10-32 or 10-24?
 

What does your team use for structural component hardware - 10-32 or 10-24? What are the situational advantages to each? Why do you prefer one thread size to the other?

Re: 10-32 or 10-24?
 

In my experience, teams go-to hardware is almost universally 1/4-20.

Increasingly, teams are not using bolts in favour of rivets, though. Particularly those with sheet metal frames.

Re: 10-32 or 10-24?
 

10-32 is normally used for machines, 10-24 is normally used for carpentry.

We use 10-32

Re: 10-32 or 10-24?
 

10-32 for two reasons:

1. 10-32 is the sze of the thread to mount CIM motors
2. 10-24 and 6-32 are the most commonly broken tap sizes due to the ratio of pitch to shank diameter.

Re: 10-32 or 10-24?
 

You already gotta use a bunch of 10-32s, and 1/4"-20 is usually overkill, so it's the obvious choice. If you wanna use 10-24, have fun breaking taps.

Re: 10-32 or 10-24?
 

The mechanical leadership on my team wanted to 'standardize' on 1/4-20 this year, until I pointed out that every COTS part we buy is 10-32. So we wound up having both, but standardized the lengths.

Re: 10-32 or 10-24?
 

...and the science teacher who is helping us wants us to use metric hardware.

:ahh:

Re: 10-32 or 10-24?
 

For our team we use a mix of 10-32 10-24 and 1/4 20
Lately however the last few years we have been using slot I aluminum pop rivets
Lighter save the weight

Re: 10-32 or 10-24?
 

We tend to use 10-32 for most applications. 10-32 reduces the strength of the bolt less than 10-24 as the thread is shallower. They also loosen less easily as the thread angle is shallower.

Re: 10-32 or 10-24?
 

We have large cases full of 1/4-20 and 10-32 nuts and bolts. 1/4-20 is for mounting to the frame, 10-32 is for superstructure and mechanisms. We're gradually getting smaller in our fasteners...

Re: 10-32 or 10-24?
 

There needs to be an option for "We have a can of assorted hardware that we pick from and hope fits."

Re: 10-32 or 10-24?
 

Our team uses both. #10-24 is nice for speed, but sometimes #10-32 are used for things like fine grain control or needing to get as many teeth in mesh as possible. I believe this year, our chain tensioning system uses #10-32 into a helicoil for these reasons. For our drive system, we typically rivet everything since we typically use a sheet metal base. We really try to determine what the right screw is for the job.

Re: 10-32 or 10-24?
 

Up until last year, we had used 1/4-20 almost exclusively. We made the switch over last year to #10-32 and 3/16" pop rivets based on the recommendations found here on CD. I never thought we would go smaller until using the 2014 VEX chassis...we now have a large collection of #8-32 hardware. Haven't had to go any higher than 1/4" this year, which is only used with the VEX "tube axle" (seriously love the concept). Definitely use #10-32 the most...small, lightweight, everything else others have mentioned so far.

Re: 10-32 or 10-24?
 

Both.

We transitioned away from 1/4-20 several years ago for the weight savings.

10-24 hardware is easier to find/get. 10-32s require 33% more turning to thread the same distance compared to a 10-24. We use 10-32 when we interface with COTS items that use that pitch.

Re: 10-32 or 10-24?
 

10-32. All the things others mentioned, plus you can tap them into thinner material and still get the required six threads of engagement.

Re: 10-32 or 10-24?
 

We standardized on 10-32 a couple of years ago and have never had a weight problem since. I would not recommend using both 24 and 32 because of the chance of mixing up hardware and causing problems.

Standardizing also reduces the number of tools needed.

Re: 10-32 or 10-24?
 

We haven't really standardized on any particular size of hardware, because different things need different sized hardware. For example, mounting SMC solenoid valves requires 2-56 hardware, while mounting one end of our roller uses 1/2-13 hardware. We use several different sizes in between, too....5/16-18 for bumper mounts, 1/4-20 for several things, lots of #6, #8, and #10 screws to attach stuff to the plywood belly pan....and rivets in 1/8, 5/32 and 3/16" sizes of various lengths.

Re: 10-32 or 10-24?
 

TechnoKats standardized on M3 and M5 for a year or two. It made finding the right tools trivial. We had a couple of plastic storage boxes with all the right drill bits and taps for the proper-sized holes. We had other storage boxes with a variety of bolt lengths.

I miss the simplicity of those days. I don't know what happened, but now we've got 10-32 and 1/4-20 and lots of other stuff all over the place.

Re: 10-32 or 10-24?
 

This is a transition year for us on a fasteners, as we have our first sheet metal frame. We went with a 3/16 rivet (using a number 11 wire gauge drill bit) which is slightly smaller than a clearance hole for a 10-32 bolt so we can drill out the rivet and bolt it if needed.

Re: 10-32 or 10-24?
 

#10-32 and 3/16" rivets.

1/4"-20 and #4-40 are stocked for places that need them, but we minimize there use.

Vex forced us to use some #8-32's.

Standard hand tools is nice, and lets us get a huge variety (L's, Ball end screwdicers, t handles, powerbits, etc...)

Re: 10-32 or 10-24?
 

Reason #3: 10-32 fits M5 nuts. The pitch is very slightly different, so this only works for a short threaded length. They fit together nice and tight. It works great with the nuts for 20 mm aluminum T slot extrusions.

Anyone is entitled to look down their noses at this practice if they feel so inclined, but our team has years of experience doing it without having bolt loosening problems. I got the M5 & 10-32 idea from these fine people, whose experience and expertise I trust very much.

Re: 10-32 or 10-24?
 

Tapped holes in aluminum and plastic should be course threads. The screw is much stronger than the base material and a fine thead will strip out much easier. If you are bolting through and using nuts or tapped holes in steel, fine threads will give more strength.

We standardize to the extent possible on 1/4-20 and 10-24, shcs or fhcs. The only exceptions are motors that require specific threads, or situations that demand a larger fastener (specifically a larger size, rather than higher strength)

The reason? Cost. In high strength fasteners, coarse threads are slightly cheaper. I doubt you could find a well designed FIRST bot where you need the strength of more than a quality 1/4-20 fastener. And the course threads give us the option of tapping into wood, polycarb, aluminum or steel without much issue.

Two box wrenches and two allen keys will take the bot completely apart and put it back together.

Re: 10-32 or 10-24?
 

We just standardized (mostly) to 10-32 this year and love it.

We have also started to use 10-32 riv-nuts for connecting thin materials and 10-32 t-nut inserts for connecting to plywood. Basically we wanted to have as many bolts as possible be removable with a single tool. It's worked out pretty well so far.

Re: 10-32 or 10-24?
 

I would suggest that you pick & stay with one thread for each size screw. The day will come that some helpful person will dump the 10-32 nuts in with the 10-24 nuts, and then you will go nuts. :ahh:

The nice thing about 1/4 is they have a broader range from acceptably tight to broken.

Re: 10-32 or 10-24?
 

That happened to us... prompting the standardizing of 10-32.

Re: 10-32 or 10-24?
 

1/4-20 almost exclusively, all button heads unless the applications does not allow. We have a drawer filled with the correct sized T-handles and a bunch of 7/16" wrenches. Also have the same set-up for 10-32, but do not use them as often.
You still have the occasional student that has issues tightening stuff up only to realize that they grabbed a metric wrench from places unknown...

It's shocking how well the metric wrenches fit in 5/32 and 3/16 hex heads...

Re: 10-32 or 10-24?
 

1296 standardized on 10-32 5 years ago. Then we go one step further and use all black-oxide socket head cap screws. It helps with the weight had another unexpected side benefit - fewer tools required in the pit.

Re: 10-32 or 10-24?
 

We primarily use 10-24, last year we considered switching to 1/4-20 but it ended up being overkill so we stuck with 10-24. But this thread has got me thinking, perhaps we'll give 10-32 a try next year.

Re: 10-32 or 10-24?
 

While this will work in some applications, be careful. Last season, we stripped the hex heads of many a versaplanetary set screw by doing this.

I had intended to include a warning... Guess I forgot.

Although they seem to fit well... It's a bad idea.

Re: 10-32 or 10-24?
 

Same here. 3/16" rivets plus 10-32s FTW in frame construction.

We also drilled out all the Vex stuff (sprockets, wheels, etc.) so we can use 10-32 on those too.

Re: 10-32 or 10-24?
 

We've hidden all metric tools in a box. A few mentors and trusted students know where it is... most team members don't know about it. If a student really needs a metric wrench, they'll ask a mentor and we will give them the wrench. We haven't stripped a bolt head using a metric wrench in years. :]


As for the topic of which bolts we use, 1/4-20 was our standard frame fastener, but we're moving towards rivets and smaller bolts. We've had issues with people not distinguishing between 10-24 and 10-32 (and 8-32). Better organization, training, standardization, and one of these should help us.

Re: 10-32 or 10-24?
 

Hence why we've upped the set screw from 1/8" to 3/16" for a deeper Hex socket. :)

-Aren

Re: 10-32 or 10-24?
 

Gotta love these guys. Thanks for continuing to make those little adjustments.

Re: 10-32 or 10-24?
 

Ok, build season is getting to me. I saw this post, and then the thread about "Multithreading on Java" and I thought they were related...

Re: 10-32 or 10-24?
 

Haha, same here, along with the 10-24 nuts that are required when we need to use 10-24 shoulder bolts or something COTS that needs them. We try to standardize to 10-32 and 1/4-20 depending on the application. This lets us use a single double ended open end wrench for almost all the nuts. Sadly even with only 2 sizes we need almost every alen key in the set due to different hex heads being used for different bolts (the button heads are smaller than the socket heads, etc...) as well as set screws that don't have nuts.

Re: 10-32 or 10-24?
 

We have an assortment of 6-32, 8-32, 10-32, 1/4-20.
10-24 is kept out of the shop so nobody tries to put a 10-24 screw in a 10-32 tapped hole.

Re: 10-32 or 10-24?
 

We use 10-32 mostly. Often we use a PEM nut in sheet metal so that means we drill a .25 inch hole and use a flange button head 10-32. This is nice because we only need an allen hex key to take things apart and the nut is attached to the metal. When, we need to shed a little weight, we knock out the PEM to switch it 1/4" rivet. We can also drill it out to add a 1/4-20, which never happens.

Re: 10-32 or 10-24?
 

We use 1/4-20, 10-24, 10-32, 8-32, 6-32, and 4-40. Typically 10-24 are used in aluminum that we have tapped and 10-32 in steel or other harder materials. Keeping the two separate is somewhat challenging

Re: 10-32 or 10-24?
 

We typically use 10-32, 8-32, 6-32 SHCS and 3/16" and 1/8" rivets.

For the most part, #10's are used for COTS items, everything else is riveted of #8 or #6. Even #10's are overkill in most applications.

Re: 10-32 or 10-24?
 

10-32's!!!

Easier to tap (saves money with fewer broken taps), stronger, get a tapped hole in thinner material.

We don't use too many on our robot. We find that for structure, welding is way lighter than 1/4-20's. For prototypes, we use 1/4-20, and (unfortunately) 1/4-28's, as we have thousands of these stupid things.

On things that I work on, I don't usually end up with too many 10 sized hardware. I find that 99% of the time, something else will fail before that bolt, so I go with 8-32's for weight.

Re: 10-32 or 10-24?
 

We grudgingly use 10-32 since a load of standard FRC hardware uses it for reasons I cannot discern.

I vastly prefer 10-24 since we are never doing anything with our bolts that requires fine thread and course thread goes together faster, but the potential confusion stemming from having two different sets of size-10 hardware outweighs the benefit.

Re: 10-32 or 10-24?
 

I'm no professional on the advantages of various screw sizes and threads, but I will say this. Whatever you choose to use, standardize it! Nobody needs to deal with figure out what type of screw they used for a specific hole when they have 30 seconds left in a time out before the 3rd match of the Einstein finals (obviously a bit of an extreme scenario, but the same thing applies for the entire build season. And competition season. And postseason and preseason). Choosing one size just simplifies things. You can always buy the same hex driver, wrench, drillbit, screw, nut, washer, tap, etc. and, except for when you have COTs parts with a different screw, you never have to worry about ordering anything else or searching through your supplies to find the right size or having to figure out what is the optimal screw to put in each and every hole. I can't imagine that the structural benefits of having the perfect screw for every joint is worth all of the hassle.

Re: 10-32 or 10-24?
 

There is no magic universal number of threads to have in the tapped material, it depends on the diameter of the bolt and the relative strengths of the fastener and the material that is being tapped.

The general rule of thumb to ensure that the strength of the tapped hole is similar to that of the bolt you are threading into it is to have the thickness of the tapped material equal the diameter of the fastener when the materials are similar in strength. When the tapped material is not as strong as the bolt you are threading into it such as a steel bolt into aluminum you want the thickness of the material to be 2x the diameter of the bolt.

So using a 10-32 instead of a 10-24 does not mean that you can universally tap into thinner material. With either fastener if you are tapping into aluminum to accept a steel bolt you'll want the material to be 3/8" thick. So for a 10-32 you want 12 threads while using a 10-24 you would only need 9 threads to achieve similar strength of threads in the tapped material.

Head to your local hardware store and take a look at the different sized nuts and you'll find that the height of the nut gets larger as the size of the bolt does and you will find that a fine and coarse thread nut has the same height. If you have a store that also stocks aluminum and/or nylon fasteners you'll find that the height of the nut is the same for those made of steel, since they are intended to be used with bolts made of the same material.

That being said the Socket Head Cap Screws that many FRC teams use is way overkill for most applications, so tapping into material that is thinner than the rule of thumb suggests will work just fine.

Here is a good discussion of coarse vs fine and the benefits and drawbacks of each. http://www.katonet.com/article/coarsevsfine.html

The part I put in bold is exactly why I insisted that we standardize to 10-24 after my first season with my team, since for many of our students being on our FRC team is their first experience with assembling things with nuts and bolts. As mentioned above the bolts are usually overkill so the greater strength of the fine thread bolt is not necessary. Using nylock nuts or thread locking compound means that the fact that fine threads are less likely to loosen isn't necessary either.