Turned Bolt, what is the term referring to?

[bjohnson3]

I keep hearing the term "turned bolt" used in specifing an A325 type III high strength bolt for fastening a mechanical actuator onto the web of a beam for lifting a draw bridge. Can someone explain to me what this term "turned bolt" means?

 

[RockEngineer]

Usually when I have heard or used the term turned bolts it is a bolt that is made from square stock where you manufacure the bolt on a lathe by turning it down from the square stock the size of the head to get the shank size and threads.

 

[SMF1964]

Cut as opposed to rolled threads.

 

[Screwman]

I can't imagine anyone specifying an A325 type III and calling out on the print that it is a screw machined part. Threads are allowed to be cut or rolled at the mfg. choosing according to the spec. That is a very strange call out.

Could it be that we have a case where they want you to tighten from the head side, as opposed to the nut side? That would make the bolt the "turned" member.

Best of all; ask for a clarification, don't have us guessing for you.

Dick

 

[Metalguy]

Could be the method used for tightening it. Usually called "turn of the nut".

 

[unclesyd]

Adding to Metalguy's post. There is two types of tightening a fastener by turning, "turn of the nut" or "turn of the bolt".
Both methods require that the fastener be in a "snug condition", a couple of hits with an impact or healthy pull on a spud wrench. Both methods require that the other component, either the nut or the bolt, not move while turning the other. Also the surfaces being bolted should be flat and in close contact prior to using either method. If the surfaces are slopped great than 1:20 a bevel washer is required.
The minimum required turn is 1/3 turn, verified by match marking either the nut or bolt or both. The amount of required turning of a fastener on flat surfaces is increased with length to a maximum of 2/3 turn.
If the surfaces are slopping more than the 1:20 mentioned the amount of turn required is a little more.
The tables of turns are in the RCSC Specifications

Going back to "turned bolt" in respect to the method of manufacture I have seen this term used with a call out of a "center turned bolt". Generally though the term for machined threads is "cut" threads.

 

[yates]

The term 'turned bolt' can either mean machined thread rather than a rolled thread, but can also mean machined (i.e.turned ) out of bar stock (usually hex.)as opposed to an upset (forged) head.