Dc Gear Motor failure

Sandpaper or steel wool?

Sharp knife (scalpel etc.), followed by previous suggestions for getting the remaining bits off. Lots of time & care.

"Fine jets of hot, concentrated inorganic nitric or sulfuric acid are used to remove epoxy packaging from ICs ..." - this is from a google hit. I don't know about you, but I'd rather not go there.

I have used a high speed die grinder, with Scotch Brite type pads, 2"diameter. Very controlled material removal.

Acetone is the first chemistry I reach for when I need to soften epoxy.

The last time I used it was to free precision optics that had been glued in place with epoxy. Repeated soaking with acetone over a period of a few day was all that was needed.

35 years of working with a wide variety of composites, epoxies and resin system is how I found out.

L.J.

Google " Attack Epoxy Remover " I have used this stuff before and it works well and costs less than $15.

Ed

Hi,

if you add to the above mentioned acetone some of the not so usual solvents (all these evaporating fast except NMP:

methyl-chloride (MC)

form-amide

dimethyl-formamide (DMF)

dimethyl-sulfoxide (DMSO)

tetra-hydro-furane (THF)

n-methyl-pyrrolidone (NMP)

and some more to be searched.

Be cautious, all are toxic (acetone and other ketones too), some will go through skin without doing harm if pure and clean but will transport any chemical impurities into you and maybe poison you by this way.

RHABE

All these work better in combination than as a single solvent.

All these will only soften the epoxy, mechanical removal is then necessary.

Prevent any corroding iron be near SmCo magnets, the hydrogen will kill the magnets.

RHABE wrote:

"Be cautious, all are toxic (acetone and other ketones too), some will go through skin without doing harm if pure and clean but will transport any chemical impurities into you and maybe poison you by this way."

That is a valid and very important caveat. Given my experience it's one I should have included but forgot.

Protective gloves are important and, given the absorption potential, they'd better be better than latex.

Thank you!

L. J.

I would stay away from the nmp. If you don't get is 100% cleaned off, the residue will attack any copper it comes in contact with. NMP is a very aggressive solvent for a wide variety of materials. It is difficult to clean off 100%. It has eventually dissolved every type of glove material I tried it with.

I agree totally,

"total" evaporation requires temperatures at or above 160°C for hours!

RHABE

Unless you just like to play around with such things, don't believe you can reliably reassemble these magnets into the motor housing. Even if you can remove the adhesive (which is probably acryllic not epoxy) from the magnets and housing, what will you do next? Magnetized magnets are very difficult to work with, and the probability of your finding the right adhesive and properly positioning the magnets is very low. But have fun. I would contact the motor mfrr. Magnets should not come loose, unless the motor is severely mistreated. Maybe you will get a free replacement, even if the warranty has expired. If this fails, buy a new motor from another mfrr. biloby

Have already purchased the replacement. Was looking to repair this motor and store as back up. The motor has been spec out by the equipment manufacture so they are the only source. Comes as an assembly about a third of the cost of the piece of equipment its on. All ready checked the motor manufacture they offer nothing that comes close. Modifications have been made in hp and output shaft length, diameter and gear reducer ratio. Been in service 4 years well out of warranty. The magnets which there are two pieces to a side. Are not the same size where not perfectly aligned in the tube with the old adhesive marks as markers can get them back in the spot they came out of. Any adhesive that I choose time will tell if it has worked better than what they used. There are plenty around to choose from. Motor was in a enclosed box that has its amp board all in great condition so there is no mistreatment of the motor.

I would like to think that my ability to repair a simple motor is more than you have given me credit for.

Ozzb,

Go with the "Attack epoxy remover" - it is commercially available and contains a blend of solvents. You will find it just about impossible to obtain some of the unusual solvents that have been mentioned here in small quantities. I won't even get into some of the hazards and safety issues. IMHO re-bonding field magnets in the shell won't be as difficult as others think - this is not a super precision job. You may want to use a little heat to cure the epoxy after you re glue it - 30 minutes or so at 140 F should do it. You can use a heat lamp ot some type of small oven. Good luck. Ed