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  1. #1
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    Default Removing the Hercus O Mill Standard Arbor

    Have had this mill sitting for about a year now and am starting to look now into getting it going.

    Before I start looking at the motor conversion or replacement I was hoping to see that everything is in good order before I spend any money. When trying to see if the vertical head fits and it has all of the required bits I got stauck on the arbor.

    I can see from some of the documentation that I have that the standard arbor has a No.3 morse taper, a collar sort of thing then the parts that you can see. The cutter and the various spacers held on by a nut.

    I have tried backing off the nut at the motor end a few turns then hitting it with a piece of timber and a hammer. This sounds very solid so I havent wanted to go too hard.

    Does the collar have any fixings in it to keep it from coming loose? Or do I need to give it a good whack? There is an allen key but it looks like it belongs to the spindle nose rather than the arbor.

    Is there a trick to locking the arbor in place to undo the lock nut? Tried placing some timber on the bed and raising the bed to stop the cutter from turning but didnt work. The timber just rotated and pushed the timebr out.

    Lastly, any good tips on removing the surface rust? Both the lathe and mill have more than their fair share. I ruined the paint of the lathe by using degreaser so I am a little shy about just jumping in.

    See attached PDF for a illustration of what I am talking about if needed.

    Would very much appreciate any advice given. Thanks!!
    Attached Files Attached Files

  2. #2
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    Noob,

    To lock the arbor, ensure that the spring loaded bull gear/ cone pulley engagement pin is engaged ( pushed in ) and then engage back gear by lifting the back gear lever up into its engaged position. ( A lot of engagements! )

    The cap screws you see on the spindle nose secure the drive dogs for the arbor. They must be removed to install the vertical head's geared arbor .

    Try some gentle heat on the spindle. Mine was stuck and was hard to remove. I made a puller from some thick plate and installed it on the saw arbor using the spacers and nut to retain it. From memory I had a pair of cap screws bearing on the spindle nose. They were screwed through threaded holes in the plate. A combination of heat, tension on the screws and pounding on the drawbolt with a big hammer and a block of wood popped the arbor.

    Hope this helps.

    Bob.

  3. #3
    BobL is online now Member: Blue and white apron brigade
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    I used a hot air gun on 650șC and the larger of these two mallets.
    The handle is redgum and the head is made from Rockoak and weight in at boy 1kg (double the other mallet) it packs a decent wallop!
    IMG_6166.jpg

  4. #4
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    I would remove the Arbor nut , spacers and cutter from the Arbor 1st before attempting to remove the Arbor from the spindle.

    You would need to return the overarm to the correct position for horizontal use, and then re-install the yoke,once this is down support will be give to the Arbor and should reduce any chance of it bending.

    You could try putting the spindle into back gear and giving the Arbor nut a good hit with a block hammer or something similar with some weight behind it.

    If you want you could put stillsons around the Arbor spacers , this may also hold the spindle from turning and take the load off the back gear.

    To remove the Arbor from the spindle release the drawbolt about 1 turn or 1/16" and give the head of the drawbolteither 1 Ora couple of good hits with the block hammer.

    If your concerned you could place a good piece of hardwood on the end of the bolt and give that a hit or use any sort of suitable dolly if desired.

  5. #5
    Join Date
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    At my last school, we had a hercus O mill that had an arbor stuck in the spindle. Previous teachers were fairly unconcerned about it, so it stayed in it for well over a decade. Well, it was at least a decade because the spindle never moved from the machine in the time I went from being a year 7 student to being a fresh out of university teacher, you could probably add a number of years on top of that quite easily. The arbor was very, very stuck. I ended up taking the spindle out of the machine and to a mate with a 100T press. We dropped a 20mm bar down the spindle and loaded it up. The 20mm bar curled up like a noodle as the pressure built up, and we were about to back it off and move to an even bigger press when it finally let go at 89 tonnes. A spark even came out of the taper when it released with an almighty bang.

    Anyway, my point is that you need to be aware that theres a time to call it quits on belting the back of the arbor and pull the spindle. All that force youre banging through its being taken up by the spindle bearings and when youve gotten tiny tim out, you need to start wondering how much abuse that bearing is taking.

  6. #6
    BobL is online now Member: Blue and white apron brigade
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    Potential damage is a product of applied force x time, so sometimes a press is not the right thing to use either. A series of short sharp hard impacts may be a better way to go. That's why impact guns do such a good job at removing stuck bolts/nuts. At the mens shed we had a stuck chuck on a small MW lathe and the blokes kept bending more and more metal bars stuck between the chuck jaws, with a locked back gear. At one point there were two blokes hanging of a bar and it would not budge and it was threatening to tip . The 87 year old fitter and turner (Our third oldest member) put some hex bar in the chuck and applied a rattle gun and it came loose.

  7. #7
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    Youre right, sometimes a hit is a good thing, but it only works because you can build up a given amount of energy before transfering it into the thing being pushed. Its just like getting a run up for a jump, rather than getting all that forward energy in one push, you build energy by running towards the place to jump. But the reality is that the force required to remove a taper is going to be the same whether you take a running jump or a slow push and theres no way anyone is going to be developing 89 tonnes of force with a hammer.

    Also, the risk of hitting stuff with a hammer is that youre going to peen things over, including the back of the taper. The 20mm rod we inserted into the arbor was threaded on the end so that both a shoulder and the thread was bearing on the arbor to try to disperse the load out as far as possible across the back of it.

  8. #8
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by scottyd View Post
    Youre right, sometimes a hit is a good thing, but it only works because you can build up a given amount of energy before transfering it into the thing being pushed. Its just like getting a run up for a jump, rather than getting all that forward energy in one push, you build energy by running towards the place to jump. But the reality is that the force required to remove a taper is going to be the same whether you take a running jump or a slow push and theres no way anyone is going to be developing 89 tonnes of force with a hammer.
    I really doubt anywhere near 89 tones of force would have been needed if short sharp impacts had been used.

    Most people give up too soon when using impacts. Think about how many impacts a rattle gun generates before something often moves. I had to hit mine about 20 times before it even moved and then another 5-6 more after that to get it out. If we were to really magnify the contact surfaces between a plug and socket we would see a few higher points on each in contact with each other and the loosening is a question of breaking these so called "stiction" points. When using something like a press it tries to break them all at the same time where as when impacts are used it breaks the grip of a few % of the "stiction" points at each blow.

    A much more relevant comparison than a jump is pushing nail into a block of wood with a press versus using a hammer. I've demoed this in front of students a number of times whereby a 4" nail usually used required around 700 - 800 kg to drive it into a block of hardwood, yet I could drive that same nail into the same block with 1 kg hammer.

    Also, the risk of hitting stuff with a hammer is that youre going to peen things over, including the back of the taper. The 20mm rod we inserted into the arbor was threaded on the end so that both a shoulder and the thread was bearing on the arbor to try to disperse the load out as far as possible across the back of it.
    I agree damage can be a problem but there are very easy ways to protect metal parts being struck using hardwood blocks or a lead or copper faced hammer. OTOH a press is much better than a hammer for things like bearings because you cannot protect the surfaces in between the bearings and race.

  9. #9
    Join Date
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    Thanks to all for the responses. Very much appreciated.

    I have found the engagement pin on the large gear. That was the part I had overlooked. The locknut came off easily after that.

    Does the end spacer pictured below also come off? When I try to remove it makes a sound off metal hitting metal. Could it be that it has worn a groove into the arbor or is it not meant to be removed?

    Also BobL and AnorakBob where do you apply the heat? from the inside with the door open? or from the front? Tried asking this is Bob's "i just bought a new mill" thread but it hasn't appeared. I am a compete newbie to using forums. Not really 100% sure what I am doing or even the etiquette. Hopefully I have got the second part right? I have given it a fair whack with a fairly big block hammer. Still no luck but will try again with the heat gun if I know where I should be heating.


    IMAG0206.jpg
    Attached Images Attached Images

  10. #10
    BobL is online now Member: Blue and white apron brigade
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    What exactly are you whacking?

    I'm just a noob myself but I applied the heat with a 650șC hot air gun with a small nozzle to the spindle (not the arbor) on the outside and the inside.
    Of course some heat will get onto the arbor there's naught you can do about that.

    Heat2.jpg

    Heat1.jpg

    You shouldn't be whacking any of the arbor at the front of the mill.
    This means any of the bar you can see.
    arbor.jpg

    I loosened the drawbar about a half turn and whacked the back end with a wooden mallet about 10 times before it came loose.
    Today Anorak Bob told me that whacking [EDIT" or more like striking or tapping] a 16mm Al rod from the back is a more gentle way to get the spindle out although I doubt that anything gentle would have got mine out
    Others may care to comment?

  11. #11
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    Robert,

    I don't know if I used the term whacking when I suggested the use of a 16mm aluminium bar as means of arbor ejection. I don't belt my arbors in so it doesn't take much more that a hard tap with the aluminium bar to pop the arbor out. No mallet or hammer required. If a drawbar was in use, I'd loosen the bar half a turn and tap it with a hide mallet or a dead blow hammer.

    Where you have indicated the application of heat is exactly were I would have applied it but I did use a puller to aid the extraction.

    BT

  12. #12
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by Anorak Bob View Post
    Robert,

    I don't know if I used the term whacking when I suggested the use of a 16mm aluminium bar as means of arbor ejection.
    I can't remember what you said but it probably wasn't whacking - it must have been my "blue and white apron" mind set coming out again.

  13. #13
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    Thanks Gents,

    I was backing of the drawbar nut a turn or so and hitting that with a dead blow hammer. Then I went up to a fairly substantial hammer and a block of timber but ended up just dinging the timber. I was only a piece of pine stud but it full of fairly deep 'penny marks' from the outline of the drawbar nut.

    Sounds like I am doing what you are describing with the heat gun. The spindle from the front and from the inside. Thanks for the pictures and advice, I very much appreciate it!!!

    Feeling a little like a butcher myself at the moment as I am whacking a precision piece of equipment with a hammer. At times a big hammer..

    My last try will be a 16mm solid bar. If that doesnt work I will either be only horizontal milling or putting it up for sale for someone else to take on as a project!!!!

    I will have a go this weekend. If I get it out you will hear me cheering from a block away.

  14. #14
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    Please please please, stop flogging those bearings and pull the spindle out, put it in a press. Do not go blasting it with a hot air gun, if youre that desperate, youre already hitting those bearings too hard. At the very lease, you can pull the spindle and arbor out together and support the spindle on a face that ISNT a tapered roller bearing.

  15. #15
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    Got it!!!!!

    Last time I ever have to hit it out!

    Thanks for all you advice, appreciate it

    IMAG0227.jpg

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