kenzie

Self tapping screws

15 posts in this topic

Posted (edited) · Report post

Recently, I installed an anchor trolly on my Hobie yak.  Most all of the install had  backing plates.  While doing the work, I was wondering about how well the self tapping screws would really hold the hardware in place, as long as they were properly installed.  Such as not stripping the threads in the hull or using an oversized bit.  So how many people here, have installed hardware on their yak, using the self tapping screws and had them  fail for one reason or another?  Or if you used them without any problems, how long have they lasted so far?  Just wondering if the self tapping screws are given a bad rap.

 

This is a question on how many people have had self tapping screws fail on their yak        Im not asking for advice.  But thanks for the advice anyway.

Edited by kenzie
clarification

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Use the special "bulb head" pop rivets recently discussed, screws in soft plastic will not hold under real load.

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Posted (edited) · Report post

1 hour ago, kenzie said:

Recently, I installed an anchor trolly on my Hobie yak.  Most all of the install had  backing plates.  While doing the work, I was wondering about how well the self tapping screws would really hold the hardware in place, as long as they were properly installed.  Such as not stripping the threads in the hull or using an oversized bit.  So how many people here, have installed hardware on their yak, using the self tapping screws and had them  fail for one reason or another?  Or if you used them without any problems, how long have they lasted so far?  Just wondering if the self tapping screws are given a bad rap.

I have installed stainless self tappers and stainless wood screws on pad eyes for leash holders and other light duty applications. Even for a rod holder when I didn’t want to use it for trolling. You have to use the torque feature on the drill and don’t strip it. Never came loose. 

 

What I wouldn’t use it for would be rod holders specific for trolling. Outriggers and any other application were it may loosen up from severe force.

 

There are people out there who troll with rod holders mounted with self rappers or wood screws and goop with no backing plate/screws and also have no issues with rod holders and ram mounts for sounders. To each their own.  

Edited by The Riddler

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The screws in my cheap rod holders came loose, just from removing/inserting the rods while fishing. They were not screwed into any 'backing'

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I had stock hobie screws strip the plastic out while removing/reinstalling the cable keepers on my Quest with little to zero effort. Backing plate is the way to go.

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Posted (edited) · Report post

Kenzie, most of us have not tried tapping screws for loads because anyone who has worked with thin PE knows it won't hold for sh*t.  It's so soft it's not easy driving it in without stripping, even using the clutch. And I have used them for simple light loads like this plate for my FF. post-15110-0-51453800-1497742207.png

 

Backing plates are nice but not necessary. Here's my post from the previous thread on this just days ago.

 

Quote

 

The easiest way is using these 3/16 dia "Bulb Tite" type pop rivets. They will hold quite a lot, I've used them for anchor trolleys. Rubber well nuts work too, but require 2x the size hole for a 3/16 fastener.

 

59b8d4651d11c413ac20382e.jpg

 

 

Edited by gellfex

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  The exploding type rivets that you see in ever jobsite toilet could work for many blind applications. 

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Posted (edited) · Report post

I will only comment on your screw & trolley application...

 

This trolley is only used when i'm in freshwater, i installed these pad eyes with self tapping screws or they might be wood screws, cant remember.... i drilled pilot holes instead of using a drill gun...... this is about 3 or 4 seasons in now, works fine, hasn't loosened at all.

 

Drilled hole size is smaller than the minor dia of the thread for a watertight seal when installing the screws, i did not use sealant.... I installed the screws with a screw driver, screw gun not necessary for stuff like this & stays in the tool box....

 

There's not much of a load on an application like this.... i have a whole box of tri-fold rivets like Mr Gellfex suggested, good choice for this, but i chose to use the screws for no special reason...

 

If you do the math  approx .156 hull thickness with a 24 pitch screw you have 3-3/4 thread engagement into the plastic.

 

With 2 pad eyes spread out over 12' the load from the anchor ring would be on a very low angle or somewhat diagonal direction, not straight out, even then, its still pretty solid for what its doing... 

 

It takes a lot to pull a screw out of the material in a diagonal direction like what you'd experience with a trolley line.

 

With the bungee that's installed on the other end pulley, there's a shock absorber built right in...


 

pulley.jpg.0f4e0a3169ed0f46d865b5d73194baa0.jpg

Edited by BillZ

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17 mins ago, BillZ said:

I installed the screws with a screw driver, screw gun not necessary for stuff like this & stays in the tool box....

That strikes me as an important point. The reason why metal fasteners are tightened/torqued is to stretch the fastener to apply force to the parts being held. Clearly, that is not going to happen on a kayak hull. All you can do is get the screwhead flush to eliminate wobble; any further tightening is only destroying the integrity of the PE.

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I Also predrill and use a screwdriver. Seen too many times the screw gun stripping threads due to the speed/heat. You have to keep it slow or heat develops. YMMV as most disagree with me

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Not to put too fine a point on it.   ;-)

but "self-tapping" is different than "self-drilling". What we are talking about here is self-drilling. Self-tapping is for thicker metal applications where essentially a machine screw needs to go into a hole that has not had threads tapped for it yet.

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Posted (edited) · Report post

I don’t understand the need for either self tapping or self drilling.  It’s soft plastic and any pointed screws will go through.  Once the holes have been made, the threads are pretty much identical and there is no benefit of a self tap vs regular screws

 

Edited by kinghong1970

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Someone troll with a Scotty 241 base mount with 4 wood screws or self tappers and report back. 

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