Machine spindle tramming

Поделиться
HTML-код
  • Опубликовано: 1 авг 2024
  • Adam the machinist:
    / adamthemachinist
    Visit my website for FAQ, a list of my machines, my products and some project documentations:
    gtwr.de/
    Consider supporting me on Patreon:
    / stefangtwr
    I post very regular on Instagram:
    / stefan_gtwr
    #practitioner_of_the_mechanical_arts
  • НаукаНаука

Комментарии • 166

  • @adamthemachinist
    @adamthemachinist Год назад +60

    Stefan , wonderful visual aids! It made me very happy to see the technique in use on a deckel again.

  • @alasdairhamilton1574
    @alasdairhamilton1574 Год назад +21

    Adam the Machinist, one cool dude 😎

  • @MarkW321
    @MarkW321 Год назад +15

    Hi great video. I am from the USA, Bridgeport mills do have 2 worm screws to adjust the head in both directions. Yes they are very top heavy. It is a very versatile machine.

  • @dauber1828
    @dauber1828 Год назад +3

    Nice CAD drawing “ cartoon, assisted drawing “ you made Keith Fenner proud
    Keep up the great videos and thank you for sharing

  • @StuartsShed
    @StuartsShed Год назад +1

    Excellent techniques, thanks for the demonstration. I had not considered these aspects.

  • @jimsvideos7201
    @jimsvideos7201 Год назад +3

    Thank you, again, for taking the time to share your knowledge.

  • @glennstasse5698
    @glennstasse5698 Год назад +1

    Thanks for the effort making the very useful visual aids. You put a lot of time into these vids and it is appreciated!

  • @Arthur-ue5vz
    @Arthur-ue5vz Год назад +1

    Thanks for doing these vids, Stefan!
    Always greatly appreciated! 🙂

  • @joell439
    @joell439 Год назад +2

    Thank you Stefan. Love the visual aides (Thank you Adam). Really helps to embed the process into my brain cells.

  • @Timeonabike
    @Timeonabike Год назад +2

    Welcome back! Another superb explanation. Thank you.

  • @walter67435
    @walter67435 3 месяца назад

    I'm very new to this stuff, about 3 weeks into learning "from scratch." What I discovered about the gauge block method is that my mill's table is not "very flat." I ended up massaging the block around for a bit until I found repeatable measurements "within some range." Well my rong-fu 30 is not very accurate. But it is very rewarding to learn how bad it is, and to understand what one can do within the bounds of reasonable badness. It's pretty obvious if you use a brake rotor then you are getting "average badness" that is more under the control of the brake rotor. I guess the idea is to throw everything you have at it and see what comes up.

  • @RossiDeakin0406
    @RossiDeakin0406 Год назад +2

    Happy days, fair play for giving Adam a shout out, love the quality content you both provide, two of my favourite channels ,quality over trash is always a winner in my life, cheers 👍👏🇬🇧

  • @624Dudley
    @624Dudley Год назад +2

    Thanks Stefan, superb graphical illustrations 👍! You are correct that the Bridgeport uses a worm drive on the head tilt, and another on the “nod”. The nod is naturally quite heavy and would be miserable to adjust if the worm drive weren’t there.
    A handy feature of the Bridgeport is that the spindle sticks out from the quill about 15mm, giving a convenient, cylindric place to clamp on an indicator holder. There’s no need to disturb a tool or swap collets.

  • @907jl
    @907jl Год назад +4

    Timely topic Stefan(and Adam), thanks for posting it! Recently took my Lagun knee mill out of tram to make some angled cuts, and need to bring it back into square. I'll give this method a try.

  • @rlsimpso
    @rlsimpso Год назад +4

    Great demonstration. The gauge block sweeping trick also works on a Kurt style vise using a drop indicator. I recently mounted a Bridgeport J head on my RF45 clone and tramming with the worm screw is a dream compared to pushing the old gear head around. The trick to dealing with the offset weight is to push in the direction of travel while cranking the worm screw. The worm shaft is fairly small and pushing also helps avoid shearing it.

  • @noberet
    @noberet Год назад +1

    So glad to see you again!

  • @billdoodson4232
    @billdoodson4232 Год назад +1

    Fantastic timing Stefan. I actually woke up at 03:00 this morning thinking I really needed to sort out tramming my 45 type milling machine. I have had it 6 months and have still not put time aside to do it fully. Life got in the way.

  • @robertpearson8798
    @robertpearson8798 Год назад +2

    As usual I learned something from your video that I haven't seen anywhere else.

  • @nicholasmcconnell7853
    @nicholasmcconnell7853 Год назад +1

    2 of my favorites, Adam and Stefan.

  • @splinky99
    @splinky99 Год назад +6

    A: a Bridgeport has reference surfaces machined into the quill housing, so that you can hold a square on the table and against the reference surfaces….for rough tramming. B:one of those 2 indicator rigs for tramming is well worth the dough!

    • @mpetersen6
      @mpetersen6 Год назад

      Most BP operators forget about or do not know this trick. IMO when manufactured the mills should have two pins that can be inserted to fo a quick alignment. When the head is tightened down remove the pins. Like the alignment pins on the turret of a CNC lathe.

  • @jeff1176
    @jeff1176 Год назад +1

    Hope your holiday was excellent. Glad to see you back in the swing of things.
    I never seen a mill in person and i understood this info perfectly.

  • @thosoz3431
    @thosoz3431 Год назад +1

    Thanks Stefan. Upgraded my bench mill and this little refresher is perfect timing.

  • @TheUncleRuckus
    @TheUncleRuckus Год назад +3

    Informative video as always Stefan, thank you! 👍👍

  • @jefflastofka9289
    @jefflastofka9289 Год назад +10

    Nice to have you back (I assume) in the northern hemisphere. I really like the old school graphics:-) I have a Jet clone of a Bridgeport and you're right about the top heavy and the worm drive, etc. It's not a big deal, though. Like you say - put a little friction on the holding screws and tap things around a little. I hadn't thought about sweeping vertically along the spindle. It's over 110mm on mine. That would normally be plenty for what I usually do, but as long as a person's doing a thing like this it's usually worth slowing down just a little and doing it slightly better than you need.

  • @stevewyckoff6904
    @stevewyckoff6904 Год назад +2

    For general work I just extend the quill to maximum and use a precision square on the table (or in the vise) with a light behind the setup.

  • @DavidR8
    @DavidR8 Год назад +2

    Love the props Stefan!

  • @bclare2544
    @bclare2544 Год назад +2

    Very informative Stefan and Adam.

  • @karlmckinnell2635
    @karlmckinnell2635 Год назад +2

    😂😂 I’ve seen Adam on CNCNYC before but today was the first time I’ve seen his own channel and now Stefen mentions him 😂😂. Love the content, thank you for sharing.

  • @richardandrews6754
    @richardandrews6754 Год назад

    Thank you Stefan for sharing this, very useful, especially if you have an older machine with wear to consider. I always enjoy your videos always full of tips to maintain accuracy of the finished work..

  • @tomeyssen9674
    @tomeyssen9674 Год назад +2

    Thank you!

  • @ianpendlebury3704
    @ianpendlebury3704 Год назад +4

    Fascinating...... as always. The last sine bar technique is particularly clever (at least to my simple mind).

  • @pirminkogleck4056
    @pirminkogleck4056 Год назад +3

    The Graphics are Superb Stefan ! !

  • @davidcolwill860
    @davidcolwill860 Год назад +2

    I'm due to take delivery of a new to me Bridgeport clone in about 6 hours so will be using this method very soon. Thanks and welcome back.

  • @norstokke4703
    @norstokke4703 5 месяцев назад

    That was a very good presentation, thank you very much!

  • @angelramos-2005
    @angelramos-2005 Год назад +1

    Very useful info.Thank you Stefan.

  • @ErikBongers
    @ErikBongers Год назад +11

    Yeah, Adam's paper cutouts are surprisingly effective didactic material.
    I actually have been thinking about that. It must be because they are physical objects and you can handle them, point at them. I guess our brains find it easier to process than fancy 3D graphics.

    • @StefanGotteswinter
      @StefanGotteswinter  Год назад +6

      Its such a great aesthetic style with the heavy black outlines, i love it. Its also quicker to do and easier to "animate" than doing it on the PC in Cad or some illustration software.

  • @caseytailfly
    @caseytailfly Год назад +1

    Good timing, it reminds me I should tram my mill. I’ll try out your technique, thanks for sharing!

  • @than_vg
    @than_vg Год назад +2

    Hey Stefan, thanks for the demo (I admit Adam's post has slipped me). A couple of comments:
    - the traditional method, indeed, doen't always work on deckel-style machines, since you have no guarantee that the table is also trammed! (the swivel tables or your indexing head could be all over the place). So, better stick to tramming VS travels, like the two other methods.
    - for the quill method, your Deckel test bar can help, I think it's 300mm long. Though, for the FP1, one could even shorten it a bit, since things are tight there.
    - for 'Adam's' aproach, the thing to pay attention is symmetry, it's a non symmetric procedure by definition (w.r.t. the X axis). So, the inevitable Z-X rocking can infuence one's measurements if one goes too far (not a big issue with your indexing head setup I suppose).
    I remember seeing your 'fix a vise on the table and never, ever, move it' some years back (Simon's as well and not only). I admit I feel more confortable with the versatility of the euromill aproach where you take nothing for granted, you just include a couple of minute of tramming (head, table, whatever you need to tram) before working.
    Cheers,
    Thanos

  • @outsidescrewball
    @outsidescrewball Год назад +2

    Good timing as my new (to me) horizontal mill has a vertical head which I just mounted….tram time via your demo/discussion will occur

  • @samrodian919
    @samrodian919 Год назад

    Thank you for that Stefan, that was very helpful

  • @TomChame
    @TomChame Год назад +2

    Excellent, thank you!

  • @heighRick
    @heighRick Год назад +1

    Thanks for the video Stefan, helps a lot!

  • @Dwarfgrinder
    @Dwarfgrinder Год назад +1

    That machine has a lot of cool features. That table is really interesting.

  • @frananzola
    @frananzola Год назад +2

    There is something that comes out of what you just explained (collateral benefits). I can look up your technique on the Internet and find a lot of them, but they come up with 'Batteries not included."
    What I mean is that it's not enough to read this literature, but there is a component that comes from your experience, your way of working, etc., that we can call art and that leads to success

  • @MrCrankyface
    @MrCrankyface Год назад +2

    Always a good day when you release a new video! 😄🤘

  • @soundlimit300
    @soundlimit300 Год назад +2

    Very helpful Stefan.

  • @mikesgabellone5089
    @mikesgabellone5089 Год назад

    just recently got to your chanel, i must say i enjoy learning from you, thank you

  • @iteerrex8166
    @iteerrex8166 Год назад +2

    Stefan, when you made this 11:05 indicator holder a few years ago, you did show how to tram the head. That was one of the main reasons you made the holder, besides indicating bores and such. One of the cool design features of it was the conical joints.

  • @Smallathe
    @Smallathe Год назад

    Missed this video... Loved it! Thank you!

  • @charlieromeo7663
    @charlieromeo7663 Год назад

    Well done Stefan. Going to check my Bridgeport right now.

  • @poetac15
    @poetac15 Год назад

    Thanks for posting. Great visual aids.

  • @rodneyeamon9876
    @rodneyeamon9876 Год назад +1

    Thank you😊

  • @mpetersen6
    @mpetersen6 Год назад

    Stefan, the best indicating tip I've seen on your channel is the one where you made up the round piece with a section taken out so that you can pick up an edge on a tilted surface.

  • @TrPrecisionMachining
    @TrPrecisionMachining Год назад +1

    Good video Stefan..thanks for your time

  • @bobuk5722
    @bobuk5722 Год назад +2

    Hi Stefan, I've just checked, there's 756 videos about how to do this ...... Seriously, a big thank you. I'm still very new to all this and I had not thought of the other two ways you showed, not to mention setting an accurate angle. By the way, well done with the CGI - it looks almost hand drawn ......

  • @-redox-506
    @-redox-506 Год назад +2

    Immer wieder große Klasse dir zuzusehen 👍

  • @escain
    @escain Год назад

    Thank you for this great video.
    I understand a 3 axis milling machine as a set of: a table (or any piece support), 3 axis ways, and the spindle. Where each of them needs to be trimmed in two angles respective to it connected component. Or a total of 8 angles to check and adjust. (Being the alignment of the table around the Z axis only useful to have the T slots aligned with X, so probably only 7 are required).
    Considering this, the two technics of rotating the dial gauge on a flat surface (the table), or moving the table are not equivalent:
    1) Moving the dial gauge on a flat surface allows to check the squareness of the spindle against the flat surface.
    2) Moving the table allows to check the squareness of the spindle against the X,Y axis.
    So that if the table is not perfectly aligned to X,Y, the result would not be the same.
    For example, if the table is not square to the X axis, the created piece will be out of squre (technique 1); while using technique 2 will result in a square piece but worse surface finish, especially with large diameter surfacing tools as only one side will be engaging.
    Not sure if this makes sense, to be honnest I am not an experienced machinist.
    Again, thank you for your great videos, I always excited to watch them.

  • @nobbysworkshop
    @nobbysworkshop Год назад +2

    Thank you Stefan for these brilliant techniques. Tramming the mill is a job I hate having to do. I'm sure these ideas will make it a lot easier. Cheers nobbysworkshop

  • @bcbloc02
    @bcbloc02 Год назад +1

    I love the art work!

  • @luisalbertotrazzi7366
    @luisalbertotrazzi7366 Год назад +1

    Very nice instructional video

  • @davidrule1335
    @davidrule1335 Год назад +2

    The last approaches would work good in tool and die work. Where the part is hanging off of the table and after square cuts, a draft angle has to be cut.

  • @bigwave_dave8468
    @bigwave_dave8468 Год назад +1

    Thank you master Stefan. Excelent video as usual! I love the Adam-style animations but now I have to go make that indicator holder as I can no longer bear to use my small mag-base Noga indicator holder on the quill.

  • @andrewdolinskiatcarpathian
    @andrewdolinskiatcarpathian Год назад +1

    Thank you for such an excellent set of methods to consider when tramming the head of a mill. 👏👏👍😀

  • @DudleyToolwright
    @DudleyToolwright Год назад

    Loved the artwork. Very stylistic.

  • @shichae
    @shichae 3 месяца назад

    Excellent technique Stefan! ^____^

  • @Rustinox
    @Rustinox Год назад +5

    It all makes perfect sense.
    BTW, I like your didactic material. It has a cute touch :)

  • @billshiff2060
    @billshiff2060 Год назад

    3:38 Most don't know that on the Bridgeport there are notches/steps factory milled into the housing at the ends of the quill stop screw specifically for use as reference surfaces for tramming using a square or indicator. On a Bridgeport that would be better than using the side of the quill.

  • @mouseyou12
    @mouseyou12 Год назад +1

    Very Nice Thank you.

  • @michaelpiotrowicz6100
    @michaelpiotrowicz6100 Год назад +1

    Wonderful work with the drawings :)

  • @eXactModellbau
    @eXactModellbau Год назад +1

    Der Anfang hat mich an die Sendung mit der Maus erinnert. Sehr schön! 👍

  • @1crazypj
    @1crazypj Год назад

    I wondered about the moving table being able to 'compensate' (?) for any wear, now I know it does I'll use that method as this is the first time Ive seen it

  • @russellforrest1730
    @russellforrest1730 Год назад +1

    Yeah, really loved the old-school graphics

  • @petersilva4242
    @petersilva4242 Год назад +2

    I have Bridgeport clone and it's a pita to tram,there's 20-40 micron change on X when you tighten y and vice versa.topk me about an hour to get within 10 micron last time

  • @Joelsfilmer
    @Joelsfilmer Год назад +2

    Just what I needed right before bedtime

    • @MF175mp
      @MF175mp Год назад

      2AM soon here

  • @jeffkeen6943
    @jeffkeen6943 Год назад

    Great to see you back in the workshop...hope you enjoyed your time trekking around New Zealand? 🙂

  • @davidrule1335
    @davidrule1335 Год назад +1

    I have a 1943 TREE knee mill. It has a collet closer witch is very nice, no draw bar on a TREE. Unfortunately during a very heavy plunge fly cutting operation. The operator noticed the machine sounded different. We had broke the casting, so now it's "tramed" and welded. No more tilt and nod for me. All I can do now is kick stuff up on a sing bar. In other words it's a glorified drill press. LOL

  • @mpetersen6
    @mpetersen6 Год назад

    When tramming on the table I never swept directly on the table. Slip a solid object with know parallel sides (1) between the indicator tip and the table. Swing the indicator around and check again. Far too many times I've seen the indicator tip take a shock. Another option is to use a good size bearing race large enough to cover the y axis dimension of the table. And sweep on toP if that. Another option is to tram up and down with the quill to a very accurate angle plate in x and y.
    Additionally the top of the table should mapped to see just how flat the table is to the x and y axis. Also an angle plate should be checked to z axis motion. Head or Knee.
    1) As you said a gage block or my personal preference a roller from a Timken type or a cylindrical roller bearing. Ground to within 0.00005"/0.0013mm or less in parallel. I preferred to use the roller out of a bearing for two reasons. One is if I drop it it. The second is I had several sets of 3 made up to different heights for doing set ups. One thing I did a lot of is rebuild machine tool spindles. On a lot of spindles the front face or a gage line are meant to be a certain dimension from a specified feature. This often requires grinding spacers to the needed dimension. These spacers need to be as parallel as possible. Less than .00005" in parallelism. This often required grinding a sacrificial surface to put the spacer on. This gave as true a surface as the grinder could produce.

  • @vincei4252
    @vincei4252 Год назад +4

    Hi Stefan, hope the year off doing your own thing is working out well! I'm seriously considering doing the same.

  • @jeremylastname873
    @jeremylastname873 Год назад +1

    If you need a brake rotor, brother, we’ve got your back! 😂

  • @ROBRENZ
    @ROBRENZ Год назад

    Good stuff Stefan!
    ATB, Robin

  • @TheIconfriend
    @TheIconfriend Год назад

    Awesome video as always Stefan! Quick question, does it matter where you place the gauge block relative to the table centre? Your techniques eliminates any inconsistencies in the table surface but for example if you place the gauge blocks so that the 2 points where the indicator makes contact is way off centre, do you think the sag of the table under it's own weight would give false tram readings? I guess this might not matter as much on rigid machines but on my smaller bench top mill, the table sag off the edges of the saddle are considerable so when I try the stationary sweeping technique you show earlier in the video, I always try and make sure that the table is centred. I'm not sure if it matters that much so curious to hear your opinion.

  • @cogentdynamics
    @cogentdynamics Год назад +1

    On the Bridgeport, the addition of the “nod” would make the reading of the quill problematic I’m thinking. I have used a parallel even a set of two. Gauge block tips were good. I always enjoy your videos and learning from your knowledge. Even before you made videos by reading the forums. Thanks for what you do!

    • @TheOpinionationer
      @TheOpinionationer Год назад

      Yes the two axis do need to be trammed separately. On Bridgeports and clones the pivot point for the nod is not centered above the axis of rotation. This means that when you tram the nod, you cannot move it half the indicated difference. In fact, if it is very far out, the indicator will be moving the same direction on both ends of the sweep, but it moves much less close to the column than close to the operator. The turret further complicates tramming if you want to use a sine bar to achieve an angle (or compound angle). when you are trying to set an angle other than precisely 90 degrees to the table, the forth and back motion of the ram must be trammed precisely parallel to the y axis, or the indicated angle will be wrong.

  • @markshort9098
    @markshort9098 Год назад +1

    I wish Bridgeports were so easy to tram, the Bridgeport is so top heavy they have a tendency to move to far and the worm screws are useless for fine adjustments.. I get it close with the worm and tighten the bolts a bit and tap the head true with a lead knocker with the worm set where there's backlash

  • @Engineerd3d
    @Engineerd3d Год назад +1

    Awesome 🎉

  • @friedrichgotze3264
    @friedrichgotze3264 Год назад +2

    Do you have any tricks how to trim the z-movement of a cnc router front/back-wise? I put shims between the blocks of the y-axis rails and the portal, but I think this is not very rigid. Also I can't adjust it later without adjusting everything else as well.

  • @Jenus85
    @Jenus85 Год назад

    This is great, Thanks!
    Would be really awesome if you could do a video on tramming the Sorotec router as well. I'm fine with just a theoretical video.

  • @greglaroche1753
    @greglaroche1753 Год назад +2

    Hi Stephen. Glad to see you are back. How was New Zealand? Great video. Thanks!

    • @StefanGotteswinter
      @StefanGotteswinter  Год назад +3

      Everything and more than I ever would have expected, just a wonderful experience :-)

  • @superdansilverman
    @superdansilverman Год назад +1

    There are a few subtle differences between the three methods. The first method sets the axis of rotation of the spindle square to the surface of the table, which makes for good fly cutting but introduces inaccuracy if the travel path of the table is not parallel to its surface. The second method sets the surface of the quill parallel to the path of the z axis travel. Two sources of inaccuracy are introduced- that the axis of spindle rotation may not be parallel to the surface of the quill, and that the travel of the Z axis might be out of square to the table surface and table x-axis path. The last method trams the axis of spindle rotation square to the travel path of the table, which generates the best flatness on a surfacing cut, but at the expense of parallelism between the finished surface and the table surface. It seems to me that each method of squaring should be used in specific situations depending on what kind of cut will be made and on which dimension has the tightest tolerances.

    • @StefanGotteswinter
      @StefanGotteswinter  Год назад +1

      The first method (sweeping on the table stationary) will create a unpredictable result for flycutting, since the table surface is not necessary 100% parallel to the axis the table moves on.

  • @garychaplin9861
    @garychaplin9861 Год назад +2

    Thank you Stefan, excellent presentation. Have you been to NZ yet, it's starting to get chilly on this side of the equator.

    • @StefanGotteswinter
      @StefanGotteswinter  Год назад

      Yep, I was there all of march, wonderful country, the vacation was everything and more than I would ever have expected :)

  • @JETHO321
    @JETHO321 Год назад

    How about smaller mills with an adjustable colum and adjustable tram? It's difficult to sync the 2.

  • @andytroo
    @andytroo Год назад

    14:00 how do you know that the table travel is square to the head? isn't the tilt of the table vs the travel of the table independent directions? (eg; the ways are worn in the middle, and the table itself ends up slightly lower at one side of that sweep vs the other, so that "0" reading won't be parallel to the table at any one place, but is pararallel to the average travel of the table.

  • @user-tw9io9nz2m
    @user-tw9io9nz2m Год назад +2

    9:40 to be honest at this point it’s to be expected that he can just perfectly tram his head by looking at the graduations

  • @OstapHelDesigns
    @OstapHelDesigns Год назад +1

    Smart! 👍

  • @ExtantFrodo2
    @ExtantFrodo2 Год назад +2

    I have to say I'm surprised the rotation scale on the head doesn't include a Vernier scale given how critical tramming can be.

  • @FCleff
    @FCleff Год назад +4

    Very nice video, Stefan. Thank you. Question: At 8:43 you use a hex wrench that appears to have a feature around the equator of the hex/ball end. Does this feature have some sort of capture mechanism (O-ring, spring, etc) to keep Allen head screws from falling off when gravity is not in your favor? If so, what is the brand of the hex wrench? Thank you.

    • @StefanGotteswinter
      @StefanGotteswinter  Год назад +2

      Thats a Wiha Magic Rin hex wrench - They are supposed to hold the screw, but it only semi-works. And the springsteel rings tend to break. Not a big fan.
      A piece of blu tack (or equivalent product) works better.

    • @FCleff
      @FCleff Год назад +1

      @@StefanGotteswinter Thank you.
      Cheers,
      F.C.

  • @iiredeyeiiredeye1569
    @iiredeyeiiredeye1569 Год назад

    Interesting Stefan, but I have a question. In using this technique...are you not transferring any error in the table to the head? If your table is worn on an older machine the error in traversing it from one side to the other will migrate into the head...no? When we sweep the head from one side to the other 180 degrees for example using the slip gauge method you mentioned the table is static...therefore any error or wear is not transferred...Or am I getting it all wrong?

  • @BigBoss-rh7zq
    @BigBoss-rh7zq Год назад

    Stefan, the technic you mentioned on the Deckel style machine do not allow you to trim the head with the table but only align the head with the vertical axis of travel.

    • @StefanGotteswinter
      @StefanGotteswinter  Год назад

      Well, thats what we want usually - Square to the axis, not to the table surface. Having the table trammed is a different thing.

    • @BigBoss-rh7zq
      @BigBoss-rh7zq Год назад

      @@StefanGotteswinter Sure, you mixed various things....

  • @wizrom3046
    @wizrom3046 Год назад +1

    Now we know how to tram a flux capacitor! 👍😎

  • @aikrondro
    @aikrondro Год назад

    Like before watching

  • @clehrich
    @clehrich Год назад

    I don't understand: doesn't sweeping a gauge block sitting on a vise simply reproduce whatever imperfections there are in the vise surface? I can see that the total surface area of the gauge block will reduce this effect, but unless you touch off/measure on exactly the same point on the gauge block on both ends of the sweep, any angle introduced by tiny imperfections on the vise surface should be repeated on the top of the gauge block, less a slight averaging effect. What am I missing?