Elektra Nino Grinder - Burr Carrier Sticking - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
cdrake39

Postby cdrake39 » May 09, 2019, 9:35 am

civ wrote:
Teflon tape will reduce the resistance in the threads significantly and also avoid the metal to metal contact that is generating the residue you found.
This has probably happened because threre have been very few full threading/unthreading operations and very little cleaning up since it was purchased.

CIV


I cleaned the threads with a toothbrush and a microfiber cloth and some rubbing alcohol, being very careful not to get any fibers in the threads. Once I was happy with the cleanliness of the threads I put one turn of teflon tape around the upper burr carrier thread. Unfortunately I still have the same issue, tight adjustment even within the first couple revolutions. I removed the burr carrier and there were small metal filings on the teflon tape. Not quite sure what the issue is at this point...

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civ

Postby civ » May 15, 2019, 8:10 am

Hello:
cdrake39 wrote: ... in the forum but it looks like it got buried.

The HB sever has been with some sort of issue all day yesterday, maybe from early on.
But Dan always gets it right and here we are again. =-)

cdrake39 wrote: ... still have the same issue, tight adjustment even within the first couple revolutions.
... removed the burr carrier ... ... small metal filings on the teflon tape.

OK.
Let's (re)start from the beginning:

1.
IIRC, your grinder is not 'out of the box' new but sold with to you in a 'lightly used' condition.
2.
You noticed the issue at hand when you first started using it, before even taking it apart ie: unscrewing the upper carrier assembly for the first time.

Is this right?
If so, I think we can safely assume that you may have not caused whatever is going on.

The filings are a sign that the threads, which should be matching perfectly within acceptable tolerances, may not be matching.

To illustrate the idea:
I have come across situations where I had a very short threaded hole or a nut but no matching screw (always small diameters), usually in stuff where a quick and dirty solution could be (reluctantly) accepted, even by me. =-)

So I find a part that is close (I have a huge collection) and just slowly force it.
Most (not all) times I manage to get the fastening done and that's it.

The result: metal shavings like what you describe.

Off the top of my head and with just a latte on me this morning, I would say that one of two things (maybe both) could be happening here: the threads are slightly crossed at a some point or there's an OEM issue to be dealt with.

While I cannot rule out a manufacturing issue (you should see my Cimbali Junior Max) the usual suspect is an unexperienced user crossing the threads when assembling/reassembling the grinder.

Please don't ask me how I know about that.

Usually this type of thing happens near the start of the threads ie: if they have not been crossed at the start and 20/25% of the thread has gone in properly, it's very difficult they will cross further on as both parts are already on the same axis.

Let's try this:

Please inspect very closely (w/magnifying glass, jeweller's loupe) the upper carrier threads.
Look for anything that would indicate a non- continuous thread path, however slight.

Then run a fingernail slowly along the thread from the end to the start as you turn the part and see if your fingernail gets caught somewhere along the thread path.

Find anything?
If so, please take a photo and post it here.

Next, get yourself a permanent ink marker (unless you have layout ink) like those Pilot brand jumbo or Sharpies, any dark colour.

After thoroughly cleaning both parts (again) with alcohol and wiping/letting dry well, paint the threads on both parts.
The thread on the grinder will be harder, just have patience. make sure then ink gets in the thread 'valleys'.
No need to cover the whole length of the thread, I'd say that just 1" will do OK.

Done that, wait for the dye to dry.

Now comes the reassembly:

Before starting to turn the upper carrier to screw it in (in whatever direction it has to go which I expect is clockwise) slowly turn it in the opposite direction so as to get a feel of where the threads start to match. ie: start of upper carrier thread catches with start of lower thread.

Done that, slowly start turning the upper carrier till it starts to get stiff and without forcing it too much, insist a bit more (always by hand).

Stop, take a deep breath =-) and slowly unscrew it.

The ink you laid on the threads should have given way to bare metal wherever the threads are touching more than they should.
Those bare metal points are where the problem is.

Please post photos of the results, both the upper carrier and grinding chamber threads.

Cheers,

CIV

cdrake39

Postby cdrake39 » May 15, 2019, 12:18 pm

civ wrote:The ink you laid on the threads should have given way to bare metal wherever the threads are touching more than they should.
Those bare metal points are where the problem is.


CIV


Thanks Civ, I'll try this today after work and report back. Assuming this is the issue and there are areas where the threads are touching more than they should, what are my options for fixing it? Would a thread repair file do the trick?

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civ

Postby civ » May 15, 2019, 1:55 pm

Hello:
cdrake39 wrote:Thanks Civ ...

You're welcome.

cdrake39 wrote:... try this today after work and report back.

Heed my words: Patience and Prudence are your best of friends. =-)

cdrake39 wrote:Assuming this is the issue ...

Let's wait and see what's up with this.
Maybe it is just a small nick causing problems.

cdrake39 wrote:... a thread repair file do the trick?

Hmmm ...
The trick could well end up being a ruined Elektra Nino.

Let's wait and see what you find doing what I have suggested.
Good photos are essential.
We'll take it from there.

Important:
- Take your time to inspect the threads with a good quality loupe/magnifying glass under bright light.
- Same with the fingernail trick.
- The threads must be squeaky clean ie: free from oils or the marker paint will not adhere and then won't do it's job properly.
- The marker paint must also cover the inside channels (valleys) of the thread.

Cheers,

CIV

cdrake39

Postby cdrake39 » May 15, 2019, 2:52 pm

civ wrote:
Let's wait and see what's up with this.
Maybe it is just a small nick causing problems.

CIV


So I had time on my lunch break to head home and get some pictures (I'll do the cleaning and marker this evening when I have more time to do a detailed job with it). I did notice some small nicks on the bottom of the upper carrier. Could these be the culprit?

Image

Edit- I had another look this evening (started cleaning and marking but wasn't able to finish it due to other time commitments) but I did notice a very small raised edge on the thread when running my fingernail around it. It looks like the carrier may have been dropped (theres an indentation on the bottom side of the thread) which caused a raised edge on the opposing side. The picture makes it look larger than in reality. But I suppose it's possible that this could misalign things just enough to create the issue.. I've attached a pic below

Image

User avatar
civ

Postby civ » May 15, 2019, 10:52 pm

Hello:
cdrake39 wrote:Could these be the culprit?

Could very well be, they are at the start of the threads.

In any case, those nicks should not be there.
The test with the marker ink will tell us more. ie: where the threads are rubbing and creating metallic bits.

cdrake39 wrote:... looks like the carrier may have been dropped ...

Now that I see a photo of the upper carrier, I suggest that the test be carried out without the burr attached to it.
This will make it lighter for you to handle and much easier to see what's going on as you thread it in.

Just to be neat, before you take off the burr, make a mark on it in relation to the carrier so as to be able to put it in place again with the same orientation.
ie: hole 1 with hole 1 and so on.

Cheers,

CIV

cdrake39

Postby cdrake39 » May 16, 2019, 11:27 am

civ wrote:The test with the marker ink will tell us more. ie: where the threads are rubbing and creating metallic bits.



I've attached some pictures of the marker test. I was unfortunately unable to remove the upper burr (didn't have the right size Allen key). It may be a little difficult to decipher anything from the photos. It does look as though the bare metal gets exposed just before that bump in the thread in my previous post..

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ira
Supporter ♡

Postby ira » May 16, 2019, 1:44 pm

The nick does not belong there and filing it off will have no effect on the operation of the grinder. You should remove it no matter what.

Ira

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civ

Postby civ » May 16, 2019, 2:12 pm

Hello:
cdrake39 wrote:... attached some pictures of the marker test.
... unable to remove the upper burr
... a little difficult to decipher anything ...
... gets exposed just before that bump ...

OK.

1. what did your visual (pre-paint) inspection of the threads in the grinding chamber show?
2. when you ran your fingernail along those threads, did you notice/feel anyhing strange eg: a crooked thread path, something sharp sticking out?

If not, I'd have to say that the problem is in the marks you have seen in the carrier threads.

Here's a generic illustration of how threads fit in between them:

Image
Image courtesy of researchgate.net

See how the internal threads fit into the external threads?

A protruding 'bump' in the mating (inclined) surfaces of either internal or external threads will be a problem.
And will produce damage (in this case some filings) in the receiving threads, in this case the chamber threads.

Of course, the severity of the problem will depend on the tolerances but in a thread set like the one we are talking about it is severe.

The fortunate thing about this is that if the chamber threads don't have any issues, you will be able to fix this without having to take the whole grinder apart.

But you'll have to find a machine shop with a lathe and a qualified operator to fix it.
It's just a question of setting the carrier on the lathe and running through the threads (at the proper settings) to rectify them with a tool.
I'd say no more than 15/20' work, but that's not a given.

I would not recommend any other course of action unless you are highly qualified and experienced in using hand tools.
eg: any experience in small die manufacturing?

But then, it is not my grinder. =-)

Hope you get it sorted out, should not cost you too much.
Certainly much less than a new upper carrier.

Please post if you have any questions.

Cheers,

CIV

ira
Supporter ♡

Postby ira » May 16, 2019, 3:17 pm

It's a tiny bump on a giant thread. it needs to be removed, how perfectly is irrelevant as long as all you do is remove the bump and maybe some of the thread it's on. As long as you don't create another bump, you're golden. Setting it up in a lathe to chase the threads requires precision beyond what many machine shops are capable of, especially since you can't tell them where to index off of to find the original axis. A minute or less with a new very fine nail file or a piece of 320 grit sandpaper folded across a knife blade should solve the problem. It's 1/16 inch in 20 feet of thread.

Ira