Small Hermle screws with hexagonal insets

Discussion in 'Clock Repair' started by NEW65, Jul 4, 2018.

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  1. NEW65

    NEW65 Registered User

    Nov 17, 2010
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    Hi Folks,
    Anyone familiar with the later Hermle movements such as the 1151's, 1161's, 451's etc etc will have noticed that the older slotted machine screws have been exchanged to the hexagonal machine screws in the chime stop, chime count components etc
    This is an improvement but i am having difficulties in finding the correct size Allen Key! I have tried a 1.5mm key but that is slightly too sloppy... it tightens but not enough! I then tried 1/16th inch key but that appears to be just a fraction too tight. It does enter the screw but doesn't fully locate so there's a risk of rounding using either of the above keys.
    Can anyone let me know what size Allen Key is needed?? I think the machine screws all the same size.
    Thanks as always.
    :)
     
  2. Uhralt

    Uhralt Registered User
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    I've been frustrated finding a fitting key for a bathroom faucet, the hidden screw that holds the handle. I ended up using one that was a bit too tight and just filed it down a little. I think that's the most time and money saving way to do it.

    Uhralt
     
  3. roughbarked

    roughbarked Registered User

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    #3 roughbarked, Jul 4, 2018
    Last edited: Jul 4, 2018
    The various tools can be purchased. Let me try and break it down a bit. Everyone knows about slot headed screws that use a blade or phillips head screws. Everyone should also be aware of the hex key or allen key which is commonly used in Ikea furniture among other things. These are all methods of both having a secure grip which increases available torque to both tighten and loosen screws or bolts as well as reducing slippage and damage of heads. Some of these types are used in electronics to discourage people from dismantling things that may cause them danger.

    Hence Torx = https://www.amazon.com/Screwdriver-Socket-Driver-Double-Sided-L2go/dp/B005XFTU9Y

    List of screw drives - Wikipedia

    How to Make Torx Screwdrivers or Allen Keys



    An Australian store that sells all these types of hardware and tools. Hex and Torx Keys available from Bunnings Warehouse
     
  4. dAz57

    dAz57 Registered User

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    #4 dAz57, Jul 4, 2018
    Last edited: Jul 4, 2018
    Also look on the bay for hex drivers used in RC helicopters and models, these have a decent machined alloy handle and a hardened machine ground tip, you can buy them individually or a in a set, both in metric and imperial.

    A set is $10 or less and so much better than an L wrench

    The set screws shown are 2mm, 2.5mm, 3mm, 4mm, 5mm in stainless, With the smaller sizes of the drivers just use two fingers to tighten the set screw, and it you do break one you can get replacement blades.

    View attachment 484537 View attachment 484536
     
  5. dAz57

    dAz57 Registered User

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    Photos of my drivers

    20180705_113543.jpg

    20180705_113644.jpg
     
  6. Willie X

    Willie X Registered User

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    They are a .1mm increment metric size, available from the clock supply houses.
    I think mine came from Merritt's. I bought mine when they first started using them and it was a set of two hex wrenches that was made to fit all Hermle movements. Willie X
     
  7. roughbarked

    roughbarked Registered User

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    1mm is difficult without specialist advice. less than that and you do need to search more.
    I asked at my local Bunnings(the shed that blocks the sun), he said, "we only go down to 1mm and we have one that can do stainless steel. You really are sure you want to use this drill bit?!".
    Me, "yeah. I often use smaller. The problem is, finding adequate replacements. The ones I have worn out are sixty years old or more".
     
  8. Willie X

    Willie X Registered User

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    #8 Willie X, Jul 5, 2018
    Last edited: Jul 5, 2018
    The afore mentioned keys, in the kit, were 1.3 and 1.5mm. The 1.3 is by far the most common but evidently you need the 1.5 mm. It may be a good idea to check the keys you have with a micrometer. I suspect you will find your 1.5 mm key either undersize or worn out. Unsersize can't be fixed but worn out can be made right by grinding off about 1/16" from the tip. Willie X
     
  9. dAz57

    dAz57 Registered User

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    3mm set screw uses the 1.5mm hex driver, 2.5mm set screw uses 1.3mm hex driver and the 2mm set screw uses the 0.9mm hex driver.

    Using cheap drivers risks rounding out the set screw hole, the divers I use have hardened ground tips and will last for years.
     
  10. NEW65

    NEW65 Registered User

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    Thank you for all you comments - Willie, I never thought about that ie., the fact that the 1.5mm key seemed a bit sloppy when the reason could be wear! Will do as you suggested 9and Uhralt suggested) and grind down the 1/16th Allen Key). I am unsure why I didn't think about that possibility, Willie!! I do like the ideas that have been mentioned on here though... Daz57 I quite like your selection of drivers too, thanks for going to the trouble of adding the pictures, I do appreciate it. Great Video roughbarked! Very informative! Willie, will take a look at Merritts too.. don't think Timesavers have these.
     

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