Chester Champion 16V Milling Machine head ‘dropping’

[Phil H1Participant @philh196021]

[Phil H1Participant @philh196021]

When lowering the head towards the work piece using the leadscrew, the head can sometimes judder/ drop downwards. No damage to a work piece yet but I'd like to resolve this irritation before it does happen. Is this a common complaint and are there any simple solutions i.e., gib adjustment or nut adjustment?

Thanks,

Phil H

[Thor 🇳🇴Participant @thor]

Hi Phil,

Seems you are not the only one with that problem – Link. I assume slideways and Z axis screw are well oiled, I adjust the gibs on my slightly larger milling machine so the head moves freely up and down and use the locking screws when milling.

Thor

[Phil H1Participant @philh196021]

Thor,

Thanks for the reply. Yes, all the parts are well oiled and I always use the locking screws when milling.

I assume the fine feed that the other forum describes is a worm and wheel on the quill?

Phil H

[Mike PooleParticipant @mikepoole82104]

You have two options on this problem, either the head has to be slack enough to be sure the weight is always on the screw or tighten the gibs so it does not slip easily and the screw always has to drive it down, this would leave the possibility of the head moving down if you forget to put the locks on. Option 3 is buy a knee mill where gravity is with you not against you.

Mike

Some people have fitted gas struts to always provide an upward force, if you choose a strength that overcomes the weight of the head then it should not drop.

Edited By Mike Poole on 14/06/2018 10:36:49

Edited By Mike Poole on 14/06/2018 10:37:19

[SillyOldDufferModerator @sillyoldduffer]

To expand on Mike's comments, what could be happening is that the gibs are tighter at one end than the other allowing the head to tilt enough to wedge slightly as it moves. The stick isn't strong enough to hold the head, so it judders, winding down with a series of jerks.

Another possibility is that the gibs are over-tight such that oil can't get to all the bearing surfaces causing binding.

Either way experimenting with the gib adjustment might help. (I emphasise 'experiment' – the gibs on my mini-lathe had a pronounced sweet spot that took a while to find.)

Dave

[Phil H1Participant @philh196021]

Mike,

Thanks – believe it or not I have bought a knee type machine!! Not for this reason – I just thought the heavier the vertical mill the better and it was a reasonable price at the time.

Mike/ Dave,

Thanks – I should have learnt from last nights experience with the top slide of my Super 7 lathe. The tool was 'bouncing' on a cast iron wheel rim. It took about 1/2 an hour working on the gib with a screw driver and spanner and it is now cutting smoothly. I was going to ask if there is a 'method' for adjusting gibs but as you put it Dave – it was a case of experimentation until the slide was moving smoothly but firmly.

Phil H

[Phil H1Participant @philh196021]

An update on the juddering during the lowering of my Champion 16V milling head;

I lowered the head gently onto a block of wood with the spindle quill fully retracted and locked. Note that I hardly tightened the lead screw – I was very gentle with it. However, this allowed me to tighten the gib strip screw – about 1/4 of a full rotation.

The gib screw was previously very tight so I assume the lowering of the head onto the wood twisted the head by a few thousands of an inch upwards – as Dave suggested above. The dropping/ juddering behaviour has completely disappeared and the slide is nice and smooth (for now).

Phil H

[Thor 🇳🇴Participant @thor]

Hi Phil,

Glad to hear that you managed to solve the problem.

Thor

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