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  1. Biggadike

    Rotary elbow joint method for wire carrier.

    I'm looking at a reasonably exposed rotary wire joint on a wire link which will need to tolerate an angular change of around 90deg. In the past I've dealt with this by careful wire path and cable selection which works OK but isn't structurally good as it takes a lot of space for the wire void...
  2. Biggadike

    Pin on Steel bearing - tough one.

    CincMace. I haven't looked at it although aren't those specialist PE variants all moulded and fairly pricey? I must admit I'd worry about chemical attack in this application and abuse by users but its a good suggestion and I'll have a look. I know that stuff is tough.
  3. Biggadike

    Pin on Steel bearing - tough one.

    Hi Mike- Lots of points there - taking them in order.. I know the pin doesn't have to be round but if you could see the detail of the design you'd see that either you let the pin wear to a flat without galling or you'll be running on an edge from flat misalignment. This is largely due to the...
  4. Biggadike

    Pin on Steel bearing - tough one.

    Thanks Screwman, I did speak to Armaloy and got a quote. I've looked into lots of different surface treatments and its suprising how similar a large range of chemically different processes can be for a given application. My current favourite is the hard graphite coating. One thing I like about...
  5. Biggadike

    Pin on Steel bearing - tough one.

    Tmoose - This has been suggested a few times - the problem is that its a long, small diameter pin. Even with a good bearing in the centre, the pin wouldn't rotate as the small torque due to the small OD wouldn't overcome the bending forces trying to jam it. Added to that, this is an unsealed...
  6. Biggadike

    Pin on Steel bearing - tough one.

    Thanks guys, I'm in the UK and, looking at the materials you've mentioned, they seem easier to get in the US. I'll talk to my supplier about UK friendly equivalents for anti-galling, hardenable stainless steels. Screwman - I like the Nickel plus PTFE coating idea. Do you have any suppliers or...
  7. Biggadike

    Pin on Steel bearing - tough one.

    Again, responses in order.. Mike - If all of this was bigger, I would do just as you suggest. The whole pin arrangement would need to be approx 4x4mm with a central spindal within that. This thing needs to be durable and reliable in a harsh environment and I just can't feel condfident about...
  8. Biggadike

    Pin on Steel bearing - tough one.

    Answers in order... 1/ Silver Steel is a high nickel 1% carbon steel which has a hardness of 65 Rockwell C when hardened. Its pretty old school. 2/ The slot isn't a straight line - more of a wierd zig-zag, I would need multiple flats on it which would be difficult - but not impossible. Its...
  9. Biggadike

    Pin on Steel bearing - tough one.

    I am coating the pin and slot in Micro-mu micro-molecular tribofluid which gives a molecular layer of oil bonded to the suface. The original trials with stainless steel on both sides went better than you might exppect so I'm now trying hardened a silver steel pin (its an easy test I can do now)...
  10. Biggadike

    Pin on Steel bearing - tough one.

    I'm struggling with this one.. I've got a sprung loaded pull lever (for a switch) the motion of which is governed by a pin in a slot profile. (This provides detents and self centring etc.) The environment is difficult (unsealed unit on landing gear of aircraft) and I'm having problems with...
  11. Biggadike

    Structural bonding of aluminium

    Cory, It may be that their web sites aren't friendly enough to tell you what you need from cold. I used them to search for adhesives for aluminium and the ones they came up with were described as being non-structural. (maybe I'm just useless at decoding their web sistes) I'll revisit and look...
  12. Biggadike

    Structural bonding of aluminium

    Thanks TVP I tried Loctite and 3M but their stuff wasn't structural enough. I'll try the others... Chris
  13. Biggadike

    Structural bonding of aluminium

    We hear all the time that Automotive folks bond their alumiminium chassis together. Can anyone tell me of a supplier of the bonding agent - its proving hard to come by? Any tips and experiences would be welcome. Chris
  14. Biggadike

    MR Fluid Clutch design.

    I'm designing a clutch unit using Magnetorheological (MR) fluid. I've done lots of research and have tons of data and so on but I'd really like to hear from anyone who has actually used this stuff in a real application. Even if its general impressions and comments, they would be appreciated.
  15. Biggadike

    Screw fatigue in bending.

    BJP, We have our own 'shaker' (I think of it as a giant loud-speaker) but as is always the way, only have time and resource to test the final complete assembly, hence the need for figures. Given how many times people have generated the S-N curves for HT bolts, it suprising how elusive the...
  16. Biggadike

    Screw fatigue in bending.

    From our source VDI2230-1 was £269.77. (Index house - Berks). Unclesyd, - aren't the ANSI Organisation part of the axis of evil? :-)
  17. Biggadike

    Screw fatigue in bending.

    Unclesyd, I can't just whizz off and check web sites out because of security restrictions on access to e-mail sites. I can only see pre-approved sites which means I have to get new sites approved first.... In this case it was quicker just to do the calculations although I will have a look at...
  18. Biggadike

    Screw fatigue in bending.

    Thanks again, I'll check that now. Chris
  19. Biggadike

    Screw fatigue in bending.

    Thanks Jeff, That looks useful. I do know the stress profile across the core of the screw. I don't know whether the thread is rolled before or after heat treat but I can always assume worst case. The design is such to ensure the screw only sees axial stresses so no problems there. When I have...
  20. Biggadike

    Screw fatigue in bending.

    Funny you should mention welds... The reason for me putting these screws in is that the assembly used to be welded. The welds failed by cracking along the HAZ. As welds create homogenous material from assemblies, the crack was able to run through the assembly along the interconnected HAZ lines...

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