Set Screws vs. Cap Screws

[Leon]

I have a commercial project coming up that requires me to build a display table for a couple of scale model airplanes, one is the Antonov

124. The models actual wing span is approximately 56", nose to tail is about 53". The airplane has a single 8mm mounting nut and is elevated from a platform by that mounting nut.

I need to mount the airplane so that it will not spin while on display, that is one of the current problems.

I have the details figured out, I think. There will be an 8mm threaded stud coming from the airplane to an elevated post and will do down into the post 3~4". I plan on embedding a 1" long set screw rod coupling

1/2" into the mounting post. The 8mm rod will go through that coupling and down another 3~4" into the post.

Finally the question. A single 10/32 set screw, in the coupling, will tighten into the 8mm threaded shaft. Since this set screw is going to be used relatively often I have fears of a hex wrench eventually rounding out. My thought is to use a hex head cap screw instead, with a larger sized hex head.

Will the cap screw hold as well as a set screw or will a snug set screw hold as well as a cap screw that is tightened much tighter?

The job of the set screw is only to prevent the rod from rotating, the bottom of the hole will maintain proper shaft depth.

Thoughts?

[Lew Hodgett]

------------------------------------------------------------------ Set screw is a failure waiting to happen IMHO.

How about an 8mm lock nut that locks the 8mm stud on the plane to the mounting post below?

Lew

[Sonny]

For whichever set screw you use, file flat a part of the 8mm threaded rod w= here the set screw will contact. Re-die the rod, if need be, if the filing= messes up the threads on the rod, for screwing it onto whatever. With a f= lattened side on the rod, either set screw would not have to be tightened s= o tight.

Sonny

[Leon]

The airplane is mounted at a 30 degree angle. I thought about using a nut in the post but that would mean you would have to hold the >4' square airplane at an angle and spin it 16~20 times to mount and again to unmount. Actually I believe that it would be best if the airplane would spin if forced, which convention folk will do. I just don't want it to spin on its own or given a lite tough. Essentially the method you are describing will be used at the airplane to stud union.

Setting the airplane stud in the mounting hole quickly will be a great advantage.

[WW]

I have a commercial project coming up that requires me to build a display table for a couple of scale model airplanes, one is the Antonov

124. The models actual wing span is approximately 56", nose to tail is about 53". The airplane has a single 8mm mounting nut and is elevated from a platform by that mounting nut.

I need to mount the airplane so that it will not spin while on display, that is one of the current problems.

I have the details figured out, I think. There will be an 8mm threaded stud coming from the airplane to an elevated post and will do down into the post 3~4". I plan on embedding a 1" long set screw rod coupling

1/2" into the mounting post. The 8mm rod will go through that coupling and down another 3~4" into the post.

Finally the question. A single 10/32 set screw, in the coupling, will tighten into the 8mm threaded shaft. Since this set screw is going to be used relatively often I have fears of a hex wrench eventually rounding out. My thought is to use a hex head cap screw instead, with a larger sized hex head.

Will the cap screw hold as well as a set screw or will a snug set screw hold as well as a cap screw that is tightened much tighter?

The job of the set screw is only to prevent the rod from rotating, the bottom of the hole will maintain proper shaft depth.

Thoughts?

Drill a slight shallow hole in the 8mm shaft for the set screw to enter. Problem solved. WW

[Leon]

where the set screw will contact. Re-die the rod, if need be, if the filing messes up the threads on the rod, for screwing it onto whatever. With a flattened side on the rod, either set screw would not have to be tightened so tight.

Thought of that too and the threads will not matter at that point. Filing would help but I personally will not be setting this display up over and over and the depth of the mounting stud "in the airplane itself" will be ever changing, which would change the location of the flat spot on the rod.

Now if only I could find a key way slotted threaded rod.....

[Leon]

[dpb]

On 11/2/2012 3:53 PM, Leon wrote: ...

Agree would be best to have a flat but probably won't matter too much...how much does the beastie weigh?

I'd suggest a regular hex set screw--they've got the cup in the base to grab the target already plus they're hard. If need be, ship the allen wrench w/ it in a little cubby spot...

[Leon]

Darn, I though you had it!. I will not be setting this display up but others will, over and over. They will be attaching the threaded stud to the airplane first and the stud would have to be clocked perfectly for the hole to align properly.

[tiredofspam]

The screw type won't matter. Either will hold. A soft screw is actually better than a hard screw, it will deform where it sets in and grab better. Some of the better screws made to lock in have brass tips to not deform the shafts, but bite in on the piece.

Can you make a small cradle for the belly where the screw will go, so that there is more support and that will help prevent it from spinning? If just mounted on that one screw point, it will definitely put lots of pressure on the fuse, and could eventually crack that area. A plane that size weighs a good amount, and you don't know how it was built. Ask about a small cradle to spread the load.

[Leon]

In display mode about 20~25 lbs for the big one.

Yeah, actually there seem to be about a dozen tips for set screws, Pointed, round, ball,

[Leon]

I am thinking a cap screw, and a hard SS shaft. I would rather the clamping screw deform than the shaft. If the shaft threads deform it may be difficult to pull it out of the hole. And i am going to try to sell the customer on there being give in the event some one grabs a wing and gives it a push. Better for the plane to turn than something crack. Or I could grind the threads off on that end to prevent the above mention possibility.

Thought of that too. Way too much detail for that, there is landing gear in that area and the customer wants a clear view. The airplane has been displayed multiple times, the single mount is adequate. They just want to to tilt and not spin now.

I think I am going to talk him into going with a snug fit so that there will be some give in case something hits a wing and there needs to be give to prevent damage.

[Sonny]

Can the 8mm threaded rod be bent very easily? If so, bend 1" of the end to= 90=B0 and imbed that end into the mounting post. Rip the mounting post if= half, carve an appropriate channel for the bent rod, insert, and glue the = mounting post back together.

Sonny

[Mike M]

My experience with small set screws that are regularly loosened and tighten has let's say been problematic. I would be looking for a way to simply be able to pin it. If you thought about it you could probably device a wedged M&T mount with the metal hardware glued in.

Mike M

[Mike M]

multirouter. Throw in your contrasting woods and I'd like it.

Mike M

[Sonny]

Would a Rigid Coupling help? Has 4 set screws and accommodates sizes 6mm to

50mm rods.

[Sonny]

50mm rods. Sonny

Available with or without keyways, also.

Sonny

[clare]

The set screw has a hardened tip with a special profile that the cap screw will NOT have.. I'd put a flat on the rod where the "setscrew" is supposed to contact - either way.

[clare]

the set screw will contact. Re-die the rod, if need be, if the filing messes up the threads on the rod, for screwing it onto whatever. With a flattened side on the rod, either set screw would not have to be tightened so tight.

DON'T use threaded rod. Use a good alloy steel "shaft" threaded to fit the airplane, and a close drop fit into the stand - with a flat ground on the shaft to take the set-screw.

[clare]

where the set screw will contact. Re-die the rod, if need be, if the filing messes up the threads on the rod, for screwing it onto whatever. With a flattened side on the rod, either set screw would not have to be tightened so tight.

Make sure that the depth into the airplane will always be the same, or simply tighten the jam nut at the airplane AFTER the set screw is installed.