A toolroom lathe spindle bearing re-scrape.
Scraping the lathe spindle bearings into alignment to toolroom lathe specification. Part 1 - the lower bearing halves. Not so much a 'How To' certainly a 'How I did'. I have much to learn and lessons to pass on - the white metal / babbit material is like hard butter from the fridge, scratches when you look at it and burrs almost with your finger nail ! So how do you go about scraping the well worn surfaces into alignment and good bearing ? Here is how I have gone about it.
There are lost of videos on KZhead about babbit bearings - most deal with re-pouring new linings, a few show massive surfaces being hand scraped but not much in the way of explanation or the desired outcome, however, there are a couple of videos well worth watching, links will follow in part 2.
I have no doubt that a lot of Experts have learned from your excellent video. Thanks.
My man, you put a lot of effort into this video. Many thanks from everyone out here. Most babbitt repair is needed for countershafts or whatever. I'm glad you took the time to do one on a lathe headstock; quite different. Thanks!!!
Quality 35 mins spent on youtube 👏👏
Thanks for watching
I've seen a lot of scraping of flat surfaces but this is the first time I've seen scraping of a curved surface. Great video of how it's done.
With the right distraction I can make a straight surface curved as well :-) Thanks for watching and commenting. All the best Mat
I play with a 1916 fire engine with a questionable lubrication system. I have scraped a lot more cylindrical things than flat things. :-)
@@andypughtube Now thats a fire engine I would like to see. I am very surprised at how well the spindle spins on the bearings now with just mineral spirits as lubrication and Ive still some tweaks to make.
Parallax errors, whatever happened to including a mirror on the scale so that you move your head till you can't see any reflection of the back of the needle (more or less), then you know you are then directly above the needle and the reading is correct. I miss my old AVO Model 8 multimeter, to this day, I curse the supervisor who decided I didn't need it anymore and passed it on to someone who immediately destroyed it. It had been through a number of hands over the years, but it was in very good to excellent condition, a testament to the old way of looking at things versus, the then, new way of looking at things. In the old days (I am an old crock before my years), you valued and looked after things because of their intrinsic value with no thought whether it was yours or not. Mind you, many people don't even look after things they have paid for, and when it comes to old stuff, especially machinery, who wants that superbly build, massively over-engineered lathe, built of the finest cast iron and other materials of the day, when you can throw it out and buy this pretty looking new (low end) Chinese lathe with nice painted covers and flashy electronics that resonates and chatters and you can't get right because of the hardened beds that aren't right (forever!), has terrible ergonomics, and rusts if you look at it sideways (not to mention the dubious castings that are hidden behind the fancy looking covers). Oops, sorry about that, time to take something and lay down.
It is coming along great , lots of patience ! Cheers .
Thanks for sharing Matt👍. Very interesting.
Awesome video! This is the best filmed bearing scraping video I have seen. Good job 👍
That is very kind of you, on the other hand maybe you have only viewed this one :-) Either way, thanks for stopping by and commenting. All the best Mat
Hi, 4 years later, I am pleased found your work > I have an prewar MG where the wm bearing is oil fed from the bottom. Rebuilding it is 'stuck', wil not turn and after measuring, it needs scraping.... The engine was not 'running' when I got the car, no history known... only 'barned' for more than 35+ years... and a crank 'possibly reground in its life'... as was smaller than factory dimensions.... Thanks for your upload, if you still see this...
I upload to try and have a helpful record of such skills n techniques for others that wish to learn and rebuild things. All the best with your MG bearings. My mentor used to rebuild RR bottom ends when necessary in situ 😳. He was far more skilled and experienced than I could ever achieve.
Excellent work as always Mat. Your dedication on this project is really something to aspire to. I can't imagine the satisfaction that is to accompany the first and many proceeding cuts on this machine. Thanks for all you share. SS
Thanks for watching and commenting Steve. Mat
another very interesting video, thank you.
Thank you for sharing this!!
Looks great Mat you really have got this scraping lark of to a tee mate, I hope it’s as accurate as your expecting when it’s finally done, can5 see why it wouldn’t be. Al.
Very valuable information in this video! Bearings are looking great, and you're successfully de-mystifying one of the "black arts"!
Cheers Daniel - I hope the part 2 is received by viewers as well as this episode.
Hello Mat. This is the first video of yours that I have watched and I thought it was excellent. Lots of information and good video of the process. I've stripped and rebuilt several machine tools (including a 20,000 lb. Broadbent Schofield lathe) but I have never done any scraping. I've always been fascinated by the process and would like to try it someday. Keep up the good work. Thanks, Ken
Hi Ken, thank you for your positive words of encouragement. It is very much appreciated. As you can see, Im no expert and doing the best I can with what I have. This is only the second machine tool that I have 'rebuilt' I started with a shaper - it being about as simple as you get geometry wise - still a challenge but it got me started. The lathe is presenting plenty of new challenges and pushing me to learn new skills especially accuracy. This Holbrook is not big, but it still weighs just shy of 3000kg, of itself a challenge :-) Thanks for stopping by and leaving the comment. All the best Mat
Ive just subscribed - I will find some time to watch some of your uploads - that is one big lathe !
Nice work Mat! ATB, Robin
Thank you Robin - very much appreciated you watching and commenting. All the best Mat
I think you doing an outstanding job with your lathe . And it should be a great machine when it is done Good Luck
With a bit of luck I will be still young enough to use it when Ive done ! Thanks for watching and commenting. All the best Mat
I really like that setup you have for your dial indicator.
The alignment jig ? Its a rough copy of a sled designed in th e50's by Mr King. there are more details on the net if you search for a 'Kingway' . Its OK but I would make some changes if I made it again. Thanks for watching Matthew. ATB Mat
Remember, when you are going for bearing, dont take all of the blue. Just cut it in half each time leaving some behind or else your bearing will only jump around. When you are scraping a bearing of that small a radius you need to use a narrower scraper, the width of the scraper controls the pitch of the cutting edge. I see you have caught on that you need to keep the back edge out of contact whilst cutting, this keeps the heel from rewelding chips back into the soft babbitt, good job. Also, get yourself a piece of old burlap sack and ball it up, use this to give the bearing a scrub before each bluing, cleans off all the burrs and gently dulls the surface to see the high spots better. Looks like you have this under control. Best regards, Chris (Ironsmith)
Hi Chris, glad you found the video and thanks very much for your words of advice over the last couple of weeks. Ive been using some old cotton bedding sheet to de-burr and like your suggestion of burlap as it should reduce the 'buffing up ' my pal Chris said he used worn out backs of cloth backed emery paper and then his 'hanky' which could well have been a scrap of sacking knowing Chris ! - I will get some and try that. A narrower curved scraper - yes that makes a lot of sense - I shall see what I can find - not sure I have anything to hand .
A bronze bearing in a lathe is inherently quite similar to a journal bearing in a car`s engine, supporting the crankshaft... The major difference is that the journal bearing in an engine has an oil pump plumbed to it, well, not exactly, but the oil does travel from the pump and gets to the bearing, so you get the point... The oil here is under pressure and force fed into the tolerance, resulting in a hydraulic film that as you said, should be the only bearing for the crank - the j. bearing and crank should never have any contact between them, and the only real reason why a perfectly made and maintained engine wears the bearings out is the cold starts where the oil film has drained and the crank rests upon the metal bearing for a short while as the pressure sends the oil where it needs to be... It`s almost the same principle as with an air bearing spindle, but using a much more viscous fluid than air to provide for greater support of higher radial forces on the shaft... Speaking of this, i would check and lap the spindle bearing areas round, if the journal bearings are worn, they are worn due to contact with the spindle shaft, while the bearing is softer than the spindle, the spindle wears aswell, and if you are match scraping to a worn shaft, you could induce trouble... Nothing that won`t wear in, but nothing good at any rate if we are talking precision restoration... All the best and kind regards! Steuss
Thanks Matt, really enjoying this rebuild. You must have the patience of a saint and no music in the background would drive me spare. Something that might give food for thought is early Ford engines, model T & A’s had splash lube for the big end journals and of course ran Babbitt. A little bit of looking into it might just give a different insight into how oil clearance and no pressure lubrication can be applied here. Cheers
I was discussing vintage engines and babbit bearing use / lubrication with a chap the other day and the conclusion was interesting in so much as the splash lubrication and small sump were similar as were the speed ranges in the upper range for the lathe. It was the slower rpm range of the lathe where we felt 'our' theory fell down. I will try and cover some of that in the follow up. It would be handy to have the original assembly drawings / notes to determine what running clearances were used and if the bearings were scraped in after machining. Ive had no luck in finding such info' - so thought I would do my best to share what I have learned thus far. Thanks for watching and commenting. All the best Mat
As a side thought Dave from “old steam powered machine shop” is actually an engine rebuilder by profession, and as you would know deals with vintage machinery and has lots of Babbitt experience. If you haven’t already it might pay to tap him on the shoulder and see if he has any insight. Cheers
This is I think the first Video of yours that I have seen. Excellent!! Have subbed and rung bell. If it is any help to you I will say my Grandfather was a marine engineer in WW1 and while he passed when I was 14 my Father told me that the rules for scraping bearings were 90% contact. After WW1 Pa ran a small business repairing cars and farm machinery, this also included scraping in bearings on cars. As I understood from Dad the scraper on Babbit was drawn away from the sharp edge as this gave better control on how much was removed and reduced the chance of digging in. At this point I have not tried my hand at doing this, however I do have Pa's scrapers and need to have a go. Thanks for posting and look forward to the next one. Cheers from John, Australia.
cheers John, I think there is a lot of knowledge fading from humanity as older generations pass. It would be nice to save some of it - it may come in handy sometime ! All the best mat
Отличная работа!
I’ve scraped a good few earring journals just to clean up for refitting bearings but scraping in the bearing is something else! I started in classic car restoration and they were doing the white metal bearings in a rolls Royce engine. I wish youth wasn’t wasted on the young and I had paid more attention now haha
My mentor used to rescrape RR main bearings amongst other things - Ive seen him scrape in a cylinder head to fit a vintage wagon - a few hours work but costless than sending it out ! Thanks for stopping by. Mat
@@lookcreations it’s amazing what can be done with minimal tools when the skills are there. Do you know of anyone offering lessons / guidance in scraping please? I have done bits but would be great to have an experienced eye cast over it and learn
Take a couple V-blocks with a test rod and see how angular misalignments will affect the contact lines, You can extrapolate that for the curved surface. If you tilt the axes of the valley, in one or other direction with respect to one and other the contact line in the V-Block from the test rod does not just shorten, but moves up or down as well. That experiment will give you clues about the alignment of the axis of the bearings in your headstock. You can also put shims under the V blocks to simulate the height misalignment. Not saying you should waste time with it, but if you get confused, it is good to play what-ifs on a known granite surface. Other than that keep it coming, like the way you are progressing through this
Hi Dee, the issue I found took me a while to get the hang of, was how each scrape was controlled to depth. The material is like soft 'aluminum' or as we like to call it aluminium in its most soft blend. Very easy to scoop out to well over 0.0015" deep. The larger curved scraper I spent a while cleaning up was just too tricky to control the weight down for scrapes of 0.00005 or less. i.e. half of 1/10,000" so atfer 'roughing it in , refining the surface was easier to control with the little scraper. It was interesting scraping in the alignment - I could really have done with a large flat ended dti to counter the round bar centre height / top dead centre issue. However, I soon discovered as the alignment improved the errors were much reduced - so it may well have aided my identifying where material had to be removed. Slight corrections at the bearings made larger corrections at the test bar due to reduced errors. All good stuff. Thanks for stopping by. All the best Mat
Great job, I don't think I would have the patience to scrape the bearings...
There has been a lot of slow and steady progress. It took me a while to get the hang of how much material to remove each cycle to adjust the alignment where I wanted - it was very easy to make too large of an adjustment. The specification is very small @ 0.015mm forward at 12" thats c 0.00075mm . Each pass at the end of the lower half process was moving the spindle c 0.0001" or less - all too easy to mess up. thanks for watching. Mat
That first scraper you sharpened looks like the 70+ year old one I have. My dad made it as an apprentice fitter out of an old ball bearing race.
I am told they were a stock item for aprentices to make - most from old files. If I ever get my forge up and running I would like to make one. Thanks for watching. Mat
Nice video with an excellent view. I find that a longer scraper is much easier to control than a short one. Those short FleaBay scapers are nothing but crude deburring tools.
I have different lengths, all depends on the job, sometimes access prevents all but the shortest. They require a different approach. Too long and you can lose the ‘touch’, it’s like carbide Vs hss vs carbon steel edges. The best scraper for the job is the one that’s sharp on hand
@@lookcreations Thanks! Also, it is a personal preference. Keep up the good work!
A great study, before the action! my cylindrical, and taper cylinder scraping is limited to alloys of Bronze to Copper, and Copper to Silver, ref resistance welding bearings, fairly slow rotation speeds. Looks pretty good to me, not sure if a stripdown is required after initial running in, or possibly examination of the spindle lubrication oil, white metal looks quite hard, not sure what grades are available/ used?. An oblique scraping action helps reduce steps, that is both left and fowards for example, oil pockets are very shallow, if used at all, an old trick is to introduce a dent via a suitable implement, rather than feather. Thanks for sharing Mat
An interesting note from an 'old hand' I have been listening to via PM was that once the seat is 'scraped to 50% contact over the 'full' face a very light oil on the journal and then rotated either by hand or under power to 'burnish' down the highest points. Im about at that stage now, using next to no Micrometer Blue and rotating the shaft in position for a minute or so then touching off the darkest / silver points it highlights. I have to agree that some 'inspection' after assembly and no load running up through the gears with monitoring of the temps - examining the bearing faces and journal to see whats going on would be interesting and time well spent. Someway off that yet ! Thanks for stopping by. Mat
@@lookcreations much expounding of knowledge, very impressive. You mentioned oil boundary lubrication, or hydrodynamic at the start, for the smaller bearings we used an a powered hand drill with either a bit of Electrical cable knotted in a loop, and driving on the chuck body to the shaft coupling, or an old belt, drive or from your trousers to rotate the spindle, to reverse direction, just cross the loop. Many thanks for replying, and imparting of knowledge. Regards John.
The procedure you have outlined will indeed reduce the clearance but it would be better to re pour the Babbitt bearings with a shim pack. I would think the original design included shims. In the end you are the gut with tools in hand and making the decisions. For a non production use like a home shop. your scraping and adjusting will make a life time usable machine for you. Good job. Thanks
Hi Dennis, thanks for watching and commenting. I elected to re-scrape as i didnt want to get into re-pouring and line boring the lathe headstock - at least it would be a fall back if I cocked up the re-scrape. I looked at the options to send the headstock out with spindle and well - i would have run out of internal spare organs to sell to fund it ! There is no doubt that this approach is not the 'best' from a machine rebuilding stand point for prolonged production use etc - but it most appropriate for my intended use. It remains to be seen if I can get the lathe rebuilt to spec' and then use it as such :-) All the very best Mat
Mullar Nickd is a Great man.. been a fan along time .. now he has given his Shaper to another guy... a nerd ... a craftman.. so Muller nicks works is going on!
Muller Nick put some great videos togther on scraping before the subject became fashionable on KZhead. I learned much of what I have learned from others through his videos and then the rest from many different places alongside doing it. Thanks for watching and commenting.
@@lookcreations me too... im going on for the 10 year.. in 2010 I looked at his video. Now a good german called Stefan Gotteswinter has taken over .. he scrapes and does also use Niks old shaper machine. He is a true pro in Prototypes and good Humor online. He''s skills are in the top of the pop. Offcourse he is not civilized and or Dane or Brittish.. ! ;9
Brilliant just about to scrape in a crank shaft on a 102 year old Amanco stationary engine
Thanks for watching and commenting. Good luck with your engine
Interesting when you dropped the RH the LH blue showed opposite to what I expected. I thought it would have pivoted on the inside edge and lifted the outer edge clear.
It’s been a learning curve !
My Porter C jointer (1.70" dia journals) has oil wicks on the bottom of the bearing base. The wick slot is ~ .375" wide by about 60% of the length of the bearing. The felt wick extends into a reservoir cast into the bearing base. The oil is replenished by a drip oiller through a hole at the middle level of the reservoir.
What rpm does it run at ? It’s good to hear of similar set ups out there.
It runs at 4K, however, I'm just a hobbiest and never run It for more than 15 min's. at a session. The bearings are 6" in length so there is quite a bit of surface area. I'm running .004" radial and .006" axial clearance. The axle journals have been hard chromed and ground.
👍👍👍
Thank you
You are welcome
I usually use a paper towel rolled up like a dumpling with a tail to apply blueing that shit gets everywhere. I also dont scrape right off the bat I use a peanut grinder with a coarse scotch brite pad to work down the initial high spots. You have to be careful not to take too much, before I start to scrape saves me time. Another thing that can be done to get it really really close is to use a very fine lapping compound on the shaft this will get 100 percent contact. We do this on gate valves all the time works well
except you absolutely should not make 100 percent contact. otherwise there is no room for oil unless bearing are a different matter than bedways
@@fuckingpippaman well it really depends on how the oil is delivered. 100 percent with oil hole feed similar to a crank shaft is sufficient. There are several fits as you would call them, also, generally speaking you are right if it's a sling style oil system.
And you also have to remember it's babbitt so there will be what's called wear in. As it wears it rides on a bed of oil better.
Even if relocating the axis wouldn't require to be undersize to begin with, that won't work unless you plan to grind the flat on the top halves to then scrap until matching, and even then you'd end up with unwanted clearance. You should try casting some babbit and to analyze the results. It's easy to cast, and perhaps too easy to work with when it comes to material removal, but the upside is that you can always start all over again with minimal fuss once you have the required setup. You'd only need two molds of such simple construction that I don't even think deserves explanation. Keith Fenner (iirc) had a nice video on casting babbit bearings.
You make a good point, the casting operation wouldn't be overly complicated - but the cast faces would still require either scraping or boring. So whilst it 'could re-establish the original axis of the spindle it was my view that it would be a good last resort if a 're-scrape' didn't prove effective. As for the upper halves, there are methods of producing the contact faces with running clearance without the shims - not simple and not the direction I am favouring at this time. So I shall be looking to make up some shims and then machine of the mating faces of the upper halves then re-scrape for fit and shim for running clearance.
You don't normally machine babbit for cases like this, it's soft enough not to need it. You simply make a "mold" which is no other than a plug of a suitable diameter with undercuts before and after the contact area, then a washer of suitable size is machined and cut by half. Two pieces of scrap iron are welded to each side (perpendicularly) so that it will make the walls retaining the pour while it lets the plug sit where it should for the cast to end up undersize. These iron pieces cover and protect the threaded holes, which are normally used as locating pin-holes on the process, on your bearings' flat while give you indication of when to stop pouring. Then it's all a matter of scraping to match. You'll have to scrape the flats as well, and maybe even start with a file, depending on how much you poured that wasn't needed, but you'll have the part of the flats that was covered while pouring as a reference. For the sides you use c-clamps and almost no post processing is needed. Your bearings are machined from factory just because of mass production, but you'll get much better performance on the long run and much better lubrication with scraping. If you plan on doing shims, well, I guess that's going to be more difficult than doing things "right", but feel obviously free to try out things knowing you can always cast as a last resort. Just saying is not that out of reach as it looks like, as a simple offsite test will show you. Will keep an eye on your progress either way!
Mat, this is a great video. Watching you bring the spindle into position through scraping is a pretty cool thing to witness. Thank you for sharing. Now, I am woefully ignorant of the subject matter, having only read a portion of Connelly's book and watching videos on YT, so please don't read to much into my forthcoming question. If there were not shims between the bearing caps and headstock bearings, why didn't you repour the babbit bearings using some shim stock between the caps and lower half, then scrape them in. This would have left room for future refitting from wear and you won't have to remove more material from the bearing caps. Again, let me reiterate that I am too dumb to be even a novice at this and my question is not meant to imply anything. :-) I am just curious. Joe
Hi Joe, the short answer is - I didn't want to get into re pouring the bearings. never done it, seamed like overkill given the limited wear in the lower half - worse case scenario ; if I messed up the re-scrape on the originals, i could then look to re pour and start from scratch all be it with a bit of babbit scraping experience. From the discussions Ive had with other Holbrook owners, the bearings were shimmed on similar machines and thus likely were on this originally. I will when the lower halves are done, rebuild with the spindle and top halves and measure the shaft lift to see how much material I have removed from the lower half. Might be interesting. All the best Mat
The only other babbit bearing reference i've run across is Keith Fenner repouring bearings for marine drive shafting. Not remotely the same class of required fit, but he does make the process look pretty straightforward!
@@somebodyelse6673 there are plenty of babbit pouring and 'clean up after pouring' but Ive not seen one yet start to finish on scraping in a bearing. Still searching mind, and KZhead has quite a few videos :-)
@@lookcreations - Your current project may be the one that makes you the (KZhead) world's foremost authority and resource on the matter. I hope you will remain able to share what you have learned with those looking to do the same!
I never knew you could work the old ones back into use thanks witch is better old lead bearing or silicon bronzes .
Well its maybe not standard practice and thats why I cant find information on line about it - but it makes sense to me if alignment issues are not too bad. As for bearing material - thats a good question. Horses for courses i guess. Both have their advantages and disadvantages - I will try and cover a summary in the next video.
thanks
those circular dovetails are memorizing! so you have a high pressure pump that continuously moves oil through those bearings (like a combustion engine) right? I have been watching some of your videos on scrapping, they have been very helpful as I start to learn to scrape, thank you for sharing
Hi Matt, the oil is wick fed from the lower bearing half - no presure feed - thats where the need ofr a good fit comes from. Ive still to commission the bearings, set the gap between the halves and confirm the contact area / profiles are correct for running on the iso 32 oil. Good luck with your scraping. take your time and get a system which works for you. All the best Mat
Loving videos but if I could make one small critique that would be to stop using the red Border on your video as I cannot see if I've watched your video or not hope that makes sense keep your updates coming great work so far
Never concidered that. I shall try something different and leave the red off the bottom see how it looks. All the best Mat
Great stuff..Been looking for a video of white metal scraping for some time...ps are you from Nottingham?
A bit further south than Nottingham - just south of Leicester - lived in the Peak District for more than half my life and still got the home accent !
A total shot in the dark Mat since I'm blind guessing. One would think if anyone had information on the actual methods and requirements of scraped babbit bearings then the manufacturers of babbit would be the ones who do. But I haven't checked that's true either. Very frustrating when you can't find information that should be commonly available though. As you pointed out turbines and likely a few other places still run babbit bearings so some information should be out there. At there speeds and using high pressure pumped oiling systems I'd guess there clearances might be a bit looser than what your needing though. Fwiw my little Atlas mill uses OEM shim packs, there lightly glued together so one or more can be peeled off after some slide wear. My next guess is they were done that way for two reasons. Likely large sheets of shim stock were glued together at the factory making it easier to stamp the shim pack to dimension. And with them held together like that it's probably a bit easier for the end user to just peel one off and not be dealing with a whole lot of loose shims. Glueing them together might make them a bit easier to drill and machine the whole lot to size in a home shop, but other than that there doesn't seem to be any real need for whatever the hell they used for glue. Very interesting video and the very first time I've seen this type of bearing being scraped in.
The shim making is giving me pause for thought. I have a pack of brass shim to start with and will see how that evolves ! Ive struggled to find babbit suppliers in the UK, a couple of 'old stock' sellers but so far no makers. That was part of the reason I went to re-scrape rather than pour replacements. Funny when I see the pounds and pounds of babbit ingots sent into folk like Keith Rucker from viewers - seams its a lot more common over in the USA. Got some head scratching to do for the next stage. All the best Mat
It is interesting how were made rotary parts of first machine tools in the world like shafts, spindles, bearings and so on without using any machine tool
Scraping in plain bearings is still a skilled hand job on large turbines and similar - it has the advantage that it can be done on site. there are some interesting posts on forums on the subject . Thanks for watching. mat
@@lookcreations can you reccomend some sources of information about this topic?
@@HaasMill I’m sorry I can’t, I struggled to find a single source so read everything I came across on Google. Then worked out what was useful and what wasn’t. There’s a lot of information out there and you have to learn what is relevant to your project. Large bearings are different to small, submerged bearings different to forced lubricant vs gravity fed. Hi speed vs low speed etc
nice video,just i see no have a good high spot on the bearings.how is the tollerance by the spindle to the bearings?when i did some job same you,i leave 0.025mm all around the spindle
I will try and answer your question here and in more detail in a future video. The bearing halves a scraped to give 80% contact over length and approx 30% contact on circumference in a solid area. That leaves the sides of the bearings to shaft clear for oil wedging. The bearing halves currently have 0.003” shims. I will look to reduce this to approx 0.002” (0.02 :0.025mm)
looks like it might come out ok!
Well thank you Emma :-) Of course it could quite easily go the other way ! All the best mat
I think now that the alignment is good I would be inclined to make a dummy shaft that I could use to lapp the contact in some on those bearings rather than trying to scrape it all for points. remember you need oil clearance for the spindle to run so in actuality you should be scraping to a master oversized by the amount of clerance you want. Doing it as you have will result in an oval shaped hole to spindle contact.
Hi Brian, I thought about a making up an oversized master as you suggest. Its part of the reason its taken me so long to get o this stage. In the end the following issues stopped me:- my Boxford Lathe is only good for 24" max between centres - workable but not easy. However, I would then have to make up a 'test bar' to ensure the alignment remained .. or maybe swap back to the spindle and see (I felt the swapping round may result in errors), then as I investigated further I discovered the internal faces are not in fact round in the true sense - they are 'lobed' to improve the oil wedging. So scraping to the oversized master while it would provide a consistent running gap would require that it then be re-worked to provide the increased clearance for the wedging. I then looked at the shape I would likely generate - as you say' 'Oval' or round at top and bottom and pinched at the sides - in fact it actually opens out at each side - so pretty much the shape of a lobed face after taking into account the lower wick, part lines and then scraped contact faces. The shimming then allows adjustment of the running clearance. I was still unable to find definite answers either way. So in the end concluded use the spindle and 'Chris aka ironsmith from PM (see comment above) gave me some really helpful advice which Ive been following. Honing - not sure how that would work - its my understanding that the 'hone' carrier has to be softer than the surface being honed; otherwise the abrasive sticks to the softer face and erodes the harder face. I would have to use some really soft aluminium or maybe copper ? I just figured I could keep picking out points and yes it takes bloody ages ! All the best Brian. Thanks for watching and commenting - I hope my replies help explain how I reached the conclusion (right or wrong). Mat
@@lookcreations Thanks for the insightful reply, I understand your methods and reasoning better now. I honestly don't know anything about this type of work either as I have never done it. I was just thinking about it from the perspective of how we work hydrodynamic bearings in engines, but I realize this isn't really that type of bearing and the speeds are much lower. Hopefully it all comes out good, it at least should for trying! :-)
@@bcbloc02 i think its important folks can know where I've come from and how I arrived at the current situation. The KZhead community has been a real help to me learning these new skills along with that of Practical Machinest - I am trying to do the best I can with the information I can gather and share the knowledge in the process; sadly my little channel has a pretty small audience and that information flow is slower than my scraping :-) Just know I really do appreciate the input from you and other commenters. All the best to you Brian. Mat
do you think its harder to scrap the soft material vs. harder stuff? It would seem to me, and I've got no experience, that the softer stuff would be less forgiving.
I feel its easier to scrape the babbit in terms of less effort. On a flat surface it would a great material to learn to curl on, its more tricky on bearing ID but still possible. Less effort means you have more control and make less errors - mind the double curved scraper is a joy to aim with ! not.
i have read in the past that the toolroom dsg17 took one fitter 3 days to scrape in using red lead as a marker.the write up is on lathes.co.uk dean smith and grace section.btw you are doing a great job.
I dont doubt that figure, I think im up to 12 hrs now on the lower halves - I am hoping the upper shells will be more straight forward as the alignment is set up. I do have to make up the shims which may prove a challenge. Thanks for watching. Mat
Nice work, slow but sure!
Best approach for me. I can take it off but not add it back on !
Hi. I am not an expert in babbit bearings but I would appreciate any explanation why do we need to scrape this bearings after machining it with precision process? Thanks for the information.
This lathe and the headstock bearings are 70 years old and well worn, so I re-scraped the bearings back to good as I dont have large enough machinery to machine the bearing faces - even then you scrape for fit.
lookcreations Hi. Thanks for the explanations... I would also like to ask if you have knowledge in power plants as I notice that some turbine and generator bearings are being scraped too to which I was actually referring at. Have a great day.
scraping spindles... whoa, all I know and hear about is about scraping surface plates and straight planes.
What clearance are you shooting for? .001 inch or better?
Tricky to say at this stage. but in the region of 0.0015 to start with.
I work in a cnc grinder maker and we have 0.001 mm on the spindles
sir kindly mentioned tools used for scraping ????
For scraping the bearings, the hand tools are available used on eBay and some new old stock. These carbon steel curved scrapers are a typical apprentice project . An old worn file is reforged into the shape required. I show a bit more of the scrapers on the first bearing video. Let me know if you need more details. All the best Mat
Indian...Pakistani...Asian 😂😂😂 Thanks for sharing, I’ve never seen scraping on round surfaces. For someone with OCD about machinery, engines and making things as perfect as possible I think this is a perfect hobby for me to take up. You earned a new subscriber. For a gearhead and perfectionist this is like porn.
Sorry if that description was a little vague and I hope it didnt offend anyone. I was watching the scraping rather than the folk doing it.
lookcreations...well people take way too much offense to too little, so if it did, that’s their problem. There are more and more people who wake up in the morning with the goal of getting their feelings hurt. I say to hell with them. I thought it was hilarious. Thanks again.
your oil observations on the bearing I think you are rit.. I got the Sherif of N Ham .. in visc fluids once... hard m th r fc k r...!! Thats why Robin went to live in sherwooed forrest.
Post #9 in this thread Mat.www.practicalmachinist.com/vb/general/dykem-hi-spot-vs-canode-333360/
too much talking, then only a view of your head for the actual scraping part.
Sorry it wasn’t up to your demands. Did you understand the issues involved? That’s where most folks need help rather than the actual ’scraping’. Thanks for watching and commenting
I it's for the community then I understand@@lookcreations