Need advice for dismantling shaft and searching for bearings for Kity 637

[Rémi52]

Hello everyone,
I'm reaching out to you today because I'm facing a bit of a repair challenge with my Kity 637 planer-thicknesser. After identifying a problem with the ball bearing, I'm getting ready to replace it. However, before I can go ahead with purchasing and replacing the bearing, I need to dismantle the shaft it's mounted on, and I must admit I'm not entirely sure of the best way to proceed.
I'm therefore seeking your advice and tips on:

Safely and efficiently dismantling the shaft's screw (photo attached). If you have any specific recommendations on tools to use or particular precautions to take, I'm all ears.
I've tried using an Allen key and a lever arm, applying penetrating oil + heating, but nothing moves, both clockwise and counterclockwise.
Knowing that I've already heated the screw, given a few punches with a drift pin. Attempted to turn in both directions...

Dentifying and finding the right bearing for my Kity 637.
If you've ever had to make this kind of repair or if you know of any resources, tutorials, or reliable parts suppliers, your help would be greatly appreciated. Additionally, if you have any general advice on maintaining this machine or recommendations on practices to ensure its longevity, I'm all ears.
Thanks in advance for your time. I look forward to your responses and advice.
Best regards, Rémi

 

[ChaiLatte]

There is a very good chance that the screw has been secured with Loctite (thread locking 'glue'). This is de-natured with heat. Random Google says 250 degrees C required. The aluminium pulley is a good conductor of heat, so you need a proper heat source applied for a reasonable time. You will not harm anything by heating. You could use an infra red thermometer to monitor your progress.

You have already considered the following: in the top photo, if the pulley goes clockwise, the screw would be a normal right hand thread. If the pulley goes anti-clockwise, there is some chance that the screw is left hand thread.

For difficult screws, a 1/4" hexagon screwdriver bit in an SDS holder with the SDS drill on hammer only can rattle it enough so it cooperates (https://wjdtools.co.uk/insert-bits/...hex-drive-short-s2-steel-shank-25mm-long.html and https://www.diy.com/departments/sil...bit-holder-100mm-1-4-hex/5055058145666_BQ.prd)

Not very helpful 636 manual here:

https://docs.machineatlas.com/Kity+636+Jointer+Planer+Official+Manual.pdf

 

[Sideways]

It is not too difficult to round out the hexagon in socket screws like that.
I think you've done well to keep it in good shape as pictured.
Good advice above.
I would make a point of only using allen keys and hex bits that are a tight fit in the socket as you try using impact.

 

[Rémi52]

Thank you for your response,I have already tried heating the assembly, but nothing moves in either direction.
Once this screw is removed, I think a hub puller is needed to remove part 54. Note that part 56 is the ball bearing.
The famous screw is not visible in the diagram.
I don't have that kind of tool at home.
I will meet with someone next week who is accustomed to cases like this.
I prefer to take my time rather than damage everything.
I will keep you updated.

 

[Fergie 307]

Are you sure it is a screw, and not simply a hex in the end of the shaft. On the 636 there is an M6 hex head bolt and washer, but not on later ones. The pulley itself is an interference fit, and will be fun to remove without damaging it. I have all sorts of pullers and presses and ended up cutting it off and making a new one. When you get to the bearings make careful note of the position and orientation of all the washers and spacers, they are NOT interchangeable, and must be fitted correctly if you want to avoid issues. And fit top quality bearings intended for that speed range. Local bearing supplier rather than e bay etc.

 

[Fitzroy]

Steve Maskery, who used to post here and I think is still active elsewhere, has a Kity 637. He's super helpful and may know if this is a screw or simply a hex hole.

 

[ChaiLatte]

Are you sure it is a screw, and not simply a hex in the end of the shaft.

Very good point. I wonder if he could try immobilising the pulley (make a wooden clamp with a hole in it, cut a relief slot and squeeze it up tight) and then attempt to turn the hexagon head.

There is an outside possiblity that the pulley itself is threaded (and the hexagon thus provides the resistance in order to unscrew it) and you would need to disprove this before assuming a simple press fit and resorting to a puller.

If you look near the number 57 in the diagram he posted, the shaft is shaded/lined slightly which might indicate something particularly if you compare with how 52 is depicted.

 

[Fergie 307]

I doubt there is any great difference between this and my 636, so I think the pulley will be an interference fit on the shaft. The problem I had was that the shaft is not that big. Having applied a few tons of pressure on a press without it showing any sign of movement I was concerned about damaging the shaft. In the end I cut a slice off on one side of the pulley to make a very thin wall, probably about 0.5 mm, then it finally gave up. Then I turned a new one. I converted mine from a flat to a poly v belt, so needed to make a new pulley anyway. I would be very surprised if you could get one of these off with any sort of mechanical puller. I have done one since for someone else, and had exactly the same issue. Never looked at a 637 but can't see it being significantly different.

 

[okeydokey]

I don't have of these machines but wonder if the machine screw could be drilled out then the pulley removed/bearing changed, a new thread cut for a replacement screw then the pulley pressed back and new screw installed.

 

[Fergie 307]

One thing you could try is to contact any of the firms who do a replacement spiral cutter block for this machine. They will be able to tell you if it is supposed to have a thread in the end of the shaft. Not sure what it would be for on your machine, very much doubt it would be for holding the pulley in place. On the 636 the threaded hole takes a small bolt and large washer, effectively forming a pulley for the very narrow roller belt. I assume that is taken off somewhere else on yours?

 

[Inspector]

I don't have of these machines but wonder if the machine screw could be drilled out then the pulley removed/bearing changed, a new thread cut for a replacement screw then the pulley pressed back and new screw installed.

There is no screw in the end of the shaft. It is rotary broached to make a hex in the end of the shaft to hold it for whatever reason. You can see the little "petals" of metal pushed into the bottom of the hex. Drill the end of the shaft and it is pooched.

Pete

 

[ChaiLatte]

It is rotary broached to make a hex in the end of the shaft to hold it for whatever reason.

And if we were to establish the reason the shaft needs holding, we might go some way to solving the OP's problem.

The manufacturer would not go to the trouble of broaching the shaft for no reason. If we can look at the entire length of the shaft and everything attached to it and find no other purpose of the hex other than removing the pulley, then once we eliminate the impossible, what remains, no matter how improbable, etc...

If, for example, the hex were needed when changing the cutters, its use would be shown in that part of the manual dealing with cutter exchange.

 

[John Hall]

According to the diagram, there is no screw shown, so the hexagon is in the end of the shaft, and as already mentioned, must be there just to hold the shaft maybe for some sort of adjustment. Until you know for sure how the pulley is held on the shaft I wouldn’t attempt any more attempts at removal..

 

[ChaiLatte]

Until you know for sure how the pulley is held on the shaft I wouldn’t attempt any more attempts at removal..

That is kind of self-paralysing: a more optimistic course might be to suggest how we could move closer to "knowing for sure" rather than "stop because you don't know".

Did Mrs Columbus say "don't sail west dear, you do not know how big the dragons are"?

List out all probable methods that would be used to secure the pulley in normal industrial settings and devise a method to verify or discount each of those methods without causing damage if your theory is incorrect.

There does seem to be a pre-requisite to this that has not been considered: find out the cost and availability of a replacement pulley. Not available? Draw it first and obtain a quote for remanufacture before destroying it.

 

[Fergie 307]

And if we were to establish the reason the shaft needs holding, we might go some way to solving the OP's problem.

The manufacturer would not go to the trouble of broaching the shaft for no reason. If we can look at the entire length of the shaft and everything attached to it and find no other purpose of the hex other than removing the pulley, then once we eliminate the impossible, what remains, no matter how improbable, etc...

If, for example, the hex were needed when changing the cutters, its use would be shown in that part of the manual dealing with cutter exchange.

Or it could be there to facilitate some task to do with the manufacturing of it in the first place.

 

[Fergie 307]

That is kind of self-paralysing: a more optimistic course might be to suggest how we could move closer to "knowing for sure" rather than "stop because you don't know".

Did Mrs Columbus say "don't sail west dear, you do not know how big the dragons are"?

List out all probable methods that would be used to secure the pulley in normal industrial settings and devise a method to verify or discount each of those methods without causing damage if your theory is incorrect.

There does seem to be a pre-requisite to this that has not been considered: find out the cost and availability of a replacement pulley. Not available? Draw it first and obtain a quote for remanufacture before destroying it.

And as I have said, the manufacturer of the spiral replacements will know this. They don't come with a pulley, so presumably intend you to use the existing one. They will therefore be able to tell you how it is secured.

 

[Fergie 307]

If it turns out to be an interference fit then personally I wouldn't bother trying to get it off yourself. Take it to a local car repair shop. They will have a variety of pullers, and probably a press. To buy something suitable yourself is going to cost far more than a replacement pulley and, if my experience is anything to go by, may still not get it off without having to destroy it in the process. Please don't be tempted to use some cheap puller from e bay or similar. You will need a proper one to have any chance atall, and they are hundreds of pounds. And don't let them just pile on more and more pressure. Sure if you put it in a 20ton press it will get it off, but may wreck the shaft in the process.

The reality is that you are looking at a piece of Aluminium alloy that has been sitting tight on a steel shaft for what, 40 years? They may as well be welded together. If it won't come off with reasonable force then you may have to accept that the pulley is expendable, and cut it off. You can make another pulley quite cheaply, but not another shaft.

As to the pulley itself, if you look on for example Gates web site you will find all the measurements for the grooves for all the normal poly v grooved belts. Anyone armed with that information, and a decent metal working lathe, should be able to turn a new one in less than an hour. The only really critical measurement will be the bore. To get that right they will need the shaft, so it can be measured accurately and the pulley bore made to the correct undersize.

I did this myself, so it cost me the price of a suitable piece of round alloy bar, about £10. No idea what a machine shop would charge you, £60 ish maybe?

Given the age of the machine I think you would be very lucky indeed to find anyone who actually has the part.

 

[Inspector]

And if we were to establish the reason the shaft needs holding, we might go some way to solving the OP's problem.

The manufacturer would not go to the trouble of broaching the shaft for no reason. If we can look at the entire length of the shaft and everything attached to it and find no other purpose of the hex other than removing the pulley, then once we eliminate the impossible, what remains, no matter how improbable, etc...

If, for example, the hex were needed when changing the cutters, its use would be shown in that part of the manual dealing with cutter exchange.

I have no proof but believe the pulley might be threaded onto the shaft. Know anyone with an Xray machine?

Pete

 

[ChaiLatte]

One thing you could try is to contact any of the firms who do a replacement spiral cutter block for this machine.

Good advice. See:

https://www.sheartak.com/spiral-cutterhead-kity-637

They say there are three versions of the 637, and show two versions, one which is threaded and one which is not. I cannot see the third version, which would provide a majority verdict...

It would be worth the OP dropping them an email with his machine serial number, posing as a potential buyer and they would tell him the info. he needs.

They need to proof read their catalogue as they sell a lot of "planning" cutterheads.

 

[Niall Church]

And if we were to establish the reason the shaft needs holding, we might go some way to solving the OP's problem.

The manufacturer would not go to the trouble of broaching the shaft for no reason. If we can look at the entire length of the shaft and everything attached to it and find no other purpose of the hex other than removing the pulley, then once we eliminate the impossible, what remains, no matter how improbable, etc...

If, for example, the hex were needed when changing the cutters, its use would be shown in that part of the manual dealing with cutter exchange.

You might try this company [email protected] they're french but also english speaking also try scheppach they do kity spares, I think!