Removing bronze bush from cast iron pulley

I am about to try to remove a bronze bush from inside a cast iron pulley (maybe steel) and am thinking that since the coefficient of expansion for bronze is higher than for iron/steel, then i might bag it and pop it into the deep freeze overnight. Has anyone tried this successfully? My experience with (perhaps too cheap) pullers is that the thread binds the more force you exert and am wondering if anyone can recommend a small hydraulic puller for this sort of job. To give you an idea of the sizes , the bronze bush is 40mm OD x 35mm ID and the pulley is about 120mm diameter and 120mm deep. It is the driven pulley on a Tom Senior Milling machine spindle.

Edited By Adam Harris on 23/05/2015 22:10:47

Adam, if you are worried about damaging the pulley, hold the pulley in the lathe chuck and turn away the bush or use a thin keyway tool in the toolpost to cut a slot (longways) through the bush. A shaper is the ideal tool for this! It is also possible to (carefully) slot the bush with a hacksaw. I have withdrawn some stubborn bushes with threaded rod and suitable washers and spacers.

I go with DaveB on this one as applying pressure on a set of bearing pullers usually gets you a damaged edge on the pulley. Just get a slot cut with the hacksaw and it will then almost fall out. No damage to the inside of the pulley.I do suggest you also cut some lubrication grooves in the new bush.

Clive

Yes the existing bushes have lubrication grooves and i thought i would copy them with a dremel. I am worried about damaging the pulley exactly as you say. If I turn it our on the lathe i might overdo it and increase the pulley ID which would remove the option of buying off the shelf bushes, although I will likely make them up myself. I do have a slotting head but it is on the machine to which the spindle belongs! What about my deep freeze idea??

Regarding the hacksaw cut , are you suggesting cutting all the way through, or just partially through in order to relieve some tension?

Hi Adam, yes cut all the way through, don't worry if you happen cut slightly into the bore of the pulley with the hacksaw as it won't harm it.

Regards Nick.

I had the same problem, cut the bearing with the hacksaw in two places, opposite each other, then just tap the halves out.

I would soak overnight in plus gas, ease it or WD40 even diesel has good penetrating qualities, which hopefully will break any corrosion gripping in the joint.

If this fails then go ahead as instructed above and good luck mate.

Edited By Jesse Hancock 1 on 24/05/2015 04:44:55

Edited By Jesse Hancock 1 on 24/05/2015 04:45:32

Hi Adam,
I would draw it out using a bolt. Make a thick washer with the OD just less than the OD of the bush. (Possibly turn a shoulder on it to locate it in the bush.) Find a short length of tube with an ID slightly larger than the OD of the bush. Put the bolt though the washer then through the bush then through the tube and finally another thick washer a plate. put the nut on the end and tighten it. This should pull the bush out.

Les.

Avoid pullers mechanical or hydraulic,a hydraulic press is usually best method for extracting bushes etc, if theses facilities are not available and a damaged pulley would be disastrous.So mount the pulley in the lathe and bore out the bronze bush until there is about 5 to 10 thou wall thickness of the bush remaining, then collapse the bush inwards by driving a small thin bladed screwdriver between the bush and the pulley, If you try cutting an oil groove with a dremmel type tool hold the tool tight as it will jump out of the groove and try to run around the inside of the bush.I have tried cutting oil grooves in bushes with a round nose chisel,tried all sorts of rake angles but never been successful ,often shown in books but I bet the authors have never done it. Once did a small end bush for a very large Polish single cylinder tractor ,like a field marshall but bigger,they must have had lubrication problems as its the most complicated small end bush I have ever seen spiral grooves and oil holes on the id and od, eventually cut the grooves with the mill and dividing head set up for spiral milling ,the owner was well pleased.

With Les Jones 1 on this one. By turning a larger washer with a bore diameter step on it you can use the same gear to draw a new bush back into the pulley. Gently attacking the boss with a heat source assists.

Regards Ian.

Les, Ian, that is my usual method of course. I was wondering about the benefit of deep freezing and a hydraulic puller....

Hi Adam, the only problem with freezing is you need a significant difference in temperature between the bush and the pulley, which would be difficult to achieve, save bunging one end up and filling the bush with a very cold liquid such as Oxygen, but you would have to work fast and have some method of pushing/pulling the bush out before the cold got into the pulley also. The gentle heating of the pulley idea would be a better bet, but needs a high temperature and applied fairly fast and with pressure on the bush whilst doing so, otherwise the heat will soon conduct into the bush and you will be back to square one.

Regards Nick.

Hi Adam,
I have just re read your original post (Which I had not read properly first time.) and now realise that there is probably a bush both ends. To get the first one out you would have to cut the washer on two sides so it would pass through the bush at edgewise and then be rotated into position. I think freezing may help.

daveb,
Sorry to have repeated the suggestion you made early in the thread.

Les.