MXR knob screw

theatreanchor

I was playing around with a new JHS pedal today and after a little while I noticed that the tiny screw that holds the Mxr style knob on had gone missing. 

Does anyone know what these screws are called and where I can get them please? I assume they’re universal. 

Thanks!

EDIT  - the screw is still in there but the knob has come off for some reason?

BillDL

Is the shaft a solid round one with one flat side?

Does the knob have a small threaded hole through the side for the screw like a Telecaster metal knob?

If so the screw is generally referred to as a "grub screw" and will either have a Hex/Allen key or small flat-blade screwdriver end for you to tighten it.

It sounds as though it just wasn't tightened fully against the flat side of the shaft, in which case you need to inspect whether the screw has an Allen key or slot for a small flat-blade screwdriver.

JHS is American made, so it's probable (but not for certain) that the grub screw will be an imperial one rather than a metric one.  They come in various diameters and thread pitches, so they aren't universal between pedalmakers.  Given that the screw is still in the hole you won't have to get a replacement.

theatreanchor

@BillDL ;

Yes, solid with a flat side. Thank you. I think I’ll take it back to the shop as I only bought it two days ago! 

BillDL

It would probably be easy enough to rectify yourself, but in view of the fact that you only bought it 2 days ago I think you are doing the right thing.  If the grub screw is stripped, or the threads in the knob are stripped, then you would never get it tight and if you mess with it you could be accused of tampering with it and stripping it yourself.  Make it quite clear that you didn't want to tinker with it yourself.  If it is stripped, let them discover this and replace the pedal with a new one.  The store should have the right sized allen key or screwdriver, but give the knob a pull after they tighten it just to be sure.  Disappointing QC there from JHS.

theatreanchor

BillDL said:

It would probably be easy enough to rectify yourself, but in view of the fact that you only bought it 2 days ago I think you are doing the right thing.  If the grub screw is stripped, or the threads in the knob are stripped, then you would never get it tight and if you mess with it you could be accused of tampering with it and stripping it yourself.  Make it quite clear that you didn't want to tinker with it yourself.  If it is stripped, let them discover this and replace the pedal with a new one.  The store should have the right sized allen key or screwdriver, but give the knob a pull after they tighten it just to be sure.  Disappointing QC there from JHS.

Yes, I absolutely concur. I was worried about trying to fix it myself as I don’t have the tools. It’s never happened to me before, so it was quite a surprise!

roberty

Set screw knobs are great but those little grub screws are very easily lost

If anyone knows what they're called let me know please because I have a small pile of knobs with no screws 

jasonbone75

If it is a hex grub it will be a "cone point grub screw" or "cone point set screw". I have thousands at work! They often come with slotted screws as well but they are usually just "standard" i.e. slotted pan head screw and sometimes slotted cheese head screw depending on the actual head shape.

BillDL

You get 4 different ends on grub screws:  Cup Point (concave), Flat (very slightly bevelled), Dog Point (unthreaded thinner end), and Cone (sharp point).  For this type of application you would usually find the cone point so that it makes a tiny impression in the shaft to help the grip, or dog point.  Cone points tend to splay a bit if they are screwed against harder metal, and flat doesn't grip as well as the other three types.

roberty

I should get my calipers out and measure

jasonbone75

To add to this I have just found a pattern Davies knob on my desk and that has a slotted cup point grub screw in it made of some spongey alloy that might survive a couple of tightenings before it imploded!

theatreanchor

Must say, both JHS and Anderton's have been helpful. JHS sent me a video showing how to repair it (but I don't have the tools), and Anderton's are getting me a replacement. So, I guess that's sorted.