Best screws - Opinions wanted!

I’m sick of VEX screws. Under perfect conditions, if a tool is held perfectly straight and the screws are never over tightened they will last a long time. However, students are the ones using the parts, not me. Therefore, VEX screws last about 5 minutes in their hands.

I would like to get all new screws next year (made of metal that is harder than plastic, haha)…and trash the VEX stuff. I’m curious what type of head people prefer. Both in style of driver, and “head type”.

Hex socket, hex, robertson (square), phillips, flat, combination phillips & flat, pozi, torx?

Button head, socket head, flat head, low profile, round head?

I feel like the hex socket style driver is not the best way to go, and when I started looking around on McMaster-Carr’s website the choices are a bit overwhelming.

Opinions?

Also…zinc plated, 316 stainless, 18-8 stainless, black oxide. Which of these is hardest? I don’t care about corrosion resistance or looks…I want hard metal.

I actuall rarely had an issue with vex screws. If your set on using nonvex screws I would suggest sticking with hex screws. Then you can interchange screws without neededing different tools for different parts of robots. Also if you borrow a screw or a tool or something from someone it will all fit with what you have pt vice versa.

Just to elaborate a bit. The screws are not the only problem. The drivers VEX sells are also very soft and part of the problem. So its a never ending chain. The soft tool rounds out, which then students use a rounded tool which wrecks the screw heads. Then the bad screw heads are used with a new tool which wrecks the tool…etc.

We have cut off our vex drivers so many times they are about half inch long, haha.

So I am really looking to buy all new screws and tools. I feel if I buy the VEX stuff again, I will just have the same problem.

Also, this is not a major issue…just annoying.

I find the new silver colored (stainless ?) screws VEX sells pretty good.

The old black oxide screws, not so good.

We second JP opinion. Our first year we used the black Vex screws, they were TERRIBLE. Then we discovered the Vex Stainless Steel screws and we have yet to strip one out. They are awesome. Not a single black screw on our bot. We have used 250-750 of them with no problems. We wouldn’t use the black ones even if they were FREE.

Socket cap screws have less resistance to the over torquing but you have more clearance requirements in tight situations. You also need a larger hex key to operate them. Motor screws for these are a local preference over socket heads due to the stripping on 5/64" hexes on those 6-32 screws. So you lose out in one way with the extra room of the socket cap over the button head. The clearance for a washer is also a wee bit smaller.

Replacing motor cover screws is #1 priority for us. Get rid of those Phillips head screws and replace with M2 screws.

Suppliers of note to buy screws in bulk:
Fastenal
Zoro
BoltDepot.com
McMaster

I found that teaching kids the “right-hand rule” helps quite a bit with the screws. It reduces the frustration factor that sometimes leads to kids mangling threads, cross-threading, etc.

The “right-hand rule” is also useful for teaching them how to change a light bulb. :slight_smile:

http://www.youtube.com/watch?v=ya7hUjszSVk

Your problem isn’t likely to be the material. Ruined or incorrectly used tools can munch up any type of screw head or nut for that matter. As you mention it’s a vicious cycle and unless you throw away damaged screw immediately they’ll end up contributing to ruined tools.

We’ve have zero issues with socket head cap screws in both steel and stainless steel materials on FTC robots. This mostly because the tool enters the head to a greater depth and a larger hex driver is used than button head screws of the same size. Never use ball ended drivers unless it’s absolutely necessary since they only contact the head over a small area thus increasing the chances of damage when over torqued.

For VEX dome head screws one approach I’ve used with students is only giving them [quality] allen keys so over tighening will hurt their fingers. Once an understanding of tightening torque is demonstrated they’re permitted to use drivers and t-handled drivers.

Just going for harder fastners will probably ruin tools quicker if the students aren’t doing their part.

This is a good point. I hadn’t really put two and two together, but of the screws we wreck they are always the black ones. Perhaps I should just chuck the black ones and purchase the silver ones.

I just did this. Bought motor cap screws from McMaster Carr. I actually ended up buying phillips #1 drive, which isnt the best. But they are so cheap we will just throw them away as they go bad. The McMaster screws are way harder than the VEX motor cap screws so I think they will last longer anywayhs.

Very true. I tell my students this ALL THE TIME. The problem is they don’t always listen. They get so “into” the build, they forget to pay attention.

If I personally used the VEX screws they would probably last forever, but as I said, it is hard to get the students to care about it as much as I feel they should. And I don’t have the energy to hover over then every moment of the day.

hex screws are terrible, both the wrenches and the screws easily strip
a star shape would be much better

Using the VEX Performance tool kit also solves this problem. Instead of overtightening or stripping the screw, the hex part just strips and turns in the handle. :smiley:

The black ones are pretty bad. We used some at first, but now whenever we find any they go into a bin of parts we will never use.

What is the part number/link of the ones that fit?

We have the “Performance tool kit” and I still have these problems…but maybe my kids are just to rough on stuff. We do have some that spin in the handle though. Its like a torque wrench…haha

McMaster Carr Part Numbers: http://www.mcmaster.com/#catalog/120/3021/=u939ap

92005A033 - For regular caps

92005A037 - For IME Caps

There are other options if you look around, but these were cheap enough to just throw away if they get wrecked.

The screws are not a perfect match, VEX uses a screw that has a .6 pitch which is IMPOSSIBLE to find in an M2 machine screw. The ones I linked to are .4 pitch, but they work just fine. Just a few more threads per inch. I tested them out and you can’t even tell the difference when screwing them in, and they hold well.

Also, VEX IME screws are 16 mm, but can’t get them anywhere, so the link is to 14 mm screws. They work fine.

After looking around and thinking about what others said I think the most reasonable option may be to:

Stick with the VEX hex socket screws, but ONLY use the silver (stainless?) screws that VEX sells. Throw away all black screws. Also, buy high quality hex drivers from McMaster Carr. This should result in decent hardness of both screws and tools, and not complicate things by having different head styles from regular VEX screws.

So I haven’t been on the vex website looking at screw options in a long time. I just looked and unless I missed something, they ONLY sell the stainless screws now. No crappy black screws to be found. They must have realized the black ones were not the best quality. That being the case, I feel a little bit bad about badmouthing the VEX screws because it appears they have basically fixed this problem!

the black allen wrenches still strip easily

Yea, I was referring to the screws only. I still think it is definitely worth it to buy better quality allen wrenches/drivers from a different source. I found some that seem pretty nice on McMaster Carr.

For buying the screws individually, they only have the silver ones now. HOWEVER, the black ones are still around, they come in every kit (clawbot, classroom, etc.) or assembled part from VEX, even with the clamping collars. :frowning: I suppose they still have a decent inventory of them they want to get rid of.

We picked up some harder, more reliable allen keys from the local hardware store and they work like a dream. Even the collar setscrews stopped stripping as often after we did that. Now we are able to use locknuts, which strain materials even more during assembly, without damaging the screws or the tools.

Also silver VEX screws are extremely nice, we buy them exclusively.