Adjusting or replacing babbit bearings in a Mars Great Scot lathe (brisbane)

[unixbigot]

My father-in-law has just purchased a new lathe and has offered me
his old "Great Scot" 6x30" lathe, made in Brisbane in the 1940s.

It has plain sleeve-type babbit-metal bearings which have seen better days, and a bit of backlash
in the cross-slide, but is otherwise in good working order. The owner admits he was never very diligent about
maintaining the wick-type headstock oilers, and has paid the price. I can feel movement when grasping the chuck and applying upward pressure.

It resembles very closely the top picture in this article (http://www.lathes.co.uk/conrik/).

Can anyone recommend where in brisbane area I might find someone to
replace the bearings, if this is what's needed?

My FiL doesn't appear to actually know a great deal about the detailed workings of this lathe, he's tinkered with it for 30-odd years but not done much with it.

It's possible from what little info I've found online about Mars/GS lathes that these bearings are adjustable via conical housings. Is anyone familiar with this kind of headstock and able to comment on how I might adjust the bearings.

This would be my first metal lathe, being a woody who has now ventured some way down the Dark Path.

Thanks, Chris.

[bollie7]

Chris
I thought someone else would have responded by now. From what I can see in the pics it looks like your machine might have some sort of adjustment on the headstock bearings. The bit on the chuck side of the front bearing that has the small holes drilled into the outside edge. To me that looks like some sort of adjusting nut that you would use a pin spanner on. I can't see whats on the other end of the spindle.
As to how it works I can't comment on from the pictures. I'm only quessing here, but its probably a fine taper in the housing and a split bush of some kind with a matching taper on the outside and a thread on the end that the nut screws onto. Tightening the nut pulls the bush further into the taper in the housing, which in turn reduces the id of the bush. It might only be a case of tightening the nut up to reduce the play. Not sure what sort of locking method would be used though.
There doesn't appear to be any bolts on either side of the bearing which you would expect if it was a split bronze or whitemetal bearing.
Hopefully someone else with a bit more knowledge of these will chime in.

hope this helps
bollie7

[Dave J]

Hi bollie
I would have answered but I am not familiar with those type of lathes.:?

What you describe above sounds like the bearing set up on the arbour support on my old horizontal mill that I picked up with the shaper. It needs a C type spanner on the inside and has a big nut on the out side to adjust the bearing smaller to suit the arbour spacer. A very good idea, and far better than the HM52 bush which has no adjustment.

Dave

[neksmerj]

UB,

I have a friend who recently purchased a Mars lathe. I'm impressed, it's really well made.

Next time I visit him, I'll take a closer look at the headstock bearing arrangement. Couple of dayz.

Ken

[bollie7]

Hi bollie
but I am not familiar with those type of lathes.:?
Dave

Me neither Dave. It just seemed logical from what I could see in the pics.:) My old Purcell lathe that I got rid of a few years had split bronze bearings. The only adjustment was by scrapping the bearing and filing a bit off the underside of the caps.

bollie7

[unixbigot]

Chris
From what I can see in the pics it looks like your machine might have some sort of adjustment on the headstock bearings. The bit on the chuck side of the front bearing that has the small holes drilled into the outside edge. To me that looks like some sort of adjusting nut that you would use a pin spanner on. I can't see whats on the other end of the spindle.
...

hope this helps
bollie7

Thanks to all who have responded.

I think the pin-spanner arrangement on the bearings allows alignment to be adjusted due to eccentric sleeves. The bearings and mounts don't appear to be have the common split-and-shim tightening.

The problem I (hope to) have isn't one of alignment, but the spindle having slight play due to wear. The owner says this tiny amount of play causes the lathe to grab during parting or heavy cuts. I'm hoping there's some kind of way to tighten the bearings, as I understand this is designed for with white-metal era machines. I'm familiar with how myfords use removable shims for this.

The lathe is still in the back corner of my FiL's shed where its hard to get a good look at the bearings. We'll have to dig a tunnel through his collection of car parts to get it out!

Also, any recommendations for engineering shops in brisbane that have know-how in reconditioning old lathes would be greatly appreciated. Aparrently the cross-slide halfnuts were rebuilt once already, and the bed re-ground, but my FiL cannot recall the name of the place that did it for him.

[SiJ]

Chris

Here's a link with some info on your lathe (edit - Doh - just seen you've already linked to another page on the site):

Page Title (http://www.lathes.co.uk/mars/)

I too think that the threaded ring acts on the bush to push it into its tapered housing, so deforming it to take up slack. I'd just have a gentle go, checking for tightness in the bearings frequently. Is the wear only apparent vertically, or in all radial directions? If the latter then the adjustment should be straightforward.

Cheers

Si

[bollie7]

I think the pin-spanner arrangement on the bearings allows alignment to be adjusted due to eccentric sleeves. The bearings and mounts don't appear to be have the common split-and-shim tightening.

Thats interesting, do you mean the spindle alignment in relation to the bed? I'd assumed the pin spanner nut was for tightening the bearings because there doesn't appear to be a removable cap as you would have on a tradional split bearing design.

[/QUOTE]The problem I (hope to) have isn't one of alignment, but the spindle having slight play due to wear. The owner says this tiny amount of play causes the lathe to grab during parting or heavy cuts. I'm hoping there's some kind of way to tighten the bearings, as I understand this is designed for with white-metal era machines. I'm familiar with how myfords use removable shims for this..[/QUOTE]
Play in the spindle bearings could also cause the job to try and climb up over the tool under a heavy cut as well

[/QUOTE]The lathe is still in the back corner of my FiL's shed where its hard to get a good look at the bearings. We'll have to dig a tunnel through his collection of car parts to get it out!.[/QUOTE]
Would be interest in seeing some more and better pics once you are able to get to it.
[/QUOTE]Also, any recommendations for engineering shops in brisbane that have know-how in reconditioning old lathes would be greatly appreciated. Aparrently the cross-slide halfnuts were rebuilt once already, and the bed re-ground, but my FiL cannot recall the name of the place that did it for him.[/QUOTE]
If the bed has been reground there is a good chance it will still be ok. re your cross slide nut, you could strip the machine down, measure it all up and then machine a new nut yourself. FIL's new lathe would be handy for that. The cross slide spindle is more than likely an acme thread (or possible a square)
Cross slide spindle thread will probable be left hand as well.
If acme, you can set it up and track it out just taking a skim off the flanks of the thread unti it cleans up over the full length. This would mean that the thread form wouldn't be a std acme any more but it wouldn't be far out. You then would have machine a new nut to fit. A bit of Phosphor bronze would be suitable for this. I did this on my old Purcell years ago. worked fine. Ground up a HSS bit slightly narrower than std profile, welded that to the end of a 6 mm Hi Ten bolt and used that as a boring bar. Had to take a lot of passes to get the spring out of the bar. Once it was to the correct depth, just kept shaving a bit off the flank of the thread until the spindle screwed in ok. OD was 5/8" x about 1&1/4" long so the bar was pretty long and springy. All work fine though. Went from almost a full turn of back lash in the cross slide spindle to almost none. The old lathe is still powering along I believe.

bollie7

[unixbigot]

Chris

Here's a link with some info on your lathe (edit - Doh - just seen you've already linked to another page on the site):

I too think that the threaded ring acts on the bush to push it into its tapered housing, so deforming it to take up slack. I'd just have a gentle go, checking for tightness in the bearings frequently. Is the wear only apparent vertically, or in all radial directions? If the latter then the adjustment should be straightforward.



Yes, the Mars page on lathes.co.uk was where I first read about the bearing adjustment. :) The play is in all directions, but either slightly worse or just more noticeable vertically.

[unixbigot]

Thats interesting, do you mean the spindle alignment in relation to the bed? I'd assumed the pin spanner nut was for tightening the bearings because there doesn't appear to be a removable cap as you would have on a tradional split bearing design.


Well, I was told that's what that adjustment was for, but I think perhaps the source for that factoid may have been mistaken.

I plan to return tonight or tomorrow with an proper camera (i.e. not my phone) to take a closer look and some more pictures.

Thanks for the advice on the cross-slide, also. My FiL is keen to help me get this lathe back in running order, and I'm sure his new lathe will be looking for some tasks when he gets it set up.

[unixbigot]

OK, as is traditional on these "newbie gets a lathe" threads, I've discovered I have told you what might be charitably called a collection of confused misremembrances, or less charitably bull#@$@.

The mechanism with the C-spanner slots *is* for tightening the bearings, nothing to do with alignment. The bearings themselves are one piece sleeves with a single split, and turning the rings (which are nuts, and not part of the bearing proper) does tighten them. For a while. I'm told they work loose again quickly.

Apparently this lathe was restored by its previous owner, then when it came to the current owner, about 20 yrs ago, he had the bed reground, the bearings replaced, and the cross-slide half nuts replaced. Of the three, the bed is still in good condition. As you will see from the pictures linked below, cleaning and lubrication haven't entirely been by the book :(

Back to the headstock bearings, I wonder if there's a locking mechanism that's been lost or something (or whether a sacriligeous dob of loctite will achieve anything)?

Still impossible to get a view of the geartrain, but I have uploaded some more pictures to this flickr set: Great Scot Lathe - a set on Flickr (http://www.flickr.com/photos/22634189@N06/sets/72157626637212378/)

My father-in-law still seems intent on finding a local engineering shop that could replace the worn parts, as part of his gift of the lathe to me. Any suggestions here?

Thank you all for aiding me on this journey to discover the limits of my own ignorance. :)

[pipeclay]

I think you would be better off wiating untill you can get clear access to the lathe from all sides,then do your checks,for clearances on the spindle.

You reffer to half nuts on the cross slide,do you know if there is actually half nuts there or are they a full nut with the cross slide screw passing through it.

If it is a full nut depending on the shape of the nut or physical size you maybe able to modify the nut to take up the majority of backlash present.

Probably have got to mention this but the Headstock needs a good clean before it is rotated either under power or manually.

The configuration of the headstock looks similar to the Hercus,Sheraton and Southbend,you may be able to adapt there gear guards to your lathe or even fabricate your own,at least then you will be able to keep the majority of swarf off the Gears.

[unixbigot]

You reffer to half nuts on the cross slide,do you know if there is actually half nuts there or are they a full nut with the cross slide screw passing through it.

(snip)

Probably have got to mention this but the Headstock needs a good clean before it is rotated either under power or manually.

(snip)


Thanks, I am of course excited to be getting this lathe into my own shed and out of its current cramped and abrasive quarters. Taking much longer than I'd hoped to achieve this.

The lathe has a powered crossfeed arrangement using bronze half-nuts, according to the owner.

A thorough cleaning and construction of a headstock cover are naturally
first order of business. Its pretty clear how the delicate mechanisms *got* so worn. You should have seen the swarfbergs before the owner "cleaned" it! :(

[pipeclay]

Not doubting what you have been told,I find it unusual to have half nuts that engage the Cross slide.
I havent had the privilidge to see a Lathe with double half nuts before.

If you dont mind when you get around to working on the Cross Slide half nuts would you mind puting some detailed photos up.

What I am interested in is the way the Feed is transfered to the Cross slide through the Cross slide half nuts.

By looking at your pictures it appears that the second screw running the length of the lathe has a keyway in its length,this normally is what I would reffer to as being the Feed Screw shaft.

The feed screw shaft would in most cases run the Longitudinal and Cross Feed through a worm and worm wheel.

The lever to the left of your carriage appears to be for the Leadscrew,this normally has the Half nuts.

[Bryan]

Thanks, I am of course excited to be getting this lathe into my own shed and out of its current cramped and abrasive quarters. Taking much longer than I'd hoped to achieve this.

The lathe has a powered crossfeed arrangement using bronze half-nuts, according to the owner.

A thorough cleaning and construction of a headstock cover are naturally
first order of business. Its pretty clear how the delicate mechanisms *got* so worn. You should have seen the swarfbergs before the owner "cleaned" it! :(

Sounds like FIL is confusing his terms and says cross slide when he means carriage. Half-nuts are used to engage the lead-screw which drives the carriage for thread cutting. I can't think of a reason you would want half-nuts on a cross slide. I think the sooner you can get it out of his well-meaning clutches the better.

[unixbigot]

Pipeclay, Bryan, I'm keen to find out what's actually going on inside the carriage too.

Since the backlash is present in the cross slide under powered or manual feed, you're right it must be independent of whatever clutch mechanism transfers leadscrew power to the cross-slide. So its probably wear in an ordinary acme nut in the cross-feed screw, not whatever mechanism (I'd guess a wormwheel) transfers power from the leadscrew. I havent seen under the hood yet, and I'm very curious to know more.

The lever on the left engages threading feed. The lever at the bottom engages in either of the two vertical slots, the left slot selects cross feed, the right slot engages fine longditudinal feed. The mechanism running across the top of the two slots prevents leadscrew and fine feed from being selected simultaneously (self-destruct mode).

I'll definitely be documenting the restoration once my team of ninjas repatriate this lathe (and its half ton stand).

[markpest]

Evening Chris, I have a similar Great Scot. These lathes were produced 1938, and were used in armament production and were marketed as a precision lathe in their time. ie adverts in SMH (1941) http://trove.nla.gov.au/ndp/del/article/17764634?searchTerm=Great Scot lathe&searchLimits= (http://trove.nla.gov.au/ndp/del/article/17764634?searchTerm=Great%20Scot%20lathe&searchLimits=)

Mine has two locking nuts which assist with the spindle adjustment, and may be an improvement on “For a while. I'm told they work loose again quickly”.

I notice that you also don’t have the bar below the apron – supports the brass lever which selects surfacing/sliding. Details of original guards as suggested by Pipeclay also included.

If you want more pics/measurements let me know.

[unixbigot]

Evening Chris, I have a similar Great Scot.

(snip)

[COLOR=black][FONT=Verdana]If you want more pics/measurements let me know.

Thanks a ton for this info! I suspect maybe the adjusting nuts on not-quite-yet-my lathe have been abused with punch and hammer instead of C-spanner and may need to be replaced.

The picture of the backgear cover and drip oilers is especially helpful. Are the drip oilers original or an upgrade?

Thanks again for your offer of more info, I'll get back to you once I get the lathe moved (hopefully this weekend or next).

--chris

[markpest]

Oilers are recent (fleabay) addition, I only had one of the originals and whilst I used greasecups for a while (with wicking) I prefer sight guage. I note the brass spigot in your tailstock casting. This is an addition from the original. I think your spigot is sitting in what would have originally been a reservoir for white lead (to be added with a brass "dibbler" originally). You may find a Steve Brews ebay site of interest eBay Australia Shop - stevewb: Kits Parts South Bend Lathe, A Guide to Renovating the South Bend Lathe (http://stores.ebay.com.au/stevewb?_rdc=1), and you might note the similarity between your lathe and the SouthBend Manual "How To Run A Lathe".

[unixbigot]

Well, I finally got the lathe home!

I've spent about 2 weekends cleaning it up, lubing and adjusting and have taken a few cuts (enough to realize I have way less idea of what I'm doing than I thought I did, and a lot to learn about tool sharpening among other things).

The bearings seem to be OK so far, they were sloppy as heck as received, probably because lock screws on the bushes weren't done up at all. I constructed custom-sized C-spanners to fit, and they tightened up nicely. The spindle spins freely with no appreciable slop and runout of under .001".

The wick oilers are working tolerably (at least, the oil goes somewhere!) but I've ordered a pair of drippers anyway. Not all the change gears are present (missing 45, 55 and 75), and one of the tumbler gears has a missing tooth. Three of the other gears are the wrong bore size or width (replacements never rebored I guess). The previous owner never did any thread cutting, since he had the lathe parked hard up against a wall. The gears appear to be 14DP with 3/4" bore.

Some of the gear trains listed on the brass plate are physically impossible at present. I presume they require a second stud and idler (missing).

My father-in-law swears he has the back-gear covers in his shed somewhere.

Heres a pic of the lathe parked in my shed. More pics at this flickr set (http://www.flickr.com/photos/22634189@N06/sets/72157626637212378/).

[unixbigot]

If you want more pics/measurements let me know.

I'd love some pictures of the thread dial (missing entirely on mine), and info on how properly set up change gears are laid out. I tried to set up 32tpi as per the chart, but couldn't make the gears mesh. I only have one movable stud, do I need two?

The brass bar set in the hole in the tailstock is the tommy bar for the toolpost clamp.

[markpest]

Evening Chris - great to see your progress on the Great Scot! A couple of thoughts regarding missing tackle - Pipeclay (Peter) makes gears for Hercus, and has received very positive comment in these pages - if you can provide him with gear profile info required; also the following might be of interest - unless you want to continue to stow your tommy-bar in the tail stock - http://www.practicalmachinist.com/vb/south-bend-lathes/making-tailstock-dauber-130321/ (http://www.practicalmachinist.com/vb/south-bend-lathes/making-tailstock-dauber-130321/). I'll take some pics of the thread index casting in the next day or so. All the best with next steps. cheers, Mark.

[markpest]

G'day again Chris - pics of thread index - it's a massive bronze casting! (Also protects leadscrew from swarf.)

[unixbigot]

G'day again Chris - pics of thread index - it's a massive bronze casting! (Also protects leadscrew from swarf.)

Awesome, thanks a lot. It must have been raining bronze when they made these lathes. I have an article from a recent issue of Model Engineers Workshop magazine on making a thread indicator for a boxford, so I'm going to try that, once I get my gear cutting merit badge.

[unixbigot]

Not doubting what you have been told,I find it unusual to have half nuts that engage the Cross slide.
I havent had the privilidge to see a Lathe with double half nuts before.

If you dont mind when you get around to working on the Cross Slide half nuts would you mind puting some detailed photos up.

What I am interested in is the way the Feed is transfered to the Cross slide through the Cross slide half nuts.

By looking at your pictures it appears that the second screw running the length of the lathe has a keyway in its length,this normally is what I would reffer to as being the Feed Screw shaft.

The feed screw shaft would in most cases run the Longitudinal and Cross Feed through a worm and worm wheel.

The lever to the left of your carriage appears to be for the Leadscrew,this normally has the Half nuts.

Pipeclay, you were dead right of course. There is a wormgear assembly which rides on the feedshaft, and engages either of two wormwheels, which drive either the crossfeed or the carriage feed by driving the handwheels.

The screwcutting feed uses a single half nut, rather worn but still giving firm engagement. The cross-slide uses a full ACME nut which appears to be a recent replacement, but unfortunately has about 65 thou of backlash.

[markpest]

Hey Chris. Have a look at the knurled end to your surfacing feed lever (which is otherwise bronze casting); now look at the screw in my pics used to secure the thread index dial - looks similar I think. What's the chances that some snoozer has repaired the feed lever with the only available 'knob' to hand? . . . Just a thought. Mark

[unixbigot]

Hey Chris. Have a look at the knurled end to your surfacing feed lever (which is otherwise bronze casting); now look at the screw in my pics used to secure the thread index dial - looks similar I think. What's the chances that some snoozer has repaired the feed lever with the only available 'knob' to hand? . . . Just a thought. Mark

That sure looks likely to me. Then of course the thread indicator casting would get lost...

[unixbigot]

I was tinkering about tonight and I notice that if I pull the carriage
toward the tailstock it will move down the bed, causing the handwheel to turn.

This can't be good for doing any significant facing and milling cuts.

I'm going to investigate whether the rack can be adjusted to tighten it up (feed feels a bit lumpy like the teeth aren't engaging fully), and am thinking about how to make a carriage lock, perhaps something that mounts in place of the right hand rear way wiper (with the wiper mounted to the new part).

Any thoughts?

[franco]

I was tinkering about tonight and I notice that if I pull the carriage
toward the tailstock it will move down the bed, causing the handwheel to turn.

This can't be good for doing any significant facing and milling cuts.

I'm going to investigate whether the rack can be adjusted to tighten it up (feed feels a bit lumpy like the teeth aren't engaging fully), and am thinking about how to make a carriage lock, perhaps something that mounts in place of the right hand rear way wiper (with the wiper mounted to the new part).

Any thoughts?

Do you have an interlock which prevents the half nuts from closing if the feed rod is turning? If not you can engage the half nuts with the leadscrew stationary to hold the carriage while facing or milling.

Frank.

[unixbigot]

Do you have an interlock which prevents the half nuts from closing if the feed rod is turning? If not you can engage the half nuts with the leadscrew stationary to hold the carriage while facing or milling.

Frank.

The feedshaft is driven off the leadscrew (a pair of 20t gears), so if I put the tumblers in neutral I could use the leadscrew halfnut to lock the carriage, yes.

Can't do that if using power crossfeed, of course.

[unixbigot]

Just got a pair of drip oilers from RDG in the mail.

I've no idea about drip rates or appropriate oils (apart from what I learned from
this thread (http://www.woodworkforums.com/f189/lathe-spindle-oil-129471/) and
this one (http://www.practicalmachinist.com/vb/general/drip-oilers-154415/).

What's a ballbark drip rate?
Is compressor oil really OK? Some people recommend Mobil 1, how about that?

Buying a 50l drum of Casmobiltrol Unobtainium isn't really an option, given my hot water system just self destructed, taking my bank balance with it. I tried air tool oil in the wick oilers and it went through the wicks like a camel vindaloo.

[pipeclay]

Do you have much clearance in the Bearings ( Not longitudinally but Vertically).

If you have more than about .002" clearance you may want to try a 68 grade oil.

If your clearance is less you may want to try a 46 grade oil,both of these oils would be hydraulic.

Others will probably advise on a more correct oil,but if cost is a factor either of the 2 listed are available in small litre sizes.

The reason for the slightly higher viscosity oil is just to try and keep a film on your bearings for a little longer than the 46.

In regards to drip rate this could also depend on bearing clearance and if whether or not there is a oil groove or small sump in the bearing houseings.

Also the drip rate could depend on how long you are planning on using the lathe for each time its used.

Generally the drip rate would be set and forget but if the clearances are excessive you may need a faster flow.

I have seen some of the Oilers from RDG they are ok but not great,but they do work.

You may find that they wont shut off properly/completely,that the metering/nedle valve can be a bit dicky.

Probably as a rough start point,you could use a measure to see the capacity of the bearing houseings,once you have worked out the capacity run the lathe,see how long it takes for the oil to dissapear from the filler or the hole on top of your houseing,(not just from the top but until you cant see any more oil in the filler hole.

After you have timed this you can adjust the drip to give 1 or 2 drips over the time it took the oil to dissapear,eg if it took 3 mins to drain from the filler then adjust so you had 1/2 drips every 3 mins,you might end up with there being a quicker flow but dont make it slower.

If possable try and remember to shut them off after use.

[markpest]

Evening Chris, Peter. I use Grahame Collins recommendation of the Chain-n-bar oil - comes in 1 ltr packs SAE20. Not too sure Peter what the hydraulic 46 is about - is this high/lower viscosity than SAE20? I'd be interested in your view.

Chris - my settings on the oiler are as per Peter's advice. Make sure you shut off, or have a mop-up the next day! Mark

[pipeclay]

I use the 46 hydraulic on the Hercus plain bearing spindle,gearbox,carriage.

The 68 is slightly thicker,which should in theory take up a bit of clearance on the spindle bearings if present.

The higher the number the thicker the oil.

The Chain bar oil has additives to make it sticky (thicker),as a guess I would say it has the consistency of 90 grade gearbox oil.

[unixbigot]

Many thanks for everyone's ongoing advice.

Waggling the chuck up and down (scientific waggling of course!) while watching a dial indicator, I measure .06mm vertical movement in the spindle (about .0023"), so I presume that equates to between one and two thou clearance?

Tested with compressor oil (what I had about) the RDG oilers seem to resist dripping any slower than about 4 drops/min.

I'm not sure I understand your drip rate instructions. I would count how many drips D the oilshaft above the bearing holds, then how many minutes M it takes a running spindle to drink it all. Then I'd aim for a drip rate comfortably faster than D/M drips per minute. Is that the same as what you said? :)

Picture of the fitted oilers added to the flickr set linked upthread.

[Bryan]

http://lsaoils.com/images/stories/viscosity%202.png


Source: Viscosity Information (http://lsaoils.com/viscosity-information.html)

[pipeclay]

In regards to the Drip rate it seems similar to what I was saying
You wont need the oil ports full all the time,but you should aim for oil on the bearings all the time.
Cant think of the correct name for this type of lub set up,so I'll just call it flow through.
At the end of the day having to much oil is better than too little,hopefully your oilers have enough capacity to last a couple of days if not longer before refilling.

[bollie7]

Cant think of the correct name for this type of lub set up,so I'll just call it flow through.
. Total Loss? lol
bollie7

[pipeclay]

Thankyou.

[unixbigot]

Thank you all. I'm at a total loss with these oilers. (pauses for groans)

One of them adjusts between steady flow and about 6 drops a minute, the other one seems to have no appreciable movement in the needle valve, and drips at about 10 drips a minute no matter what I do. They empty out in under half an hour. RDG have supplied me with two oilers having the same product code, but different boxes and slightly different shapes, for added aggravation.

(Still using compressor oil, which I suspect is too thin, and does not admit to being any recognizable grade on the bottle). BTW, thank you very much for for the viscosity chart, Bryan, very helpful when comparing ISO to SAE.

Anyway, the oil shafts hold about 30 drips, and take about ten minutes to drain with the spindle at 300rpm, so a ballpark drip rate of 3 drips per minute seems to be what I need. I'm going to have to go get some proper ISO68 hydraulic oil on the weekend, redo the consumption test, and see if the oilers behave any better.

[unixbigot]

I tracked down some Castrol Hyspin 68 spindle oil.

Still no control over oiler drip rate, so I stripped down the oilers and worked out the problem.

The needle valve barrel hadn't been deburred at the bottom end, and wasnt screwed fully into the valve seat. This meant the body of the oiler was too long, and the needle would not fully enter the seat even with the adjustment screwed all the way down. I filed about 1mm off the barrel length, and cleaned up the rough ends, allowing the needle to seat fully.

I get controllable drip rate now, though adjustment is still very hair trigger. The finish on the needle and seat was rather rough, I suspect I should strip them down again and clean that up.

The next problem is drip formation---when reassembled I got a good view of drip formation through the sight glass, then after a few minutes dripping stopped and oil wicked down the inside of the glass instead. The oilers are still delivering oil, but its impossible to tell how much without removing them from the headstock entirely. I had the same problem originally with one of them, before I dissassembled them. I suspect this is a finish problem on the bottom of the needle seat, where it forms the top of the sight chamber.

I wonder what shape it /should/ be for good drip formation.

Here's a picture of the disassembled oiler, although it doesnt show the bottom of the seat/top of sight chamber.

[Bryan]

I would think you need to provide a lip for the drop to form on. Can you turn a groove to relieve the outlet a bit, except for right around the hole?

[unixbigot]

I would think you need to provide a lip for the drop to form on. Can you turn a groove to relieve the outlet a bit, except for right around the hole?

Hmmn, I will have to strip one down and take some more pics of the bottom of the valve seat, but I think that would work. Holding the sucker while turning it shouldn't be too hard--can use the barrel of the needle valve as a mandrel, gripping it at the unthreaded part.

[Stustoys]

Hi guys,
Which part are you guys talking about?
Wouldnt a short taper on this part make the dip form there?

Stuart

[unixbigot]

The part pointed to by the arrow (which I have been calling the barrel) screws into the large part above and to the right, which contains the conical needle seat. The glass windows in that part are the area for sighting drips, as they form on the underside of the seat.

The needle with it's conical tip engages with the needle seat, and the closeness of engagement (via spring and top screw collar) controls speed of drip.

I will post a disassembled picture of the seat-and-sight-glass part tomorrow.

[Stustoys]

lol, forget what I said then, I thought the seat was in the bottom of the piece I arrowed.
Thanks for clearing it up

Stuart

[unixbigot]

lol, forget what I said then, I thought the seat was in the bottom of the piece I arrowed.
Thanks for clearing it up

Stuart

Here is a picture with the needle seat removed from the sighting chamber (inset is the top side of the seat, main picture shows the needle and underside).

I lightly filed off the burring around the hole and reassembled---same behaviour, one or two drips form nicely, then one will "go sideways" and all further flow wicks down the inside of the glass instead of forming visible drips. Maybe the hole is too large causing drips to become too fat, or the angle is too shallow.

Will try some turning operations on the drip cone at the weekend.

[Stustoys]

Chris,
You seem to have forgotten something.

Stuart

[unixbigot]

Chris,
You seem to have forgotten something.

Stuart

The forums really didn't like my edited picture. I lowered the res and uploaded a new attachment.

[Stustoys]

Thanks Chris,
Sorry I dont have any ideas about fixing it.
Who would have thought it would be so tricky.

Stuart

[Bryan]

I'm struggling to see how it can wick onto the glass unless the glass is really close to the nose, ie not much bigger than the outlet. If that's the case all you can do is turn down the nose cone to give it a bit more clearance. That's all I can think of anyway.

[unixbigot]

Progress update:

Still haven't got the oilers forming visible drips, but am satisfied enough for now that they drip at an acceptable and steady rate.

The parting-of-the-red-sea that my father-in-law achieved to clear a path to the back of his shed to get the lathe out has ended---a second miracle will be required to get the base out---not for several more weeks.

I've glued up a new endless leather belt to replace the alligator-clip belt which was a bit too wide and would brush against the backgear cog. New belt runs very quiet.

Started turning up some missing parts--leadscrew end nut and a second changewheel banjo stud are first up.

[Stustoys]

How level have you got the lathe? If its just sitting on a bench and not very level, maybe thats why the oilers dont drip?
Stuart