To screw or not to screw?

[Project_Mayhem]

The title of this really should be "To thread or not to thread" but this gets a bit more attention. Anyways, my tongue extension is a rectangular steel tube that slides inside of the tongue. I designed it to have some plastic inside the tongue. This acts to fill in the gaps between the rectangular tube and tongue and allows for easier sliding (no metal to metal contact)

I'm trying to figure out the best way to attach the plastic to the inside of the extension. This must be fastened to the tongue, not the extension. Adhesive is probably not an option since the plastic is HDPE and/or UHMW. I've found that carpet tape adheres to it and that might be useful for installation. Right now I'm thinking some screws going through the tongue and into the plastic might be my only option. If it is, would you recommend machine or sheet metal screws? The tongue extension is made of 1/8" steel. Most of the plastic is 3/16-1/4". I can tap both if using machine screws.

Here's a representation if you were to look down both tubes (with hitch removed).
Blue is the trailer tongue
White is the plastic
Red is the extension (which is actually hollow)
Gap between plastic and extension tube is greatly exaggerated. In reality its only a few hundreths or thousandths of an inch

 

[Captain Larry-DH]

Rivits

 

[PaulK]

If duct tape isn't going to work, sheet metal screws will be the simplest solution. Drilling the right sized holes will enable you to avoid having to tap for them. They won't need much "catch", since they're only holding lightweight plastic, and the outer tube will hold them in place when it's in use.

 

[Project_Mayhem]

Rivits

The extension has plastic riveted to the aft end of it. This is the end that lives inside the tongue. When the extension slides out, the plastic on the extension will hit the plastic on the inside of the tongue. When the plastic is touching, the holes for the pins will be lined up. This is why the plastic in question must be fastened to the tongue. Unfortunately this also means that the plastic must be secured while the extension is installed inside of the tongue. Rivets was also one of my first thoughts before realizing this. The extra effort is worth it as it currently takes two people to get the holes aligned within 10 minutes

If duct tape isn't going to work, sheet metal screws will be the simplest solution. Drilling the right sized holes will enable you to avoid having to tap for them. They won't need much "catch", since they're only holding lightweight plastic, and the outer tube will hold them in place when it's in use.

These drill/tap combo bits are awesome. If I tapped them I'd drill all of my pilot holes through the tongue and into the plastic, pull out the plastic and then tap it. I'm wondering if only a few threads on a sheet metal screw is enough. Then again, smaller screws would have more threads.

The extension is around 100lbs and slides quite easily with the plastic. I'm sure at some point someone is going to give it a good pull and the plastic will slam into one another with some force

 

[Joe]

As pictured the vertical sides will provide support for top and bottom sides... then three or four self tapping screws on each side should give them the security you need. You could also run a bead of 5200 between the plastic and the tongue if you thought you would never want to remove and replace it.... on second though that may be too permanent. Finally, I would consider some kind of edge at the open end of the tongue to decrease the chance of one of the plastic sheets from sliding. An L bracket, mounted on the outside of the tongue secured with some of the self tapping screws would work. Will be interested in your solution, so please follow up with us.

 

[Project_Mayhem]

As pictured the vertical sides will provide support for top and bottom sides... then three or four self tapping screws on each side should give them the security you need. You could also run a bead of 5200 between the plastic and the tongue if you thought you would never want to remove and replace it.... on second though that may be too permanent. Finally, I would consider some kind of edge at the open end of the tongue to decrease the chance of one of the plastic sheets from sliding. An L bracket, mounted on the outside of the tongue secured with some of the self tapping screws would work. Will be interested in your solution, so please follow up with us.

They could provide some support just like the tubing walls provide support perpendicular to each piece of plastic. Ultimately the fasteners need to provide support mainly to keep them from sliding in or out of the tongue.

Hrmmm... I wonder how big of a fire it would take to melt it all out if 5200 was used

Instead of fabricating an edge or using an L channel, I could simply use a 1/4" bolt tapped into the tongue. No fabrication needed!

When you say self taping, are you referring to machine or sheet metal screws?

 

[sailme88]

How long ? Can you freeze the plastic and heat the steel? If so, cut the plastic a few hundredths over and freeze it .. Then heat the metal and introduce the frozen plastic ..

 

[dlochner]

Hrmmm... I wonder how big of a fire it would take to melt it all out if 5200 was used

Most smelters would make short work of this.

I don't think it will matter much which method you use. The important element will be the screw head and the countersink.

Rounding over all the edges will make it easier to slide the pieces together. If you look, the corners inside the trailer tongue will be rounded. Ease the edge to a slightly smaller radius.

 

[BarryL]

Hey,

Serious question; Why bother? What problem are you trying to solve? Back when I trailered my Catalina 22 I had a long extension for trailering. I don't recall really caring about the fit of the extension inside the hitch. The extension was used for launch and recover only and only took a few minutes. I would coat the extension with grease and that was it.

How tight do you expect the clearance to be? Will it work when the temperature is 60 degrees and when it's 90 degrees? How long with a few mil of plastic last? I am not a mechanical engineer but I don't see the point of this.

Barry

 

[dLj]

Rivits

+1

dj

 

[SailingLoto]

panel bond.... talk to you local autobody supply house.

 

[dlochner]

Thinking about this a little more, it is only necessary to put the spacer on the first few inches of the extension. This will keep it centered in the trailer tongue.

Rivets will work, so long as the head is counter sunk below the plastic.

If you use delrin, there will be no issue with wear.

 

[MikeHoncho]

Millions of trucks have nothing. Metal to metal is not an issue. For taking up the slack/slop in a receiver a very common approach is to drill a hole in the receiver and weld on a nut over the hole. screw in a large bolt once the hitch is in and tightens down. This takes up the slop when accelerating and braking. I have this system on my truck when using a 3 ft extension due to my camper overhang on the back and it worked perfectly.

 

[Stu Jackson]

Serious question; Why bother?

I agree, I, too, used grease.

 

[Project_Mayhem]

Rounding over all the edges will make it easier to slide the pieces together. If you look, the corners inside the trailer tongue will be rounded. Ease the edge to a slightly smaller radius.

You are correct. The pieces of plastic only cover the flat parts of the tubing. Doing this also allowed me to account for not so straight cuts with a miter saw (forgot my table saw that day)

Serious question; Why bother? What problem are you trying to solve? Back when I trailered my Catalina 22 I had a long extension for trailering. I don't recall really caring about the fit of the extension inside the hitch. The extension was used for launch and recover only and only took a few minutes. I would coat the extension with grease and that was it.

How tight do you expect the clearance to be? Will it work when the temperature is 60 degrees and when it's 90 degrees? How long with a few mil of plastic last? I am not a mechanical engineer but I don't see the point of this.

It's to take up the slack and ease the load on the pin holes. Imagine what happens when you put the load from a trailer on a small portion (due to circular holes and bolts) of a hole in 1/8" steel. Also, it was the largest size of tubing that would fit inside the tongue that I could get my hands on. The extension lives inside of the tongue full time. It "telescopes" out when launching and retrieving. The ball coupler is bolted onto the extension

The plastic is soft and not exposed to UV. Rigid plastic would've broken pretty quickly. This is the same stuff that's used for the lower portion of ice rink walls. It may deform slightly over the years but it's highly unlikely it will fail.

I'm not sure what the clearance is but it's worked at 35-40 degrees and at 80-90. My guess would be 1/32-1/16" on all sides. Most of the plastic is already cut and was held in place by duct tape last year for haul out.

There was close to a 1/4" inch gap between the two tubes initially

Thinking about this a little more, it is only necessary to put the spacer on the first few inches of the extension. This will keep it centered in the trailer tongue.

Rivets will work, so long as the head is counter sunk below the plastic.

I have about 8" of plastic on the ends of both the extension and tongue. The plastic is riveted and countersunk on the extension but this is not possible for the tongue.


It seems that I have not explained this very well. Hopefully the diagram below will clear things up