Beauty in The Beast: Webb 5BVK Barn Find/Conversion

[Charlieman22]

Well - win some lose some.
Had spindle guy come in.
He checked to start - the run out appeared just as in Extropics drawing when he repeated the process (which is what he did on arrival).
He then did the set up and the grinding - but when done - we didn't get the expected results.
That got even worse when we put a tool in.
Spindle taper itself was smooth and able to wipe the test marks off his tool cleanly.
But the runout was still there.
Some further testing - and he said - the spindle bearings were damaged from a crash...
Extropic - you can fill in your comments here...
[ ]


So - disappointing and expensive.
Thought I had insured myself against that with the tests he ran prior - but that wasn't the case.

So that leaves me with the question:
Am I able to replace bearings by dropping the spindle down out of the quill?
Is this the dreaded head disassembly and removal?
Tough morning.

 

[JimDawson]

Well that just sucks.

I'm trying to get my head around how it is possible to grind the spindle in the bearings and still have runout.

You should be able to just drop the quill out. I think on that machine if you remove the link between the ball nut and the spindle, it will literally just fall out. (after removing the draw bar). So keep it supported until you are ready to drop it out. Probably weighs about 30 lbs or so.

 

[Charlieman22]

I'm trying to get my head around how it is possible to grind the spindle in the bearings and still have runout.

When he was done grinding - I could still see some runout - though it was small.
I inserted a tool and it read with lots of run out.
We took the tool out - and the run out seemed worse than when he had completed the grind.
Perhaps the tightening - or the hammering of the draw bar to extricate the tool was the reason.

I asked if we could out a small threaded lug in the spindle and tighten the draw bar - to recreate the "loaded" condition of when a tool is in.
Thinking: if we grind like this - perhaps it will be in spec when a tool is in and tight.
He said tightening the draw bar like that would have no effect.
I'm still not certain.

Assuming it is the bearings - I am trying to get my head around what it would take to repair.
I assume when you drop the quill out - the bearings come with it?
I could do some YouTube searches - might help if I know other brands/ models that are likely similar in build.

Below is an exploded view from the machine's book.
Also some pictures of the machines quill,

You should be able to just drop the quill out. I think on that machine if you remove the link between the ball nut and the spindle, it will literally just fall out. (after removing the draw bar). So keep it supported until you are ready to drop it out. Probably weighs about 30 lbs or so.

Looks to me like there is a set screw on the side of the quill that would need to be taken out - then the "nose piece" 48 would unscrew. If this were unscrewed - would the spindle just fall out?
What number in this picture is the ball nut you are referring to?

 

[JimDawson]

Items 37 thru 48 come out as an assembly. The bearings are inside of the quill. The spindle is inside of the bearings. The spindle is item 44.

Remove the 2 screws (32) and the Yoke (33) and the quill will just fall out I think.

The quill is the part with the set screw in the side of it. It is about a foot or so long, and the spindle is almost 2 feet long.

Do not remove the nose nut (where the set screw is at). You do not want to try to disassemble that in place. You really can't, there is a nut on the top that holds the assembly together, and you have to remove the quill to get to it.

You want to take the entire quill assembly to the spindle rebuild shop.

 

[Charlieman22]

You want to take the entire quill assembly to the spindle rebuild shop.

That's now on the list.

Items 37 thru 48 come out as an assembly

Ok

Do not remove the nose nut (where the set screw is at). You do not want to try to disassemble that in place. You really can't, there is a nut on the top that holds the assembly together, and you have to remove the quill to get to it.

Ok - but I have a hole in my bucket Liza.
That is to say, I'm not sure how to remove the quill (with its contents) from the mill head.
In fact - I'm not really clear where to begin.

 

[JimDawson]

That is to say, I'm not sure how to remove the quill (with its contents) from the mill head.
In fact - I'm not really clear where to begin.

Remove the 2 screws (32) and the Yoke (33) and the quill will just fall out I think.

 

[Charlieman22]

Oooo. Sneaky.
33 is a key that the quill bottoms out on?
Removed - and it should just keep sliding downwards.
Blocks of wood on the table - and then use the knee to lower it out.
If I wanted to get fancy - perhaps use a chuck inserted and lower it on to a rod.

Off to call the spindle rebuild shops to see how much I spent today.
Fairly certain its more than I earned...

Thanks Jim

 

[JimDawson]

33 is a key that the quill bottoms out on?

Not exactly, but close. If everything is working right we hope it doesn't bottom out, at least in normal operation. The yoke is what the ball nut attaches to. So you will most likely need to remove items 1 thru 12 to get to the screws (32).

At least you got one screaming deal today.

 

[extropic]

<snip
I'm trying to get my head around how it is possible to grind the spindle in the bearings and still have runout.
snip>

I suspect that the crash resulted in plastic deformation of the one or more bearing journals.
The spindle will never be stiff until all (quill and spindle) bearing journals are repaired to the proper diameter, precisely round and coaxial.

 

[Charlieman22]

I suspect that the crash resulted in plastic deformation of the one or more bearing journals.
The spindle will never be stiff until all (quill and spindle) bearing journals are repaired to the proper diameter, precisely round and coaxial.

Well - that is a polite I told you so (owed you that ).
And you are right - you did predict that was the case.
The only question on a 1980's CNC mill that someone gave to me might not be - did it crash into something - but rather - how many times...

Below is the image of the quill - and also the head.
I think I am clear on how to remove the quill/spindle assembly.
Are you saying that some of the bearing journals in the head assembly - also pictured below - also in need of removal and replacement if I want to get to factory or better perfection?