Lets re-evaluate what we have read so far: It would HELP if we all had some photo's to look at, so we are not guessing. I am trying to help him figure out what to do as a professional point of view. I tell my students when I am rebuilding a machine and I find ways out more then .005" to get them machined as scraping off .011 and keep it square, parallel, flat, and the right amount of points when done take a lot of work and in my case, a ton of time. As a pro, time is money because I have no doubt quoted the machine before getting the job. You owners who have lots of time can spend 100's of hours and time is not money if it's a hobby. On average on all the Bridgeport or clones I average 40 to 60 hours for the rebuild of the ways including the column, knee, saddle and fitting a reground table to the saddle, all the gibs. The machine spec's are better then new at .0002" per foot and 20 PPI. (I would never scrape a Knee Milling machine to .00005") I get the table reground and this does not include rebuilding the head.
To understand what he has I had him measure the machine. It's difficult to help over the internet but this will take a while. Rich in the UK, we spent weeks getting him on track, not 2 posts. Jack you have to be patient and the others lets analyze everything before getting to excited please.
I had Jack measure the ways so I could give him professional advise as I have probably re-scraped over 400 + Bridgeport's in my 40+ years of re-scraping Bridgeport's. My brother and I would have contests on who could scrape one the fastest.
I first asked Jack to measure the using the dowel pin's then the surface gage. To me .011 is terrible but can be repaired. The double "scraped" was a typo this morning as I was under the gun to get to the church, but wanted to help you. You need to relax and let us help you figure this out before calling the former owner. I have seen machines with deep scores, worn .020 and the owner says it worked great as he was using it more for a drill press then a mill. If you look back in this forums past posts. You will see some imported new machines that were sold new and were off .012" Now that's terrible too.
You don't tell us what you paid for the machine, so we can't judge your price and the machine value. Last spring LQQQ, I apologize if I botched the name, but he bought a machine that had cardboard behind his gibs, the knee, column and head stock were from different machines. He as far as I know fixed his machine. His machine was a mess and also terrible.
OK lets get to helping him on his machine.
Next thing I would like you to do is to remove the rear saddle wiper and see if the gib can be moved back future. Many times the gib hits the aluminum wiper plate and it appears like it is out of adjustment. Next you have to tell me or us what your expecting from the machine when your done? Can you live with .002" slop in the gib clearance. Have you also checked your table? Is it sloppy too?
In order to scrape the knee you are going to have to buy some tools, a straight edge a hand scraper, a precision blade square, bluing, etc. Probably a minimum of $500.00 in tools if you are lucky to find good used ones. and probably $1000.00 to $2500.00 or more if you have to make or buy newer ones.. If you have more machines to rebuild in the future then the investment would be worth it. If not you may look for a local rebuilder to do the work for you.
If you need help posting some pictures call me and I can help. If you don't have a digital camera and cant afford one, take some regular pic's and mail them to me. Those digital camera's are really amazing and if you don't have one you can buy them reconditioned or new for cheap online. PM me or call me and i'll help you.
I will be at home tomorrow and if you want to call me, please do so. 651 338 8141. It is so much easier to understand from a phone call. Then we can write here so we keep everyone in the loop. Rich
I added some info to his first post.
My newly purchased 1979 Millport (Bridgeport J-head clone) has a lot of slop in the table (.003" low when checking off a clearance surface on top of the knee that has never seen any wear and was no doubt machined on the same setup as the flat and dovetail ways are worn low and from approx. .004" per side on the dove tail ways. or .004 + .004 + .003" = .011. All with in the .005" spec I say to use when thinking about scraping of machining.)
I've tightened the gibs but still get a fair amount of rotating on the center line motion when pushing or pulling crossways on the end of the table. I can make the problem disappear by tightening the x and y locks. Like most mills that are well used, the problem is most noticeable in the central area of movement. ( he has a situation where he can tighten the saddle gib and it will not "rotate" as he calls it. I would say to remove the slop, but when he moves the saddle to the front and back it will bind up. What to do? I would scrape the top of the knee as it can be done. It sounds like he has never scraped before, so it's "terrible" to be a first timer to scrape one this bad.)
I guess I already know that the answer to my question is "complete scraping job", but I was wondering if there is a method that will tighten up the table without all the investment in specialty tools and the learning curve for scraping. I know that is the only way to bring my Millport (Bridgeport J-head clone) back to new standards is scraping, but at this time, I don't have to have 100% precision in the ways. I haven't checked them for wear, but would there be any benefit to truing up the gibs only at this time?
Thanks,
Jack
Fort Loramie, Ohio
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I have no experience in this but have read somewhere that a product called "Moglice" was developed for this sort of problem.
Anyone have any experience of this product?
I used to be a Moglice Rep and have used it many times. You need to have a precision surface to mold the Moglice to. His ways are worn and Moglice is used where Turcite / Rulon would ride against the scraped way. Moglice has a product called Score Ex, but would not be used in this area.