Help! Crossthreaded ? My burr casing

[EspressoAdventurer]

I would recommend using a vacuum cleaner rather than compressed air, otherwise agree with everything else EA suggests...

Mal.

Bingo .....Thank you Mal !
And please everybody don't respond to this ...As Ive got No explanation ....
oh well too many offs on a MX track and maybe it wasn't such a great idea to take up masters afl as a later in life true blue qld'er who's never played afl before ...ke sara !
and yes I got panced more than once .....bloody Vics / SA's - no ethics even less morals don't mention the rules !

[Yelta]

Think it's pretty difficult to cross-thread the average grinder burr-carrier/body though, given how coarse and substantial the thread usually is. Anything is possible of course...

Mal.

Morning Mal, difficult but not impossible, some people even have the knack of being able to cross thread a UNC bolt, I know, I've worked with a few of them over the years.

[Dimal]

If you have access to an air compressor / air nozzle - blow out the grind chamber and collar.
Use safety glasses please!

I would recommend using a vacuum cleaner rather than compressed air, otherwise agree with everything else EA suggests...

Mal.

[Dimal]

an experienced tech who had it back to normal in no time at all using that method.

Yes, agree with the need to "chase" the thread if it appears to be damaged. Think it's pretty difficult to cross-thread the average grinder burr-carrier/body though, given how coarse and substantial the thread usually is. Anything is possible of course...

Mal.

[EspressoAdventurer]

I just bought a second hand grinder, got it home and pulled it apart to clean, (was absolutely filthy) all was going fine until I was putting it back together, got the burr casing all the way on and in the process of backing it off to set the stop screw and something bound up - not sure if a foreign object or if it somehow managed to crossthread itself?? Either seems implausible, but it has completely jammed up and I cannot move the top casing AT ALL  I am in tears, I don’t know what I have done wrong, I am devastated.

it is a K3 push 2013 model. All internals looked excellent when I had it apart.

Please do read the attached thread(s) that CL posted. And as Caffienator said this collars / grind body threads are bound up with gunk.
Id suggest you need to turn the collar back in the other direction - Yes I know you want to get it off!
But once moving Then continue to turn in ever increasing circles - never more than the free turning / oops its binding up again tension - tells you. Back and forth to free up the threads from the gunk (still) in there.
I.E. 1/3 of a turn then maybe a 1/2 turn etc each way back and forth. Ever increasing.
With the aim to move more and more progresively towards the Gross / Courser direction which will get the collar fully unwound. Eventually!
These threads Are very very fine therefore the angle of the thread walls are steep And hang on to virtually everything. Thats why they can and do gunk up when for instance turn back in the other direction as happened to you. The back and forth motion allows the threads to naturally clean themselves or disperse the gunk more evenly.

As it frees up more and more Keep to the same routine. DO Not try to spin it off in the one direction In One go. As it could bind up again.

Once removed re- clean the threads on both components.
I use a small thumbnail brass wire brush that is very fine. It doesnt damage the threads.
Or get yourself 2 x 1inch paint brushes. Cut the bristles on one down by half for a stiff cleaning brush.
Finally wipe with a fine cloth as youll get a lot of black grey film of the threads which is the fine metal galling referred to above. Check the threads fully on both. D

Don't lose the tension springs out of the grind body!
If you have access to an air compressor / air nozzle - blow out the grind chamber and collar.
Use safety glasses please!

Good Luck.
Ps I'd also suggest to replace the burrs whilst the collar is off - Unless you are very certain of the throughput with these burrs.
Also clean out the grind chamber every 4-6mths at the outside. As accumulated coffee fines leach there retained oils over time and turn into a coffee version of Mechanics Grind Paste.

[CafeLotta]

Similar situation was discussed here - https://coffeesnobs.com.au/grinders/...compak-k3.html

I still firmly believe people just don't use enough lube and "feel" on reassembly with the early K3s. Doesn't really help once they're stuck though.

The suggestions of using a Penetrating oil that will wick down the threads is probably your best bet if tackling this yourself. You may need to do this over a couple (few) days before it wicks it's way down. You may get lucky. The other choice is to take it to someone like The Coffee Machinist as mentioned in the link above.

[Trixitrine]

Thankyou all so much. At the moment I cannot even access the threads, so will tackle that if I get there....

I considered more force as in a vice maybe but not sure if I would do more damage, regardless I don’t have access to one. A strap wrench I do have.... I could try that. Really depends on the cause of the jam; if it’s a thread galling issue more force might be fatal for it, if it’s a grain of coffee, potentially that would be ok....

[level3ninja]

You could try a strap wrench to loosen the upper carrier

[Gavisconi007]

Using a short handled ~9.0mm artist brush is what I use and it gets right into the thread valleys without problem.
The dry Teflon based lubes use a solvent carrier that evaporates very quickly, and leaves the lube behind...

Mal.

Hi Mal- I believe a pointed metal instrument may be more suitable in case the threads have been crossed. Running the point through the original threads could help to reinstate the original running lines if the cross threading is not too bad. That’s what I read on another forum anyway where some guy had thought his grinder was not salvageable and he took it to an experienced tech who had it back to normal in no time at all using that method.

[Gavisconi007]

i absolutely can’t get it out/move it at all :-( it bound up very suddenly and firmly. I tried to go back and forth when I felt it grab, to no avail. Thankyou for your detailed answer, and if I can get it out trying the penetrol suggested, I will then examine the thread

Have you tried using a vise? I would try that, using cloth on the vise jaws to prevent abrasion.

[Dimal]

Using a short handled ~9.0mm artist brush is what I use and it gets right into the thread valleys without problem.
The dry Teflon based lubes use a solvent carrier that evaporates very quickly, and leaves the lube behind...

Mal.

[TampIt]

Preferably, I would use a dry Teflon based lubricant rather than a wet one. At a pinch, you could also use Graphite Powder available from most hardware stores (which is used as a dry lube for locking mechanisms of all types)....

Mal.

Usually I would agree, however the fine thread on most grinder burrs is too fine for the dry stuff to get in (even dry Lithium paste usually does not penetrate in far enough), so they do not often work in that situation. The OP use of the word "jammed" usually requires Penetrene. Cleaning up any extra "wet stuff" is pretty easy given her 40 minutes to clean it out so far... She sounds very thorough, if a bit unlucky. Happy to be proven wrong, as I do not know that particular grinder at all.

TampIt

[Dimal]

Preferably, I would use a dry Teflon based lubricant rather than a wet one. At a pinch, you could also use Graphite Powder available from most hardware stores (which is used as a dry lube for locking mechanisms of all types)....

Mal.

[Otago]

Penetrene not penetrol

[Trixitrine]

What I would do is the following:

If you can wind it back out and off then do so.

Then get a fine pointed instrument (a variety pack of picks, pokers, and hooks can be bought cheaply at Bunnings) and a magnifying glass. Clean out all threads one by one. Apply food grade grease to both sets of threads. Look for the thread feed in point with the magnifying glass- slowly move the other thread into it, rotating back and forth as you go. If you feel any resistance back it out immediately. Keep proceeding rotating back and forth. This is likely to re-cut in the original threads and you should be back in business.

i absolutely can’t get it out/move it at all :-( it bound up very suddenly and firmly. I tried to go back and forth when I felt it grab, to no avail. Thankyou for your detailed answer, and if I can get it out trying the penetrol suggested, I will then examine the thread