Problem axle thread- New Cromotor

[pchen92]

Hi guys,

I have a problem on one side of my Cromotor axle.
I use these nuts http://www.graphskill.co.uk/426/8376-m16-hex-nut-a2-stainless-steel-fine-pitch-4-pk-5055624407143.html . On the freewheel side, they screwed more or less easily but it works but on the disc side, I totally screwed up the axle thread Yet I was sure the nut was straight when I screwed it on the axle !

Now when I try to screw it, it works up to the thread that is not screwed up. After it's really hard to screw the nut and it destroys the thread

I don't know what to do...

See pictures


Freewheel side


Any idea ? :?

 

[Icewrench]

Awful easy to start the nut in a crossed up way with the flats cut into the axle like all hub motors have.
Good thing there is still some good threads close to the drop out where you need them.
Time to break out a file and a hacksaw blade to clean up the damaged threads.
Work slow and watch what you are doing.
You could file off the threads that are damaged and likely have enough to hold the nut.
If you are patient and calm use the saw blade to slowly re groove the threads valleys.
Do this with only a saw blade in your hand, might wear gloves to save some skin and hold the blade at an angle to match the angle on the threads. Try to remove the mashed bits and keep as much material as possible on the axle.
You might find a thin file with a narrow edge that will fit the thread groove again work slow and double check what you are doing.

Go slow and good luck

Looking at the pics again on the side with the derialer that nut looks to be barking up the threads as well?
Can that nut be turned by hand or is it also jammed up?
Metric threads are measured in diameter 14mm 16mm etc then also pitch 1.0 1.25 1.5 etc..
If you have the correct size and pitch nuts they should freely spin on by hand until there is contact with the drop out.

 

[nicobie]

I'd use an thread file.

http://www.zorotools.com/g/00056324/k-G1309061?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&kw={keyword}&gclid=CLqix7qh4bUCFcdxQgodiDQA3Q

 

[Lebowski]

Would it be possible to fix this with a thread cutting tool ?

 

[Icewrench]

Yes a thread chaser or die would be a good tool for the job.

Does anyone know the thread dimensions ,diameter and pitch, for a cromotor axle ?

 

[jpgey]

Yes a thread chaser or die would be a good tool for the job.

Does anyone know the thread dimensions ,diameter and pitch, for a cromotor axle ?

M16
Thread Pitch - 1.5 mm

 

[knighty]

Yes a thread chaser or die would be a good tool for the job.

Does anyone know the thread dimensions ,diameter and pitch, for a cromotor axle ?

it'll be pretty hard to screw a die down on there, and have the new threads line up perfectly with the good threads further along

there's plenty to hold the nut on if you fill the damaged ones off


fill damaged ones off, and then use a hacksaw blade on the very first thread the nut will see

job done

 

[Wurly]

You want to throw those SS nuts away. It's not your fault, they are too soft and pick up metal which damages the threads. Don't use a dia either, clean the thread with a blade or file as suggested and replace with some Grade8 steel quality nuts. Use a little grease and run the nut back and forwards to clean it up. Luckily you got the nut off ok. We use SS fittings at my place of work and i've seen both parts completely welded to each other.

 

[DAND214]

I'd use an thread file.

http://www.zorotools.com/g/00056324/k-G1309061?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&kw={keyword}&gclid=CLqix7qh4bUCFcdxQgodiDQA3Q

That would be the best option. Have used one many times.

Dan

 

[dogman dan]

Agree with above. Step one is chuck those damn nuts, they are ruined, and will continue to ruin the remaining threads. One option for a replacement nut could be a proper size and thread lug nut. A thicker nut, so more threads will grab the axle.

Step two is fix the smeared threads with the file suggested, or if you can't come up with one, the hacksaw. Get it so your new nuts will hand thread on there, and don't wrench on it till it's on the good threads and tight.

Second option, make yourself a pinching dropout.

 

[pchen92]

Ok thanks you guys. For me it's easier to sand down the crappy thread. I'll give it a try this weekend.

The picture with the nut is taken on the other side of the axle. The nut spins freely with hands.

I will put a new nut when the job is done

 

[pchen92]

Hi guys,

the problem is solved since a couple of weeks. A guy in my neighborhood had a nice tool, "thread-maker". So he fixed the crappy thread.

8)

 

[knighty]

just fitted my cromotor at the weekend

took me 2 or 3 goes to get one of my axle nuts on, was surprised how far on it went while cross threaded without catching - I was only doing it hand tight so no damage at all - and I was using an old nut I had lying around,all the one in my box of random 16mm nuts were the wrong thread pitch, had to dig in the buckets full of random nuts/bolts/crap

so it almost caught me out, and I'm used to working with my hands like that... so if it's not the kind of thing you normally do, take your time, and only use your fingers until it's all the way on and just needs tightening up a bit

 

[Farfle]

I'd use an thread file.

http://www.zorotools.com/g/00056324/k-G1309061?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&kw={keyword}&gclid=CLqix7qh4bUCFcdxQgodiDQA3Q

Use a thread file, its 1.5 pitch IIRC then when you have the threads somewhat established, then run a threadchaser or die over it.

Edit, looks like you got it solved!