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View Full Version : Mag Base: Grip Strength Restoration / Enhancement



EddyCurr
11-11-2015, 03:14 PM
I have several magnetic bases for dial indicators and such.
Some appear to have diminished gripping strength when
the magnet is engaged.

I am interested in hearing from folks who have successfully
restored or even enhanced the grip strength or holding power
of a magnetic base. Has anyone taken up manufacturers on
their offer to remagnetize a base? Does anyone have steps
that they have employed on their own?

.

becksmachine
11-12-2015, 12:09 AM
Maybe it hasn't been here long enough, but the lack of replies makes me wonder if anyone has ever been able to do that.

I know I have never been able to, I can't even take one apart and put it back together without diminishing the magnetic holding power.

Dave

Kiwi
11-12-2015, 12:13 AM
Yep mines getting that way too

Paul Alciatore
11-12-2015, 12:39 AM
They have a simple mechanism. I wonder if the handles may have moved on the shaft to a different position so the magnet does not align properly. Perhaps removing the handle and setting them for maximum holding strength before reinstalling the handle would help.

darryl
11-12-2015, 01:52 AM
I wonder what kind of magnets are in them- ferrite I would assume. Much has been said about them losing their strength when they aren't in a closed magnetic loop. The traditional 'closed loop' is the keeper on a U shaped magnet. Maybe there's a built-in feature to do this, possibly part of the release mechanism- I don't know- but possibly they should be kept on a steel plate when not in use as a magnetic chuck. I'll have to check into this to satisfy my own curiosity.

If you can define the norths and souths, you could possibly restore some of the strength by using a neodymium magnet with suitable pole pieces to match.

RichR
11-12-2015, 02:06 AM
Many years ago I worked for a company that made small motors (possibly servos). The rotors were magnetized in a special
machine. Once magnetized, they were slid from the machine straight into a steel ring called a keeper. From the keeper it was slid
straight into the housing. My understanding is that if the rotors were not kept surrounded by steel at all times they lost some of
their magnetic strength. I don't know what's inside a magnetic base, but it's something to keep in mind if you're thinking about
disassembling one.

macona
11-12-2015, 03:32 AM
The couple I have seen apart appear to be an alinco type magnet. These things are really not designed to come apart, they are held together with blind pins. When "off" the housing acts as the keeper for the magnets. Don't leave them "on" and not on a steel plate.

You might be able to remagnetize them with something like what they used to use on magnetos, but frankly you could buy a whole munch of cheap mag bases for that price.

interiorpainter
11-12-2015, 04:26 AM
Scrape the base. Once flat they hold again. Scraping steel not nice.

Peter.
11-12-2015, 04:57 AM
Seems to me if someone called EddyCurr can't re-magnetise one then probably no-one can :)

Zahnrad Kopf
11-12-2015, 01:17 PM
Seems to me if someone called EddyCurr can't re-magnetise one then probably no-one can :)

Hahaha! Well played, Sir. :)

Paul Alciatore
11-12-2015, 02:15 PM
Yes, they do have a KEEPER feature. Here is an article that explains how they work. The author may have been tripping over ON and OFF at one point in the text but the drawings show the idea quite well.

https://en.wikipedia.org/wiki/Magnetic_base

And it is easy to see that if the knob is put on incorrectly then the operation may not be correct. Do check the position of the knob if yours does not work properly. I would be sure to do that before any attempt to re-magnetize them.




The couple I have seen apart appear to be an alinco type magnet. These things are really not designed to come apart, they are held together with blind pins. When "off" the housing acts as the keeper for the magnets. Don't leave them "on" and not on a steel plate.

You might be able to remagnetize them with something like what they used to use on magnetos, but frankly you could buy a whole munch of cheap mag bases for that price.

J Tiers
11-12-2015, 07:09 PM
It's no mystery how they get de-magnetised....... Sticking them to thinner material, rough material that produces a larger air gap, sticking them to a round thing using the V-groove at the bottom (makes a bigger gap)etc. All things that happen as a matter of course when using the bases.

When they don't stick, your choice is to re-magnetise, or to get another. One's easier, and probably cheaper than the other.

vpt
11-12-2015, 07:54 PM
I took mine apart, cleaned it, lubed, and reassembled seemingly without a problem?

Mcostello
11-12-2015, 08:40 PM
I have heard that some lawn mower repair shops used to remagnetize lawn mower flywheels, never needed to call one. Or try a welder or motor repair shop.

10KPete
11-12-2015, 11:06 PM
I took mine apart, cleaned it, lubed, and reassembled seemingly without a problem?

Andy, please give us some more details about the base (make, age, etc.) and how you disassembled it. I've never done
this and am really curious to know. The knob on one of mine is getting a bit sticky and I want to do just what you did.
Your post is very timely!!

Pete

vpt
11-13-2015, 07:41 AM
Andy, please give us some more details about the base (make, age, etc.) and how you disassembled it. I've never done
this and am really curious to know. The knob on one of mine is getting a bit sticky and I want to do just what you did.
Your post is very timely!!

Pete


It was like a million years ago. It was a mag base I believe came with my lathe when I got it and I believe I tore it down at that time as well. I will have to look at it to get a name off of it.

I believe there was just a single "set screw" that needed to be taken out and the magnet could be then pulled/slid strait out the front. Mine needed a pair of pliers to turn and is why I took it apart. So it didn't exactly just "slide out", I had to use the pliers to turn and twist the magnet while pulling to get it out.

I don't think I took any pics of it either, if I did they are on my old puter. I will dig it out today and check for the name and maybe snap a pic. Hell might even pull the screw and slide the magnet out for a pic.

George Seal
11-13-2015, 09:00 AM
Andy
You are a Gentleman and scholar and their are darn few of us left

Juiceclone
11-13-2015, 09:21 AM
depending if its possible, you can replace/modify the magnet/s with the newest neodymium mags. much stronger. u cant drill or form them, but they are available (eBeast) in a lot of sizes/shapes. making a steel piece to the dims of the original magnet, and then drilling it to accept a stack? of the neo mags might be a way to go? I've been looking at this to restore vintage m/c alternator rotor.

10KPete
11-13-2015, 10:00 AM
Andy, that's wonderful. There's no need to do anything special, please don't go to any trouble for this. I just thought
the disassembly might have been done recently. I'll take a close look at mine, which I haven't done yet, and see if
the answer is obvious. It may well be!

Thanks,
Pete

damianpoirier
11-13-2015, 10:33 AM
If these are designed similar to magnetic chucks, then you would not be able to "just remagnitize" it. The magnetic chucks have alternating strips of magnets with (i believe) non-ferrous material between each strip. If that's the case, then trying to remagnitize it would probably make it worse. If it's a single neodibnium and you can free it from the housing, then by all means give it a try.

Glug
11-13-2015, 11:10 AM
Here's a post I made on this topic a while back. I think I mostly said it there - thin and flimsy plastic cage. The cage is thin so the magnet can be close to the enclosure without actually touching. Once the cage is broken, repair is tricky. You could clear out the broken bits and grease it up - the outcome from that was a good improvement. Given the price of the cheap bases, and the fact that the magnet was never especially strong, I was able to resist the urge to 'fix it right'.

My noga base has a 175 lbs magnet and the knob turns almost effortlessly. I'd guess their magnet must rotate on a bearing.


On mine, the magnet is held in a very flimsy, thin plastic cage. That cage is subject to damage. Then the broken pieces will bind up. Without the cage, the magnet contacts the enclosure, making it hard to turn. You can clean it out and lube it, and that will make it usable.

If you want these to last, be gentle with the knob, maybe add some lube, and sacrifice a small chicken.

Apparently those magnets will lose their power if the halves are separated. So avoid that.

The metal faceplate on mine hid a couple of screws that retained the plastic faceplate and knob.

vpt
11-13-2015, 11:33 AM
I took some pics. It is a Browne and Sharp mag base. I must say I don't know how this mag base performed when new compared to when I got it. Because it was sticky when I got it the turn knob spun on the shaft obvious of the marks left by the set screw on the shaft. And I wasn't able to get it to hold well when I first got it and played with it. After the disassembly, cleaning, and resetting it works again but I have no idea if it works as well as it should/has. So take it for what it is worth.

The set screw is in the bottom/side of the turn knob. Once you loosen the set screw the knob should come off the shaft. Once the knob is off the magnet can be pushed out the back of the base. There is a pin in the base that stops the magnet from coming forward and is used to limit the turning to on and off.

http://i.imgur.com/jfggKw2.jpg

http://i.imgur.com/x39oFGr.jpg

http://i.imgur.com/31gd9Rq.jpg

The mark of the original set screw placing. When putting the knob back on I line the set screw up with this mark obviously but when tightening down the set screw I will lightly turn the knob back and forth while turning the set screw to feel for "its spot". The cut out area on the backside of the knob is what limits the turning from on to off on the pin in the base. If you turn the magnet in the base without the knob attached you can feel the magnets "pull" to both the sines and the base where the on and off positions would be. Would be a good idea to check this if you feel your knob ever slipped.

http://i.imgur.com/5iS7FYR.jpg

vpt
11-13-2015, 11:37 AM
After pics and putting it back together again I dug around till I found the biggest piece of metal the magnet would lift. This is 1" thick, about 8-9x12ish" with a couple chunks cut out. Guestimate around 15-18 poundsish. It took me a couple attempts to lift this piece because of me twisting my wrist just a tad. I had to do a perfect strait lift so this piece is right at its limit now. It was threw the millscale for what it is worth. I just cleaned the area so it was flat and clean, millscale left behind.

http://i.imgur.com/QDlOMJv.jpg

mars-red
11-13-2015, 01:16 PM
Scrape the base. Once flat they hold again. Scraping steel not nice.

I'll second that. Mine is one of the cheap Chinese ones (probably about 12 years old), I used it as-is for a long time, then finally got motivated to scrape it flat after needing to mount it on a vertical surface. It felt like it had become weaker over time, but after scraping it felt better than new. It'll stay wherever I put it now. The base on mine is iron so it scraped really well.

EddyCurr
11-14-2015, 01:11 PM
Thank you for the replies.

By way of example. Amongst my collection of mag bases are
three vintage Eclipse 903. Their contempory equivalents
are the Eclipse 903CP and these are described as having
a load capacity of 66 lbs. I do not know how load capacity
is determined, but I would estimate that my 903's might be
capable of lifting/holding perhaps 20 lbs.


http://www.slalom4me.com//imaged_a01/jpg/other/tools/Instruments/2015.11.14_EclipseMagBase_01.jpg

The pole orientation of push-button style magnetic bases is
at the front and back of the devices. The north end of a
compass needle points to the back face of a 903 mag base,
denoting that side is the south pole (opposites attract).
The front or face plate side is the north pole. As an aside,
mag bases with rotary knobs have their poles situated on the
left & right sides of the base.

I am confident that my 903 bases are of an age such that
their magnetic strength is not derived from one of the modern
wonder materials. As such, while they are subject to losing
their magnetic strength, they are also likely to be able to
have their flux strength restored by contact with a strong
magnetic field while assembled.

There are commercial magnetizers and shop-built magnetizers.

I have been making enquiries locally amongst companies that
service auto/aviation/industrial magneto, ignition and charging
equipment. Someone may have a magnetizer like Allen Equipment's
E-161 or its modern-day equivalent. The following Allen E-161
manual is informative


Allen Equipment E-161 Magnetizer (http://www.jd2cylservice.com/Misc15AllenE-161Magnetizer.pdf)
Courtesy: Nancy Larson, in memory of Duane Larson

My other options are to contact Eclipse here in Canada, look
to magneto repair firms like Joe Hunt in California or to build
my own magnetizer, either battery or mains powered along the
outlines provided in the following references:

Dave Gingery's book "How to Build a Magneto Magnetizer" (http://gingerybookstore.com/MagnetoMagnetizer.html)
Peter Rooke's article Design Your Own Magnet Charger: Pt 1 (http://www.gasenginemagazine.com/equipment/make-your-own-magnet-charger.aspx)
in Gasoline Engine Magazine (2009.09)
Peter Rooke's article Make Your Own Magnet Charger: Pt 2 (http://www.gasenginemagazine.com/gas-engines/make-your-own-magnet-charger-part-2.aspx)
in Gasoline Engine Magazine (2010.01)
Joseph J. Stupak Jr.s presentation
Methods of Magnetizing Permanent Magnets (oersted.com/magnetizing.pdf)
Courtesy Orested (2000.10.01)
There are numerous other resources with varying levels of
complexity available for the searching.

.

EddyCurr
11-14-2015, 01:22 PM
It's no mystery how they get de-magnetised.......
Sticking them to thinner material, rough material that produces
a larger air gap, sticking them to a round thing using the V-groove
at the bottom (makes a bigger gap)etc. All things that happen as
a matter of course when using the bases.Not to mention the effects of being dropped or struck.
Likewise, but perhaps less common for instrument mag bases,
getting hot.

I am curious whether anyone has any links to manufacturer's
information about mag base "Do/Don'ts". Particularly w/
respect to storage (proximity to metal &/or other mag bases;
On or Off; & ect ...) I have more than one base I purchased
new and do not recall ever seeing any Thall Shalt Not's either
in product literature or in the many publications I have read
oveer the years.

.

vpt
11-15-2015, 02:45 PM
Mine sits here, all the time, in the off position.

http://i.imgur.com/GcxAqg4.jpg