Cutting and threading rigid
- Thread starter zappy
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liquidtite
Senior Member
- Location
- Ny
i like to give a 1/8 inch of play but thats just me also i know its more expensive but if you use compression couplings and connectors it can save time on threading if your runing alot of pipe
make sure your specs allow rigid compression connectors, as some do not
- Location
- Illinois
- Occupation
- retired electrician
The quality of the conduit bodies is so poor that you cannot use a set amount of thread length. With the same die setting and the same brand of fittings the number of threads showing can vary from none to 3 or 4 when the conduit is made up wrench tight.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Using some Red Dot stuff right now that is really irking me.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I feel you pain with conduit bodies not threading on all of the way.
These things are the bane of my existence, sometimes requiring that the RMC be shortened by half the thread length just to get these on to a point where the two conduit ends can touch. Or if we're using an adjustable threading machine we'll set the cut a little deeper than standard. I cannot understand why a rigid coupling will thread on all of the way but these pieces of junk won't. :rant:
These things are the bane of my existence, sometimes requiring that the RMC be shortened by half the thread length just to get these on to a point where the two conduit ends can touch. Or if we're using an adjustable threading machine we'll set the cut a little deeper than standard. I cannot understand why a rigid coupling will thread on all of the way but these pieces of junk won't. :rant:
liquidtite
Senior Member
- Location
- Ny
Ya we had the same problem with erikson connectors.Left threads showing could not tighten all the way.Witch I'm Shure will lead to rusting more rapidly than if threads were in connector all the way
- Location
- Illinois
- Occupation
- retired electrician
I only use the Red Dot MALBs and they seem to thread on ok, but the inside edge at the cover is very sharp and you have to be careful not to get cut or damage the conductor insulation.
The conduit bodies I use are Crouse or Appleton form 7s and we have the same issue with both brands. The threads or the amount of galvanizing on the threads are not consistent making difficult to get the threader set correctly. I have started setting is much deeper than normal and cutting the threads shorter than normal, letting the taper at the end of the thread tighten against the female threads on the conduit bodies.
kwired
Electron manager
- Location
- NE Nebraska
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Wouldn't that depend on the RMC size? Larger sized RMC has up to 2" of thread.
kwired
Electron manager
- Location
- NE Nebraska
Yes, but in no case will the taper be any longer than the die that cut the thread, even if the threaded portion of the pipe is longer.
Not quite sure if larger sizes use a different taper or not, I was thinking it is all the same taper, just the thread pitch is different in larger sizes.
kwired
Electron manager
- Location
- NE Nebraska
I feel you pain with conduit bodies not threading on all of the way.
These things are the bane of my existence, sometimes requiring that the RMC be shortened by half the thread length just to get these on to a point where the two conduit ends can touch. Or if we're using an adjustable threading machine we'll set the cut a little deeper than standard. I cannot understand why a rigid coupling will thread on all of the way but these pieces of junk won't. :rant:
Some factors that will make a difference, cast vs machined threads, straight vs tapered threads.
Last sentence in 300.6(A):
- Location
- Illinois
- Occupation
- retired electrician
The taper of the conduit threads is to be 3/4" per foot. This is fixed by the die and as others have said the tapered part of the thread for fixed dies can be no longer than the die itself.
When we cut "deeper" threads, we do not change the taper, it is the OD that changes.
When we cut "deeper" threads, we do not change the taper, it is the OD that changes.
Cow
Senior Member
- Location
- Eastern Oregon
- Occupation
- Electrician
For me, I measure to the center of the coupling. But I also check the depth after doing a couple to verify it's correct, then adjust/deduct as necessary. It's different depending on if I'm hand threading or using a pony/power threader. Condulets/boxes are tough for a depth measurement, because like Don said, they don't always thread consistently. I usually figure 5/8" into the hub as a starting depth for those.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The threading machines that we use for 2.5"-4" RMC taper the entire thread with a die that's only an inch long, this is even for threads that are close to 2" in length. That's because the die adjuster rides on an angled block which allow the entire thread to be cut as a taper.
Cow
Senior Member
- Location
- Eastern Oregon
- Occupation
- Electrician
Yep, that's how our Rigid threader does it on the bigger sizes.
kwired
Electron manager
- Location
- NE Nebraska
But the tapering still stops at some point. You can't continue threading until you break through the inner wall of the pipe
- Location
- New Jersey
- Occupation
- Journeyman Electrician
- Status