Can Portland Bolt make fully threaded headed bolts?

It depends. To answer this question, we have to go into the details about the different ways to we can thread a bolt. As well as different head styles.

 Roll Thread

 We can thread to within 2” of the head. We can thread up to 1” diameter bolts that are mild steel, stainless steel, or Grade 55. The rule of thumb is that we need 2” of unthreaded shank to roll thread and we also need at least 2” of thread. The shortest bolt that we can roll thread is 4”. The type of head on the bolt does not matter for this operation.

 Cut Thread

 We can within an inch from the head, depending on the head style. For a hex, heavy hex, square, or countersunk bolt we can hold onto the head of the bolt and thread an inch away from the head. For round headed bolts i.e. carriage, timber, etc. we need to be at least 3” of unthreaded shank.

If you absolutely need a bolt with thread closer to the head, we have two different options:

 Commonly available Products

For some bolts in some grades and sizes, fully threaded bolts are readily available. Mostly A325T, A307A tap bolts, and Grade 5 tap bolts are common. With the A325T bolts you will find them off the shelf up to 4 diameters in length and typically smaller diameters. You can read more about fully threaded A325T bolts in this FAQ. A307A and Grade 5 bolts are more of a hit or miss on what is available.


 Another option that we have is that we can outsource the threading to a machine shop. They are able to produce a precision thread and thread all the way to the head of the bolt. This may add to the lead time and cost of manufacturing the bolt. If you are looking for a fully threaded bolt to be used in a tapped hole, this would be the best option.

If you are looking for a bolt with a custom thread length, give Portland Bolt a call, email us, or chat and we will be able to help you out.


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