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  • rod mill new mech. & wheels for

    From Richard Smith@21:1/5 to All on Sat Aug 2 03:00:40 2025
    Hello there

    New mechanical part of rod-mill proposed design

    http://weldsmith.co.uk/greet/rodmill/pics/ptmp/250722_rodmill_mech_new.jpg

    Two questions I wanted to ask:
    * Overall does it look good?
    * what wheels should I use?

    Overall:

    Have friend with lathe, milling-machine, plenty of stock, etc.
    Hence design should be achievable.

    Already using electrical Variable Frequency Drive - no need to provide mechanical means to change speed.

    I propose the gearbox (with motor) is "free" on the shaft with "only"
    a moments / torque resisting connection from the motor feet to the
    machine frame.


    Wheels:

    The two on one shaft, closer side in the sketch, are driven.
    Need to transmit torque to the rod-mill shell.

    I looked through catalogue(s)
    eg.
    https://www.castors-online.co.uk

    Find would be wanting polyurethane tyre'ed wheels as slightly
    conformant and likely increase grip. Rubber would be fine too (?).

    Problem for this intended purpose is all have roller-bearing insert
    for "free-wheeling" on a fixed tubular mounting.

    I need those two wheels to be fixed onto the shaft - "locked" to the
    shaft.
    Suggestions?


    Regards,
    Rich S

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  • From Snag@21:1/5 to Richard Smith on Fri Aug 1 22:06:25 2025
    On 8/1/2025 9:00 PM, Richard Smith wrote:
    Hello there

    New mechanical part of rod-mill proposed design

    http://weldsmith.co.uk/greet/rodmill/pics/ptmp/250722_rodmill_mech_new.jpg

    Two questions I wanted to ask:
    * Overall does it look good?
    * what wheels should I use?

    Overall:

    Have friend with lathe, milling-machine, plenty of stock, etc.
    Hence design should be achievable.

    Already using electrical Variable Frequency Drive - no need to provide mechanical means to change speed.

    I propose the gearbox (with motor) is "free" on the shaft with "only"
    a moments / torque resisting connection from the motor feet to the
    machine frame.


    Wheels:

    The two on one shaft, closer side in the sketch, are driven.
    Need to transmit torque to the rod-mill shell.

    I looked through catalogue(s)
    eg.
    https://www.castors-online.co.uk

    Find would be wanting polyurethane tyre'ed wheels as slightly
    conformant and likely increase grip. Rubber would be fine too (?).

    Problem for this intended purpose is all have roller-bearing insert
    for "free-wheeling" on a fixed tubular mounting.

    I need those two wheels to be fixed onto the shaft - "locked" to the
    shaft.
    Suggestions?


    Regards,
    Rich S


    Use 2 shafts coupled by a belt or chain . Your wheels can be
    immobilized by injecting the bearings with epoxy resin . Locked to the
    shafts with shaft retaining loctite .
    Alternate suggestion : Use 2 pairs of cogged pulleys with enough
    slack in the belts to form a "saddle" for the drum to ride in .
    --
    Snag
    We live in a time where intelligent people
    are being silenced so that
    stupid people won't be offended.

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  • From Richard Smith@21:1/5 to Snag on Sat Aug 2 08:33:03 2025
    Snag <[email protected]> writes:

    On 8/1/2025 9:00 PM, Richard Smith wrote:
    Hello there
    New mechanical part of rod-mill proposed design
    http://weldsmith.co.uk/greet/rodmill/pics/ptmp/250722_rodmill_mech_new.jpg >> Two questions I wanted to ask:
    * Overall does it look good?
    * what wheels should I use?
    ...
    Regards,
    Rich S


    Use 2 shafts coupled by a belt or chain . Your wheels can be
    immobilized by injecting the bearings with epoxy resin . Locked to
    the shafts with shaft retaining loctite .
    Alternate suggestion : Use 2 pairs of cogged pulleys with enough
    slack in the belts to form a "saddle" for the drum to ride in .

    Hi there

    Friend helping is very opposed to belt-drives.
    He comes from and works in a commercial marine environment. A slipping
    or broken belt would mean death if you were trying to ride-out a storm.
    Someone else I independently know had to motor heading 30 hours heading
    to the Atlantic because there was not a moment they dared to turn the
    bow away from the weather so they could turn and run for their home
    port.
    I see where they are formed.

    But he does have a very good lathe, very good milling machine, etc.
    "The dream spec." is there to be had.

    I would have had a shaft with a wheel mounted to each end, and a
    belt-drive to a pulley in the middle, between the bearings.

    He did give me my "Mark 1" rod-mill - which is significant.

    Thanks for the idea of locking the wheels on with glue.
    Just not worth quibbling - get the mass produced item and pour in glue. However;
    Shaft diameter going into gearbox is something like 20mm - and
    presumably wheels would need to press over something about that
    diameter.

    What I did not say:

    Size of wheels - is constrained

    [using my function]
    (mill-crit-speed-familiar-units 220e-3 40e-3) ;; 99.69758329725619 ;; RPM
    So 100RPM would have my mill "centrifuging".

    You might want to run up to 70% of critical speed - you could have a
    shell configured as a ball-mill.

    So that is 70RPM for the mill shell.

    UK mains is 50Hz and motor runs at 1500PRM
    However; Variable Frequency Drive will go up to 60Hz, giving 1800RPM

    Have gearbox 15:1

    (/f 1800 15) ;; 120.0 ;; RPM - the fastest the drive-shaft can turn.

    70RPM of mill with 240mm outside dia. the wheels are working on...

    (* (/f 70 120) 240) ;; 140.0 ;; mm dia.
    140mm dia. is the smallest drive wheel which can be used.

    So 150mm diameter wheel looks good if 140dia wheel not available.
    Given induction motor's presumed typical phase slippage - 150dia
    wheel...

    The gearbox has a "female" coupling taking an 18mm diameter shaft.
    The drive shaft will be likely 20mm diameter - turned-down to 18mm and
    keyway milled for the gearbox. The 20mm diameter is what the wheels
    would need to mount on.

    Does this take us to a different solution?

    My friend repairs and replaces engines, makes custom machines, etc.,
    etc.
    The solution can be "precision".

    Rgds Rich S.

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