Shop All Carriage & Plow Bolts
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Carriage Bolts, Plow Bolts & Timber Bolts
The common features of bolts in this selection are that they are drive-less featuring either a domed or flat head, and that they feature a square section underneath the head of the bolt which grips the application surface to prevent the bolt from turning. This type of bolt is commonly used with a nut and washer in timber and lumber applications, as well as on heavy machinery.
A carriage bolt has a domed or countersunk head and the shank is topped by a short square section under the head of the bolt. The square section grips into the part being fixed, preventing the bolt from turning when the nut is tightened. Carriage bolts are often used to fasten wood panels or board to masonry or to one another. The square shank of the bolt allows it to lock into place when inserted into a round hole in wood or a square hole in a metal strap, the unthreaded square shank pulls into the wood creating a tight connection.
Carriage bolts are available in 18-8 Stainless Steel, Hot Dip Galvanized, and Zinc Plated 307 Grade A Steel. Each metal and finish offers its own benefits including hardened metal and corrosion resistance.
Plow bolts are designed with a short square countersunk section beneath the head of the bolt. This square section is used to prevent spinning while being fastened by a nut. Plow bolts are commonly used on plows and other heavy duty equipment. These bolts received their names from their use attaching the cutting edge of a plow to the plow blade. Plow bolts are stronger than standard bolts making them the ideal choice for heavy machinery.
Plow bolts are like carriage bolts but have a flat head that sits flush once installed. They have this flat head because they are commonly used where a domed head would be exposed. The flat head deters wearing and allows the bolt to last longer on the scouring surface (area where the head of the bolt would be exposed to high wear). Plow Bolts are measured from the top of the head all the way to the tip of the bolt. They can be removed by taking the nut off the bolt and tapping the tip with a hammer until the square section backs out of the hole.
A Timber bolt, also known as a Mushroom head bolt or Dome head bolt, is like a Carriage Bolt in appearance but with an oversized, heavy duty low profile head. Timber Bolts are typically used in marine and wood applications to protect timber structures from the elements. The underside of the oversize head of a timber bolt features rings that help prevent water from entering the hole and nubs or fins which prevent the bolt from turning. The timber bolt's oversize head eliminates the need for a washer on the bolt head side. Our Timber Bolts come in 3/4" and 5/8" size diameters.
To learn more about the different materials, check out our Fastener Grades, Strength and Materials page.
How to Install and Remove Carriage Bolts
Carriage Bolt Installation & Removal Transcript
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Bob: Welcome back to Albany County Fasteners - Fasteners 101. I'm Bob and today i'm going show you how to install a carriage bolt and remove it.
I have here my carriage bolt. Carriage bolts are typically installed with the carriage bolt, a washer and a nut, to follow. Also you should know that to prevent carriage bolts from moving, in the wood, they have this square at the top that's notched. It has no threads (on the square shoulder) so the threads on a carriage bolt do not run all the way to under the head. So you can see that here and once i start drawing in the nut, this will prevent it from turning.
Also, you will need a hammer because sometimes, its a little tight. You could use a ratchet. I have an open end wrench here so that's what i'm going to use. Use a ratchet if you'd like.
You can see it drawing that head right on in there. Nice and tight. You can see it's pulling the head right in. That's the installation of a carriage bolt. As you can see here, the head is nice and flush with the wood. That's typically the way that a carriage bolt should be completed and finished. If you start to draw the head in, you can do that if you like, but its going to start to dimple the wood on the face. Typically, you don't wanna see that.
Now, if I want to remove this, all I would do is loosen the nut, bring the nut back to where its almost going to come off the carriage bolt, take a hammer, and just hit the opposite side (the nut side). Bang it out. Back off the nut a little bit more, as much as you can. Of course I'm doing this because, this way, I don't ruin the actual carriage bolt and I can reuse the carriage bolt.
If you just don't care then just take the nut off and yank it out. You can use the claw (backside of your hammer) like this. To just pull it out. There you go: removed.
Finding The Right Drill Size For Carriage Bolts
Carriage Bolt Drill Sizes Transcript
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Bob: Welcome back to Albany County Fasteners - Fasteners 101. I'm Bob and today I have a quick tip on a common question from a lot of buyers. They constantly ask "what size hole do I drill for the carriage bolt that I'm installing?"
Whatever the size of the carriage bolt is, in this case, it's a 1/2"-13. You drill the same diameter you use the same size bit. So if you have a 1/2" carriage bolt, like I have here, you drill a 1/2" hole. If you have 3/8" you drill a 3/8" hole.
Now, depending on the type of bit you use, for this I use a spade bit but, depending on the bit you use this could be a lot snugger. So what you do is you just put it in place... oh also I just want to point out to you the carriage bolt typically has a four sided shoulder on the underside of the head here and the reason for that is: when you either put the nut-I mean the washer nut on you torque it down and it prevents the head from spinning and twisting on the other side because you have nothing to grab.
So in this situation, what I like to do is take a hammer and I just whack it down in place. It won't go 100% but just enough. Put your washer on, put your nut on okay. I'm not going to torque it all the way down, this is for demonstration purposes, but you get the idea.
Then put your wrench on it and torque down the head and you can torque the head down to where it's even with the wood. If you torque it too much, it's going to start to dimple the wood and start to recess into the wood depending on the type of wood you're using. The softer the wood the more it's gonna pull into wood.
Thanks for watching.
How to Remove Carriage Bolts
Removing Carriage Bolts Transcript
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Bob: So I'm going to demonstrate to you how to remove a carriage bolt. It's pretty simple, I get so many questions about this so I just wanted to do a video on it.
Basically what you need to do is just loosen the nut on the backside, bring it to the end. A little bit past where the the carriage bolt is no longer flush about halfway through the nut.
This is so you can reuse the carriage bolt if you want it if you don't just remove the nut and then bang the thing out. Use a hammer and just whack it until it comes out or till the nuts up against the back. Back it out a little bit more take the washer off and the nut. I have those here.
Take the claw of the hammer and pull it may wedge in there and just put it on the other side and pull it out. That's basically how you remove a carriage bolt.