not OT but pretty trivial - drill press tram scraping?
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  1. #1
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    Default not OT but pretty trivial - drill press tram scraping?

    I have a little drill press I just cleaned up and put new bearings, belts and motor in. This is what it looks like:



    I restore Taiwanese drill presses from time to time just because I like to do it. I think this one will be the last one, though, and I plan to keep it for now.

    The table can rotate, obviously. The combination of table rotation about the spindle axis and the whole table mechanism including rack swiveling about the column allow any point on the table to be brought under the spindle axis. You can also loosen a bolt underneath and tilt the table left and right.

    I want to tram the table, i.e. make its surface perpendicular to the spindle axis. It's easy to get it correct in the left-right direction because that's just adjusting the table tilt. I had been adding shims to correct the tram in the direction of the long axis of the head (in/out). Since I've been learning to scrape, it now seems to me I should be able to scrape two mating parts and thus bring the table into tram.

    My problem is I don't know how to accurately measure out-of-tramness on the parts involved. The table has an integral round boss on the bottom which fits into a support arm. I could make a round piece the same diameter as that boss, put it into the table support arm, and measure between it and the column low and high to see if there's an error. But once I take the table support arm off the machine, I don't know how to scrape its mating surface flat and perpendicular to the column.

    Anyone have any ideas? I can post more pictures.

    metalmagpie

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    Here's one approach. You measure the diameter of the flange where the support arm attaches to the column bracket. Say it's 3'' in diameter. Set your indicator to sweep a 3" circle on the table top and see how much slope you have front to back. Again, supposing the indicator shows .0025 low in the front of the table. (Not the whole table, just the smaller circle) This tells you how much you have to take off the top edge of the support arm flange to bring it square.

    With the support arm out where you can work on it, hold it somehow and start scraping a shallow groove in the high side of the arm. You can lay a straightedge crosswise and use feeler gauges to check your progress. When you can just get a .0025 feeler in your developing groove, put some magic marker in the bottom of the groove to mark the area not to touch. Then start scraping both sides, away from your shallow groove and re-establish the flat surface to where you're now just touching your magic marker ink.

    This should be closer to having the table square, front to back, so now just test and repeat.

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    Not to throw a wildcard, but is the column the same diameter thru the entire table up and down range?

    L7

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    Not sure where the question is leading.
    An Indicol tells you spindle to table and a CAD layout shows errors.
    In this case do four checks with the rotary moved 90 degrees which tells you about that joint.
    On these machines which are not to be talked about here the head can sometimes be "nodded" on the column with shims.

    Remember that these things bend a lot under drilling load.
    Mount a DTI on a long arm out to the front and just lean on the table a tad or bring the chuck down with a normal drilling pressure against the table
    This may change you mind about trying to hand work it real close.
    All machine tools deflect under actual cutting conditions, some much more than others.
    Bob

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    Quote Originally Posted by CarbideBob View Post
    Not sure where the question is leading.
    An Indicol tells you spindle to table and a CAD layout shows errors.
    In this case do four checks with the rotary moved 90 degrees which tells you about that joint.
    On these machines which are not to be talked about here the head can sometimes be "nodded" on the column with shims.

    Remember that these things bend a lot under drilling load.
    Mount a DTI on a long arm out to the front and just lean on the table a tad or bring the chuck down with a normal drilling pressure against the table
    This may change you mind about trying to hand work it real close.
    All machine tools deflect under actual cutting conditions, some much more than others.
    Bob
    My table is already drooping as if under load. And it's not 2.5 thou, it's more like 25 thou.

    I will post some pictures. I happen to have a parts machine just like this one, so I can mess around without risk.

    metalmagpie

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    So, one other strategy. Take the arm off and stand it up on your surface plate. It has a 90 degree bore on the other end for the table. With the arm upright you can indicate each end of the bore and scrape the bottom face until everything is square.

    That assumes that the casting on the column is also square but you can do the same thing with it. That should ensure that the bore for the table shank is parallel to the column, at least when not rotated.

    Then you'll also want to know that the face of the table is perpendicular to its axis. You can check that by rotating the table with an indicator from the quill. Here you should be able to face it off in a lathe if necessary. Or if you just want lots of scraping practice you could scrape it too.

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    These are the parts. I think of them as the knuckle and the arm. Knuckle is upper left and it rides on the column. The arm bolts to the knuckle. The knuckle's bolting face has to be parallel to the column. The arm's bolting face has to be perpendicular to the axis about which the table rotates.



    I like the idea of indicating to test for squareness. On the knuckle, I cannot directly blue the bolting face on the surface plate. So I ground a "blueing ring". It's within about a thou. Not dead nuts, but much better than what I have now.

    metalmagpie

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    Quote Originally Posted by metalmagpie View Post
    My table is already drooping as if under load. And it's not 2.5 thou, it's more like 25 thou.

    I will post some pictures. I happen to have a parts machine just like this one, so I can mess around without risk.

    metalmagpie
    You can "mess around without useful results" as easily as "without risk" until 12th of never and not force enough "extra goodness" into the fool thing to repay the effort.

    Do you more good, faster and cheaper, to simply fab an adjustable brace, center underside of the table, back to a second yoke or collar around the column.

    Store-bought "turnbuckle" hardware, some allthread, couplers, a clevis.. wotever fits the size and need.

    I use a small "6 Ton" hydraulic bottle jack. OTOH, the rectangular table alone on a 4400 lb Avoir Alzmetall AB5/S might mass FOUR of your entire drillpress. With bench. I don't have enough years left on my clock to "scrape" the heavy-ass big bugger with a column the size of a cannon barrel!



    Either way...

    Adjust out the "droop" for any given height setting AND the mass of the vise and WORK... that is adding to the UNLOADED "droop".

    Yah CANNOT scrape for THAT part, nohow.

    Not unless you will only ever be drilling the same mass of vise and work. How likely is that?

    Even then. yah only BOTHER to adjust IF/AS/WHEN it actually matters. EG: "not always". Nor even "often".

    25 thou UNLOADED? Learn to compensate, then "Run what you got". MOST days, all it takes is to slip one of the 2 or 3 shims you can easily put right handy under the low edge of the vise and/or work.

    Drill yer hole(s).

    Go do something ELSE as is a better use of your time.

    Small, light, cheap, already imperfect... drillpress.. ain't never gonna be no Moore nor SIP-Genevoise jig bore, no matter HOW much you wish it was so.

    But YOU.. can still do decent work with it....if you but adapt to what it IS.

    Like everybody else has had to learn to do... my "other Alzmetall" being a salvaged 1940's Walker-Turner bench top DP!


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    Quote Originally Posted by thermite View Post
    ....
    Either way...
    Adjust out the "droop" for any given height setting AND the mass of the vise and WORK... that is adding to the UNLOADED "droop".
    No way
    Are you saying that suspended on this rubber band a vice or big or small work piece will move the tram?
    It is steel and steel does not move. Once zero in free state it is always zero.
    You are trying to ruin my trust in the world as stable and measuring things without working loads.
    Hand scraping, axis alignment, spindle square, backlash comp and all are done without worries about loading and chased to microns all the time.

    These machines maybe not to be mention here and I sure Mr King appalled but some lessons that do transfer to much bigger stuff.
    No matter the size or weight everything moves or bends when working, static free state measurements will never be right.
    Bob

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    Having, in the dim past worked on a similar POS, I remember that IT was also way off tram the wrong way.

    When I then tried to correct the tram, I found that the cast iron was some junk that was harder than the hobs of hell, and decided that the whole thing needed to be somewhere other than in or near my shop.

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    Quote Originally Posted by CarbideBob View Post
    You are trying to ruin my trust in the world as stable and measuring things without working loads.
    Hand scraping, axis alignment, spindle square, backlash comp and all are done without worries about loading and chased to microns all the time.
    Could was you are just spoiled from working stiff Carbide instead of wimpy Iron alloys?



    Unfortunately for the "rigid (amongst) Earther's" if not also FLAT? Science reached a point many, many years ago when they could measure perturbation in the axis of our Mother Earth to a very fine resolution.

    Fine enough to track the effect of the cumulative shift of mass from parts of North America to OTHER parts, net-net, and temporarily. Then back again.

    They had correlated it with Labour Day holiday traffic.

    More recent years, one can find the reports of the shift from several major identified Earthquakes.

    That 4,400 lb Avoir Alzmetall "big dog on a big hunt .." drillpress moves, too, of course.

    Just not as easily, nor by as much as the "piss-ant on a melon stalk" here.
    Taiwanese or the other, either one.

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    Quote Originally Posted by JST View Post
    Having, in the dim past worked on a similar POS, I remember that IT was also way off tram the wrong way.

    When I then tried to correct the tram, I found that the cast iron was some junk that was harder than the hobs of hell, and decided that the whole thing needed to be somewhere other than in or near my shop.
    The just-shy of 8-foot tall Alzmetall had to bunk-out on the carport for about a year, about 35 feet fom the sidewalk, but hulking like a Pterodactly guarding its eggs...

    A neighbour down the street and his wife passing on their usual stroll:

    "We have been meaning to ask.... what IS that thing?"

    "You ever do military service?"

    "Oh, yes! Now I remember. A Hobart! We had one of those in the mess kitchen for making huge tubs of mashed potatoes and mixing bread dough to feed hundreds of men at a meal!


    "Well this isn't a Hobart. It's a 1951 or so German-made ...






    The Devil made me do it...?

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    I took apart the real machine (pictured above) and started scraping the arm today. OMG I couldn't believe how little of it blued up. All big dings. Before I started scraping I filed and stoned a bunch of the worst off. It's easy to see how this part got so far off. And it scrapes just fine, like all of the (2 or 3) other cast iron I've scraped.

    I have to say, I find it really exciting to be able to restore a machine to its intended alignment. And yes, of course, if you push down hard on a flimsy DP table, it will flex. That's not the point. The point is to learn to fix machines.

    And of course it isn't an Alzmetall. I used to own an Alzmetall! There were things I liked about it and things I didn't. For sure, it was heavier built.

    metalmagpie

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    Quote Originally Posted by metalmagpie View Post
    I took apart the real machine (pictured above) and started scraping the arm today. OMG I couldn't believe how little of it blued up. All big dings. Before I started scraping I filed and stoned a bunch of the worst off. It's easy to see how this part got so far off. And it scrapes just fine, like all of the (2 or 3) other cast iron I've scraped.

    I have to say, I find it really exciting to be able to restore a machine to its intended alignment. And yes, of course, if you push down hard on a flimsy DP table, it will flex. That's not the point. The point is to learn to fix machines.

    And of course it isn't an Alzmetall. I used to own an Alzmetall! There were things I liked about it and things I didn't. For sure, it was heavier built.

    metalmagpie
    I'd forgotten - given it's over 45 years.. that I had "tuned up" the already OLD (might be 1942?) $90 Walker-Turner. The table adjust lever is one repurposed off the steering-wheel tilt of a mid 1960's Chrysler Imperial Crown Coupe, for example!



    One surprise, done perhaps to keep its tiny "benchtop" self from wandering about, is that the vertical column is around 80 lbs of solid Cast-Iron, where most are hollow "tube" even if centrifugally cast, not bored.

    The AB5/S column is hollow. But the net wall thickness is as great as the W-T's column diameter!

    I'm trying not to let it discover whether there is anything I don't like about it.

    Some tribes are kinda bloody-minded about disagreements and holding grudges. It can get expensive to piss-off 7 HP across a genuine PIV Werner-Reimers drive system already nearly 70 years in use. Infrequent use, it seems. That's why I bought this one, and not one as had been worked harder.


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    Quote Originally Posted by metalmagpie View Post
    I took apart the real machine (pictured above) and started scraping the arm today. OMG I couldn't believe how little of it blued up. All big dings. Before I started scraping I filed and stoned a bunch of the worst off. It's easy to see how this part got so far off. And it scrapes just fine, like all of the (2 or 3) other cast iron I've scraped.

    I have to say, I find it really exciting to be able to restore a machine to its intended alignment. And yes, of course, if you push down hard on a flimsy DP table, it will flex. That's not the point. The point is to learn to fix machines.

    And of course it isn't an Alzmetall. I used to own an Alzmetall! There were things I liked about it and things I didn't. For sure, it was heavier built.

    metalmagpie
    This is an interesting project and thanks for bringing it up. I hope you will get the results you want and i am sure it will be a learning experience.

    Charles

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    Since Alzmetall has been brought up, here's a picture of my old one sitting next to my shop-built gantry. It is an AX-2S model. I bought it from a French airplane seat company pulling out of Paine Field in Everett, Washington, for $400. For that, it was a real good buy. My knock on it was that it had a 2MT spindle and only went down to 250 rpm. - metalmagpie


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    Nice DP, but even more I like your gantry adaptation for uneven ground.

    L7


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