Simple upgrades for the Index 40h vertical mill.
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  1. #1
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    Default Simple upgrades for the Index 40h vertical mill.

    Warning, rambling preamble ahead. Feel free to skip to UPGRADES to learn what I did that helped.

    Not really sure where to post, it's only around half a ton but certainly no Bridgeport. It's from WWII but the guys over in antiques all have Lunkenheimer oilers and babbitt bearings, so here I am.

    The first vertical mill worth the name I ever owned was an old Index Mdl 40. Some while ago I got nostalgic and bought myself one to replace the one I'd sold, thinking I'd want a mill when I retired and might be short on space so the Index would be a good mini-mill. Thing is, the one I'd bought (sight-unseen) was really very rough cosmetically, and not ideal mechanically. So I got it off the truck and immediately completely disassembled it. That was over five years ago. A few days back I decided it was time to quit fooling around and just put it back together, just barely as some parts had drifted to difficult to locate areas, so now I have a mill that is rather uneven in it's appearance but usable. I had planned a lot of labour-intensive tasks, Cleaning, prepping, and painting the base and knee took a lot of my time but only a couple quick things got done mechanically. So I'll share those along with the admonition that it's unwise to start a restoration of a machine if one already has a lifetime worth of projects underway in the shop.

    I also did miss the rapid-quill option (one reason I sold my first Mdl 40) so I bought a nice clean Bridgeport M-head I could put on in case that came up for me. Of course, the whole short-on-space thing hasn't really come up for me and since I bought a 4200' building it seems unlikely to. Or at least I might be short on space but not short enough that the difference between a Mdl 40 and full-size mill is going to matter. :-)

    UPGRADES:
    The ACME screw for Y was pretty tired but really most of the wear was in the nut. Simply slitting the nut on the bandsaw about 3/4 of the way through 5/16" from one end, then drilling, tapping, and spot-facing for a cap screw on either side, gave me a nut I could adjust for wear and reduced quite significantly the backlash in travel.
    Of course it's important to tighten it only as much as sensible on the least used part of the screw. In my case that was the very back of the travel. I also found that putting the part with the flexure in it toward the front of the machine made it easier to adjust and helped me get a better fit.
    Get some roller thrust bearings and thrust bearing washers, the ones for X and Y are 5/8"ID (4 total). They are stupidly cheap these days and replacing the worn bronze or cast steel washers with then made table movement vastly smoother and easier. I was also able to run a little more pre-load on the gibs and lead-nut as a result. It looks like there is also room for one on the screw that presses down the quill, 1/2" shaft there, but I was rushed so that one didn't go in.
    DRO. Even with improved handwheels and leadscrew nuts, for that matter even if I got new acme screws, there would still be some backlash. Handwheel measurements are time-consuming as well and my eyesight isn't helping that any.
    So, for much less than the cost of new acme screws I picked up the bits to put glass scales on all three axis.
    For machines with tight-quarters I like magnetic scales, but this little machine actually has plenty of space in reasonable places to put the glass scales. For $300 for three axis plus readout head I couldn't cost justify a nicer setup.

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    Nice. I have this same mill. I did a clean and paint to it a couple of years ago and made these same changes. The table in mine is horrible but I have a fixture plate I can secure and tap and put stainless inserts in.
    Mine has the rapid quill and table feed which is not currently operating because it will take a second VFD. That's difficult to justify without using it.
    I hate to say it but I haven't used it one time since the refurbish. Got any pictures?

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    You can also turn the thread with lathe to get it uniform. I had my mill y axis lead screw fixed this way. Then made a new thread cutting hss bit to match the "new" thread of the screw and turned new bronze nut with that. The feel is same the entire motion.

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    Well, I'm embarrassed since as I said I stopped my methodical rebuild to just throw it together and get to work.
    But here's one after it was assembled but before it's first test. DRO head is on but no scales yet.
    I'd intended to send the spindle out to Wells-Index for regrinding, but they never called me back or emailed with a current quote or anything and in the mean time I've actually grown rather fond of the Universal Engineering double-taper collet adapter (size Z, up to 3/4") the machine came with. I think it's faster to swap than R-8 and if the taper in the adapter gets too beat up you just replace the adapted and keep your #9BS taper unmolested. I loose some height under the nose but so far that's not an imposition.
    dsc_0114.jpg
    Here's what I camp up with for the Y axis. It's true there is no splash-guard over the scale, it would have made for an unwieldy installation plus I don't douse the machine in coolant and honestly scales are cheap enough that if I have to replace it some years from now I doubt I'll care.
    dsc_0129.jpg
    Then the Z axis. On my first Mdl.40 I stuck a stand-alone indicator on the quill by sacrificing the quill stop. Over the years I've changed my habits to use the knee a lot more so decided to put a scale on that. It was simple to mount to the irregular base casting by drilling a pilot hole (later tapped) and then using a piloted bit to spot-face a flat around the pilot. After I mounted the scale with the slot toward the table as a test, I simply made a larger flexure and flipped the scale slot to face the back of the machine.
    dsc_0133.jpgdsc_0134.jpgdsc_0135.jpg
    I mounted the X axis on the front but got a defective scale, waiting for a replacement. I did change from a 500mm to a 550mm scale because with that little travel it hurts to give up even the 1/4"

    Another couple observations about this mill compared to my previous Mdl.40:
    The belt change sucks. Mine has a center spindle that pivots on one side of the case so if you aren't careful it's easy to bind the lower belt between the pulley and case, the sliding center spindle is much easier to use. Also my current machine has a screw in the back of the case to move the motor sled which is vastly less convenient than the models with the quick-change handle.
    I have 3-phase at my shop but am planning to install a VFD just so I can vary the spindle speed with fewer belt changes.
    While I was working on it, I had a heavy/caster wheeled base I was rolling it around on. In testing I liked the additional height so much I've decided to leave it and just screw down the leveling feet. I noticed pictures in the catalog/manual of a cast-riser for the machine and now I see why you'd want that, the extra several inches of height is a real back-saver! I guess that counts as a simple upgrade. :-)

    Yes, I'm missing the upper belt-handling bits from the top of my power-feed. If anybody is parting a machine or has spares, I'd like to find those parts. Otherwise I'll just strap a servo on and run it that way.

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    As for pics of the work I did on the Y-axis, here's some breakdown:
    taken apart showing the parts for the handwheel assy. Note that the ball for the thimble is easy to lose and the bore for that ball is in line with the grub screw so you know where to hold your hand over to prevent the ball from popping out and getting lost.
    Note also that on the inside I used one bearing and one washer, there is a small cut in the old thrust washer that I didn't want the bearing riding over. I suspect if I turned the worm shaft back 1/8" or so I could get that much additional table travel, I just didn't care enough to take the time to fuss with it but when I make my new worm I'll fool with it.It is also the case that two washers over-filled the space between the outside and the thimble-ring so you can see a little gap between the graduations and index mark in the finished product. One can push push the ring closer to close the gap but it would have been better to remove a little material someplace to close that gap. There isn't quite enough space to omit the second washer.
    dsc_0140.jpgdsc_0142.jpgdsc_0145.jpg
    As for the nut, here are couple pictures of the finished article. My backlash ranges from .003" to .013" due to the worn acme shaft but when I started it was in excess of .035"! As has been mentioned one could turn the screw to even it out, but I think I'd rather spend the ~$100 for a new length of shaft and just have to turn the ends. Oh, it's a 7/8"-5 LH screw in case anybody is wondering.
    dsc_0143.jpgdsc_0144.jpg
    I treated the X handwheel setup similarly with the following exceptions:
    I used washers on both sides of both thrust bearings because there was significant galling on what I think they call the bearing bracket.
    I didn't see an easy way to tighten the acme nut, so I still have over .020" of slop to contend with but at least with the better feel of the handwheel I could tighten up the gibs and with the DRO it works out fine. Just have to be circumspect when thinking about climb-cutting! The shaft is RH rather than LH.

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    Can I get a photo of a proper drawbar please? My mill came with two poorly made drawbar.
    Thanks

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    Quote Originally Posted by challenger View Post
    Can I get a photo of a proper drawbar please? My mill came with two poorly made drawbar.
    Thanks
    Not much to see really, length of rod with a ~1-1/8" threaded portion on one side, wrench flats on the other and a collar in between.
    Threaded end is ~13", collar is ~3/8" long and then another 1-3/8" of shaft for wrenching on.
    Did they turn the whole thing out of 5/8" rod or make it up out of two parts, I'm not sure. I am lucky enough to have the rejection nut as well.
    Mine is a #9B&S spindle and so far I'm just using the universal engineering double-taper adapter, so I can't promise it works with all #9 tooling.
    Here you go:
    drawbar.jpg

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    Quote Originally Posted by teletech View Post
    Not much to see really, length of rod with a ~1-1/8" threaded portion on one side, wrench flats on the other and a collar in between.
    Threaded end is ~13", collar is ~3/8" long and then another 1-3/8" of shaft for wrenching on.
    Did they turn the whole thing out of 5/8" rod or make it up out of two parts, I'm not sure. I am lucky enough to have the rejection nut as well.
    Mine is a #9B&S spindle and so far I'm just using the universal engineering double-taper adapter, so I can't promise it works with all #9 tooling.
    Here you go:
    drawbar.jpg
    Thanks. I have one that's turned down to 1/2"-13 on the collet end from 5/8" all thread. I have another that's made from 1/2" round bar but uses a nut on the pulley end so I'm going to use that with a double nut or some other arrangement to keep the drawbar from coming apart at the pulley end. I'll make a better one someday maybe. I hate the idea of always smacking it with a hammer but that's how it was designed so I'm stuck with it.

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    Quote Originally Posted by challenger View Post
    Thanks. I have one that's turned down to 1/2"-13 on the collet end from 5/8" all thread. I have another that's made from 1/2" round bar but uses a nut on the pulley end so I'm going to use that with a double nut or some other arrangement to keep the drawbar from coming apart at the pulley end. I'll make a better one someday maybe. I hate the idea of always smacking it with a hammer but that's how it was designed so I'm stuck with it.
    If you make one up like mine and put the rejection nut on there, it will push out the collet/tool with no hammer required. I think I saw a sketch for the nut already posted someplace.

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    Quote Originally Posted by teletech View Post
    If you make one up like mine and put the rejection nut on there, it will push out the collet/tool with no hammer required. I think I saw a sketch for the nut already posted someplace.
    I suppose it requires a bushing secured inside the spindle?

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    Quote Originally Posted by challenger View Post
    I suppose it requires a bushing secured inside the spindle?
    No, you should have a outside-threaded portion at the top of your spindle that it screws to.
    Courtesy of some other user who's name I forget (sorry):index-collet-removal-nut.jpg

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    Quote Originally Posted by teletech View Post
    No, you should have a outside-threaded portion at the top of your spindle that it screws to.
    Courtesy of some other user who's name I forget (sorry):index-collet-removal-nut.jpg
    I don't have threads on the outside of my spindle.


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