NU tool milling machine

[joseph tatlerParticipant @josephtatler55359]

Hello

I have a NUTOOL manual miiling machine, which is similar to Warco and other generic types.

When i lock the spindle and take cuts its fine, but sometime when i unlock it moves down a touch,

 

Checked and there is some up and down movement on the spindle.

Is there any way of taking up or adjusting  this play .

 

Thanks in advance

 

Joe

[parovozParticipant @parovoz]

Hi.

I have a similar Warco mill in the small workshop. It’s ‘ok’ but one does have to understand it’s limitations, it’s fine for a little ‘indoor’ mill. The mill should only be used with the quill locked, unless either drilling or down feeding with a slot drill etc. The worm on the handwheel shaft can be adjusted in and out of mesh and can be adjusted tighter to reduce backlash, but backlash is always going to be there. If the spindle ‘drops’ when unlocked, it may be that the quill return spring is not properly tensioned, but it should never be too heavy in operation.

In general, when down feeding with this little mill I always have the spindle clamp not fully slack so that it provides a little resistance to keep the quill ‘in check’, and when milling it is locked always. It is only ever fully loose for rapid positioning and or drilling.

At the end of the day, if used with care, these little machines can produce fairly decent work.

Hole that helps…..

[joseph tatlerParticipant @josephtatler55359]

hi

thanks i will try that suggestion(s)

 

Joe

[BazyleParticipant @bazyle]

It sounds like you have fed it down to depth against the spring using the fine feed then locked it. During use the vibration has moved the quill feed handle over the range of the backlash. However I would expect the quill spring to be strong enough to pull it up when unlocked so that dropping when unlocked would be impossible. Do you use a very heavy flycutter block or something?

[joseph tatlerParticipant @josephtatler55359]

Hi

Thanks for the reply.

 

No i just use standard cutters 8, 10 12 etc.

Joe

[DiogenesParticipant @diogenes]

It’s because the spring is essentially a ‘handle return spring’ acting on the pinion and, because of the necessity for having clearance between that and the quill rack, there will always be potential for a bit of backlash between the two.

– the pinion has the spring-load but not the lock, and the quill has the lock but not (always) the spring load – it’s okay but not brilliant.

I always run the cutter clear of the work before releasing the lock, and fitting some kind of read-out to the quill helps immensely because you can then see where the quill actually is, all the time..

[VicParticipant @vic]

Mill Drills were very popular years ago so do an internet search on modifications and upgrades. Someone else may documented a possible solution.

[BazyleParticipant @bazyle]

Diogenese has sussed it. There have been two solutions written up in ME over the years – one was to replace the spring with a Tensator spring acting directly on the quill and the other was an eccentric bush for the pinion to take up the clearance with the rack.

[DiogenesParticipant @diogenes]

What I wish I had said last evening, was that it’s a minor pain that goes away – the more work you do with it, the more you will develop a ‘feel’ for coordinating the handwheel & lock lever

– I have to say that it’s been some years since I’ve even thought about it, although I still have the same mill.

Perhaps others might attest the same.

 

 

[Diogenes]

On Diogenes Said:

What I wish I had said last evening, was that it’s a minor pain that goes away – the more work you do with it, the more you will develop a ‘feel’ for coordinating the handwheel & lock lever

– I have to say that it’s been some years since I’ve even thought about it, although I still have the same mill.

Perhaps others might attest the same.

 

 

i have one too. you will soon learn to live with it.

[Martin ConnellyParticipant @martinconnelly55370]

I have disk springs between the head and the locking handle to maintain some friction on the spindle at all times. This allows it to be locked and unlocked enough to move it but keeps pressure on the spindle to resist its tendency to rock when the lock is released. I have 8 disks in four dished face to dished face pairs.

Also maybe reduce the spring return strength, it’s set high for drilling so that the spindle pulls up when released. Since milling forces with positive rake cutters try to pull the cutter into the workpiece it is better to always have the spindle rack down on the pinion rather than held up to it up by the spring and friction working against gravity and the downward pull.

Martin C

[Martin Connelly]

On Martin Connelly Said:

I have disk springs between the head and the locking handle to maintain some friction on the spindle at all times. This allows it to be locked and unlocked enough to move it but keeps pressure on the spindle to resist its tendency to rock when the lock is released. I have 8 disks in four dished face to dished face pairs.

Also maybe reduce the spring return strength, it’s set high for drilling so that the spindle pulls up when released. Since milling forces with positive rake cutters try to pull the cutter into the workpiece it is better to always have the spindle rack down on the pinion rather than held up to it up by the spring and friction working against gravity and the downward pull.

Martin C

<p style=”text-align: left;”>The above is the best solution to the problem of locking absent replacing the locking system with something better.</p>
<p style=”text-align: left;”>The locking system uses a clamping mechanism with a split cylinder having a concave relief cut halfway down the cylinder.  The cylinder is split at the centre of this relief and when the locking handle is turned the two halves of the cylinder are drawn towards each other and clamp on to the quill (one day, I’m going to draw this out in CAD for use in discussions such as this; for some reason I find explaining this mechanism particularly hard).</p>
One of the problems with this mechanism is that, unless the quill is a very close running fit in the head casting (and even in the Taiwanese models, let alone the Chinese ones, it very rarely is), it leads to the quill moving in the radial axis.

The RF-45 and clones have the same locking mechanism and Stefan Gotteswinter had one and did an excellent video about fixing this problem.  It is rather a drastic fix, mind you, and one that most of us with round column mills or even RF-45s are likely to find somewhat intimidating.

[joseph tatlerParticipant @josephtatler55359]

Dear all

the advice given is really appeciated and i will try to see if i can make good use of it all

 

Joe

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