Medding MF4 drill pulley

[Mark Davison 1Participant @markdavison1]

 

I'm trying to remove the pulley from the 2 speed gearbox input shaft, without much success. It looks like it is a taper bush, but the hole on the pulley that would usually be used to remove a taper bush doesn't line up with a hole in the pulley (45 degrees out, which is a bit wierd). I tried to create the half hole in the pulley but then decided to tackle the issue a different way.

I've drilled and threaded a couple of holes into the top of the taper bush (assuming that is what it is) and made up a small puller. It pulley up on the bush and pushes down on the pulley. No joy. All I have done is bent the steel bar that I made the pulley with. I've even tried a very modest amount of heat (hot air gun as opposed to torch).

 

http://www.model-engineer.co.uk/albums/member_photo.asp?a=46419&p=769555

 

Edited By Mark Davison 1 on 09/10/2017 07:47:09

Edited By Mark Davison 1 on 09/10/2017 07:47:44

Edited By Mark Davison 1 on 09/10/2017 07:51:06

[Mark Davison 1Participant @markdavison1]

Removing a taper pulley from Medding MF4 drill

[Marcus BowmanParticipant @marcusbowman28936]

Is there a grub screw hiding in the groove of the pulley? My MF4 has grub screws as well as tapered keys in both pulleys. I'm not convinced its a tapered bush. I think it is a parallel shaft.

Meddings would tell you.

Great drills. I have had mine since 1975 and use it a lot.

Marcus

[David George 1Participant @davidgeorge1]

I think you are on the right idea looks like a taper bush to me but don't understand why the extraction holes don't line up. I would be tempted to warm up the pulley to try expansion, start with a hot air gun then maybe a blowtorch at the last resort also make a new puller bar out of thicker material.

David

[Mark Davison 1Participant @markdavison1]

There is an untapped hole for a grub screw but it is empty and i can see what i think is the shaft. I agree that the shaft is parallel, but i think the centre of the pulley is seperate from the outer alloy part. They fit togther on a taper which causes the bush to clamp the parallel shaft. Will try doubling up the steel bars and use larger diameter bolts for the pushers as they are only M5 and buckling!

Edited By Mark Davison 1 on 09/10/2017 08:24:07

[JourneymanParticipant @journeyman]

Looks like a Fenner taper lock bush. See *** Fenner Video *** for how they work.

John

[Mark Davison 1Participant @markdavison1]

Thanks. Problem is the removal hole isnt there in the pulley. The thread in the half hole in the bush doesnt look great either. It also looks like there is a crack in the bush where it is designed to flex at the thin bridge between the two halves. This appears to have allowed one half of the bush to sit fractionally higher than the other causing the threads not to align. That might explain why i cant get a grub screw started in it where i attempted to add the half hole into the pulley.

I now have the exploded diagram from Medding. That would suggest the pulley should just be a push fit onto the parallel shaft secured with a grub screw. I wonder if someone modified the pulley to add the taper bush in place of the grub screw?

Edited By Mark Davison 1 on 09/10/2017 23:06:08

[damianParticipant @damiannoble34800]

My pacera (meddings) is just a push on fit held on with a double grub screw.

[John PenfoldParticipant @johnpenfold74932]

Sorry if it seems silly – are you really sure there isn't a small grub screw hiding at the bottom of the hole. I've been caught by a seemingly empty little black hole only to find a short grub at the bottom.

J

[Mark Davison 1Participant @markdavison1]

It wasn't a silly question, but no there wasn't. I eventually managed to remove it. I managed to build a revised puller and ended up dragging it half an inch up the shaft before the threads in the cast iron bush failed around the holes i'd drilled and tapped into it for the puller. I re-drilled and tapped them deeper (they were already 3/8" deep) and tried again. I also drilled two large holes down through the bush on the split line, in an attempt to remove some of the stress. This resulted in the bush itself finally giving up and one half coming out. The other remained and had to be separated from the pulley once it was off.. It would appear that it was the bush being stuck to the key amongst other things that was causing the issue. New bush and key ordered for a few pounds, so other the the hassle that bit was cheap to fix.

The expensive bit was discovering that I need to replace one of the two fibre gear wheels in the gear box. It is great that Meddings still sell the parts, but they aren't cheap. My bargin drill had ened up costing more than I budgeted for, but still happy with it.

 

Edited By Mark Davison 1 on 13/10/2017 07:41:59

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