Mitutoyo magnetic base repair...

[tinman123]

i bought this a few weeks ago off the bay, its in mint condition with all the plastic the paperwork and the box but it has one flaw, it wont switch off fully.
it works as it should apart from that.
the little black knob will turn fully to the on postilion but when you go to turn it off the knob will only go about 2/3 of its travel before it hits something solid inside.
it dosent look like it was ever dropped or anything nor is there any force marks on the knob, it seems to have just failed.

like i say, it works ok but it id be fond of holding onto the swarf so id like to fix it if i could, thing is i cant see any way of getting into it without going through the knob and it comes across as something thats very fond of where it is.
i didnt like to pry it yet so i thought id ask here to see if anyone might be able to shed some light on it.

http://www.ebay.co.uk/itm/Mitutoyo-...r5%2Bew9jB5DcylGVPG8Q%3D&orig_cvip=true&rt=nc

 

[Turbo]

If you can't get it fixed I would suggest you keep in inside a small plastic bag like a sandwich bag. Makes it a lot easier to remove the accumulated swarf & iron filings.

BTW you got a good deal there!

 

[Pete.]

They couldn't be more simple. The switch is connected to a magnet inside which also turns. When you rotate it to 'ON' the magnet spans two magnetic pieces and the flux loop is completed by you setting it down on something magnetic so you get a pull. When you switch it to 'OFF' the magnet is turned to span across a pair of non-conducting pieces and the sides act as keepers. Why it doesn't fully turn is anyone's guess but you really should make it work or the magnet might suffer over time. Peel the front sticker, remove the screws and it'll come apart.

 

[slim_boy_fat]

As Pete says, it must be possible to investigate by dismantling. It wasn't grown organically, someone assembled it.

The only reason I can think of for not proceeding as outlined above, is if it is named Wall-E and starts shouting "No disassemble" at you.

For those who don't get the relevance of that, see here https://en.wikipedia.org/wiki/WALL-E

 

[Seadog]

Be careful when dis-assembling. The magnet will lose magnetism quickly if it's not slid into a keeper. You're then left with a weak magnet and the problem of re-magnetising it.

 

[Kram]

Does the round bar screw into the base? My cheap chinese one needed an additional washer. The thread was too long and blocking magnet.

 

[MattF]

There's an easy way to find out.

Pop the rod in the vice, (protected with some lead or copper sheet/strips etc.), and then try unscrewing it. Unless you go at it like an ape, you'll not risk damaging it, and if it doesn't want to unscrew with moderate pressure, just leave it be.

 

[Pete.]

As Pete says, it must be possible to investigate by dismantling. It wasn't grown organically, someone assembled it.

The only reason I can think of for not proceeding as outlined above, is if it is named Wall-E and starts shouting "No disassemble" at you.

For those who don't get the relevance of that, see here https://en.wikipedia.org/wiki/WALL-E

Actually, it was Johnny 5 who shouted 'No Disassemble"

 

[slim_boy_fat]

Actually, it was Johnny 5 who shouted 'No Disassemble"

I stand corrected , but I had the film correct at least - and it was clean and funny......

 

[tinman123]

If you can't get it fixed I would suggest you keep in inside a small plastic bag like a sandwich bag. Makes it a lot easier to remove the accumulated swarf & iron filings.
BTW you got a good deal there!

cheers hi.
the chinglish stuff would do a similar job but i do like a brand name, when i looked up a new one for a guide price i had to sit down, its a fair shot given its just a switchable magnet and a fairly basic design.
it would of been a steal if it had of been 100%, but thats e bay.

Be careful when dis-assembling. The magnet will lose magnetism quickly if it's not slid into a keeper. You're then left with a weak magnet and the problem of re-magnetising it.

enlighten me a bit more on that one if you wouldnt mind, a keeper you say?

They couldn't be more simple. The switch is connected to a magnet inside which also turns. When you rotate it to 'ON' the magnet spans two magnetic pieces and the flux loop is completed by you setting it down on something magnetic so you get a pull. When you switch it to 'OFF' the magnet is turned to span across a pair of non-conducting pieces and the sides act as keepers. Why it doesn't fully turn is anyone's guess but you really should make it work or the magnet might suffer over time. Peel the front sticker, remove the screws and it'll come apart.

if im honest i didnt give it too much time to see if anything is hidden thats holding it together, i was half afraid that they might of assembled it where it snapped together and if i went to pull it apart id snap it but not in the apart way.
ill study it a bit more when i get a chance to see, there probably is screws behind the face of it.
the bar will screw out iirc but i didnt get that far either.
some day i have a half an hour to spare ill give it another coat of looking on to see, cheers for the help so far lads.

mind you, i wonder what has happened inside when its such a simple affair.
sorry about the delay in replying to this, we had a new addition to the family last week so things are a bit all over the place at the moment.

 

[slim_boy_fat]

Johnny 5 was the star of the 1986 film 'short circuit', whereas wall-e was the main character in the 2008 disney animation 'WALL-E'...

Which film did you see again?

The original.

 

[slim_boy_fat]

(last o/t from me, promise )

So I take it you haven't seen wall-e then, otherwise you'd know the only similarity is the vague shape of the robot - it's not a remake, it's
an entirely different storyline (military robot given emotions by a lighting strike vs. waste handling robot that returns humanity to an earth considered dead).

That's right, the only one I was aware of was the original, which I saw. But I'm old and remember things from waaaay back.....

 

[Seadog]

enlighten me a bit more on that one if you wouldnt mind, a keeper you say?

Sorry for the late reply, I've been in Spain the last week. The magnetic alloy used is capable of being heavily magnetised but it needs to be maintained in a closed system. When the base is set 'off' the magnetic circuit runs through the body of the base, which provides a closed loop for the magnetic lines of force. When the base is 'on' and in contact with a steel or iron surface, the magnetic circuit goes through the base material which is what provides the 'adhesion' to that surface. You need to keep the magnet in a closed loop, otherwise the magnetic energy dissipates. The keep would need to be a steel or iron tube which is a close fit around the magnet, and ideally you'd want to slide the magnet from the stand base straight into the keeper for maximum effect, and vice versa when refitting.

 

[tinman123]

Sorry for the late reply, I've been in Spain the last week. The magnetic alloy used is capable of being heavily magnetised but it needs to be maintained in a closed system. When the base is set 'off' the magnetic circuit runs through the body of the base, which provides a closed loop for the magnetic lines of force. When the base is 'on' and in contact with a steel or iron surface, the magnetic circuit goes through the base material which is what provides the 'adhesion' to that surface. You need to keep the magnet in a closed loop, otherwise the magnetic energy dissipates. The keep would need to be a steel or iron tube which is a close fit around the magnet, and ideally you'd want to slide the magnet from the stand base straight into the keeper for maximum effect, and vice versa when refitting.

your quite alright.

thats a new one on me tbh, interesting tho.
i wouldnt of thought that the magnet would dissipate by just removing it from the housing, that fast at least.
i didnt get a chance to fiddle with it yet but when i find out how it comes apart you say the best thing to do with it is to slide it into a tube while its out.

 

[Seadog]

Just passing on my experience from stripping down an Eclipse magnetic base a few years ago and a seized Eclipse V block more recently. Good luck, Graham