How to determine which surface to scrape first on a bed ways.

I would start with the easiest one, probably the tailstock flat way, then the tailstock V.

No I do not want my misleading and bad advice broadcast anywhere else.

I'm not a professional scraper so I just shudder at the thought of scraping a lathe bed with two v's and flats using just a straight edge as reference. If you have a master sled for bluing that particular lathe then no worries. Without, I'd send it out for grinding and use the freshened up bed as a master for saddle, tailstock, maybe headstock if needed.

L7

I also meant to add, you should always start at the beginning. Imagine of you started at the end, the job would be done before you started.

RC99 said:

I also meant to add, you should always start at the beginning. Imagine of you started at the end, the job would be done before you started.

Click to expand...

Now thats a novel approach. :-)

Am still checking into a raft to float the bed over for grinding !

lucky7 said:

I'm not a professional scraper so I just shudder at the thought of scraping a lathe bed with two v's and flats using just a straight edge as reference. If you have a master sled for bluing that particular lathe then no worries. Without, I'd send it out for grinding and use the freshened up bed as a master for saddle, tailstock, maybe headstock if needed.

L7

Click to expand...

I was reading about 'master sleds' for multiple V ways a few months back - my thoughts at the time was it seamed a lot of extra scraping - now - I think I can appreciate the benefits of such a sled on beds with multiple inverted V's on the same mating part.

Mat

Lurk said:

I was reading about 'master sleds' for multiple V ways a few months back - my thoughts at the time was it seamed a lot of extra scraping - now - I think I can appreciate the benefits of such a sled on beds with multiple inverted V's on the same mating part.

Mat

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I've done it! Richard will condemned me for saying it and admitting of doing so. But you have to remember, for the sled method to work, you must have at least three surfaces co-planer to each other that are known to be straight, unworn, that are not a bearing surface. They have to part of the bed ways and machined at the same time the original way surfaces were machined. Surfaces for consideration is the side of the bed, possibly the top of the vee ways, and the flat surfaces at the bottom of the vee ways. I won't go into anymore details than this. Every lathe bed is different and this method may not work for all. Remember, don't expect it to make the ways perfectly straight as they were when it left the factory. There's alignment issues you have to consider with the head stock and tail stock using this method, too. This is not to replace sending the bed out to a grinding or planer service to have done. It's kind of a "patch" to improve the performance of a lathe over what it was performing before the rework.

If you do some searching here on PM, there are several threads where people, including myself, have used this method to straighten up the ways on their lathe beds. There's also ton's of you tube videos out there where people have done nice jobs and those that did a butchered up job of grinding beds and such, too.

Ken S.

4GSR said:

There's also ton's of you tube videos out there where people have done nice jobs and those that did a butchered up job of grinding beds and such, too.

Ken S.

Click to expand...

Yea look at this dodgy one My Lathe Way Grinder in Action - YouTube

RC99 said:

Yea look at this dodgy one My Lathe Way Grinder in Action - YouTube

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Yeah, that's pretty interesting. It looked like it was taking off the most material close to the headstock where you'd expect the most wear. Then sort of sparks out when it gets to the tail end. (All except the part his sled doesn't reach.)

Thermite - If I understand you correctly - as long as the bed -re-scrape provides a consistent alignment even if it differs from that which was originally machined/ ground it will prove serviceable. So trying to reproduce a surface to exactly the same specification / profile as original is not the only option.

Makes sense. As long as I adjust the associated geometry of mating parts accordingly.

I am trying to get as many ideas / options as I can; to then assess which will be most appropriate for my lathe and future refurbishment projects.

Thanks for taking the time to comment - very much appreciated.
Mat

or Lurch on occasions it now seams ?

Richard King said:

Hopefully when Lurch shoots his You Tube show he will acknowledge he gets the majority of his information from Members of PRACTICAL MACHINIST and doesn't say a word about who he learned from, making it look as if he is some genius thinking this up on his own. Here is a thread on scraping a lathe bed. I helped with this effort in in person talks, phone calls and email. https://www.practicalmachinist.com/.../american-pacemaker-lathe-restoration-259065/

Pretty much everything has been talked about on PM one time or another, some really good info and some really bad. Also watching some You Tube shows, some are excellent, some are so fake it makes pro's puke. But if the producer of the show knows a bit more then the watcher, he seems to look like he is an expert.

There are a few that I have also written over the years and my students have done lathe beds either on You Tube. Jan Sverre Haugjord has several rebuilding YT's scraping all sorts of things. Keith Rucker of Vintage Machinery has a few too. I expect there are several others. Lurk talks about he has a friend named Chris who is a professional rebuilder and if that's the case why is he asking us? A set up for his YT show?

Click to expand...

Am in the process of researching Richard - the answers / approaches may or may not make it into a video - rest assured I will do my best to acknowledge the sources. The pacemaker thread is noted and I will read it later. I have been watching Jan, Rucker etc etc for a long time now - but as yet I have not seen the explanation I seek.

Perhaps you can suggest it ?

'once the bed is mapped out and areas of wear determined etc - the plan or sequence for which face of the profile gets addressed first, second and so forth.' I am sure there has been a great deal of thought put into this and by now a 'standard' approach developed - I just don't seam to be able to find it on line - either here in these threads (although Ive several years of threads to research yet) or on YT etc.

As for asking Chris - he has not been in the best of health over the last few months - I am off to visit him later to wish him a happy new year and cher him up a little.

All the best for 2019
Mat

Lurk said:

Thermite - If I understand you correctly - as long as the bed -re-scrape provides a consistent alignment even if it differs from that which was originally machined/ ground it will prove serviceable. So trying to reproduce a surface to exactly the same specification / profile as original is not the only option.

Makes sense. As long as I adjust the associated geometry of mating parts accordingly.

I am trying to get as many ideas / options as I can; to then assess which will be most appropriate for my lathe and future refurbishment projects.

Thanks for taking the time to comment - very much appreciated.
Mat

or Lurch on occasions it now seams ?

Click to expand...

The GOAL remains to conserve the OEM alignment, regardless. Among other reasons it is simply less WORK to preserve than to deviate. It need not be "perfect". Only "better than it was".

The point, really, is like the prolific "80/20 rule".

IF/AS/WHEN.. one can gain 80% of a useful improvement at 20% of the cost and effort? Or even 50/50?

A great many "tired" lathes might be made far more useful, even if not all that close to "as new". The "full monte" is tough for a(ny) commercial shop to justify. Quite often, a new(er) machine-tool is sounder economics. Or even an OLDER one as simply has less wear and/or damage.

"We chick'ns" are they as snatch-up the cast-offs as they are shoved off the lot - seldom giving a thought to the REASON it was sold-off quite often being that it was beyond economical repair!

Now the "fun" begins?



Sometimes a reasonably effective "monkey patch" or two will see even a hobbyist's machine making stuff, rather than spending a year or so all apart as he "learns to scrape".

And eventually sees it sold-off as a literal basket case - "good in parts"- but never actually finished, re-assembled, and put back to WORK!

Whom is paying whom, here? For WHAT?

And just WHEN LAST did a customer add an extra hundred bucks onto an invoice because they liked us having lovingly restored Old Iron vs anything from who-cares-comma-"Inc." that simply delivered product - or project - to the needed specs?

Being ABLE to do the finest of work is commendable. Knowing when to NOT BOTHER and do something a better way is how you live long enough to actually HEAR a commendation!

The proverbial "command decision" or "judgement call" is one of the first areas one deals with after assessing a machine.

The review: "I now know what it needs, how much of that is WORTH even starting?." A Management exercise, "decisions" are. Not a labour one.


"Wise asses" tend to simply run what they got, all the while searching for a better machine.

OCD asses would hand-scrape the entire crack of doom for a gas-tight fit, or scrape and flake a LEVEL for "oil retention pockets" just because they CAN.

But who has the time? Who has the coin? And was there REALLY no OTHER priority in life?


2CW

Lurk said:

'once the bed is mapped out and areas of wear determined etc - the plan or sequence for which face of the profile gets addressed first, second and so forth.' I am sure there has been a great deal of thought put into this and by now a 'standard' approach developed - I just don't seam to be able to find it on line - either here in these threads (although Ive several years of threads to research yet) or on YT etc.

Click to expand...

Looking in the wrong place. The "process" - and there IS a formal step-by-step - is now too old to have much of a footprint on the internet.

What you seek is in hardbound books, not You Tube - it takes more TIME to do and to explain. The books have been mentioned many times, this forum and others.

- back for an edit. Got to go look at mine for a point or three.....

OK... here's the deal. The best "overall" English-language source seen to date came out of the Moore Special Tool Company. Not ONE book. MANY.

If you can only ever find the time to read "just the one", then go here and download

"Foundations of Mechanical Accuracy":

https://ia800104.us.archive.org/20/...curacy/Foundations_of_Mechanical_Accuracy.pdf

CAVEAT: There are over 500 illustrations. All of them explained. And superbly. Of course. See how hard that would be to convey in a short "instant gratification" You Tube clip?

Next one is a tad dodgy. "Machine Tool Reconditioning" edited by a non-practitioner who aggregated the work of many others.

https://ia801902.us.archive.org/24/... Tool Reconditioning - Edward F. Connelly.pdf

No surprise he got a few things out of proper order.

He charged right in to scraping.. ran for 22 chapters.. and only AFTER that took up the assessment process that determines whether one NEEDS to scrape, grind, or simply scrap the machine and go find a better one!

That cart before horse sequencing seems to have infused some folks with the religious zeal that if only they become grand hands at scraping, magic becomes theirs to command and all other humans become lesser serfs.

Well. personally, I might vote for brain surgeons, statesmen, or competent gene-splicers "now and then" if kissing of "anatomy" were to become a legitimate form of taxation... not to mention healthy and interesting WOMEN any hour of any day, taxing or not!

But there you have it! Common sense has been banned as too disruptive of "belly push" muscle-memory.

Richard King said:

Lurch you have quit the instructor listening to the biggest fool on here. Thermite. 2 peas' in a pod. At least Lurch you do the work and show photo's. Thermite on the other hand is a Fake as he has never scraped anything accept his windshield IMHO. I know you both like egging me on, but unfortunately you are spreading again how to do it the wrong way. Hopefully the new readers of this post will recognize neither of you two would ever be paid by someone wishing to have their machine rebuild in a reasonable amount of time and better then new accuracy. Your both guessing and you hope someone will walk you through it so you can copy cat the correct way IMHO. It will be a cold day in hell before I help either of you.

Click to expand...

That is a pretty sad state of affairs Richard. I am sorry that you seam to have taken the view that I hold little regard for your comments by the fact I listen to others as well. Last time I checked there were many on this forum that are both professional, semi professional, in house, and then a good number of members not interested in the business end (getting paid to scrape / rebuild) merely the method / techniques for their own ends.

For my part, I have no intention of selling my skill set as a service - were I to, what business is that of yours ?

I have asked a simple enough question which I thought would help others like myself - the purpose of these threads - or so I understood.

By all means add nothing further - it is just a pretty sad way to start the year - the very fact you have contributed to so many threads over the years I am afraid will continue to help myself and others like me do as you say 'copy the correct way' . 17 times I have made reference to your advise / teachings in the videos I put up last year - admittedly, I havent counted up every acknowledgment ref' to PM threads over the same time. All that appreciation wiped away by a single harshly edited video uploaded in a rush to get it online and subsequently corrected with acknowledgments when you flag it up in less than an hour.

Looks like Im off to re-read some old text books and think through the process for myself and learn by trial and error and then to share those findings to hopefully save others some time and effort.

Thanks again to all contributors.

mat

(previously known as Lurk)

Lurk said:

...

'once the bed is mapped out and areas of wear determined etc - the plan or sequence for which face of the profile gets addressed first, second and so forth.' I am sure there has been a great deal of thought put into this and by now a 'standard' approach developed - I just don't seam to be able to find it on line - either here in these threads (although Ive several years of threads to research yet) or on YT etc...

Click to expand...

Mat,
I'm afraid you're chasing a red herring: on a lathe bed all surfaces are either parallel or the lines of intersection between their planes are parallel (and parallel to the spindle axis).
It is rather different than tackling a shaper or a milling machine, where you have to restore perpendicularity of planes of movements, therefore some more thought on what to scrape first and use as reference is of paramount importance.
In a general case, the order in which the various components of a lathe are scraped (bed first, tailstock, then headstock-unless you're building a new TS base because of too much wear-, saddle-which could be in parallel with HS/TS-, etc.) is important. However, the order in which the various surfaces on the bed are scraped is much less important and will largely vary from project to project and from rebuilder to rebuilder.
My general preference would likely be similar to RC99: scrape the TS ways first, since they generally have less wear and have better conserved references (i.e. the absolutely unworn area under the HS-unless the ways end before the HS-and the TS end), and you can leave the TS ways higher than the saddle ways (i.e. if you find only .002" wear on TS ways and .005" on the HS ones, you do not need to scrape .005" off the TS ways to bring them down at the same level: you just need to remove .002", increasing the lathe swing by 0.006").
Templates: are great if you are in the business of scraping multiple identical machines, making mostly interchangeable parts. Given the above example, a template would force you to unnecessarily remove .003" from the TS ways.
Since the finished bed will become your template for scraping the other elements, preserving precisely the angles of the ways is not necessary. What you need to be concerned with is to preserve the parallelism of ways and intersection lines between planes. This can be easily achieved with a precision level and KingWay-like tool or dedicated test indicator-holding fixtures (see Connelly's book).
To be noted that, given that a template is generally rather short, if used alone, it is likely to introduce twist.

Paolo

What Paolo said, and there is another related "nugget" stashed deep-old in PM's annals on the same vein.

"Sleds" are also difficult to NOT have go out-of-line as well.

The late - and sorely missed - Harry Bloom beckley-something-or-other PM UID - was remarkably good at sharing his disappointing experiments easily as well as his successful ones. The value in that was that paying attention to what Harry had found wanting can save a great deal of TIME by NOT repeating what did not work well, over and over again.

My personal "take away" on the typical short "sled" approach, an "adjustable template with active components" in a manner of speaking, was that if a person wished to avoid the professional hire of a proper bedway grinding job, the "guide rails" for a sled could NOT be a mere short section of the lathe's own bed.

They must be long-baseline ones. "In theory" long enough to not rock or tilt even with full-length traverse. Also stiff enough that if a grinding head is incorporated, the forces involved in powering and applying a wheel can be controlled.

Can it be done at all? I'm not optimistic that it is possible or practical with "legacy" solid-metal means.

As with portable goods for line-boring IC engines or refinishing valve guides and seats, or boring and honing cylinders, if a "portable" as-in take TO the machine rig was viable, it would already be common, if only because it saved the cost and downtime delay of breaking down a lathe and freighting the bed to and from the grinding contractor, then re-assembling it and still "not quite done" nor even all that close to "done".

Might it become "possible"? Could was.

Witness the shift to ACTIVE tracking of, for example, a laser beam. And other electronic "guidance", small scale. Also incredible precision.

The time MAY come when a "Pelican Case" is shipped in, a device unpacked and attached to a the worn machine, it is rough milled, then ground, and all without any part of it needing to leave the machine-hall it resides in.

Downside? It may save TIME. I do not expect it to also save MONEY.

Paolo_MD said:

Mat,
I'm afraid you're chasing a red herring: on a lathe bed all surfaces are either parallel or the lines of intersection between their planes are parallel (and parallel to the spindle axis).
It is rather different than tackling a shaper or a milling machine, where you have to restore perpendicularity of planes of movements, therefore some more thought on what to scrape first and use as reference is of paramount importance.
In a general case, the order in which the various components of a lathe are scraped (bed first, tailstock, then headstock-unless you're building a new TS base because of too much wear-, saddle-which could be in parallel with HS/TS-, etc.) is important. However, the order in which the various surfaces on the bed are scraped is much less important and will largely vary from project to project and from rebuilder to rebuilder.
My general preference would likely be similar to RC99: scrape the TS ways first, since they generally have less wear and have better conserved references (i.e. the absolutely unworn area under the HS-unless the ways end before the HS-and the TS end), and you can leave the TS ways higher than the saddle ways (i.e. if you find only .002" wear on TS ways and .005" on the HS ones, you do not need to scrape .005" off the TS ways to bring them down at the same level: you just need to remove .002", increasing the lathe swing by 0.006").
Templates: are great if you are in the business of scraping multiple identical machines, making mostly interchangeable parts. Given the above example, a template would force you to unnecessarily remove .003" from the TS ways.
Since the finished bed will become your template for scraping the other elements, preserving precisely the angles of the ways is not necessary. What you need to be concerned with is to preserve the parallelism of ways and intersection lines between planes. This can be easily achieved with a precision level and KingWay-like tool or dedicated test indicator-holding fixtures (see Connelly's book).
To be noted that, given that a template is generally rather short, if used alone, it is likely to introduce twist.

Paolo

Click to expand...

Happy new year Paolo - all of that is to my mind very logical and most appropriate for my particular lathe restoration. I am part way through putting the parts together for a 'kiingway-like' tool - thats a project in and of itself. My friend Chris had talked about the tools he made use of across the machines he rebuilt over his career and with luck and (I hope) his return to good health in the near future, I hope that he will be able to share that knowledge with me and I can pass that on in turn.
Mat

One area often unmentioned is the area the rack bolts onto, it is machined in the same plane as the ways, and will be totally unworn.

Also there is the same at the rear of the bed. It also should be unworn, although I would not take that as gospel until investigated to confirm. So you can use it as a reference.

RC99 said:

One area often unmentioned is the area the rack bolts onto, it is machined in the same plane as the ways, and will be totally unworn.

Also there is the same at the rear of the bed. It also should be unworn, although I would not take that as gospel until investigated to confirm. So you can use it as a reference.

Click to expand...

Point. There are anywhere from 8 to 16 "parallel, because why NOT?" surfaces on the typical "good lathe".

Even those not done to the best of all possible finishes are generally STRAIGHT and parallel. "Critical surface" or not, there was no POINT to making them any other way. For the OEM it would have been EXTRA work to do so and made all-else as had to be done to complete the assembly harder to do. So they are generally really, really "good".

Hey Mat, Im not sure theres any one right way to sequence things per say, reckon it depends on the design of the machine some. On a lathe bed, probably best to collect any unworn surfaces and ride those to see where you are and indicate the others, RCs suggestion of the rack mounting surfaces is a cheeky confirmation, never thought of them . Even if the non wearing surfaces are just planed is should get you in the ball park, a straight edge and Kingway/sled with levels should help with confidence as to their straightness/ twist. Getting in the tailstock surfaces first makes sense, youve a pre made sled in the tailstock base and the surfaces will 'probably' show less wear.
One thing id caution in my minor experience, dont take the headstock spindle as gospel. My DSG showed signs of previous works. Seems rather than going straight down the guys scraped the least amount out to of the top surfaces to get them straight and aligned. With the usual wear near the headstock this effort left the gibed surfaces /headstock /drive screws out of alignment. They 'remedied' this by rough scraping the back end of the bed where the headstock mounts to get the vertical spindle alignment number back.
Been so long ago I cant remember exactly how I approached things, was the first time round though so pretty sure it wasnt the err, optimum route

Happy New Year all

A New-Years message for the pensioners about here:

Happy New Year!