sweatykeith
Member
I want to cut 1/4" NPT on a galvanized bolt. Does the coating affect hardness when cutting this thread? Do I need to remove the coating?
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Cutting threads on a Galvanized bolt
- Thread starter sweatykeith
- Start date
won't be an issue. more important is that the OD be correct , or are you single pointing on a lathe?
and if you leave coating behind on the top of the first "perfect threads ", they may not seal properly .
and if you leave coating behind on the top of the first "perfect threads ", they may not seal properly .
OP
sweatykeith
Member
Cutting new threads, mogandave. Thanks for the reply.
OP
sweatykeith
Member
The OD is not an issue & this will be hand threading. I don't think any coating will be left to hinder sealing. The 1/4" NPT will be on the unthreaded portion of the bolt. It will have M14 x 1.5 on one end & 1/4" NPT on the other end with a hole bored through the center. This is a crossover air fitting. Thank you, the Cobbler.
Why not go with brass? I lot easier cutting.The OD is not an issue & this will be hand threading. I don't think any coating will be left to hinder sealing. The 1/4" NPT will be on the unthreaded portion of the bolt. It will have M14 x 1.5 on one end & 1/4" NPT on the other end with a hole bored through the center. This is a crossover air fitting. Thank you, the Cobbler.
alfadan
Well-known member
If you're using a die, figure on a SOLID way to hold the bolt. NPT threads take a lot of force.
A grade 8?If you're using a die, figure on a SOLID way to hold the bolt. NPT threads take a lot of force.
nbpt100
Well-known member
You should be fine depending on how much the Galvinized coating built up. The OD for a 1/4" iron pipe is .540. The shank on a M14 bolt would be around .545 plus or minus. Hopefully minus. The Galvinizing may build up more and that may make it harder to cut with a die.
Go slow use some cutting oil or some kind of lubrication and use a good sharp die. You may want to buy a standard zinc plated M14-1.5 Class 4.x bolt. It will be the softest metric bolt you can get and eliminate the galvanizing.
As suggested you need a good way to hold the bolt while threading.
Let us know how it goes.
Go slow use some cutting oil or some kind of lubrication and use a good sharp die. You may want to buy a standard zinc plated M14-1.5 Class 4.x bolt. It will be the softest metric bolt you can get and eliminate the galvanizing.
As suggested you need a good way to hold the bolt while threading.
Let us know how it goes.
alfadan
Well-known member
He didn't specify but any steel bolt would be a ****** to cut a npt thread on with a die, especially if he doesn't cut the taper before hand.
I guess my main point, for what its worth, is to plan ahead to hold the thing while threading it. Like cutting some flats on it.
I guess my main point, for what its worth, is to plan ahead to hold the thing while threading it. Like cutting some flats on it.