoulder, if the length is chosen correctly, does not extend past the c-channel, allowing you to tighten the nut fully.


ooh ok
makes sense

So I tried out the shoulder screws, but a problem with them is that I can’t use them on box bolted structures (at least not where they have one c-channels sandwiched between 2 others, like on a drive) is that it doesn’t connect both of them. It also doesn’t work to connect two connected by spacers. Does anyone have any techniques for connecting those?

in situations like these you could use 2 shorter shoulder screws on each side and use a standoff as part of your box bolt. This weighs more though, and it’s really not bad if only one metal on metal connection gets the shoulder section of the screw.


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