Introduction

[Richard King]

Hello Everyone.

I have been thinking about future topics we should discuss on this thread:

- Leveling and Aligning machine tools
- What's, Why's and How Come we Hand-scrape and 1/2 Moon Oil Flake
- When a machine needs to be rebuilt
- Can You Rebuild your own machine?
- How do I pick a rebuilding company?
- How to adjust a Gib
- Where and how to install wear-strips and shims on machines
- Oil Lubrication
- Preventive Maintenance
- The use Kinematics or 3 - Points suspension in machine tools


I hope you can suggest some topics too.


I have been a Machine Tool Rebuilder for 40+ years apprenticing under my Dad. I was very fortunate during my apprenticeship. My Dad, who was a Journeyman Machinist and Machine Rebulder, worked at a used machine dealer in Minneapolis where we rebuilt dozens of different types and brands of machine tools. I saw so many problems and issues like worn ways, replaced bearings, rebuilt hydraulic pumps, built hydraulic systems. I got a great education.

Over the years my Dad specialized in scraping precision machine tools and surface plates where I learned how to scrape very very accurately. Before granite became popular as surface plates, machinists and rebuilders relied upon scraping 3 exact sized cast iron plates to generate precision flat surface plates. We would lap them together and then scrape them using Prussian Blue and then they were scraped to precision classes. In machine tools we consider .0002" per 12", precision and .00005" per 12" for Super Precision.

Bearing points are generated using hand scrapers. A Bearing spot or point is a high spot left when we rub the plates together using Prussian blue on one plate and where it rubs off on the other plates, we scrape it off and the more you scrape it the flatter it gets and as you scrape shorter and shorter scrape marks you get what we call is "points per inch". Conventional machine are scraped 12 to 18 points on average and 38 to 42 on Super Precision.

As a rule of thumb machines like a South Bend Lathe, Bridgeport Mill, KO Lee Surface Grinder, Cleveland Planers, etc. are considered "Conventional" style machines and are considered "Precision". Machines like Studer Cylindrical Grinders, Moore Jig Bores, Cincinnati Mon-o-set Tool and Cutter Grinders, Brown and Shape Surface Grinders, cast iron plates, cast iron straight-edges, etc. are Super Precision.

More on scraping next time.


I will do my best to answer any questions you have about machine repair and machine rebuilding. I will try to look at the web-site 2 to 3 times daily and more when I am not rebuilding machinery. At the moment I am scheduled to rescrape the ways on a Okuma Howa Vertical Machining Center, the Ways, alignment of the head-stock and tail-stock on a Drake Thread Grinder and I will be teaching a scraping seminar here in Minnesota.

I am always looking for hosts to hold scraping classes. I will be teaching the next class inside the garage shop of a friend and former student. All we need is a surface plate and work benches and some assorted tools that most of you have.

I also teach seminars inside plants and shops all around the world. I have been teaching seminars for several years now and have taught over 15,000 men and women to scrape in companies like GM, Timken, Cummins, John Deere, etc. here in the USA and have taught at several new machine builders in Taiwan. I will gather together some pictures and add them soon.

Thanks for asking me to your Moderator.

More later. Please ask away.
Richard

 

[bcall2043]

Welcome aboard again Richard. It is exciting to have a real professional rebuild expert here on our forum. Many of us here have older machines many of which need some form of repairs. Looking forward to your topics and the questions from the other forum members.

I have a couple of projects to tackle and have collected a few scraping and inspection tools but have not felt I had enough knowledge to take a scraping project on. Maybe having a go-to professional will give me the confidence to move forward.

Benny

 

[Richard King]

Welcome aboard again Richard. It is exciting to have a real professional rebuild expert here on our forum. Many of us here have older machines many of which need some form of repairs. Looking forward to your topics and the questions from the other forum members.

I have a couple of projects to tackle and have collected a few scraping and inspection tools but have not felt I had enough knowledge to take a scraping project on. Maybe having a go-to professional will give me the confidence to move forward.

Benny

There is a book called "Machine Tool Reconditioning" that is sold online that is what we call "the Bible of rebuilding. It was written in the 50's and most rebuilders have a copy. Another good book is The Foundations of Mechanical Accuracy by Wayne Moore, but he talks about super precision scraping and it scares people. I always say "scraping is the easy part and I can teach any mechanically inclined person to scrape in a matter of hours , but knowing were to scrape and how much to take off is the hard part....or "The trade of Scraping". There are a couple of other DVD's and books sold on Ebay besides my DVD that people use too. Learning from an expert who can stand there or walk you through it is the key. I would hate to have brain surgery by a doctor who only read a book.
Rich

 

[FarFar]

Hello Richard King

Boxford and Southbend lathes were designed to be cheap in manufacture and was surely lousy at work.At least my Boxford was.
I will never be able to understand people that restore cars,motorbikes and tractors that killed people,polluted etc to as new condition.
No respect for old iron.
Main problem with my Boxford was lack of rigidity.If it is level or not is not important but rigidity and thermal stability is.
Putting a block of seasoned granite under improved matters imensely.
First picture show some 100 mm steel and 125 mm alu disc parted from bar and cleaned.Second picture show parting tool and third lathe set up.
If backgear comes to grief it will be removed as VFD drive enables thread cutting in direct drive.
Dog is sometime lying under grammophone and having a nap.
Now comes my question:
I maybe overdid something putting lathe bed directly down on granite in six points.(Go please to Your nearest Southbend and confirm that there are two normally unused flats from manufacture under middle of bed)
Putting a testbar in spindle and a clock in the usual tool position confirms that lathe turns cylindric within 0.01mm over 100 mm .
If I put clock on top of testbar picture is not nice:bar is going 0.08 mm up on 100 mm.Have thougth this of no importance but discovered that lathe faces convex.Not much,very little indeed but still the wrong way and it did not in first part of our relationship.It did concave as it should.
Question is how did fitters make lathes face concave?
Scraping V guides can not have been easy or cheap

Kind regards Farfar

 

[FarFar]

A picture of Boxford on granite showing VFD drive

Kind regards

Farfar

 

[cjtoombs]

Richard,Glad to see you started this thread, I'm still in the process of getting everything I need together to scrape my worn out machines. This is an area of interest that I got into by accident (I bought a worn out machine) and it sparked an interest. There are some resources out there that are helpful in learning this subject, the book previously mentioned is very good to get an understaning of machine alignment and how it is measured. Scraping itself is a very technique based skill that is more easily learned by watching some videos and then doing. Richards class was very good, and helps with the confidence to dive into a project. Home Shop Machinist is currently doing a series of articles on scraping in the home shop. The book Machine Tool Rebuilding will also give you a good idea of the equipment you will need to embark on this project. Scraped straightedges, squares and parallels will be needed, as well as a surface plate, height guage and dial indicators. Of couse, scrapers, blades and means to sharpen them will also be needed. Looking forward to seeing projects and solutions here.

CJ

 

[rebush]

Richard: Glad to see we have someone with your credentials to guide us in machinery rebuilding and scraping. Since most of us are hobbyist we're buying used equipment that often need some work done to it. I'm usually willing to jump deeper into a project when I know I can ask for information from someone who has experience. Roger

 

[Richard King]

A picture of Boxford on granite showing VFD drive

Kind regards

Farfar

I am preparing a letter, but not enough time at the moment. I will be scanning in some info about "The 2 collar test" to check head stock alignment (Z axis)to the bed ways and how to correct it by normally twisting the bed, but if yours is off you may have to shim the bed between the granite and bed. Did you remove the headstock from the bed by chance? Whats the machines history, did you grind, plane or scrape the bed? Was it scraped when new or is it a Rungfu or Grizzly* quality (It's my opinion) I consider those cheap and non precision) Have you considered how much weight you have introduced to the headstock and is it twisting the bed?

Where are you anyway? UK or Canada, over the pond? I have to get out my charts to convert the metrics..ha ha. When I teach where they are Metric I have a cheat sheet to convert to inch.

I plan on explaining how to test the concave / convex of your (X axis). Give me a couple of days to finish up your reply. To be honest I believe the South Bend Lathe is a Precision lathe and not a cheap lathe, it my have been inexpensive, but it was a quality built machine for its time and place. It made machining affordable to all American machinists. I have never seen you brand lathe. It looks pretty good accept the square gib and set screw adjustments. The SB lathe has tapered gibs that are fare superior to set screw adjustable gibs.

* I understand Grizzly bought South Bend and I am calling the older model Grizzly's non Precision as I have not seen any of the recent, newer models.

Rich

 

[Tony Wells]

Take your time, Rich. This topic deserves thorough treatment, and I don't want you to feel rushed or pressured into putting something up that isn't up to par. Not that you would, from what I have read of your posts elsewhere.

 

[FarFar]

Hello Richard

Boxfords are british Southbend copies and I am danish.I think I can manage the problem by removing some shims under the two midbed supporting points.I do not know history of lathe but it also turned very cylindrical when standard supported on four points and at that time facing was concave.Problem at that time was shatter and vibrations and I do not want that condition back.
Do not let my problems(wich I have made myself )disturb your educational line of thougths.
I will wait with patience till You reach crosslide renovation and adjustment.

I will try to upload Boxford spare parts list and a picture of a still wet granite block

Regards

Farfar