Elu mff81 bearings - help needed!

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andrew_2

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Hi all
First post and I'm coming begging!

I have an Elu MFF81 planer and the main bearings are now mostly filings. It's a nice clean machine, I've had it from new and it's only seen medium service, so I think it's worth having a go at repairing it.
I saw a similar thread here:
https://www.ukworkshop.co.uk/threads/replacing-bearings-on-an-old-elu-mff80-electric-planer.135385/If simonharper is still on the forum, I would be grateful for his wisdom!

Problem 1: I'm not a mechanic and I don't know how to get the pulley off the armature shaft. Presumably it's a clockwise turn (the shaft appears to be threaded rather than a locknut), and I've tried putting grips on it. I'm scared of damaging the teeth if I start bashing it. Is there a right way of removing the pulley so I can get to the bearing underneath?

Problem 2: Black and Decker say that one particular bearing is no longer available as a spare (I can get the other 3 no prob). Does anyone know what it is and where else to go look? simonharper mentions he changed his with SKF bearings, but until I get that pulley off, I don't know what that bearing is!

I would be grateful for any help here!
Andrew
 

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@simonharper isn't a prolific poster here. His last posts are over a year ago but he has looked in on the forum early this year. Once you yourself have made another couple of posts, you can use the conversation feature to send him a message that may send him an email alert if he's set it up that way.
I have the same planer but sorry, no time to take it apart and look for you in the next few months.
Elu are good tools from before the throwaway culture and would have been made to allow servicing.
Bearings : Dewalt are infamous for using cheap and nasty bearings. Don't buy bearings from them. Tqke it apart first then buy SKF / NSK / FAG name brand bearings from one of the online sellers like bearingboys or bearingsrus. These will be cheaper and better.
As you strip the machine you should find the bearing size etched in small numbers somewhere on the side of each one. Note the nature of the side seals and ideally replace like for like. The code 2RS for example means Rubber Seals both sides. Z is metal seal one side only, 2Z is metal seals both sides, etc. SKF et al publish catalogues online that include useful technical sections and it is worth reading up a bit on the basics of bearings and the way your chosen manufacturer does it's part numbering (they are all similar but differ in the details).

The bearings will almost certainly have internal, external diameters and thickness that are a nice whole number of millimetres. Even if not marked, you can just measure them and buy bearings of the same size.

A properly running MFF80 is a noisy beast with a big torque reaction (it rears up in the hands as you start it) but very smooth.
 
Thanks Sideways - that's some good info to digest.

I wouldn't expect you to break yours down just to find a bearing part number for me! But I would appreciate some advice on getting that pulley off the end of the armature without chewing up the teeth.

My best idea so far is to put the square bit on the end of the armature screw thread into a vice, blast the pulley with a hot air gun and then try to devise a way of getting some grip on the pulley and try to loosen / unscrew it that way. I was thinking of making a softwood form in 2 halfs that I could stick a G-clamp on to hold it firmly and then bash it with a hammer. In a gentle sort of way of course, but it looks like it's on very tight.

I'm thinking that gripping it with softwood would be less likely to damage the teeth when force is applied. Is there a more intelligent way to approach it? Sorry, it's not something I've had to do before. I don't want to start hitting it in case I can't replace it when I break it.
 
a small three pronged puller to tease the gear cog up

All my bearing pullers...

I do wonder sometimes if people actually read the question before hitting reply.

The OP says "the shaft appears to be threaded".

So a bearing puller is the last thing you would use.

---------

To the OP. If you plan to replace the drive belt, wrap that around the pulley and then use mole grips or pipe pliers to grip the belt. The belt is toothed, so will grip the pulley very well and having it between pulley and plier jaws will prevent any damage (at the expense of dmaging the belt).

Work out from the motor's (and cutter's) rotation what hand thread will be on the pulley.

An alternative, if you do not want to buy a belt is to use a strip of inner tube. Wrap it around the pulley in the unscrewing direction (same concept as PTFE tape on a pipe fitting).

I assume you have attempted to locate a parts diagram for the machine. There is one for an MFF81 type 2 here:

https://www.partshopdirect.co.uk/elu-mff81-type-2-planer-spare-parts-s3242/
If that happens to be the correct one, you can click on part 39, the needle bearing (which appears from that site to be available) and the photo shows it as HK1010, a common needle bearing.

Solent Tools might be also be a source of assistance.
 
Goodness - thank you for all the comments!

I didn't want to sacrifice the drive belt because it's actually in very good nick, so I was trying to save myself £15. But if needs must.

I would never have thought of using an inner tube and I've literally just thrown one away. Hells teeth. But I have a couple that are past their sell by, so I don't mind chopping those up. Thank you for that, ChaiLatte.

Oddly, the needle bearing is the only one that appears to be in good nick. I'll replace it anyway. The main bearing on the cutter has disintegrated and the one under the pulley has gone very wobbly. Still, not too bad considering that I must have bought the machine in the late 90s.

As Sideways says, good machine and built to last. Right. Off to the shed. If you hear screams it's only me.
 
Cut two pieces of say 3mm round bar/wire that will drop into opposite groves of the pulley and use them to clamp onto with grips have you thought it might be screwed on L hand thread? soak it with WD40 then give it a try.

Edit: added wire
 
Looking at the layout of the machine, if the toothed drive pulley is screwed onto the motor shaft (which would be logical) then it should have a left handed thread so that the motor spindle is trying to tighten into the pulley as it drives the belt and cutter block forwards.
To unscrew the pinion from the motor spindle, I think you'll need to turn it opposite to the "normal" way of unscrewing.

If it's stuck tight, heat is often the answer. Apply heat to the pulley and it should expand (a very little) and give you a chance to unscrew it before the heat conducts through to the spindle. Heat also softens any loctite. On a tool like this, I wouldn't attack it with the blowtorch but careful application of a hot air gun might help. A few heat / cool cycles maybe needed.
 
20230630_113046.jpg


Mine's an mff80
The drive pulley is fixed on with a screw that goes into the end of the motor spindle.
It's absolutely solid so no idea whether it's left or right hand thread.
Belt is poly V rather than timing belt style so clearly they updated the mechanism.
Given the visible flat on the spindle end in your photo, I think your drive pulley is likely to be screwed on where mine is probably push on with a key to transfer the force and a screw to keep the pulley in place.
 
Brake fluid works better at penetrating and loosening than WD40 "penetrating oil" does.Brake fluid"s viscosity is lower than that of penetrating oil, and it is the capilliary action that you want to draw the stuff in.But it also strips paint, so be precise in your application of it.

The WD part is for water dispersal..it was invented as an anti-humidity oil..it"s actually not very good as a penetrating oil .

You can also make an effective ( better than WD40 ) "penetrating oil" by mixing acetone with mineral oil(s) or even mixing it with vegetable oil(s).
 
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Or just use PlusGas.
Not everyone always has access to the same branded products..Which is why it's helpful to know what works, rather than a name on a tin which might not be available everywhere..or the shops might be shut / amazon not deliver etc.

If the answer is always "just use X brand" it might as well be "pay someone to do it for you". ;)
 
I did it. Yay.

No PlusGas needed, sorry Phil

It is indeed threaded with a clockwise turn to undo it (looking down from above, so a backwards thread then. Just for interest, the inner tube trick didn't work - it just tore the tube to shreds. I can't heat it cos there's a captive plastic fan on the other side of the casing that you can't see from my first photo. The tiny square tab on the end of the armature spindle is too small to hold securely in my old vice. I did soak it in wd40 for a bit, but I can now see that the oil didn't even make it into the threads.

Finally I put an adjustable in the vice to hold the armature tab, found an old pair of pliers whos teeth just happened by pure fluke to fit the pulley teeth exactly and even then I had to put a bit of pipe on it for leverage. It's such a diddey little thing too. But at least now I can get all the bearings off.

Sideways - thanks for all the trouble you've taken again. Mine is the MFF81-2, so it is superficially a lot different to yours. I can't photo it as it's in various tubs all over the bench, but the casing is aluminium, and the cutter pulley actually drops over a large conventional 12mm nut that's threaded onto the cutter spindle itself. So once you take the belt off, the front pulley just lifts off.

There will now be a short hiatus while I purchase a small bearing puller. There's only about a mil and a half gap to play with between fan and bearing. So I can't just hit it with a chisel.

Thank you ever so for all your comments. I would probably have chucked the machine by now and gone down to Screwfix without all this support, but now it has become a PROJECT.

mff81_pulley2.jpg
 
Certainly, but PlusGas is easier and readily available. If the OP is going out to buy brake fluid or acetone he'd just as well buy PlusGas.
if the OP is like me ( and I suspect many of us here, including yourself Phil ) he already has acetone and mineral / cooking oil to hand and doesn't have to go out and buy any. Plus brake fluid is available in the shops almost everywhere , all countries ( if one has neither of the foregoing ingredients for homemade penetrating oil ) whereas plusgas..outside of the UK , in big DIY stores or Halfords* type places or garages ? I certainly have never seen any in France. Plenty of it's branded equivalents though, which you couldn't get there in the UK, with unpronouncable "furrin" names too Not everyone here is from the UK, despite what it says in the address bar up top. ;)
Edited..great to know that you cracked it @andrew_2 :)
Halfords may no longer be a "thing" for all I know..could be a coffee chain or a nailbar by- now..Are they open 24/7 including holidays. My workshop / atelier is ;)
 
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@andrew_2 that's in beautiful condition. The armature, spindle end, pulley and the plastics look crisp and clean.
Take a look at the armature and a photo or two for your future reference. Notice the fine laminations and the v grooves machined into them which are for dynamic balancing of the armature. They may well be at both ends of the armature, not just one, and multiple shallower cuts (if needed) rather than just one or two deep ones.
As the manufacturing was cost reduced after the DeWalt acquisition, parts like this were tweaked and a later equivalent - though it may well fit - may not be so nicely made. I've noticed this with the routers.
Good on you for taking up the repair and reuse challenge.
 
If you have a piece of flat steel that will fit under the bearing then you might be able to remove it without a special puller. Just cut a slot in the plate wide enough for it to slide under the bearing, and make the plate wide enough to span out beyond the fan. Then support the ends of the plate in a vice or whatever and tap the end of the shaft with a suitable mallet to free it. Something like an old industrial bandsaw blade can work well, not that I suppose you have one of those kicking about, but might give you an idea. Or, rather than buying a puller or anything else, why don't you just take it down to your local car repair shop. They will probably do it for you for the price of a beer.
 
Hi Fergie. That's a very useful idea, thank you. I don't have a bandsaw, but I do have some steel. I'll have a go at that tomorrow.

Hi Sideways. Yes, I was really surprised at how nice it was inside when disassembled. Very clean indeed after the gank was brushed off. Even the brushes look only a little used. I didn't know about the v grooves, and it does have a lot of them machined into the armature in all sorts of sizes. I wondered what they were for. Anyway, order for bearings goes in tomorrow once I've looked up a supplier. Onwards!
 
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