Series 1 Saddle - scraping and oil grooves
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  1. #1
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    Default Series 1 Saddle - scraping and oil grooves

    I have a new-to-me 1969 B'port. Came with an Albrecht chuck, 6F-B power feed, Acu-Rite AR-5 scales and model 200S DRO, and a slotting head, all for a bit under $2K. Evaluation is on-going, but I've found a few things that should be fixed.

    I'm doing all the basic maintenance - cleaning everything including oil lines and oil passages, new felt wipers, new lube metering units, new filter on the lube pump, etc.

    The table gets tight at the ends, as expected for a 50 year old machine. Table ways show at least some flaking everywhere, and no gouges or scoring. Measuring the male (table) dovetail over 5/8" rods shows a variation of 0.002" from ends to center. The hard chrome on the top of the saddle is worn at the ends, but faint traces of flaking are still visible and there is no scoring, peeling, etc. I'm not planning to mess with the saddle-to-table fit.

    The knee-to-saddle is in worse shape - probably due to 50 years of chips landing on the ways and sneaking under the wipers. The chrome on the top of the knee is worn in the center to the point that the flaking almost disappears in spots (first photo). Careful measurement says that the flats are worn about 0.0008" deeper in the center than the ends. Measuring over 5/8" dowels shows the center about 0.002" looser than the ends.

    The bottom of the saddle is pretty ugly. (second photo) On the flats, the center relieved section has no wear, but all flaking is gone from the contact areas and they are pretty badly scored. The dovetails are in better shape, with traces of flaking still present.

    A professional rebuild is out of the question for a variety of reasons. Although I'm a hobby guy and like working on machines a full rebuild is well above my skill level and is also not going to happen. However I don't want to put the saddle back on the way it is.

    I have some scraping experience - I can scrape flat to a surface plate, but I've never done dovetails or scraped for alignment. Since the flats of the ways are by far the worst part, I'm thinking I want to scrape them "fairly" flat. I'd rather do too little than too much, because I want to preserve alignment

    My current plan is to scrape only the flats on the bottom of the saddle, using a surface plate as a reference. They won't fit the knee ways perfectly - over the 12" length of the saddle the knee ways are about 4 tenths hollow, so the saddle will bear more at the ends. But somehow it feels wrong to scrape the saddle to fit the curvature of the knee ways. And I'm not re-doing the top of the knee - stripping the chrome and re-scraping those ways is more than I want to tackle.

    Looking for input - does this seem like a reasonable course of action? To me it seems like it falls somewhere between "just put the damn thing back together and use it" and an obsessive-compulsive "make it perfect" rebuild.

    Second question is more specific. Third photo shows the oil grooves in the bottom of the saddle. They seem very inconsistent, especially the one on the bottom left. Seems like it should get closer to the edges of the way. Not sure if its just a coincidence, but the blue seems to show that the worst wear is in the areas outside the ends of the oil groove.

    Will I do any harm if I make the oil grooves longer, so they end maybe 1/4" from the edge of the way? Is 1/4" the right number?

    Any other suggestions for stuff I should address while the machine is apart?

    Thanks,

    John
    Attached Thumbnails Attached Thumbnails 20200101_233653s.jpg   20200105_220306s.jpg   20200105_225108s.jpg  
    Last edited by jmkasunich; 01-07-2020 at 12:50 PM.

  2. #2
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    If you can scrape and have or can borrow some alignment gear, a Bport knee is easy to scrape. Aim for the flats to be 1 thou high above 90deg at end of knee. As for should you do the dovetails- yes, you must. Not much point otherwise.

    Why not start by scraping in a 30” long dovetail straight edge. You’ll need it for this job and will quickly give you an idea if you enjoy scraping.

    Oil grooves look fine. They may not have experienced much oil in their lifetime...

    What are you using for rods to measure the dovetails?

    Lucky7

    Btw- I haven’t seen that many chromed Bports and have never had a chromed one apart. Is it usual for the saddle to be chromed or is just the top of the knee?

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    Quote Originally Posted by lucky7 View Post
    What are you using for rods to measure the dovetails?
    I had a bit of 16mm (0.630") TGP bar laying around - cut off a couple 2" lengths. The main problem with the dovetail measurement is that my mics only go up to 6". I had to use a dial caliper for the measurement.


    Quote Originally Posted by lucky7 View Post
    Btw- I haven’t seen that many chromed Bports and have never had a chromed one apart. Is it usual for the saddle to be chromed or is just the top of the knee?
    On this mill, the column is cast iron, the back of the knee is chrome (99% sure about that, I haven't removed the knee yet). The top of the knee is chrome, the bottom of the saddle is iron. The top of the saddle is chrome, the bottom of the table is iron.

    John

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    So my worry or thing to think about is this... "some scraping exsperience" yet never scraping for fit or alignment. At what point is getting this where you want it worth making it worse? One of our rebuilders in the back said that it would be pointless to only do the scraping you are talking about. He says you will probably cause your table to be outta whack and create more rock than you already have. His exact words as he reads this is "its pointless" to do what you are talking of doing.

    Our vote is put it together and use it, if the other option is scrape one part of one axis.

    Jon
    H&W Machine Repair

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    You went through the trouble of taking it apart so clean everything, but did you even take a test cut or try to drill a hole pattern before you stripped it down?

    In my opinion that looks like 40 or 50 years of wear or 40 minutes in a dirty shop with no lubrication. If the machine was levelled properly it may still cut planer and drill straight. Changingone area of alignment may throw out the rest of it.

    Unless you're making parts for NASA, you may just end up spinning your tires.

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    OK, I'm hearing a consensus here. Sounds like I should just put it back together and run it.

    I certainly don't regret taking it apart and cleaning it. I found several oil metering units that weren't flowing oil, and some of the oil passages were filled with gunk. At least now I know everything will get lube. I also found a 0.002" brass shim on the back of the saddle gib that was peeling off in chunks. I removed it and will measure and fit a new one during re-assembly.

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    It’s a very good thing to ensure your mill is getting lube and cleaning out gunk. I wouldn’t fit a new gib to your saddle without first rescraping the saddle etc. Just re-shim. Since you already know how to scrape for flat, I’d suggest slowly accumulating straightedges, a big enough grade A surface plate and other gear to re-scrape your mill (and other machines) in the future. Cheaper to buy stuff when you don’t need it today... Sounds like you have the interest. One small hint is to either machine the tooling you’ll need to re-scrape your mill prior to disassembling it again, or make sure you have access to another mill. Yes, it will take you longer than a pro to rescrape it, but so what? Go for it when you’re ready!

    L7

    And compared with a K&T, Cinci, and others, a Bport really is a simple mill to scrape...

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    Quote Originally Posted by jmkasunich View Post
    I also found a 0.002" brass shim on the back of the saddle gib that was peeling off in chunks. I removed it and will measure and fit a new one during re-assembly.
    Quote Originally Posted by lucky7 View Post
    I wouldn’t fit a new gib to your saddle without first rescraping the saddle etc. Just re-shim.

    Oops, I wasn't clear when I wrote "fit a new one". I meant fit a new shim, to replace the trashed one. I definitely agree that it doesn't make sense to fit a new gib unless scraping everything.

    Thanks for the advice, you guys probably save me from some pointless effort.

    I do want to get better at scraping and may tackle the mill in the future. I'm signed up for Richard King's course in May in Oswego New York and looking forward to it.


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