Qualters &Smith QDM750 pillar drill – back gear.

[charadamParticipant @charadam]

My recently acquired specimen of the drill in the title has a lift-pin to engage/release the spindle gear.

Diametrically opposite the lift pin there is a short 3/8BSW hex-headed screw that seems to also engage in the spindle gear.

I have the manual, but there is no mention of the screw.

Can anyone enlighten me as to its purpose and use?

Incidentally, it is an excellent piece of kit.

[charadamParticipant @charadam]

[charadamParticipant @charadam]

Might have solved the mystery myself.

I have enlarged the drawings in the manual and can now see that the hex-headed screw is not intended to engage with the spindle.

Since this drill revs to 3000/min, I now think the screw is a mass balance.

[RobboParticipant @robbo]

Have seen a similar arrangement on a different machine where the screw is used as a jacking screw to lift/keep the pulley clear of the drive gear underneath to prevent friction/binding. Of course it needs to be slacked off when running, once the head is locked in either backgear or normal.

Equally of course this may have nothing to do with your Q&S!

[Dave HalfordParticipant @davehalford22513]

Posted by charadam on 28/03/2015 23:38:38:

Might have solved the mystery myself.

I have enlarged the drawings in the manual and can now see that the hex-headed screw is not intended to engage with the spindle.

Since this drill revs to 3000/min, I now think the screw is a mass balance.

I've not got the manual, but my QDM is the same – a balance weight, otherwise the gear shift takes too long to operate.

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