Thread: Elu 177 stuck top bearing.

G'day Grant and welcome to the forums - sorry I can't help ypu but I'm sure this bloke can - should he not pick up on the thread send him a PM.

https://www.woodworkforums.com/members/10036-damienhazo/

Regards,
Bob

Thanks for the welcome and info. I shall contact Damien. Hopefully I can contribute meanfully to the forums in some way.

Alu expands about 3 times the rate steel does...well near enough
The gearing is steel the housing in Ali. stick the whole thing in the oven for about hr and hr on about 80 should do it and the bearing should fall out.
I do mean only the housing holding the bearing not the router.

Hi Grant,

it's been a long time since i took a 177 apart, but if my memory serves me correctly, i think you've done everything right and there should be no obstacle left after removing the circlip from the axle.

I have far more experience with the older Elu router series and i have encountered several occasion of stuck axles in top bearings, in most cases because of severe bearing overheating. Top bearings in routers are known to suffer from soiling and dust penetration, because they are in the middle of the motor cooling airstream, which is sucked inside through the motor housing's top louvre slits. These bearings are known to run hot and fail much sooner than the bottom bearings.

As a rule, the large bottom bearings are enclosed in the cast aluminium bottom shield and the armature is mounted through pressure on the bearing's inner ring, until the armature arbour seats properly against the inner ring. In the case of Elu, a dust labyrinth ring in screwed on the threaded section of the arbour just in front of the inner ring. In this way the arbour is truly locked without any axial play.

During mounting of the motor housing onto the fan side shield, the necessary axial margin usually comes from the smaller bearing. In many motor housings the smaller bearing on the armature's commutator side is already mounted on the axle when the entire array is shoved into the motor housing. The small bearing's outer ring slides in the mounting until the motor housing seats against the shield. In most cases there is not a great deal of pressing force involved while achieving this, meaning that there is the tiniest amount of play between the mounting and the outer ring and a real tight fit would mean considerable pressing force. This tiny amount of play is good enough for the motors in circular saws, grinders and drills, since the motor arbour in such machines is not the actual "work" arbour and only has to copy with typical gear forces. The saw blade arbour, the grinding disc arbour or the drill spindle are the actual work arbours who have to bear the brunt of really complex and intense forces.
Eugen Lutz thought it better to minimalise play in the mounting of the top bearing, since a router motor's arbour is also its "work" arbour and any amount of play has an adverse influence on routing precision. So, like the bottom bearing, the top bearing was also to be secured inside the motor housing first and the motor housing was to be pressed into position through pressure on the top bearing's inner ring, just enough until the upper motor housing part fit snugly against the bottom shield. This way of putting the motor together was the secret of proper and longlived Elu bearing practice, including minimal friction running from the beginning and a very good routing precision. Putting pressure on the top bearing's inner ring meant that the inner ring had to be accessible from the outside, meaning that the top bearing was to be inserted from the outside instead of from the inside. In vintage Elu's, the top bearing's circlip secured the bearing's outer ring. In newer Elu's, the circlip rests in a groove in the axle; this solution was chosen because it was cheaper (easy to turn on a lathe and a smaller and lower-cost circlip is needed).

Anyway, with a vintage generation Elu you should be able to pull out the armature axle from the top bearing's inner ring without obstructions in the way, and with the newer generations like your 177 you should merely need to remove the circlip from the axle to succeed. Loctite is not used by the factory, so if the axle doesn't budge it is stuck to the inner ring for sure, and almost certainly because of bearing overheating. Top bearings in routers are vulnerable because they are in the middle of the dust laden motor cooling airstream, which is drawn in through the motor housing's upper louvre slits. These bearings are known to fail much soonner then the bigger bottom ones, because of soiling, lubricant being sucked out by dustcake and penetrating dust through the seals. I've seen axles and bearing parts run blue because of heat, and bearing rings having run so hot that the surrounding housing nylon was deformed or partly molten. So the axle may have bonded a bit inside the inner ring.

Use drops of WD40 to penetrate between the surfaces (take care that WD40 does not drip along the copper windings or the commutator) an repeat this treatment with a tiny drop every day, for a week or so. Than use a pulley jack (is that the right name? it's a thing with two or three claws and a screw to exert force on the axle's top), but do it gently. I once cracked the entire mounting's bottom seat ring open when exerting too much force with the jack, rendering the entire upper motor housing part useless.

Study exploded drawings of the DeWalt DW625 first (it's synonimous to the MOF177) and yes, do ask Damien also. Because i'm not a perfect 100% sure.

Success

gerhard

Hi again,

in your mail to Damien i saw that your 177 was a 177E, which means that there is an electonic module on top, which has to be removed first. From memory i think the tacho magnet in the 177E was mounted close to the commutator, under the top bearing instead of above it, which is the case with the 96E. If i'm correct, the ring magnet is not in the way when pulling out the arbour from the top bearing; after removing the circlip there is no obstruction in the 177E either. When using a pulley jack though, take care when positioning the claws underneath the bearing mounting. The ring magnet is probably a bit in the way and is easily chipped off, crushed or broken, after which it is useless for proper rpm control and must be replaced.

success

gerhard.

Thank you all for the assistance. The bearing is indeed a tight press fit but I was able to finally dislodge it with the aid of penetrating oil over some days and the cautious use of a two armed pulley attached to the underside of the upper bearing seat. The 4 cone spring washers under the bearing had acted as shock absorbers to my earlier efforts. Once they were compressed, it removed without much difficulty. Bearings replaced and all working beautifully.

One small concern was that the pulley centre had slightly spread the top of the rotor axle and when I replaced the electronic speed "dooflacky", the round magnetic spinning thing on top, it cracked across (the dooflacky not the axle). I filed the shaft down fractionally back to original size and glued and clamped it back on using high strength super glue. It has so far withstood the full revolution speeds, is still in place and the electronic speed control works perfectly.

I now need to repair my MOF96 as the slide lock has finally given up but concensus on the forums seems to be that it would be better taken to a repair agent as the adjustment is rather tricky. If anybody oiut there thinks I should give it a go, let me know.

Cheers
Grant

Hi Grant,

great to hear that you succeeded! The pulley jack's center point having to be pressed into the axle's centre bore hole to such an extent that the entire axle top is widened by it, is a telltale sign that the pressure needed was way to high for the axle's steel density grade. That's how stuck bearings can get. To prevent such axle burring, pulley jacks with flat anvils are availiable as an alternative to jacks with a mere centre point. These flat anvils also have a centre point sticking out in the middle, for correct positioning and to prevent the flat surface from sliding away, but they have the advantage of taking over the pressure from the centre point and pointing the exerted force straight downward instead of outward as an axle splitting force.

You also succeeded in restoring the ring magnet. The disadvantage of a broken or split magnet is, that the loose parts adjacent to the split become separate magnetic poles all on their own. If left split, the ring magnet becomes a system with more and weaker poles, no longer able to generate the original voltage in the tacho pick up coil, which is incorporated in the moulded electronics module. The electronics will compensate for that by cranking up the motor rpm until the generated voltage reaches the designed level again. But you were successfull in mending the magnet by binding the cracked parts tightly together again and thus restoring the original two poles. Should the glue give in the future (acrylate super glue becomes grainy and brittle over time), you may notice this through deviating rpm behaviour of your router. In that case, switch it off immediately, to prevent bits of the magnet coming loose and getting stuck between the armature and field, where the fragments will damage the motor's copper windings.
Should you want to replace the ring magnet, you can use the spare part of the DeWalt DW625, which is identical.

The MOF96 is easier to dissassemble than the larger Elu's, but this may not be necessary. Arresting the machine's routing depth is done by tightening one of its handle knobs. Behind this knob's threaded pin is a copper or brass stud, which is wrenched tight against one of the sliding rods. Over the years and after many tight squeezes, the stud may be compressed and deformed to such an extent where it loses grip on the rod. The stud is attached to the knob's threaded end and can be pulled out togehter with the knob assembly when this is entirley screwed out of the frame. However, if the stud is burred and deformed too much, it is stuck inside and you will pull out the knob and its threaded end without the stud attached. Only in that case the machine needs to be disassembled, because the motor housing has to be taken apart before you can remove the rods and reach the stuck stud from within.

The stud is available as a separate spare part (numbered 23 in the drawing). See the spare parts list for the DeWalt types DW614 or DW615.

succes and greetings

gerhard

Again thanks Gerhard, I have a pulley with a flat anvil but the arm hooks were too large to fit under the housing cover. I think I shall have to make some sort of adapter for next time. I am also trying to get a replacement ring magnet but it is one of the spares that are not available in Australia. I have tried DeWalt Australia with no success and it looks as though I shall have to import. You would think that they would at least keep replacement copper slide lock pins for my 96 (614) as it should be a much needed part but that is also unavailable. My pin is totally destroyed - I got both routers from old friends who no longer had a use for them and they had led a hard life. Taking the 96 apart was incredibly easy - much easier than the 177 where I forgot that the slide on/off switch needed to be in place before I closed it all up and had to dissasemble the whole thing again. Bugger.
Cheers Grant