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Spare parts Double Bass endpin

Discussion in 'Setup & Repair [DB]' started by Ian Johnson, Dec 2, 2017.


  1. Ian Johnson

    Ian Johnson

    Dec 2, 2017
    6D1F66D7-A830-4F47-82F9-391DECD81E9A.
    Hi I am trying to locate a piece for my Double Bass end pin.
    The threads have stripped on the thumbscrew, rendering the recipient ring piece around the pin useless.
    Could I buy a spare ? Can’t find one on the web.
    The hole circumstance is exactly 1 inch.
    All help appreciated
     
  2. Steven Ayres

    Steven Ayres Supporting Member

    Mar 11, 2007
    Northern Arizona
    It looks like the screw has stripped, so it's probably better to keep the ring and get a new steel screw instead of brass. This is a very common repair. In the worst case you'll have to get a larger screw and run a matching tap into the ring.
     
  3. neilG

    neilG

    Jun 15, 2003
    Ventura, CA
    If it's just the screw, replace it. But if it's the female thread, you need to repair. I just repaired the thread on my endpin last night using an EZ-Lok insert. It's quick to do if you have the needed parts and tools. Here's the insert: Solid Threaded Inserts | Carbon Steel Inserts | E-Z LOK
    I also had to get a new thumbscrew. I have more of the inserts so if you live in the USA, I'll mail you one.
     
  4. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Another option is to drill and tap a new threaded hole somewhere else on the collar. Replace the thumbscrew in any case, and you might try M6 instead of 1/4-20 since there are more threads. You can get thumb screws and taps at McMaster.com. I prefer an "Iron Wing-Head Thumb Screw". If you aren't comfortable tapping the hole, any auto shop can do it.
     
    Last edited: Dec 4, 2017
    misterbadger and neilG like this.
  5. neilG

    neilG

    Jun 15, 2003
    Ventura, CA
    I used an insert with M6 internal threads. Outside tap was 3/8-16 which you can get at any hardware store in the USA.
     
  6. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    That approach has extreme durability, but don't you need a specialized tool ($) to install it?
     
  7. neilG

    neilG

    Jun 15, 2003
    Ventura, CA
    No, these you can drive with a screwdriver. It has two notches. They make a drive tool, but you only need it if you are doing a lot of these. Except for stopping to sharpen my drill bit, the whole repair took less than 5 minutes.
     
    robobass likes this.
  8. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Sorry about the repeats. Some scaffolding is blocking my WiFi connection, with weird results.
     
  9. Don Kasper

    Don Kasper Supporting Member

    I think you are thinking of a "Heli-coil", which does need a special tool.
    Here is a pic of a 3/8-16 o.d., 10-32 i.d., E-Z Lok threaded insert (in Stainless Steel.)
    So cool...
    Thanks.
    IMG_3183(1).JPG
     
  10. Steven Ayres

    Steven Ayres Supporting Member

    Mar 11, 2007
    Northern Arizona
    Bearing in mind that if you're using a brass screw, you'll be back where you started pretty quick.
     
  11. turf3

    turf3

    Sep 26, 2011
    There is no reason why a brass screw in that location should strip if the female thread is in good condition, unless you routinely put Vise Grips on the screw and crank it down with all your strength. That said, I would still use a steel screw. Also, the ring is very lightly stressed so another hole in it won't hurt; I would just drill and tap another hole, a bigger one than current. (that way you can't try to force the new screw into the old hole.) Also I would file a point on the screw so it will be guaranteed to engage the notches in the end pin.
     
  12. misterbadger

    misterbadger Supporting Member

    Sep 13, 2012
    Northern California
    A strong vote for a brass screw. If something's going to wear, it's good practice to make it the part that's easier to replace. Buy a spare thumbscrew, which pretty much guarantees that you'll never need it. I wouldn't file the screw tip to a point because it reduces the bearing surface on the pin. Just chamfer the screw tip enough so it can easily find the notch and seat well.
     
  13. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    That collar is probably plated brass, but even if not, the threads in the hole will probably be damaged if the screw is stripped, whatever the material. I would use an iron screw, which will last a very long time.

    There is more force on that spot than you think. Otherwise, why would this be such a common problem? Think about setting a 30-40 lb. weight on the edge of a 1/5th" protruding shaft and constantly bouncing it around. Any mechanical engineer will tell you it's a bad idea:)
     
    Last edited: Dec 7, 2017 at 4:18 AM
  14. turf3

    turf3

    Sep 26, 2011
    Yeah, but the force is perpendicular to the screw, which is why the screw getting stripped is a bit of a mystery to me. My money would be on either bad female threads to begin with, or someone using a screw of the wrong thread, or bouncing it around with the screw not tightened so it cocks back and forth.

    To the poster just above this, I agree not to file it to a real point but rather just chamfer it down so it will engage the notches. Easy enough to match the shape of the end of the screw to the shape of the notches.
     
    misterbadger likes this.
  15. misterbadger

    misterbadger Supporting Member

    Sep 13, 2012
    Northern California
    And, if the collar's brass (I'll find a magnet and check mine), using an iron screw is a good way to insure that if something strips, it'll be the collar.

    My local hardware store carries thumb screws. DB endpin collars? Not so much. Much less trouble and time involved in changing a screw than reworking an endpin collar too. YMMV.
     
    DoubleMIDI likes this.
  16. Steven Ayres

    Steven Ayres Supporting Member

    Mar 11, 2007
    Northern Arizona
    My point is that the materials have to match in hardness. In the OP the plating is clearly gone off the screw and the threads appear worn down, indicating a brass screw in a steel ring.
     
    misterbadger likes this.
  17. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Guys,
    There are a lot of things I don't know much about, but threads in metal is not one of them:)

    Because the screw bends and deforms each time you set your bass down with anything but the most gentle force. The screw threads become compressed and no longer parallel, so when you turn the screw, you damage both them and the threads in the collar.

    Again, damage to the screw thread leads to damage in the collar thread, even if it is steel. A harder and stronger screw will reduce both phenomena. As bad as this system is mechanically, once you have purchased an iron screw and prepared a fresh threaded hole or mounted an insert, you should be good to go for a long time.
     
    DoubleMIDI likes this.
  18. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Look at the ring again. It's unquestionably plated brass. That ain't the issue though. See above post!
     
  19. robobass

    robobass

    Aug 1, 2005
    Cologne, Germany
    Private Inventor - Bass Capos
    Here is an argument for my case:
    screwdeflection.
    Unlike conventional shaft/collar assemblies in machinery, there is a fair distance between the inside of the ring and the pin. Push on the pin and you have a lot of bending force on the the set screw. This system is not durable no matter what you do, but a strong screw is advantageous.
     
    John Chambliss likes this.
  20. misterbadger

    misterbadger Supporting Member

    Sep 13, 2012
    Northern California
    And to think that this poor schlemiel joined TB with a simple question about his endpin collar!
     
    Povl Carstensen likes this.