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  1. #1
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    Default Hercus Model O Vertical Head Clearance

    I am the owner of Hercus Model O serial number OLM670. A couple of years ago, I posted problems I was having with a noisy spindle on my mill. That was fixed but then I experienced a lack of torque which caused me to not use the machine. I was doing other things which meant I didn't get back to work out why the lack of torque. I now know what the problem is. I fitted a Teco FM50 VFD as I only have single phase supply in the shed and the motor was a 3 phase. The motor which came with the mill was rated at 415 in delta. An electrician came and pointed out that the VFD was only putting out 240 volts and this accounted for the lack of torque. I have just fitted a new motor and the electrician will come back later in the week to finalise the connection of this new motor (240V in delta, 0.75kw) to the VFD. In anticipation of the machine working properly again, I have been looking at another problem which needs to be fixed. When I tighten the vertical head down, the machine binds up. What is happening is that there is no clearance between the gear on the end of the spindle and the vertical head housing. The lack of clearance only shows up in the last few thous of tightening the vertical head. The photo below shows that the interference between the spindle gear and the housing has caused damage though rubbing on the vertical head housing. I don't know whether the clearance problem came about when I re-installed the spindle after its repair. Regardless, what I am thinking is that the vertical head needs to be relieved slightly to provide the necessary clearance with the spindle gear. I was thinking that the light use of a die grinder on the vertical head housing would be suitable for increasing the clearance. Any thoughts? Greg
    Hercus Mill 1.jpgHercus Mill 2.jpgHercus Mill 3.jpg

  2. #2
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    Hello Greg,

    I hope you don't mind but I took the liberty of rotating your photos.

    The head is different from the older 2 slot table mills. You have 4 mounting bolts, we have three. Can you post a photo of the drive gear and arbor assembly, mounted and unmounted?

    Bob.

    Hercus Mill 1.jpgHercus Mill 2.jpgHercus Mill 3.jpg

    ps. Flash looking vice, how about a few photos of it as well.

  3. #3
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    Wink

    Bob,

    No problems with rotating the images. I have not worked out how to do it. The images I have attached to this post are also not upright. Let me know how to do it and I will get it right next time!

    The first image shows the drive gear that seems to be interfering with the vertical head housing.

    The second image shows the vice that came with the machine. I am not sure if this is a Hercus vice. Do you or anybody else know? It certainly is a very substantial item.

    The vice that you saw in the earlier post (picture below) is a Vertex vice that I bought from Hare and Forbes here in Sydney a few years ago at one of their sales. It has been a fantastic piece of kit. Quite expensive but I am happy I spent a bit extra to get a quality piece of kit.

    You may have noticed the four washers between the vertical head and the main body of the mill in the earlier post. The reason they are there was to give clearance between the drive gear and the vertical head housing. However, it is not a long term solution to the problem I have got.

    Thanks for any advice you can give me.

    Greg


    photo copy 2.jpgphoto.jpgphoto copy.jpg

  4. #4
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    Greg,

    I save my photos in Pictures and simply rotate them there. You can save them anywhere really and you should be able to fiddle around with them . I also resize all the images I post on this forum.

    Bob.

    photo copy 2.jpgphoto copy.jpgphoto.jpg

  5. #5
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    Talking

    Bob,

    Thanks for that. I was trying to rotate them inside the post and I couldn't see how to do it.

    Greg

  6. #6
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    The first thing I would check is how well the gears are meshing. I am guessing without you washers the gears may only be making 90% or so contact. It would be pretty easy to measure from the column to the rear of the drive gear and from the back of the vertical head to the rear of the driven gear. That should at least give you some dimensions to work with.

    Ew
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  7. #7
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    Quote Originally Posted by Ueee View Post
    The first thing I would check is how well the gears are meshing. I am guessing without you washers the gears may only be making 90% or so contact. It would be pretty easy to measure from the column to the rear of the drive gear and from the back of the vertical head to the rear of the driven gear. That should at least give you some dimensions to work with.

    Ew
    A question to ask is did the head fit properly prior to the spindle removal? The 3 slotter differs considerably from the older mills. I could pop the head of mine and measure up but we wouldn't be comparing apples to apples. I'm wondering if Greg's spindle is seated correctly?

    BT

  8. #8
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    To answer Bob and Ew's questions below:

    Bob, I didn't fit the vertical head before I refurbished the spindle so I don't know if there was interference beforehand. That would have been nice to know.

    I have measured some of the dimensions that Ew has mentioned, as best I could. The drive gear projects 47.64 mm to the outside face of the gear beyond the column. The drive gear is 19.12 mm wide and is 28.52 mm from the inside face of the gear to the column.

    The housing of the vertical head is rough cast on the inside surface (as you can see from an earlier photo) but the depth of the housing is approximately 47.62 mm measured from the face of the housing. So you can see that nominally there is .02 mm of interference between the outside face of the drive gear and the inside of the housing. The driven gear inside face (closest to the column) is 29.51 mm away from the face of the vertical head and the driven gear is 16.87 mm wide. So there is complete engagement by the driven gear with the drive gear.

    So how to fix this interference problem? There seem to be two options:

    Option 1: machine a suitable amount off the drive gear to eliminate the interference between that gear and the housing or
    Option 2: relieve the vertical head housing slightly (with a die grinder or similar) to give the required clearance with the drive gear.

    There does not appear to be an option of moving the spindle to give the clearance as the spindle does not have an ability to adjust in its design. The spindle take up night pulls the whole spindle assembly up tight in the column and you can't move it or shim it to get the required clearance.

    I am thinking that Option 2 is the way to go because I don't want to mess with the drive gear. It won't need much material removed (notionally something like 0.02mm) to give the required clearance.

    Greg

  9. #9
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    Seems odd that the gears are different thicknesses.

    Since it is such a small amount grinding might be the easiest option, however you want to make sure you don't get any of the dust in the head or any left on the gears. In that regard skimming a little of the gear may be better, either put it in the lathe or mount a tool on the mill table.

    Ew
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  10. #10
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    Hi Ew,

    I decided to do what you recommended today and it has resolved the problem. I put bearing blue on the drive gear and saw where the gear was interfering with the housing. I used the die grinder with a cylindrical burr to deal with the areas of interference and eventually the drive gear did not rub any more.

    Trying to keep the abrasive particles from the casting off the gears and the inside of the housing was a major consideration. I used compressed air to blow the area out and WD40 to wash away any residual abrasive. I hope that this has been successful. I took a lot of care to ensure there was no abrasive left in the area. But you cannot be completely sure you have been successful.....

    Thanks to you and Bob for your advice.

    Greg

  11. #11
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    I'm glad you have it fixed-time to make some chips!

    Cheers,
    Ew
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  12. #12
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    It's great to hear that the O is now working as it should Greg.

    I would love to see some photos of the 16 speed drive setup and some shots inside the main body having never seen a late model mill.( I am happy to rotate them.)
    Another thing. Have you checked that there is no grease in the nipples on the head? My mill had a "use oil only" warning which was ignored.

    Bob.

  13. #13
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    Bob,

    Here is a photo of the drive arrangement inside the column and a photo of the speed table inside the door (sorry about the flash). The spped table is upside down. I re-oriented it in Picasa, which is a photo management applciation. I don't know why it is upside down!

    My mill has a VFD so the speeds are actually completely variable between close to nothing through to 2000rpm.

    Have you go a photo of the earlier model drive arrangement?

    Greg

    Hercus Mill 4.jpgHercus Mill 6.jpg

  14. #14
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    Hi Greg,

    The innards look much the same as a 2 slotter's. The motor mount must be where the difference lies. How are the speeds changed on the motor pulleys?

    I plan to reinstall a single phase TECO motor I had on my mill before I acquired a VFD. I will take a few photos while it's apart.

    I'm too old for handstands so here's your photo the right way up.

    Bob.

    Hercus Mill 4.jpg

  15. #15
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    Bob,

    You are right. There is a two speed gear on the motor drive. i should have sent a photo of this in the earlier set. Photo of the motor drive gear enclosed.




    Greg
    Hercus Mill 8.jpg

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