Holbrook lathe

[RDfella]

Bit of a long shot this ....
My B17 Holbrook lathe is playing up. After changing the oil it has now decided to stop pumping (they have an oil pump which supplies oil to the spindle, amongst other areas). A sight glass advises whether oil is flowing or not.
Point is, whereabouts in the lathe is the pump located? Have taken the casting off where one adjusts the clutches, suspecting it would be in there, as that casting actually contains the (car-sized) oil filter element. But can't see it. The plumbing to and from the filter is 3/8" bore so the pump can't be that small .........

So, does anyone know where it hides, or know someone who does, or can point me to a service manual? I have the operator's manual, but that's of no help.

Thanks,

[Triton Thrasher]

I suppose you already check this lot out, now and again.

http://www.lathes.co.uk/

[groily]

Think I'd give Tony Griffiths a call RD - he probably knows and has always been very helpful. I think he has or had one or other B variant himself.
Also lists one or other book on the B series on the site - but if it's what you have already you don't want to make a £42 mistake  . . .

[RDfella]

Been in touch with Tony @ lathes.co.uk - on his site he says he has a B17 (same as mine) and it was from him I bought the operator's manual a while back. Trouble is, that doesn't cover what I need - a workshop manual so I can locate the oil pump. Tony doesn't have any other documents on these. Don't want to do a massive strip down unless it's absolutely necessary.
Problem is that these lathes were so well built that no-one probably ever needed a workshop manual, so none now exist.
Tried joining a forum supposedly for Holbrook lovers, but it seems a rather strange set-up.
Would be a tragedy to scrap a lathe of this precision / quality just because the oil pump is not working, but the way things are headed, that's becoming a possibility. Certainly no more work on the new vee twin ..... 

[chaterlea25]

Hi RD,
You could try asking on the "Practical Machinists" forum or maybe Madmodders forum, there are a couple of Holbrook guys on there.
Does the lathe have a separate oil tank or built into the castings? It would make sense that the pump is as low down as possible, in or next to the oil tank??

John

[RDfella]

The 'main' section of the lathe takes around 15 - 20 litres of oil. The pump is in there somewhere. I can see the oil pipes that feed / deliver from the oil filter but they disappear towards the tailstock end of the lathe. Could be a massive strip down to get into that department ie spindle out etc etc - and these castings ain't light. To give an example, reckon the saddle goes 300 - 400 lbs.
As noted previously, the lack of documents / knowledge probably arises from the fact these machines were so over-built that no-one has ever had to strip one down.

[RDfella]

I have found the pump! 
Having taken the massive top cover off to expose the spindle, I was able to peer down into the machine's guts.
With the help of my son and his endoscope thingy we were able to determine that the oil feed pipe doubled back towards the machine's drive end.
By removing the change gears and the hefty casting behind them, we found the pump. What a relief.
Pics: a- spindle from top, b - where pump mounts, and the pump ready for disassembly. Note the oil delivery to the spindle area - that feeds into a sight glass and a spray rail mounted in the top cover that directs oil to the individual gears and bearings.

[groily]

Well done RD.
That is one hell of a machine.
Is the pump broken, can you say?

[chaterlea25]

Hi RD,
Since the problem started when you changed the oil I wonder if the pump has lost its prime?
Would it be possible to back fill the pump from up top?

One of the lathes where I used to work would lose the prime from its pump every so often,
a "cure" was to fit a container (about 250ml) on the top of the lathe with an on off valve and this was piped down to the pump feed, opening the valve let the oil drain down into the pump, once started the pump would re fill the container, then close the valve before it over flowed

John

[RDfella]

Well, stripped the pump this morning.
All seems fine n dandy except I was mystified by the damage to the top of the inlet ball valve that sits under the 1" diameter piston.
OK, piston fit to cast iron body might benefit from being .001" tighter, but it's not worn enough to cease pumping entirely.

So, examining the valve more closely, I now see what's happened. Referring to pic c we see the valve, a ball and a pin. Now, I when I removed the valve the pin just fell out. Also, the hammering that's occurred to the top has slightly closed up hole A, meaning the pin was never in there (where it should have been to prevent the ball rising too far). It must have been lurking in the delivery hole B (under the ball) thereby allowing the ball to rise too far when the piston performed its upstroke.
Now, that pin can't have put itself there, so whoever was last in there failed to assemble the valve properly (wasn't me - I didn't even know where the pump was!). And I've had that lathe 30 yrs, so it might even have been wrongly assembled from new. I did notice the oil flow in the sight glass was lower than that in a friend's similar B21 model, but fortunately it was still sufficient. So clearly the ball has been allowed to rise too far - meaning further to travel down again before it seats and diverts oil to where it's intended.
Let's hope that's all that's wrong!

Update - no joy I'm afraid. Oil pumped up to filter, then a couple of fountains from the spindle standpipe - then nothing. I suspect it's getting air from somewhere, but sadly the plumbing is inaccessible without - apparently - a total strip down. Which I'm definitely not going to attempt.
Dunno where I go from here. My Boxford lathe is neither accurate nor man enough for the jobs I do. OK for making a valve guide - maybe - but that's about it. And at my time of life I've no intention of becoming involved with the hassle of getting the Holbrook to the dump and then sourcing / installing another decent lathe. What with my car expired just as 2nd hand car prices have gone up and the foul weather meaning I haven't yet been out in my boat this year, sometimes I just wish I didn't wake up in the morning.

[Topdad]

Rd, try to lose those thoughts they do nothing useful and are therefore a waste of energy and being a practical man file them away as futile! TAKE A BREAK , try and move your thoughts from what won't work to what is ok and sort from there. You have got to remember your worth there are so many people on this forum  who you have helped particularly on the engineering front, to simpletons like me we  are in awe of your skill and knowledge !( although half the time I haven't a clue I always read what you've posted hoping for inspiration ) In a few days an idea will form and move onward from there . Take care Bob
   

[RDfella]

try and move your thoughts from what won't work to what is ok and sort from there.

Like a stick of dynamite, only I don't have any.

Just back from working on it now - have established:
1. pipe from oil pump to oil filter is OK
2. pipe from filter to spindle standpipe is OK
3. established where oil enters pump from 'sump' - it's at base, way down under spindle - would need substantial dismantling to get there, but see no need (and would not countenance doing that massive amount of work, especially with no workshop manual for settings / clearances etc).
So it has to be the pump but, having restored the offending ball valve, can see nothing wrong with it. Earlier I tried holding my finger over the hole that feeds the filter - a strong pulse of oil every 4 seconds (the shaft driving the pump revs @ 15rpm). But ... after a short while that became every 8 secs, then none at all .....

I'm a little happier now that it at least appears fixable, even if I have to make a new pump (how do I do that without a decent working lathe?)
I just don't need this hassle, coming on top of several other current aggravations in my life. Time for a brandy or three ....

[muskrat]

G'day RD.
Would there be an way of plumbing in a small electric pump?
Cheers

[RDfella]

Would there be an way of plumbing in a small electric pump?

Had considered that a day or so ago. But I have a plan....
Now old engineers will tell you a Holbrook - with the possible exception of DSG - is the finest precision lathe ever made. I agree but, at the risk of being excommunicated by the Holbrook aficionados, I have to say the oil pump is, having spent the afternoon analysing it, sub optimal and not to the high standard of the rest of the machine.
It has two failings. First, the suction side of a pump is usually bigger than the delivery, but here the suction is 3/16" and delivery 5/16". That's occasioned by the fact the suction is actually a tube pressed into the pump - to compensate for failing number two, that the suction is very close to the edge of the pump and, to make matters worse, there's no fastening nearby to ensure a tight clamping to the lathe's body.
Now, without access to an appropriate workshop / spares publication, I cannot say whether this tube was original, or whether it was fitted post production to help seal the pump / lathe oil orifice. Whatever, I plan to bore this tube out to at least 1/4" and chamfer the end to assist oil flow into the pump. It would be better to remove the tube entirely but, as stated, the hole is very close to the edge of the pump and there's a fair likelihood without the tube's 'backup' the hole would not seal.
Here's hoping .....

[RDfella]

Yesterday I drilled out the tube as far as I dare (17/64) and refitted the pump. Refilled sump with Tellus46 and it was pumping. But not consistently. However, with the spindle top casting still off - and the benefit of thinner oil -  I could hear a noise I recognised. The pump was drawing air, despite the intake being below oil level. Happens, during my investigations using a piece of wire, I determined the oil entry in the casting to the pump was funnel shaped, and that was presumably allowing the oil surface to draw down. And so I added more oil. Instead of halfway up the sight tube at rear of lathe, it was now ¾.
Success! Vigorous pumping and, with casting over spindle replaced, spindle sightglass is now full (it had never been before).

Conclusions:
1. Pump is mounted outside main body, behind change gears
2. Pump only operates when spindle is turning.
3. Oil pipes cannot be accessed without total strip of headstock. As a retired engineer used to working on this type of machinery, I reckon
    that's two day's work. Crazy, just to access flexible oil pipes.
4. Either someone has been at this lathe post manufacture, or the oiling system was roughly assembled originally. A pin that should have
    restricted movement of a ball bearing was found loose in a hole below the ball, and the copper oil feed pipes to the spindle bearings were
    loose and incorrectly located.
5. The suction pipe pressed into pump body unduly restricts oil flow.

A couple of week's nightmare now over.
Had despaired more than once over this. I've currently got several things requiring my attention (like building a new roof on my washhouse) and I didn't need a problem potentially requiring more work than I was prepared / able physically to do AND with no drawings or workshop manual available. Nor anyone able to advise on account of these lathes being pretty rare and so well built that there's probably no-one alive today that's ever done serious work on one. The buck stopped here! Like my daughter said (she gave me a plaque with these words for my birthday) 'If dad can't fix it, it's fu**ed'.