screws used as clamps

What kind, options, etc.

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frank-h
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screws used as clamps

Postby frank-h » Sat Jul 17, 2010 8:48 am

hi this is my first post hope i am in the right place,can't get much newer than that,i am still planing that first boat,don't know how many pages or forims i am in it takes a long time to get through even one topic here(i here a lot of arent you comming to bed yet its 2am) o well i have bin reading a lot about using sheetrock screws to hold things in place than removing them,i have used a lot of screws in my 70+years and found most of the time sheetrock screws are good for sheetrock..?...i found if you need to use a screw as a clamp and don't want to make a mess on the top sheet(counter sink holes)or having to pree drill to pull the pieces togethether use pocket hole screws(kreg screws)they have a flat sholder you can get them in fine or course thread.they are easy to use can be used over lots of times & if you search on line you can get them pretty reasonable. hope this helps it works for me.
thanks frank-h

Nova SS
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Re: screws used as clamps

Postby Nova SS » Sat Jul 17, 2010 9:51 am

The problem with using non wood screws is that the threads go all the way to the head on them. IF the two pieces of wood are not together when you drive the screw in they will not be pulled together with the screw as the threads near the head will hold the two pieces apart. That is why wood screws have an area by the head that doesnt have threads on it. It allows the wood to be pulled together when the screw it tightened.

Secondly the wood often used to make boats is more often then not a lot harder then your typical 2x whatever framing material so driving in a drywall screw will be much harder then it would be when building a house. The fact its a philips head type screw will not make it any easier to drive in the harder wood either.

And finely drywall screws are brittle. I'd be conserned that the extra effort required to drive them into the harder woods will result in a lot of broken off screws. This is just my 2 cents on this possibly others will say differently.

BTW welcome to the site. :)

frank-h
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Re: screws used as clamps

Postby frank-h » Sat Jul 17, 2010 12:27 pm

hay thanks for agreeing with me.i suggested the kreg screw because it is a wood screw the fine thred is for hardwood course for soft,the head is square drive letting you use them over&over thought you might like to know.frank-h

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ttownshaw
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Re: screws used as clamps

Postby ttownshaw » Sat Jul 17, 2010 7:42 pm

Yeah, I'm not so sure using screws as clamps is the right approach. Why not use clamps and the correct screws to begin with. Just a thought. One of those "right tool for the right job" approaches.
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jcallends
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Re: screws used as clamps

Postby jcallends » Sun Jul 18, 2010 8:16 am

I have used drywall screws for clamping purposes and all of the reasons given here for not useing them are true. One minor exception to this screw not pulling two pieces of wood together that I have seen in some instances is if the base piece of wood is thicker than piece being attached the threads in the wood in the attached piece will strip out and the piece will be clamped. Also, sheet metal screws have similar threads and I use them sometimes when I am fastening in soft wood, like pine, because the taper on a wood screw sometimes results in stripping the entire length. if I had a little more control of my driver I could probably eliminate this but I don't have that control anymore. The problem of stripping the entire length can be corrected by use the same length screw in the next bigger number size.

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ttownshaw
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Re: screws used as clamps

Postby ttownshaw » Sun Jul 18, 2010 9:16 am

Good point jcallends! Actually, thinking about it...I did use screws as clamps when I attached my bottom skin. I used steel screws with buttons and fender washers. The next day I came back and replaced them with permanent bronze screws. I was really thinking in terms of attaching hardwood to hardwood so your point is still valid.

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DaveLott
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Re: screws used as clamps

Postby DaveLott » Sun Jul 18, 2010 10:52 am

I used the zinc screws with fender washers a LOT on the decking. But as far as sheet rock screws, I tried one time and it immediately broke on me so I just bought a box of #8x 1.5".
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frank-h
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Re: screws used as clamps

Postby frank-h » Wed Jul 21, 2010 4:24 pm

from the comments to the post it seems most are not getting what a kreg screw is.it is used for pocket construction the bottem of the head is flat,so you don't have to use washers or any outher thing to keep from going threw the ply,it is made for wood(wood screws)and it is square drive makeing them easier to use over again.i agree a clamp is better if you can use them,but from what i am reading in these forems there are a lot of builders using screws and then removing them.sence i havent started my boat yet.just thought i could help frank-h

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J Purcell
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Re: screws used as clamps

Postby J Purcell » Wed Jul 21, 2010 4:56 pm

These what you are talking about Frank?

I still think in many places you will want washers or wood blocks to displace the load, or like in Dave's case, to have a large area to hold down the decking.

They are pretty slick though.
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kens
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Re: screws used as clamps

Postby kens » Wed Jul 21, 2010 5:03 pm

if your 'clamp' screw is a different thread than your final boatbuilding screw, then you upset more wood down in the threads of the hole. the final screw can strip out before it grabs real well.
I used plain steel screws of same thread pattern in many areas. then I had a pre-sized hole and the final screw went in very well.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

frank-h
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Re: screws used as clamps

Postby frank-h » Sat Jul 24, 2010 1:07 pm

hay jermey you got it even if you have to use warshers you won't break the screws,and you can use them over and over.i didn't mean to use another screw in the hole after you used them as clamps,why would you want to do that? frank

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Re: screws used as clamps

Postby Grampa Steve » Sat Apr 30, 2011 6:17 pm

Some guys will hate this, but I use high tensile vinyl coated "guaranteed for life" deck screws with "Torx" driver heads. Killer grip, excellent clamping, thin cross section which reduces splitting tendency, and the plastic coating helps them to slither right on home. They are counter sunk, and I just drive them in until they're flush, or even beyond. If they wont get in the way of the power planer I just epoxy over and leave them in as my boat will be fresh water only. Am I nuts?

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raymacke
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Re: screws used as clamps

Postby raymacke » Sun May 01, 2011 6:15 pm

If they wont get in the way of the power planer I just epoxy over and leave them in as my boat will be fresh water only. Am I nuts?

I wouldn't leave them in. I have experimented with this type of screw and for me they are unacceptable for anything but use with treated lumber. I pre drilled and drove these into solid wood. I then removed them and took a look. What I found was a high percentage of the "coating" was gone leaving only a cadmium plated screw. I repeated this test in treated lumber and the coating remained. I have to assume the high moisture content of most treated lumber acted as a lubricant. Without this the friction of driving the screw in dry wood rubbed it off.

And even though the structure is sealed with epoxy steel screws will still rust inside. On my Cabin Skiff I used some of these as temporary fasteners and then removed and installed bronze for the final assembly. Somehow it appears I forgot to replace two. These are passing through the side plywood planking into cleats on the inside and are about 10" above the waterline. They are under the glass cloth and epoxy coated on both sides. On the outside of the hull I can now see two small circular "pops" over the heads of the screws. I assume that rust is building on the heads and pushing the filler and glass away from the surface. At times there is a tiny amount of rust traces leaching from them.

I am sure these are two of these steel screws that were left in by mistake. On my next repaint I will have to dig them out and fix it. And yes, I operate almost exclusive in fresh water. So as I said I would not use them.
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