Lister Engine Forum
How to / DIY => Engines => Topic started by: MachineNLectricMan on June 17, 2021, 12:49:50 AM
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I was reading some posts about makeshift bearing journal repairs and there were surprisingly few mentions of babbit metal. Our early American railroad westward expansion was built with babbit bearings. The unique feature of this material was easy field repairs without needing machine shop equipment or having to keep a large inventory of spare parts. My grandfather use to often talk about this metal. In today's times with shortages all over, maybe it's time to re-visit this material.
There are many different variations of babbit alloys for high speed, low speed, heavy loads, ect.. If I remember right, the metal expands slightly when it solidifies, so it adheres well to clean and properly prepared bearing case bores. Sometimes these bearing case bores were just rough cast using green sand molds at the cast iron foundry with no machining needed before the babbit was poured in. The shafts were simply coated with some greasy release material or special paint, centered in the bore and the metal poured in. Clay was often used to seal the bottom and any gaps, and if an oil hole was needed, a coated steel, or iron rod was inserted before pouring. After pouring, and when cooled, the shaft was removed easily if everything was done right, and the proper clearances were hand scraped into the bearing bore, along with smoothing out any imperfections.
Also, the metal was extensively recycled in the field. When a bearing got excessively worn, the old metal was removed, often by melting, then it was re-melted and some extra metal added to make up for metal lost from wear and any melting slag, then re-poured back into the bearing case to form the renewed bearing.
If babbit can support locomotives weighing more than 100 tons, it ought to work well for any emergency Lister repair if you choose the correct alloy, and I believe the early Lister's actually did use babbit. Henry Ford was likely responsible for the demise of the widespread use of this metal because he needed interchangeable parts for his auto manufacturing. Although babbit was used in the early replaceable bearings, it was not well suited for thin coatings inside replaceable steel bearing shells.
Sometimes modern technology throw's the baby out with the bathwater. Seldom does new technology actually completely eliminate the use or need for all of the older technologies. There is always some nich that only one type of technology does the best. We should think of new technology as adding another useful tool to the technology "toolbox", but not going and hastefully dumping out all of the other tools that will always have some special uses.
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Sure, there is no reason that babbit bearings could not be used in almost any old stationary engine. The hard part is sourcing the material easily then the preparation and setting up accuratly of the dummy shaft ready for pouring. Then the heating of the babbit material, pouring and finally scraping to size.
I have a few engines that run babbit bearings from mower engines, hit n miss engines and even a diesel engine made here in Australia.
At the end of the day the use of bearing shells is simpler and far easier to source and replace and is the main reason for the old system of babbit. So it would be the case of cost against effeciancy. I think I prefer bearing shells over babbit for convenience but there is nothing wrong with the way a babbit works or lasts.
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I was reading some posts about makeshift bearing journal repairs and there were surprisingly few mentions of babbit metal. Our early American railroad westward expansion was built with babbit bearings. The unique feature of this material was easy field repairs without needing machine shop equipment or having to keep a large inventory of spare parts. My grandfather use to often talk about this metal. In today's times with shortages all over, maybe it's time to re-visit this material.
There are many different variations of babbit alloys for high speed, low speed, heavy loads, ect.. If I remember right, the metal expands slightly when it solidifies, so it adheres well to clean and properly prepared bearing case bores. Sometimes these bearing case bores were just rough cast using green sand molds at the cast iron foundry with no machining needed before the babbit was poured in. The shafts were simply coated with some greasy release material or special paint, centered in the bore and the metal poured in. Clay was often used to seal the bottom and any gaps, and if an oil hole was needed, a coated steel, or iron rod was inserted before pouring. After pouring, and when cooled, the shaft was removed easily if everything was done right, and the proper clearances were hand scraped into the bearing bore, along with smoothing out any imperfections.
Also, the metal was extensively recycled in the field. When a bearing got excessively worn, the old metal was removed, often by melting, then it was re-melted and some extra metal added to make up for metal lost from wear and any melting slag, then re-poured back into the bearing case to form the renewed bearing.
If babbit can support locomotives weighing more than 100 tons, it ought to work well for any emergency Lister repair if you choose the correct alloy, and I believe the early Lister's actually did use babbit. Henry Ford was likely responsible for the demise of the widespread use of this metal because he needed interchangeable parts for his auto manufacturing. Although babbit was used in the early replaceable bearings, it was not well suited for thin coatings inside replaceable steel bearing shells.
Sometimes modern technology throw's the baby out with the bathwater. Seldom does new technology actually completely eliminate the use or need for all of the older technologies. There is always some nich that only one type of technology does the best. We should think of new technology as adding another useful tool to the technology "toolbox", but not going and hastefully dumping out all of the other tools that will always have some special uses.
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Catch up with Starfire here, and ask him about the coke-can-big-end shell adaptions - or just search for it here
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Actually some if not all modern engine earing shells still use a layer of babbit over the backing metal it serves to cushion shock loads and provide crankshaft protection. How thick depends on the application. Ford may have had something to do with thin shell development but Henry's Model Ts and As had poured babbitt bearings.
As for pouring an emergency repair bearing it is indeed a satisfactory repair when there is no other option. As an example there are no big end shells available for the Z4 Banfords engines. When I rebuild one the rod goes to a specialist who pours babbitt directly in the rod and adds a shim pack so it can be adjusted down the road if needed. Same would work for a CS type but when replacement shells in every conceivable undersize are easy obained and cheap there is really no reason go another route outside of an emergency repair and try to find Babbitt in your home town, might as well order a bearing as order babbitt.
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I use old poured babbit bearings on some of the sawmill shafts. I get the babbit from a comersial saw mill. They use the babbit in their gang saw. They call it high speed babbit or hard babbit.They also say it is lead free with a lot of tin.
I coat the shaft with a coat of carbon applied by a Acetylene flame. As mentioned clay or something to seal the gaps. Poured directly through the oil hole and then drilled. No need to scrap. Works fine, no searching around for probably none existent bearing shells.
I am currently working on replacing the small end bushing on a small, old, slow speed gas engine. I am not aware of any organization that sells bushings for these old engines. This hard babbit is a dream to mill. It will be a DIY schooling project. I might coat the wrist pin and pour the babbit around it and then machine it to fit the small end.
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Out of curiosity I did a search. Looks like babbit comes in a lot of different flavors,and is readily available.
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Actually some if not all modern engine earing shells still use a layer of babbit over the backing metal it serves to cushion shock loads and provide crankshaft protection. How thick depends on the application. Ford may have had something to do with thin shell development but Henry's Model Ts and As had poured babbitt bearings.
As for pouring an emergency repair bearing it is indeed a satisfactory repair when there is no other option. As an example there are no big end shells available for the Z4 Banfords engines. When I rebuild one the rod goes to a specialist who pours babbitt directly in the rod and adds a shim pack so it can be adjusted down the road if needed. Same would work for a CS type but when replacement shells in every conceivable undersize are easy obained and cheap there is really no reason go another route outside of an emergency repair and try to find Babbitt in your home town, might as well order a bearing as order babbitt.
Actually it is a thin layer of a special aluminum alloy applied over a layer of copper on the soft steel backing shell for most modern shell bearings. Some manufacturers cut corners and do not use the copper under-layer. The copper under-layer also was once used when babbit was used for the bearing material as it helps the bonding of the babbit to the steel.
You have to appreciate the simplicity and effectiveness of some of the old technologies. With so much of the world going down the toilet now days, we may find ourselves reverting back to some of these older methods in the near future.
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Out of curiosity I did a search. Looks like babbit comes in a lot of different flavors,and is readily available.
Yes , Babbitt is a blend of metals and there is no stabdard mixture. Hardness varies with the application. If the babbitt is too soft it actually flows over time and if too hard it cracks and chips,
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Interesting observation 38ac. I hadn't considered that sort of thing. I think I will try brass rather than the babbit I have here.
I believe I read a post where you might have a lathe. Have you ever made bearings or bushings?
I am including a couple pictures showing what I will try first in my attempt to make a proper bushing. One shows a shaft slightly smaller that the wrist pin. The second pict is the outer container to hold the brass. If I can get the brass out or off of the these two items I will consider myself lucky.
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Yes I do have a fairly complete machine shop. I have turned 1000s of press fit bushings and made a few sets of bearing shells from Silicon Bronze.
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Somewhere on the forums, I remember a post about using an aluminum can as shell material. Of course now,
i can't find it.
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Somewhere on the forums, I remember a post about using an aluminum can as shell material. Of course now,
i can't find it.
That may have been me. Around 5/6 years ago I made complete shells from aluminium sheet, 1.5mm thick by memory. These were pounded into shape using a wood dowel as an anvil. The crank journal was badly scored, this was smoothed out with a strip of emery paper, the shells were then mounted using shims made from a drink can. The rod was spun around the crank and high spots scraped off until the contact surface was great enough to support an oil film. The engine was run under no load for short times and shims were gradually removed from between rod and cap until it all bedded in. This engine runs great still after all this time. I figured at the time that if Briggs and Stratton can get away with a steel piston in an aluminium cylinder with very marginal lubrication, then my 3.5 CS should cope fine. I never expected it to work so well, there is considerable loading on that shell. I did make larger oil grooves to increase oil flow from the dipper, was worried about the initial heating during the bedding in process.
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Just to expand on the process if anyone tries this. The alloy was cut 1 inch wider than the journal, bent roughly to shape and squashed into the big end using a 2 inch wooden dowel to force it into the shape of the big end hole. The sides are then peened over the sides of the big end to create the thrust faces. The shells then were filed to shape , the ends made nearly level <crush> with the big end faces between cap and rod. The rest is very time consuming ,to get a good contact surface, using emery , files, and a sharp wood chisel to scrape the high spots
To repair a crank journal its not sufficient to just remove scoring, it also must be round, with as little taper as possible. Initially use strips of emery paper to remove as much damage as possible. Then tackle the finish.
The easiest way here is to make temporary steel shells to fit the rod, these become sacrificial to complete the process of final grinding with valve paste. Again, shims between cap and rod are removed as the journal decreases in diameter. When there is no more binding throughout the rotation, job is done.
Handy Hint...... BRAZE THE OIL DIPPER TO THE ROD CAP.....
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So 38ac glad to hear some one has been there done that. What would be your procedure for making a bushing to fit the small end of the con rod ?
Ingenuity and perseverance, just what MachineNlectricMan was talking about, well done.
All done without fancy tooling.
Did you need to use Prussian Blue or something to located high spots.
Nice touch, valve grinding paste.
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A permanent marker or sharpie will suffice for Prussian blue, or even nothing. After grinding, if the rod is spun dry, shiny marks on the shell will appear on the matt to show the highs. The small end bush could possibly be replaced with a section of copper pipe. If copper is heated to red and cooled slowly, it hardens, the complete opposite of steel. I cant see why it wouldnt work as well as the original bronze bush. In my experience, its the pin that wears, this easily remedied by a length of 1 inch bright shafting. Even without hollowing out the central hole, the extra weight does little, given its just a few grams over the total kilos of rod and piston. These engines are overly engineered for continuous rated duty, something the car people cannot figure when they wonder why their engines develop huge horsepower for only a comparatively very short time. So, there is a bit of wiggle room in patching these things I think.
I have often wondered why Lister didnt spend a few more design minutes to make the barrel more symmetrical. This would allow it to be mounted upside down to put the worn part at the bottom where it wouldnt matter, thus saving a rebore and sleeve.
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Yes a copper pipe would be ok with me if I can find one. The old bush is fairly thick, perhaps I could bore the old bushing out and push a copper liner in.
The wrist pin has any where from 1/2 to one thou wear, measures 7/8 in and is very hard.
I took the old bushing out and set the rod on a granite plate. The rod little bore does not seem to line up to the big bore. I need to check that out. If babbit does in fact swell as it cools I could try filling the small end and then somehow drilling and reaming to align with the big end.
The small end bore is roughly tapered by about three to four thou . By design or just loose tolerances?
I jumped the gun on the bushing I made and did not discover the taper until too late.
The old bush is not tapered and appears to be soft steel with bronze or some fairly hard liner. Possibly I could bore it a little and pour babbit or tin solder and ream it.
Oh well, I will be thinking about it.
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Are you certain that the taper should be there? I haven't come across that design before. It has always been a parallel fit with either circlips or even a lead plug hit into place to keep it there. Even if the fit was a bit firm in the piston to help hold it.
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So 38ac glad to hear some one has been there done that. What would be your procedure for making a bushing to fit the small end of the con rod ?
For Bamford Z2 and any other small ends I turn a piece of brass with the OD being size to size with the bore, this gives a press fit. The ID is drilled undersize while in the lathe. After pressing it in the rod it goes to the mill where a correct size mandrel for the big end is clamped on the table. The is holds the rod in proper alignment to bore and finish the small end bushing once the center is located.
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Sorry about that, I didn't mean to imply that I thought it was a factory taper. It was basiclly a question and you answered
it. Highly unlikely, even for some kind of alignment problem.
Also, the actual measurements of the bore were all over the place to some degree and averaged out as a taper.
38ac's explanation of fitting and sizing a bush is good news. I think if I make mandrels about say three or four inches long
for both bores I should be able to easily determine if the bores are parallel to each other. If needed I can use his
technique to bring things together.
Did I read somewhere a long time ago that a hone will have a tendency to straighten things out in a bore ?
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I am sure that the more creative and skilled people could fit a bushing with basic hand tools but I am not one of them, LOL. I measure the ID of the big end of the rod. Then turn the mandrel to size and square the ends that way I can just clamp it on the mill table. If doing this on a Bridgeport type mill it is imperative that the head is trammed in square to the table. The pin clearance for the small end is best described as small as you can make it and still push the pin through with your fingers. I don't own the Sunnen honeing machine I should own to fit the pin. I get as close as I can with a boring head and finish with an ordinary brake cylinder hone.
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Is all good, sometimes we can read things and mis-interpret them, I'm guilty of that a lot.
Something that may help you out is to go to YouTube and type in what you want to do. You will be amazed at how many videos are out there on every topic you can think of. I am about to retire and only about 18 months ago I bought a cheap Chinesium metal lathe 2nd hand. I have then watched many videos and started to buy more tooling and even had to make my own thread chasing dial because my lather has a metric lead screw and I need to make BSF and BSW threads. Yes, I could stop the lathe and reverse it but this has no brake on it so damage would happen. My research paid off and now have a dial perfect for the job.
So have a look and see some options that might help you out with the tools you have.
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I would be interested in how you make your thread dial work as it has always been my understanding that if one released the half nuts that the dial can only be right after 127 revolutions when threading metric on an imperial lathe or vise versa. As you may know there is no mechanical way (gearing) to EXACTLY convert an imperial lathe to a metric one, the math equation goes to infinity, much like pie, 3.14,,,,,,,,,,,,, the 127 ratio used for lathe conversation gets things close enough for most work but in an exact world a lathe can only thread one or the other without changing the lead screw.
I am not downplaying what you have done! I like to replicate it if I can. I thread a lot of metric stuff on my imperial lathe and have always backed it up but I have a clutched headstock which makes it quite a bit easier to accomplish.
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Hi 38c,
My Chinesium lathe runs a 20mm lead screw. I have all the gears for the head to change the TPI as per the chart on the lathe itself. As you must be aware the big issue is to be able to engage the half nuts at the same position each time as you make your pass a bit deeper each time. This is where I came up with some help on a machine shop form on the Smokstack Forum and for the BSW and BSF threads I required 2 different size gers to mesh onto the lead screw.
I haven't got those numbers here tonight but I can go out to the shed tomorrow and take some pics and show you what I made and as basic as it looks, it works. I also bought a booklet which also had a lot of information for general machining work and some of it goes right over my head as I am not a machinist by any means and only a beginner at best with a lot to learn and willing to do so.
Let me know if you wish to see what I made and use.
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Yes, I understand what you are doing. My big lathe is a Colchester copy and Imperial, my smaller lathe is Chinese but also Imperial but both work the same way. Mine are equipped with Norton boxes so I don't have to change gears, just flip levers but it accomplishes same end. Places a 127-1 ratio in the lead screw to allow metric threading. Also have threading dials but they are worthless when threading metric. They won't put me back on the lead. Now it is my understanding that using a metric lathe adapted to imperial that the same thing happens? Makes sense but also can be wrong. There may be some new techniques out there but old school taught one to leave the half nuts in and back 'er up.
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Yes, exactly, leave the half nuts engaged and reverse and that is fine IF your lathe has a brake and will stop as soon as you hit the stop button but mine runs on so If I was running a thread up a shank to the head of a bolt I would crash into the head of the bolt.
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My mill is not marked but looks like a jet type with a round column that will swing around and the tram is, I suppose, fixed. There are no marks to tell me when I am straight out with the deck. Bought used with lots of tooling.
I should check the tram before I do anything about this small bore project. I made up a mandrel for the big end but this is turning out to be too time consuming, needs to be a winter project.
I have a south-bend garage sale lathe with lots of tooling. I consider the thread dial indicator to be a form of magic. One mark for even threads and another mark for odd threads. Metric a whole different story, indicator with several different gears.
Cobbadog, are you going to post what you did to build a indicator ??
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Sure will as soon as time allows. we have been away on holidays and now my work is bombing me with way too much. Would love some time to take a breath. As soon as I can I will do for you.
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Ok I dug this out of the file and hope it shows you how I built it. It shows 3 gears that I bought off a Chinaman and the product was brilliant and cheap off Fleabay auction site. I welded the round pieces at right angles and use the single bolt as a pivot and a lock to hold the dial indicator onto the lead screw. I also made the marks on the top of the indicator and used a white marker pen. The theory was after I worked out which size gears I needed and I will post a copy of the info I found, I then put the indicator in the hole and used the grub screw to hold the gear on the end of the shaft. So far this has worked well for me to make some BSF threads using a 20mm lead screw.
THREAD CHASING DIAL INFO
I have 3 gears on the stem of my metric thread cutting dial and they are 28, 30 and 32 teeth. Those give you the prime numbers 2,3,5 & 7, which combined with a few different gears will give you all the metric thread pitches you will need. Not quite as straightforward as cutting TPI on an imperial lathe, but 95% of the world's machinists cope. I can take a photo of my thread chasing chart, ie dial teeth v pitch, if that will help.
So that means I would need a 20, 21 and 27 Tooth gear to get all the thread pitches my lathe allows for....
The screw-cutting thread indicator dial meshes with the leadscrew via a 30 tooth gear. To get the indicator dial to rotate once the carriage has to move 90mm (number of teeth x leadscrew pitch). Only those metric pitches that divide exactly into 90 will be able to use the dial when screw-cutting. Thus pitches of:-
0.5, 0.6, 1.0, 1.25, 1.5, 2.0, 2.5 and 3 will work, pitches of 0.7, 0.8 and 1.75 won′t work.
Replacing the 30 tooth gear with a 28 tooth gear would work for the missing pitches but not for all. With a 28 tooth gear the carriage has to move 84mm for a full turn of the indicator and 84 is divisible by 0.7, 0.8, and 1.75. So either change the gear, make an indicator that has both gears or just leave the leadscrew engaged and reverse the lathe.
I think on my leadscrew a 21 tooth gear on the dial indicator will get me the missing pitches. 21 * 3 = 63mm per full turn
For 0.45 pitch: 63 / 0.45 = 140.
For 0.7 pitch: 63 / 0.7 = 90.
For 1.75 pitch: 63 / 1.75 = 36.
Therefore a 21 tooth gear will give these pitches on a full turn and half turn. It will give the 1.75 and 0.45 on each quarter segment.
So I guess I need to source a 21 tooth gear.
With a 3mm pitch lead screw, you do not need a threading dial for the 1mm and 1.5mm threads. They will be synchronized at any place that you engage the half nuts. You literally can not get them wrong unless you remove and remount either the tool or the work.
I have not worked with a lathe with a metric screw, but I believe they usually have thread dials with some internal gearing. This is one of the things that proponents of the metric system do not talk about when they are bashing the English system which uses threads defined in threads PER inch and therefore has much simpler threading rules. I can attempt to give you some guidance for a simple dial that would work but may not be as convenient to use as the ones usually provided by the OEMs. The suggestions below assume a simple dial with the gear and the dial on the same shaft with no additional gearing between them.
The 1.25mm thread will synchronize at multiples of 5mm (1.25mm x 4 = 5mm) that are evenly divisible by 3mm. So you would need a gear that would allow you to travel one of those distances (15mm, 30mm, etc.) The obvious one seems to be 15mm and you would get that with a 5 tooth gear. That's too small. 10 teeth would give you a 30mm distance and that may be workable. If you have an even number of divisions on the dial face, you would be able to engage the half nuts on two of those lines that are 180 degrees apart as they would represent distances of 15mm.
Likewise the 1.75mm thread will synchronize at intervals of 7mm (1.75mm x 4 = 7mm) that are evenly divisible by 3mm. A 7 tooth gear would provide a 21mm distance (3 x 7mm) but I don't know if that would be practical. You may have to go to 14 teeth for a distance of 42mm. With 14 teeth for a distance of 42mm, if you have an even number of divisions on the dial face, you would be able to engage at two of them that are 180 degrees apart. So the same dial would work for both of the threads that you mention that actually need a threading dial.
You can work out other gears for additional thread pitches in a similar manner.
If you use these suggested gears you will have to wait a bit for the synchronization points. It may be faster to just leave the half nuts engaged and back up the spindle. That will work for all threads.
I would appreciate it if someone can check my logic and figures above.
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Wow, a lot of thought went into that. Thanks.
Even though my lathes have clutched head stocks and a brake it is near impossible to stop close to a shoulder when you cannot disengage the half nuts. Another technique is to mount the tool upside down or on the back side of the spindle. You then cut a small relief groove up next to the shoulder (no different than you end up with when using the half nuts to stop the carriage) and cut the thread from the shoulder out running the spindle backwards leaving the half nuts in. Aligning the next pass is accomplished by turning the spindle by hand once you are close bumping the switch.
All in all of I had to cut many metric threads I would find a metric lathe😊
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Doi ng all the sums with help I must add really did my head in but I got there in the end. Even now just briefly reading the memo I wrote out I started having a migrain and all the pain came flooding back and I too wonder how this all worked out.
I received so much help in working this out from another Forum I visit and that is Smokstack and it is based in the USA and has so many topics it will make your head spin. In the machine shop section which covers nearly all types of lathes, mills shapers drills etc and the guys there are always polite and very helpful. I have had a lot of help from these guys in making improvements on my lathe. Things I never knew about like centering the tailstock and for this I bought a dial indicator that measures down to 0.001mm w2hich for me is accurate. When applying the information on how to centre it I did get it to being 0.000mm, perfect by the dial and I am certain that the final adjustment was more about the grunt I made rather than the adjustment of the screws.
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That is for sure a grand amount of information. I am still trying to get it.