Scraping and Machine Repair Help

Hi Everyone, If any of you need any free advice on Machine Repair I would like to help. You can ask here, in a Private Message, Email me or call me. I can help with simple repairs and consult with you on what to do. I am a Journeyman Machine Tool Rebuilder and have been teaching Scraping, Rebuilding and building for over 35 years.

I also will be teaching some weekend classes this coming spring, summer and fall all over the USA. In (GA April 5-7 that is FULL as of 2/17), March in CA, June in WI and Aug in IA. I will teach a class anywhere (almost) in the world. You can check out my website Handscraping.com
I talked to a fellow from GA last night for 1/2 hour and helped him so he can repair his Bridgeport mill.

Thanks and have a great weekend. Rich

Hi Richard,

I have a question about a Bridgeport series I mill that I have in my shop. I have had the table and saddle off to clean the lube system and everything else along the way. My question is about the Y axis gib. It is protruding out of the back side of the saddle and presses up against the wiper cover. I am pretty certain that it is due to wear but am wondering if a new gib might be a quick fix or does it sound like the ways need scraping? Also, if a new gib would solve the problem, would it need to be scraped in before using it?

Thanks in advance.

Big B

I like to say, first off do you want a Rebuild or a Tune-Up. Tune-ups are not the best way, but will make your machine better and easier to use.

If your gib is bad, then probably the ways are bad too. Remove the wiper covers and move the saddle to the middle of the knee and screw it in moving the saddle back and forth until you feel a slight drag. Then move the saddle to the extremes or ends and see if it binds up. I bet it will bind up as they all do. Are the ways chromed? If they are, it's a pain to repair them and they need to be stripped before you can scrape the ways. If it doesn't have chrome then you can scrape the ways.

First thing you need to do is figure out how worn the ways are. get 2 - 5/8 x 1 or 2 inch dowel pins and put on one each side of the dovetail and mic it. Your choices are; You will have to leave it that way, scrape the top of knee and dovetails, or leave it and shim the gib. Buying a new gib when the knee is bad does not make sense. You will be making a repair until you can afford to rescrape the machine. You will need to install the worn gib so the big end or the screw end so it is flush with the back and where it was when new. Then insert a feeler gage between the gib and dove and discover what size shim you need. To do it the best, you should take off the saddle and clean everything. It all depends on how worn the doves and flats are worn as I said before.

Remember your tuning it up so this way is not the best way, but will help it get better then it is now.. Be sure to cut a slit the shim so the oil flows threw it.

The guy I helped last night is a maintenance tech at a Paper Mill, so he was famillar with Rulon and gluing it. He had his saddle off, cleaned and his bottom saddle ways are worn, so he is going to machine off some of the cast iron and put .047" Rulon / Turcte on it and glue it to the wear side of the gib. You can use brass or steel shim, phenolic or a plastic shim behind the gib for a temp fix. Have to be careful where the lock hits the gib as plastic or phenolic gets squished. I had a Bridgport I repaired last summer for a small shop and I glued Rulon to the wear side of the gib. It wasn't worn to bad so bonded the Rulon on the wear side and it compressed on the ends and worked great. Check it out and let me know. I can help with the Rulon bonding when you know whats the matter.

I'd be interested in reading anything you care to write on the subject of relining ways with Rulon, Turcite, Moglice or anything else. I have an older Cadillac 14 x 40 lathe that is going to need some attention soon, and I am trying to form my plan of attack.

Richard, as you know, I'm coming to the GA scraping class. My current restoration project is an Abene VHF 3 milling machine and it is now apart for clean up and paint. I felt no wear when the machine was together, anywhere. But in taking it apart i am seeing some wear on the top of the flat ways under the saddle. Like a slight dip in the middle and over a span of maybe 3 inches. Not much, but I can see it by the naked eye and when I put a straight edge longways on top of the dip you can see small (really small) glimmers of light under the edge. What is the rule of thumb about when it should be scraped? Should I bring it to the class? Thanks, Jim

Using a wear strip material is pretty simple to use, but you have to qualify the surfaces prior to gluing them. I can be used in the "Tune Up" or complete Rebuild as New machines. I would estimate 80% of all machine built today use Rulon or Turcite, The remaider use Moglice or are Linear ways. I have had a number of companies call me to re-glue new Rulon on the ways.

The hardened and ground ways on the machine are still in good shape, but the Rulon has broken loose or worn out. In this case I double check the machine alignment using a level. I decided to say it that way because many times a machine doesn't need to be level, just have the ways parallel. On a VMC it is important to level the machine though as as you build up from the base you can use a level to keep the ways parallel to each other.

The ways need to be clean and on used machines I recommend you sweat out the oil by heating it with a low heat torch to bubble out the oil. I also use acetone or fast drying brake cleaner to clean the ways. After it is cllean I roughen the surface or sand blast the part, mark where the oil holes are, Be sure to clean all the oil out of the lube system...and do a dry run before gluing it. 90% or the time I glue the part on the mating part and spray the mating part with a wax release agent. I use to sell Moglice and have met the President of the company from Germany. I also am friends with Drew Devitt the President of Moglice USA. Moglice has revolutionized the machine rebuilding industry. Mogice has a great website and shows how to mix it on You Tube.

You can use the same techniques bonding Rulon as you use with Moglice. I will be in GA in April and we will be doing a Rulon demo and will scrape it. I believe there is a great article online describing how to bond Turcite too..
http://devitt-turcite.com/pdf/turcite_application.pdf

Just Google Turcite and look for more info.

1HobbyMachinist said:

I'd be interested in reading anything you care to write on the subject of relining ways with Rulon, Turcite, Moglice or anything else. I have an older Cadillac 14 x 40 lathe that is going to need some attention soon, and I am trying to form my plan of attack.

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When a builder and rebuilder scrapes the ways we leaves the center 1/3 low and the 4 ends or pads higher usually from .0002" to .0005". Why?
Because, where does the dirt get in first? The ends under the way wipers you never replaced (ha ha). Many times a machine will begin to rock when you change directions if the way was left flat all the way across. Rock like a rocking chair. The old Bridgeports that used grease would relieve the middle sometimes .020", but the grease filled in the gap so chips would not slide in there. Some machine are scraped concave in the base so as a table extends out past the base the table sags where it is not supported, but because that end is moving up slightly the sag is equalized. I will show all of this during the classes.

I have a question about scraping
On high precision machine tools (say a SIP Jig borer) the table and cross rail ways are not scraped straight they are scraped convex within few .0001 high in the center. The reason for this is that ways wear concave so by starting out a few .0001 high in the center over time they will wear straight then convex until the machine is wore out. How do you scrape a way say 4 feet long .0003 high in the center?
Thanks
Todd

On the Sips I've seen the top way was an in-verted vee. Just saying. Regards Tyrone.

Flat, Vee, Inverted Vee is all the same as far as the question I'm asking

I guess I stumped him.

I have a Lansing lathe with unharded ways that I just bought and the lon ways are wore about .004ths how much will this affect anything.And is there any fix for it or just live with it Thanks Terry

SIP6A said:

I have a question about scraping
On high precision machine tools (say a SIP Jig borer) the table and cross rail ways are not scraped straight they are scraped convex within few .0001 high in the center. The reason for this is that ways wear concave so by starting out a few .0001 high in the center over time they will wear straight then convex until the machine is wore out. How do you scrape a way say 4 feet long .0003 high in the center?
Thanks
Todd

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Hey Todd Ill take this on .... I had the singular pleasure of working on a SIP 6A with the tech from American SIP, he was most gracious and gladdy answered my questions ... seeing as I had two SIP's in my shop to rebuild a #`1 and a MPK3 I figured I could help myself out a bit. So I picked his brain as much as I could ..... so here's the deal ....
Sip cross rails, all of them no mater the size have 5 seconds of arc in the cross rail and also 5 seconds of arc on the lower vertical guiding way. this is to counter act the weight of the head/transmission assembly when its put on, if you do everything just right it should show as .0001 high in the center of travel. it does require a special tool to check the rail ( I'll load some pic's up later) a sled that bridges from the top V way down to the vertically orientated guide way. for checking the amount of arc you can use precision levels, an autocollimator, deferential electronic levels or a laser. I have always used the electronic levels. With the level oriented in line with the top V way move the sled along the way stepping it off as you would if checking a surface plate ( each new sled position barely over laps the last one) as you check closer to the center your going "uphill" by 5 seconds as you reach the center of the way you are now going "down hill" by 5 seconds. you really end up with more of a low rounded pyramid. I use a shorter straight edge about 1/3 the length of the way long enough to see the contact and easy to use. on the vertically oriented flat way you turn the level 90 deg's to the "V's" and that will show you the " bow in the flat way. I hope that give you some idea of what we're after ... I'll post up some pic's of the seld and if I can get back into the shop where the MPK 3 is I'll post a pic of the sled on the way ... it will make more sense then.
Cheers Don

I didn't check this thread for a couple of days. I need to put my Email in the first one, so people write me when they have a question.
Bebop is correct when the service men go out in the field to repair a machine. A experienced tech can look at the high spots and what we call step scrape he high spots using a level and short straight-edge and once they have one side finished the use a "sled with Electronic level to make it parallel to it. I use a King-Way Alignment Instrument. At the factories they have what we call "Dummies" an they are precision straight-edges that they use to blue up both ways at the same time. They have been scraped concave and inspected beforehand, to scrape the ways convex . If you have a copy of the Moore book, The Foundations of Mechanical Accuracy" They have pictures showing them using dummies. Leaving parts high is used in many applications so as the machine wears it gets better. I leave the tail-stock of a lathe high in the front as that's were the dirt gets in and wears plus weight and pressure is more in the front. If we left things zero flat as they wear they get worse. I have watched the Sip / USA guys scrape at John Deer and I have helped a Swiss Magerle Grinder Tech scrape the ways on a Crush Grinder up here in MN. It's cool watching them pull scrape. Another cool thing about Sips and Moore for that matter. They have the machines on 3-points to avoid twists. I was just writing about 3 points in another forum today. I hope Bebop and I have helped answer your question.

Richard & Bebop:
Thanks to both of you, Yes you have answerd my question I understand what your talking about. I will get my copy of the Moore book out and read more on the subject.

Bebop: would like to see pictures of your work on a SIP. Do we have a mutual freind in Lee C

Thanks Guys

Todd

SIP6A said:

. Do we have a mutual freind in Lee C ?

Thanks Guys

Todd

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Indeed we do , Lee's a fun guy ... OT somewhat but Im hoping to make it out on this years "Cabin fever" / tool shoping trip :-} as for the SIP's ... the #1 was rebuild and sold Ive lost track of its where abouts, the MPK3 is at a shop here in town .. I'll see if I can get in and take some pics of it ... it was 10 years or more ago when I rescraped all the alinments but I hear that there still doing very high tol work with it .0005 true pos and the like.
Cheers Don

I was thinking about a class I taught at Spinner in Istanbul...They build new CNC lathes. They had a Italian made CNC surface Grinder and the ground the humps in the ways on it. It's amazing how CNC has revolutionized everything involved in machining.
But In Taiwan where many companies in the 90's tried to eliminate scraping discovered you can not build an accurate precision machine unless it is scraped. Have a great day. Rich

Hi Rich and thanks for the advice. My B'port is a 1969 machine with Tibon chrome ways. I took the table and saddle off a few months ago and cleaned out all the lube ports and everything else. When I get a chance I will take the wipers off and check for wear. At this point I am just looking to tighten things up a little rather than completely rebuild it. I will let you know what I find.

Thanks again,
Big B

Hi Todd ...back again here's a pic of the sled on the SIP cross rail .... there are others on my photobucket account please feel free to browse :-}
Cheers Don

Richard King said:

When a builder and rebuilder scrapes the ways we leaves the center 1/3 low and the 4 ends or pads higher usually from .0002" to .0005". Why?
Because, where does the dirt get in first? The ends under the way wipers you never replaced (ha ha). ........

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Hey Rich,

How would this be handled if you've had the lathe bed ground? As you can see, I still don't know whether to scrape the ways of a newly ground lathe. (SB Heavy 10)

Rob