Thoughts on damaged thread

[grim_d]

This is the nose of the spindle in my CNC router.

The nut was put in as normal, I always clean the collet, nut and nose taper on a tool change (just like on the mill) but the threads galled so badly when trying to remove the nut I had to cut it off and was left with the damage in the picture...I did not so much as graze the threads with the grinder.

It has not been cross threaded, the first couple of threads are in tact and functional, tested with my spare collet nut.

The machine is now INOP, and this happened the day before my warranty expired.

They are refusing to fully warranty the spindle because the threads are damaged. Long story short they are blaming me for damaging them or saying it was dirt ingress (can't imagine a bit of wood dust causing that?

I think it's crappy Chinese threads that finally gave up.

Thoughts?

 

[Stueeee]

What diameter is the spindle nose?

 

[mike os]

I would just dress it out with a file… and ensure that it’s lubed after

 

[8ob]

I would just dress it out with a file… and ensure that it’s lubed after

Dont know how slowly the spindle can run, if slow enough a thread file would probably sort it.

Bob

 

[maroon]

run a die over it.

 

[mike os]

Dont know how slowly the spindle can run, if slow enough a thread file would probably sort it.

Bob

No power at low speeds usually (assuming it’s not a geared head) … and significant risk of injury

 

[knighty]

I've always used a junior hacksaw to clean up threads.... gets in just nice as long as they aren't super fine threads

 

[graffian]

I would just dress it out with a file… and ensure that it’s lubed after

How much thread engagment is there?

As to crappy chinese threads. It can happen to the best of them.
I have an autlock chuck that the screw in bit galled and locked in place.

 

[grim_d]

Missing the point guys, I know how to fix a damaged thread I was more interested in if this could be a case other than thread galling.

What diameter is the spindle nose?

M25x1.5 IIRC. I can get a die easy enough but that's not the point.

Dont know how slowly the spindle can run, if slow enough a thread file would probably sort it.

Bob

600rpm. Have run a thread file over it but it's not done terribly well. Not convinced by my lang thread files to be fair.

How much thread engagment is there?

As to crappy chinese threads. It can happen to the best of them.
I have an autlock chuck that the screw in bit galled and locked in place.

I reckon it would be reduced by about a half if I removed the damaged areas, some of the threads have started tearing from the root.

The autolock.. if it was within warranty would you expect a replacement?

 

[voipio]

What was the spindle nut made from, out of interest?

 

[grim_d]

What was the spindle nut made from, out of interest?

Some sort of alloy steel.

 

[Johnnybravo]

That thread is galled and it has picked up and seized. I would say dirt ingress too. Very common on stainless steel fasteners if you are not careful.

 

[Stueeee]

M25x1.5 IIRC. I can get a die easy enough but that's not the point.

Metric conduit thread; so, quick and simple to fix.

 

[MattH]

I had this happen on a Chinese spindle routing wood. Throw it away and replaced it.

Clean threads, no dirt, just one day galled so badly the collet could not be removed.

I run three Chinese spindles daily for 7+ years and it’s happen once.

 

[Rrobson]

Looks like a poor choice of materials. how bad is the nut? Seems odd it hasn’t damaged the entire spindle thread, unless the nut isn’t too badly damaged?
This could be foreign material ingress into the threads, but it could also be they’ve used incompatible materials between the nut and the spindle and due to a lack of lubricant it’s allowed galling between the two.

 

[Dieselman 63]

I have a brand new set of Presto dies for that! If only you were in NZ you could have them!

 

[doubleboost]

If you strip the spindle out .
Chase the thread on a lathe .
(i would happily sort it out for you )

 

[Agroshield]

If you strip the spindle out...

Given that it is a multi-thousand rpm router spindle, a great deal of thought should be given to how it will be reassembled (i.e. what bearings it has in it, how they are preloaded, etc.) before pulling it apart.

If reassembly is difficult, an in-situ repair is much more preferable.

 

[mike os]

It doesn’t really do a lot, as long as the collet nut has a few turns over the damage I think it will be ok

 

[tom2207]

What was the spindle nut made from, out of interest?

Cheese