What am I doing wrong?

[ColJack]

Coljack you and I seem to be of the same type. Do a good job but dont sit at home at night and fantisize adout the perfect thread like some people on here do. They must have very little to do.

you do the best you can with the tools and materials you're given.
if you have crap dies then you either go and get a new set or make do with the ones you have..

if i've bent a complicated piece of conduit and then cut the end to size and thread it, I'm not going to throw it away and start again just because the thread is chewed up.

if the coupler or conduit bow doesn't tighten onto it right then I would.. but not if it's still a good fit..

 

[ban-all-sheds]

I forgot.

7. I did cut the grass as well.

it's not your fault.. some stocks and dies are just crap..
I take it they came in a box, and the ends of the handles are sort of squared off ( slight dome to it but a definite sharp corner )

They did come in a box...

It all seems to be well made.

it may be that they are "oversharp", or that the conduit is cheap and nasty stuff..

Could be.

are they photos of 4 different ends or just the first one you did?

Just the first one.

BAS the die can be run onto the thread the other way around.

What I mean it it won't go into the stock the other way around, not and be locked in place...

 

[NotHimAgain]

BAS I agree that you cannot mount the die in the stock the other way around.

However, you can run the die onto the thread the other way around. The thread would have to have been cut in the normal way first as - whilst a reversed die will cut - it is very difficult to make it start a cut, as it does not have a 'lead in' taper in that direction.

If you look at the cutting surfaces you should notice a small taper from front to back. This results in a tapered thread over the length on the die - so on a typical thread it is just the last die length of thread that has a taper. The conduit socket binds onto this taper. The trick is to tighten it just enough for a good mechanical and electrical joint, without over doing it, as if you do the socket will start to 'bell' on its leading edge and would eventually split.

A socket to conduit joint relies on this binding for a tight fit. Contrast this to the normal use of a nut and bolt - in which the bolt is stretched slightly to provide a secure fixing.

As I said above - the one time you might want to run the die in reverse would be on the long thread of a running coupler. Here you simply want to be able to run the socket onto the long thread and then tighten it onto the conduit you are extending. Running the die in reverse removes the taper and stops the socket binding on the long thread. A lock nut is then used to tighten the joint between the socket and the long thread.

Just as an exercise - try cutting a thread on some PVC conduit . You have new sharp dies so you should be able to do it. You will probably need to hold a short length of conduit in a standard bench vice by crushing it. You should not need the handles in your stock as you don't need too much force. You will have to cut slowly and keep backing off and cleaning - good practice for steel .

 

[TicklyT]

IMO it will always be hard work getting a nicely finished thread from a die on a conduit, or anything else with a big hole through the middle, because the work springs out of shape as the die passes over it. The steel has to be quite ductile, or you'd never be able to bend the stuff.

the work adopts a pentagonal/hexagonal/octagonal shape (depending on how many cutting edges your die has). The 'springing' closes up the top rake of the cutting edges until it 'bites off more than it can chew', then the conduit springs to a different shape under the die. That closes up the back rake of the cutting edge, and tends to roll bits of swarf you've cut back into the cut threads rather than letting them fall clear.

A little bit of wear on the cutting edges reduces the tendency of the die to dig in too deep.

A mandrel to stick in the end of the conduit to stop it springing so much is problematic, because the bore generally isn't well finished. Usually there's quite a lump in it where the seam is welded.

 

[regsmyth]

Lyndon is a good make. You shouldn't have any problems. You can see the first three threads are good, then they deteriorate.
Is the conduit 16mm O/D?
You should back off a full turn every half a turn to break off the "nibs" that form behind the cutting teeth. It's these nibs that catch in the following teeth and rip the new thread off.
And use lots of lube.
HTH.

 

[ban-all-sheds]

The photo of the Lyndon 16mm die was just to illustrate the way it locks into the stock, (maybe they all do, but I can envisage other ways of accomplishing the same thing) - I hadn't grasped what NHA meant about using it reversed.

My die (and the conduit!) is 20mm.

I'll try more backing off - I'm pretty sure I wasn't doing it every half turn, and certainly not by a full turn.

 

[regsmyth]

Oh.

Well a full turn back off is ott, but since the stuff is so soft, you can't be too careful.

 

[ban-all-sheds]

You should back off a full turn every half a turn.

a full turn back off is ott

Maybe I'll just practice more and learn to feel when I need to back off...

What's the best way to clean Trefolex off? White spirit?

 

[regsmyth]

A nice oily rag.

Come on now, let's have a photo of a better one!

 

[ColJack]

bloke at where i used to work has a set of dies that are a dream to use..
easy on and cuts a perfect thread every time..
offered him £40 for 'em once but he didn't sell...

 

[davelx]

Dave do you actually work for a living or live in an Ivory tower??

Anyone that works for a living bends, cuts and uses an electric threader. You dont walk around inspecting the threads ---- if the coupler or box fits thats all thats required.

What an attitude perfection LOL its only a thread on a bit of conduit.

I personally DO NOT remember the last time I used conduit to carry the earth I always run in a cpc.

Yes - and in my line it has to be completely right or my customers can lose hundreds of thousands of dollars per second.

I'm not saying that every thread must be perfect - just that that is what you should be aiming for, and you should aim to continously improve your skills until turning out near perfect work takes you not much longer than work that will just "do".

 

[Spark123]

I'll try more backing off - I'm pretty sure I wasn't doing it every half turn, and certainly not by a full turn.

For every turn cutting forwards, try going back half a turn then jiggle the die so it feels free.

 

[ban-all-sheds]

So let's see - go forwards, backwards, jiggle it about and use plenty of lube.

 

[holmslaw]

..

 

[RF Lighting]

So let's see - go forwards, backwards, jiggle it about and use plenty of lube.

Anyway, back to conduit....

I go with one and a half turns forward, and then half a turn back.

I did this with temaxol, but trefolex should do exactly the same job. You need just enough for a light covering all the way round the tube, and only where the thread is to be cut.