Purpose of Grub Screw

[steveoelliott]

Hi Folks,

 

Anybody know the purpose of this grub screw in the photo? Whether it is tight, loose or not present seems to make no practical difference. On some of my doors they have a habit of working themselves loose and need tightening every now and then.

 

The handles are made by M.Marcus.

 

I've noticed that some of the handles have play / movement in them, I presume this is simply down to wear on the spring etc inside.

 

I'm not a great fan of these handles in general as they have a tendency to work loose on the door requiring tightening periodically but from speaking to some carpenters I know it is a fairly common issue.

 

Thanks...

[SteamyTea]

1 minute ago, steveoelliott said:

not a great fan of these handles in general as they have a tendency to work loose on the door requiring tightening periodically but from speaking to some carpenters I know it is a fairly common issue.

Is that because the grub screws on both handles are not tightened down to the shaft? 

[Onoff]

I tend to take out and very lightly drill the square shaft where the grub screw has marked it in order for the point of the grub screw to go into something.

 

For repeat looseners I'll apply low strength Loctite. 

[Jenki]

The grub screw one on both sides grips the spindle that actuates the latch. The idea is that it prevents the handles becoming loose.

Some spindles are spit and the grub screw expands the shaft thus locking it in place. If not do as @Onoff suggests.

[Onoff]

Some square shafts have a V groove in them for the grub screw to locate. I've drilled them too!

[Onoff]

Grubscrews in door handles are often made of cheese nowadays. Over zealous application of the Allen key results in the hex in the screw rounding off.

[SteamyTea]

27 minutes ago, Onoff said:

Grubscrews in door handles are often made of cheese nowadays.

Artisan cheese is often made with grubs.

[steveoelliott]

Now that I have "tightened" these the handles do seem to hold a little firmer. Not sure I can be bothered with drilling them now but I can see the logic.

[saveasteading]

If you don't have them already, it is worth getting a set of small, precise, hard screwdriver heads. I find I use them a lot on watch straps, electronics etc...and grub screws. They provide a better fit to very small screws, are harder steel and so can tighten better. I think mine was a set of heads with handle from TS.

 

[Onoff]

31 minutes ago, SteamyTea said:

Artisan cheese is often made with grubs.

 

Ah yes, casu martzu...I wouldn't! 

[Temp]

5 hours ago, steveoelliott said:

I've noticed that some of the handles have play / movement in them, I presume this is simply down to wear on the spring etc inside.

 

There is no global standard size for the square door spindle ! Some are 7mm, 7.6mm, 7.8mm 8mm etc

 

So locks are made with 8mm holes (?) on the basis that its better to have a loose fit than no fit. Tightening the grub screw may make the handles fit the spindle but the spindle will be loose in the lock. 

 

I recently purchased a 7.8mm spindle to fit the lock on our front door and ground down the ends to fit the handles. However for some sizes spindle adapters sometimes called "spindle converter sleeves" are available.

 

 

Edited July 29, 2022 by Temp

[Temp]

PS: The nice thing about standards, is there are so many to choose from.

[Simplysimon]

7 hours ago, steveoelliott said:

Whether it is tight, loose or not present seems to make no practical difference.

you're saying that if the grubscrew is slack the handle doesn't come off? if you remove the circular coverplate on the handle are there screws holding the handle to the door?

[steveoelliott]

3 minutes ago, Simplysimon said:

you're saying that if the grubscrew is slack the handle doesn't come off? if you remove the circular coverplate on the handle are there screws holding the handle to the door?

Yes screws hold the handle to the door behind the plate.

[Simplysimon]

2 hours ago, steveoelliott said:

Yes screws hold the handle to the door behind the plate.

the handle then is generic, will have different fixing types and the grub screw is more useful on a type without the screws into the door. won't do any harm tightening it though

[SteamyTea]

5 hours ago, Temp said:

PS: The nice thing about standards, is there are so many to choose from.

What is needed is a standard that incorporates the existing standards.

Or in other words, an extra standard.