Best DIY tool or method to create a flat face on a needle roller bearing ?

Discussion in 'Engineers' Talk' started by free_flyer, May 27, 2022.

  1. free_flyer

    free_flyer Member

    What is the best DIY tool or method to create a flat face on a needle roller bearing ?


    These are the needle roller bearings..

    I need to do this to 18 needle roller bearings, I tried with an angle grinder and despite the bearings being hardened, it did remove the material.

    But its not possible to get any kind of accuracy with an angle grinder and a vice.

    This is the other issue, how to clamp the bearings when creating the face?

    Attached Files:

  2. nigel willson

    nigel willson Screwfix Select

    Think you need to go to your local small engineering works for something like that
  3. free_flyer

    free_flyer Member

    Thanks, from quotes I’ve had for similar parts it’s been very expensive to get parts machined
  4. nigel willson

    nigel willson Screwfix Select

    Didn’t say it would be cheap, you asked how to do it!
    Abbadon2001 and malkie129 like this.
  5. They best way I can think of is to clamp via the flat surfaces then use a surface grinder.
    free_flyer likes this.
  6. MRY

    MRY Screwfix Select

    I have no idea what you are up to, but I made some octagonal roller bearings once, by running them in the big end of a Matchless motorcycle....

    Anyway. How accurate does this need to be? If you've been trying with an angle grinder, my guess is "not very", but....

    You could pull them up in a vice, remove most of the material with your grinder, and then finish on wet'n'dry, used wet, or perhaps make a carrier by drilling and cutting a steel block to suit and then using a belt sander/wet'n'dry or a carborundum stone to finish... does the hardness of the finished article matter? Aggressively grinding these will make them hot and change their hardness.
    free_flyer likes this.
  7. free_flyer

    free_flyer Member

    This is for a magnetic switch design, all I need is the shape as shown and the material to be ferromagnetic.

    Maximum tolerance at a guess would be +/- 0.5mm, maybe ideally +/-0.2mm

    I do not need the hardness that these bearings have, its just that they were cheap, have a smooth top and bottom face (which is important) and are coated so wont corrode.

    Although I'm not sure if creating this face will mean they will then be susceptible to corrosion ?

    This is a similar sort of magnetic switch design...

    The problem with the bearings is that there is an airgap between the magnets and the bearings (up to 2mm) which drastically affects the efficiency (magnetism vs airgap falls away exponentially) so that means you need bigger magnets and bigger bearings to achieve the same pull force.

    I need to make the package smaller, which I believe I can do if I can remove the air gap, but this requires a flat face on the bearing.
  8. MRY

    MRY Screwfix Select

    I am not sure what "coated" means. Roller bearings aren't coated with anything, they're just fairly high carbon steel, possibly with admixtures. Bearing in mind the wide acceptable tolerance of +/-0.2mm, you could just use the required diameter steel rod stock and file it up, or as above for grinding down bearing rollers.
    free_flyer likes this.
  9. Hausfix

    Hausfix Screwfix Select

    Hot melt glue all the bearings in a neat line next to each other on to a thin strip of wood that’s slightly narrower than length of each bearing. Then clamp this collated strip of bearings into your vice so only the portion you wish to remove is exposed above the jaws. Then evenly remove the bulk of the material from all the bearings at the same time with your angle grinder, cooling them with water after each pass. When you are a tenth of a mm from the finished size, complete the job with a belt sander with gradually finer grades of abrasive.
    Abbadon2001 and free_flyer like this.
  10. free_flyer

    free_flyer Member

    Thanks, I didnt realise the bearings arent coated/plated.

    Are these bearings resistant to rust ?

    If so, if I created this flat face would that face also be resistant to rust ?

    I made a prototype using square stock rod (see me earlier post )

    But these were difficult to make using just a hack saw, vice and file. In fact they came out terrible and I need very smooth surfaces otherwise the magnetic switch becomes too difficult to operate (high force required).

    In addition to this the bar is not plated, so will rust over time.

    Whereas I 'assume' the bearings wont rust and they have a very smooth surface on the flat ends which makes a huge difference to the operation force.
  11. free_flyer

    free_flyer Member

    PS. There is a linisher at work I could use. Though when I used it with multiple pieces of the square bar the pieces went flying everywhere !
    Last edited: May 28, 2022
  12. vrDrew63

    vrDrew63 Active Member

    I think a benchtop disc sander is your best bet. (Your linisher would work perfectly!)

    Take a piece of wood roughly 20mm x 40mm x 80mm and drill an 8mm diameter hole down the centre of the 20x40 face. Saw this block in half on the small face so you end up splitting the hole, ending up with pieces with semi-circular "gutters" in them. Superglue your magnets into the "gutters". You'll only get about half your magnets in each piece of wood, so you'll either have to re-use the wood, or make another similar/identical piece. Just make sure the end of this piece of wood is cut absolutely perpendicular to the hole you've just drilled.

    Use the mitre-gauge attachment of a bench top disc sander (the table of which you've made sure is absolutely perpendicular to the sand disc) to gradually grind away material from the bearing, creating flat, smooth, and even faces.

    It might take a little experimenting to get perfect. But I think with some effort you could achieve a fairly high degree of precision and accuracy.
    free_flyer likes this.
  13. MRY

    MRY Screwfix Select

    Only insofar as they normally run in oil. They're just plain steel.


    Your idea of grinding a flat on the side of bearing rollers seems rather different from the near-cubes of metal in your other thread (which seems to have fizzled out)!
    free_flyer likes this.
  14. MRY

    MRY Screwfix Select

    You could use such a thing, but holding the workpiece will be your difficulty, hence using some sort of holder. I doubt sticking them onto something will work, 'cos they will get hot.

    Perhaps you could use two pieces of bar, drilled and threaded, to hold the rollers and act as a stop for the grinding?
    Last edited: May 28, 2022
    free_flyer likes this.
  15. Astramax

    Astramax Super Member

    You need a powerful magnetic table and a surface grinder to do this job with accuracy.
    free_flyer likes this.
  16. MRY

    MRY Screwfix Select

    Something like this... (you would have to find something that the bearings would fit into, and arrange them so thet the jaws grip the flat ends).
    free_flyer likes this.
  17. free_flyer

    free_flyer Member

    Thanks all, I'm going to try a different approach.

    Rather than use hardened needle roller bearings, I'm going to try spherical bearings which are actually catapult ammo balls and therefore not hardened...

    I've already got some 12.7mm diameter balls and tried filing them. As expected, they are a much softer material to work with.

    However, it does mean that I need to file 3 faces on each ball (each face will be a diameter of 6mm). Therefore it will involve more work and requires some kind of jig to hold them in place whilst filing.

    I have designed a 3D printed jig to hold the bearings, although I don't know how well this will actually work.

    The jig is in 2 parts so the balls can be inserted and then clamped together with bolts...






    As the jig will be 3D printed from plastic, I expect the balls will move around as I wont be able to clamp it with much force. And also whilst filing the balls its likely to file the plastic too, so I might have to print multiple jigs. Unless there is a better way to do this ?

    I did ask if its possible to buy unhardened loose needle roller bearings, but the supplier said they have tried to get these from the manufacture in the past but without any success.
  18. MRY

    MRY Screwfix Select

    So anneal them.

    But I don't know, I've seen cubes of mild steel, soft ball bearings, roller bearings, and I still don't understand what you're trying to do or why any of these shapes are interchangeable.
    free_flyer likes this.
  19. free_flyer

    free_flyer Member

    How do I anneal them at home ? I dont have a furnace or access to a furnace, unless a kitchen oven is suitable ?

    To understand what I'm trying to do, watch this video which explains how to build a magnetic switch...

    In the video he uses stock round bar, but for the parts I am using there is up to a 2mm air gap between the magnet and roller bearings as shown below (top plan view)...


    Magnetism drops off exponentially when there is an air gap, so this drastically affects the holding force of the magnet switch
  20. MRY

    MRY Screwfix Select

    So why not use your needle rollers end on? Then you would not need to file or machine anything.

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