Need help connecting an aluminium shaft to a steel shaft
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  1. #1
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    Default Need help connecting an aluminium shaft to a steel shaft

    Hello everybody,

    This is my first post here and I was wondering if somebody could help me with an issue I'm having.

    I need to connect two hollow shafts together. The main problems that I am having are:

    1)One is made from steel and the other aluminium.

    2)They have a different outer diameter and inner diameter (therefore won't fit without some kind of insert).

    The dimensions are as follows:

    Steel piece - Inside dia = 19mm
    - Outside dia = 27.1mm
    - Length 25mm

    Aluminium piece - Inside dia = 6.8mm
    - Outside dia = 15.9mm
    - Length = 24mm

    I had an idea to make a type of bushing insert that I could then secure inside the steel piece. To secure it I thought I could either shrink fit it in, it with something like Loctite 638, or a combination of both. The aluminium shaft could be welded to the insert if it was made from aluminium.

    The torque on the shaft will be around 20Nm so this is also something that needs to be considered.

    Thank you for any help you can provide

    Jon

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    Depends on if it needs to come apart again. Can they overlap (one inside the other) or just butt up to each other. ?

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    If it can overlap I would make an OD/ID threaded reducer.

    This reminds me of a time I walked into a friend's garage and he says to me "Hey I thought you can MIG weld aluminum?" I started explaining to him yes you can but you need a constant voltage/current machine and a spool gun and 100% argon, yada yada. I stopped mid sentence when I looked down and realized he had been using his 110 buzz box to try and short arc a piece of aluminum sheet to a piece of steel tubing. I couldn't help but lmao

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    IMO the simplest way is the best. Machine the bushing/adapter to close sliding fits, Loctite, and perhaps use a few radially dispersed tiny roll pins as supplemental connection.

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    That's what I was going to suggest also, light press fit bushings and secure with roll pins.

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    Quote Originally Posted by Scottl View Post
    IMO the simplest way is the best. Machine the bushing/adapter to close sliding fits, Loctite, and perhaps use a few radially dispersed tiny roll pins as supplemental connection.
    and with finding what the needed/best clearance for the loctite might be
    Or have some flats at sides at that clearance for a place for loctite to go/fill.

    May need to decide if it need come apart..some lictite can be set free with heat and some can not.

    or threads at OD of aluminum and ID of steel and some lictite...

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    Quote Originally Posted by AJ H View Post
    .........I looked down and realized he had been using his 110 buzz box to try and short arc a piece of aluminum sheet to a piece of steel tubing. I couldn't help but lmao
    It works fine! Don't you know you just have to use unobtainium wire???

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    There's probably a number of ways to do this, but I would want to consider more factors. For instance, the alloys. Some aluminum alloys are hard and others are dead soft and could easily deform with the loads imposed by something like a roll pin or set screw. Even a threaded adopter between the two shafts that is properly tightened into aluminum threads could ride further up on those threads in time, particularly with shock loads.

    My first thought is that a compression style connection to at least the aluminum shaft would be best. That could be a two part clamp tightened with a pair of screws or a split clamp tightened with one screw or one that uses a collet or compression ring tightened with a tapered nut. Or one of the fancy, proprietary ones.

    Also, do you need to provide for any misalignment between those shafts? Offset? Angular? Both?

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    Machine two flanges that bolt together . Each flange has a hollow stub that fits over the tube. Fasten the flange to the pipe any way you want. Bolt flanges together. This method allows the pipes to disconnect if needed.
    mike

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    Does it need to be 2 different materials?

    Sounds like your trying to make an adapted to go between 2 different couplings? Is it easier to make 1 new coupling than an adapted ?

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    What Mike said, and put a piece of rubber sheet between the two flanges to take care of any minor misalignment.

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    Press or thread a slug into the steel piece with an extension. Drill and tap the slug, then cut threads on the aluminum end and thread them together.

    Or, if you need it hollow, you could bore out the smaller aluminum shaft a bit, then turn a plug the entire length of the two, stepped to the two different id's, press them together, then bore a single hole through the slug.


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