Elliot omnimill 00 loss of drive

[OllyO]

I was drilling brass and it snagged and I subsequently lost drive (pulley continued to rotate but spindle stopped)

I don’t have a manual but having read post here I expected to be able to release the clock spring and dropped the quill out. That didn’t work.

I had to remove 3 bolts on the head and withdraw the pulley with part of the casting from above

The revealed not the parallel shaft with long key in I’ve seen on other machines but a splined shaft

On the top of this is a plastic sleeve that has (had) two keys set into it held captive on the pulley.

It looks like when the drill snagged the keys mangled the plastic sleeve so must be acting as a shear pin type arrangement

Anyone seen this before? What can I do as a replacement?

it’s a pretty annoying feature as I wasn’t taking a big cut so can I just engineer a way of getting rid of this feature? Surely if there’s a big smash up the belt will just slip? I really don’t want to be changing this plastic things everytime I drill a big hole ‍

 

[Agroshield]

Anyone seen this before? What can I do as a replacement?

Strangely enough, yes. Only a few days ago.

Elliott 00 drive spline repair | Model Engineer & Workshop Magazine

Thanks to Ian McVickers (https://www.model-engineer.co.uk/forums/topic/the-workshop-progress-thread-2023/) who had the same issue with his Omnimill 00 as I. ...

www.model-engineer.co.uk

Your "just engineer a way of getting rid of this feature" requires some calm contemplation.

How old is the machine? How long has the original part lasted? What level of service has it likely seen previous to your ownership? And with that service, how long has the original part lasted? What level of duty cycle will you require of the machine under your stewardship? So how long would you estimate a like-for-like replacement will last under those conditions?

The people who made the machine knew what they were doing.

 

[Agroshield]

If you did not want to broach all the splines in it, there is a technique for making lead screw nuts by controlled heating of delrin and then forming the threads by pressing the original leadscrew into the hot plastic. That might work here.

As always, a 3DP option might work - maybe a composite item where the spines and a thin surround are printed and then the body and ears are machined from solid plastic, with the two pieces joined together.

At the least, a 3DP version would allow you to tweak measurements to get the proper fit on the splines before machining the real one.

 

[OllyO]

Hi folks

A mate of mine kindly volunteers to make me a new sleeve for the mill and it looks great.
Only issue is there’s a bit of slop between it aNd the splined shaft.

I’m concerned that as it’s aluminium that over time it will wear the splines down and create a lot of slop

Is this a realistic concern? And is there anyway to rectify this without making a new one?

 

[Agroshield]

And is there anyway to rectify this without making a new one?

Bodge it.

Wax the male splines, slather the aluminium female ones with JB Weld and unite the two. Wait 24h for it to set.

There is a high grade epoxy, whose name I forget, used for very much the same purposes.

 

[OllyO]

I’m glad you said that cos I was thinking exactly the same thing but was too scared to post it! Haha

I have some Belzona that would do the job well