Removal of bearings from shaft

[Jonburt83]

I’ve recently purchased a 10-speed 1978 Meddings MF4 Mk3 pillar drill which has high range and low range Tufnol gears - the high range gear is stripped and needs replacing. I mainly do woodworking, so this kind of maintenance is a learning curve for me.

Having started to disassemble the gearbox I was hoping to obtain some advice on removing the bearings from both the input and output shafts (15mm and 25mm diameters, respectively) as some of these need replacing (damage and play between inner race and rest of bearing) and at least one needs to be removed to allow replacement of the gear anyway..

From what I’ve seen bearings should be removed with the force applied to the inner race (I had previously thought of using some 3-legged gear pullers to try and get them off). There are budget sets of bearing pullers available online and it’s stated these are 2” or 3”, for automotive use, which are obviously larger than the shaft sizes on this machine. I’ve not seen any smaller sized tools available and wondered if anyone could suggest a way these bearings might be removed.

I’d be very grateful for any information or advice anyone might have

 

[ShopShoe]

I see that you are in the UK, so I'm not sure what options you have. (And, by the way, thank you for posting your location).

Here in the USA, there are some auto-parts stores that will rent specialty tools. There are also tool rental firms that sometimes have specialty tools like gear pullers available.

What I thiink you need is a puller that includes a part that will fit between the gear and the bearing, as illustrated below:

--ShopShoe

 

[creast]

If you are going to replace the bearings then you don't need to worry about using a 3 leg puller on the outer race.
The way I would do it is support the bearing on a thick steel plate with suitable cutout to clear the shaft and then tap the shaft through using a nylon or copper mallet so as not to bruise the end of the shaft.

 

[timo_gross]

If you are going to replace the bearings then you don't need to worry about using a 3 leg puller on the outer race.
The way I would do it is support the bearing on a thick steel plate with suitable cutout to clear the shaft and then tap the shaft through using a nylon or copper mallet so as not to bruise the end of the shaft.

That is the point, often things do not go smooth and the hammer gets harder, bigger and the users become violent .
The shaft on the picture has probably enough clearance to use a cheap 3 arm puller.
I have a small one from the local "everything shop" not a good tool, not an expensive tool. (More than 8USD less than 20USD)

As pathetic as it is, it did a few succesful removals, that would have been not as easy without it.
Proper tools from name brand Automotive or bearing suppliers cost multiple times as much. They work on a different level.

 

[Jonburt83]

Many thanks all for advice and input. The others I should be able to do with 3 leg pullers but there isn't quite enough room between the bearing and the gears for that on that one bearing - I will have a look at using a steel plate to get that one off. I think I'll also put the whole assemblies in the freezer a couple of hours prior, and then heat the bearings to hopefully make things come apart more easily.

 

[ajoeiam]

Many thanks all for advice and input. The others I should be able to do with 3 leg pullers but there isn't quite enough room between the bearing and the gears for that on that one bearing - I will have a look at using a steel plate to get that one off. I think I'll also put the whole assemblies in the freezer a couple of hours prior, and then heat the bearings to hopefully make things come apart more easily.

and ordinary steel plate will deform quite easily - - - bearing puller (whatever that cup is called) are not really normal steels

You know - - - if you're just trying to get rid of the bearings there are a number of cheap but violent ways to get rid of the things.
1. cutting torch with careful hands
2. hold so whole piece doesn't jump and beat on bearing with a bfh (big f hammer) that smashes the outside race.
its hard on your cold chisel but use same hammer and score across inner race
flip over and do same one opposite side (this one is a little harder to break and I prefer to cut this one off with my cutting torch)

once you break off the outer race and get rid of the balls you could carefully warm the inner race (you are trying to put no heat into the shaft so you have to
move fast) and then beat the inner race off

these techniques are neither pretty nor real easy but they do work
(have even just put the new bearing over the nick on the shaft from cutting the old bearing off so perfection is not necessary but a big divot 'is' a problem that should be fixed)

 

[Joe]

I’ve recently purchased a 10-speed 1978 Meddings MF4 Mk3 pillar drill which has high range and low range Tufnol gears - the high range gear is stripped and needs replacing. I mainly do woodworking, so this kind of maintenance is a learning curve for me.

Having started to disassemble the gearbox I was hoping to obtain some advice on removing the bearings from both the input and output shafts (15mm and 25mm diameters, respectively) as some of these need replacing (damage and play between inner race and rest of bearing) and at least one needs to be removed to allow replacement of the gear anyway..

From what I’ve seen bearings should be removed with the force applied to the inner race (I had previously thought of using some 3-legged gear pullers to try and get them off). There are budget sets of bearing pullers available online and it’s stated these are 2” or 3”, for automotive use, which are obviously larger than the shaft sizes on this machine. I’ve not seen any smaller sized tools available and wondered if anyone could suggest a way these bearings might be removed.

I’d be very grateful for any information or advice anyone might have

Not addressing your question but I think you might enjoy and benefit from a few youtube videos on one of those drills by a guy whose channel is "workshop friend"

 

[ignator]

Both these bearings are easy removals with the bearing separators shown in post#2 and #4.
DO NOT HIT the ends of the shafts with any sort of hammering tool that can mushroom even slightly the outer diameter of the shaft end. You'll make the last 1.5cm of the shaft removal, life irritating, removing the bearing.
What I noticed in the second photo, showing the stripped high speed gear, that was not fully meshed, the press/wear pattern on the bottom bearing, indicates it was not full seated in it's machined recess pocket, by the amount of un-damaged stripped gear. Seems it was never correctly assembled from the factory. You should see if there's a machining defect preventing that bearing from fully being inserted in it's machined pocket. Or some other defect of the shaft length or upper component bearing mount.

 

[Jonburt83]

Both these bearings are easy removals with the bearing separators shown in post#2 and #4.
DO NOT HIT the ends of the shafts with any sort of hammering tool that can mushroom even slightly the outer diameter of the shaft end. You'll make the last 1.5cm of the shaft life irritating, removing the bearing.
What I noticed in the second photo, showing the stripped high speed gear, that was not fully meshed, the press/wear pattern on the bottom bearing, indicates it was not full seated in it's machined recess pocket, by the amount of un-damaged stripped gear. Seems it was never correctly assembled from the factory. You should see if there's a machining defect preventing that bearing from fully being inserted in it's machined pocket. Or some other defect of the shaft length or upper component bearing mount.

Many thanks, I see what you mean about the wear pattern on the bearing - I will have to have a closer look at that to see what the explanation is

 

[ignator]

Many thanks, I see what you mean about the wear pattern on the bearing - I will have to have a closer look at that to see what the explanation is

I'm going to assume the shaft and bearing pair, is held between two 'clam shell' end blocks. There may be a missing spacer on the top bearing that would have pushed the bottom bearing home if it were a component in the assembly/parts-list drawing for the drill press. You must have a source for the new gear. Original has a phenolic type (?) 'plastic' gear for noise reduction. I don't know if it died because it was only capable of half mesh, but the detent that holds it in high gear would not have 'locked' it in gear, and I bet it would slowly release, and each time, chew a bit of the gear until it just decided to chew it to pieces. That mating drive gear shaft assembly, done in steel on that secondary shaft would be noisy, but tough. Existing design would probably be OK if the factory did not mess something up.

 

[ChazzC]

You must have a source for the new gear. Original has a phenolic type (?) 'plastic' gear for noise reduction.
I don't know if it died because it was only capable of half mesh, but the detent that holds it in high gear would not have 'locked' it in gear, and I bet it would slowly release, and each time, chew a bit of the gear until it just decided to chew it to pieces. That mating drive gear shaft assembly, done in steel on that secondary shaft would be noisy, but tough. Existing design would probably be OK if the factory did not mess something up.

Non-metallic gears are used in power transmission systems for a number of reasons including noise reduction, but also for cushioning impact and to act as a (relatively) low cost failure component rather than destroying the entire assembly & supporting castings/frame.

Older gears for these purposes were typically made from Micarta, which is linen impregnated with Phenolic resin; these gears appear to made of Phenolic resin mixed with a reinforcing powder (most likely Asbestos or talc). Micarta replacements or glass (or carbon fiber) printed gears would be a good choice to retain the original design intent.

Steel gears would be tougher, but the preferential failure element would be sacrificed.

Older (and I believe current, lower cost) Mini-Lathes & Mini-Mills used plastic gears as part of the spindle drive trains, creating an industry that made all-metal replacements with, in my opinion, probable higher cost repairs when the replacement gears didn’t fail under higher than originally designed loads. Newer, higher cost machines use more efficient DC motors with fiber reinforced cogged drive belts, which are quiet, and control systems that will shut down under high loads to prevent damage.

 

[Jonburt83]

Apparently the original output shaft gears are made from Tufnol - the replacement I sourced from someone who makes these and sells on ebay, this is made from Delrin. They are also obtainable from the manufacturer made from Delrin now, but at a significantly higher price.

The top bearing sits in a housing machined into the gearbox cover (this was properly seated before I took it out); the bottom bearing sits in a similar housing machined into the drill head casting and, consistent with what Ignator noticed, the marks in the grease show this bearing was not seated to its full depth here (as pictured in the photo). I suppose I will have to try and work out what's going on with this when I come to put the shaft back in position.

 

[ChazzC]

Apparently the original output shaft gears are made from Tufnol - the replacement I sourced from someone who makes these and sells on ebay, this is made from Delrin. They are also obtainable from the manufacturer made from Delrin now, but at a significantly higher price.

The top bearing sits in a housing machined into the gearbox cover (this was properly seated before I took it out); the bottom bearing sits in a similar housing machined into the drill head casting and, consistent with what Ignator noticed, the marks in the grease show this bearing was not seated to its full depth here (as pictured in the photo). I suppose I will have to try and work out what's going on with this when I come to put the shaft back in position.

Delrin® 100AF (20% Teflon fiber filled, brown color) would provide more lubricity than Tufnol and could have similar properties as Tufnol (and may cost less). I couldn't find an apples-to-apples comparison.

 

[Lloyd-ss]

I tried the bfh method that @ajoeiam mentioned earlier to get the bearing nut off an old drill press. Big socket, 24" breaker bar. No go. 24" cheater pipe. Ahhh. There you go. Hmmm. Left hand thread. Sigh. Luckily, the nut was saved from stripping when the hollow shaft broke first.

 

[ajoeiam]

I tried the bfh method that @ajoeiam mentioned earlier to get the bearing nut off an old drill press. Big socket, 24" breaker bar. No go. 24" cheater pipe. Ahhh. There you go. Hmmm. Left hand thread. Sigh. Luckily, the nut was saved from stripping when the hollow shaft broke first.

Sorry Mr Lloyd - - - don't think I was advocating applying large amounts of force without knowing what needed to happen.

I've used a total of 10' of snipe on a 24" pipe wrench and I was bouncing on it to break a stubborn nut on a 1-1/8" stub that was machined on the end of a 1-1/4" square shaft. But - - - - these techniques have their place but not in every place.

Any idea why it was a hollow shaft in the first place?

 

[Lloyd-ss]

Sorry Mr Lloyd - - - don't think I was advocating applying large amounts of force without knowing what needed to happen.

I've used a total of 10' of snipe on a 24" pipe wrench and I was bouncing on it to break a stubborn nut on a 1-1/8" stub that was machined on the end of a 1-1/4" square shaft. But - - - - these techniques have their place but not in every place.

Any idea why it was a hollow shaft in the first place?

Ha ha, no big deal Joe. We are all grownups here (in years anyway) and are capable of making our own bad choices.
The broken shaft was a "perfect storm" kind of situation. The drill press was big and cheap and of questionable national origin. I was working late in the shop back before I permanently put the cork in the bottle. I might have been chasing a chuck runout problem. If I had studied the situation before putting the big cheater pipe on it, things might have turned out better. Or if I had just called it a night and looked at it the next day.