FP2 logn reach head nod, can it be?? (very long post) - Page 3
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    Quote Originally Posted by Colt45 View Post
    Hi Thanos,
    I think you mentioned earlier that you are missing some clamps or bolts for your head? You need to fix that.

    ...

    After you check the table for "truth to the axis movements", you can install an indicator in the spindle. ....
    Hi Colt45, thanks for the reply,

    I appreciate your input, it seems to me though that there is an easier way, more direct. I am thinking using Deckel's own advice (intended for verifying tilt, right to left) for verifying possible nod. That is test bar in the vertical spindle and dial indicator mag base on the vertical slide (one could even keep the table if it does not intefere with the test bar, have to check) and moving table/indicator up and down. As I mentioned earlier, this measurement would suffer by table droop, which will be different for different Z regions. However, if I check on the lower region and the higher region of Z travel, then I can reach conclusions.

    Also, please help on this, this would need a flat point tip on the dial indicator, right? Or else, one cannot separate tilt from nod easily. Deckel in the manual, of course assuming zero nod, could make do with a regular tip without issues. What are your thoughts on this?

    (yes, clamping strap is a priority, I know)

    Quote Originally Posted by AlfaGTA View Post
    Seems two questions going here.....

    Invest is some test tooling.... A good parallel (granite?) 12" long or more would be a good start....A good known indicator that can read accurately to .0001" or better is a must along with a good magnetic base (Noga!)
    Further a known (certified) surface plate large enough to test the truth of your parallel would eliminate lots of questions....
    A qualified square (can be done by yourself ) would also be invaluable to test the relationships between the axis moves......

    "Colt" has outlined a process to test the "Y" move of your machine...If you need further help i am sure members here can help...

    Cheers Ross
    Hi Ross, thanks for the reply,

    As I said earlier in this post, I am considering a slight different approach for checking possible nod, that does not involve the table, among others to avoid being infuelnced by table rocking, which I know is there to some extent.

    Regarding tooling, thanks for the advice. I've acquired a couple of indicators, best one being a nice Tesa reading 0.002 mm. Non certified I am afraid. I've also bought myself a granite surface plate (chinese but new, come with a certificate and all), indended, among others, to help build a parallel (CI it will be) and a square. Limited budget won't allow for all tools to be bought at once, some must be made and I thought that using a surface plate to make a reference parallel would make more sense than the other way around...

    Thanks for the input, I'll try to investigate geometry later this week and then retry cutting change tools and conditions and ask for further advice providing extra details.

    BR,
    Thanos

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    Generally, a round tip indicator will function better if the indicator tip will be moving across something. Flat bottom indicator tips will tend to drag or bite. You should be able to separate tilt from nod regardless of what type indicator tip is used.

    Checking a Test bar is a valid method for evaluating head tilt or nod, yet doesn't tell you anything about the truth of the table to the axis movements. I don't think it's necessarily any easier nor more accurate than using an indicator arm.
    The method I described is more comprehensive, uses tools that have more varied applications (other uses) than a test bar and has the potential to be more accurate because you can indicate a larger sample.

    You need to check the table because you are mounting your part to the table (either directly with clamps, or indirectly with a vise)--the head can have perfect tram (tilt and nod at 90 degrees relative to the Y axis) and still not machine flat/parallel if the table is not in tram with the movements of the machine and the head in tram with the table.
    Last edited by Colt45; 08-08-2018 at 11:25 AM. Reason: spelling

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    Quote Originally Posted by Colt45 View Post
    Generally, a round tip indicator will function better if the indicator tip will be moving across something. Flat bottom indicator tips will tend to drag or bite. You should be able to separate tilt from nod regardless of what type indicator tip is used.

    Checking a Test bar is a valid method for evaluating heat tilt or nod, yet doesn't tell you anything about the truth of the table to the axis movements. I don't think it's necessarily any easier nor more accurate than using an indicator arm.
    The method I described is more comprehensive, uses tools that have more varied applications (other uses) than a test bar and has the potential to be more accurate because you can indicate a larger sample.

    You need to check the table because you are mounting your part to the table (either directly with clamps, or indirectly with a vise)--the head can have perfect tram (tilt and nod at 90 degrees relative to the Y axis) and still not machine flat/parallel if the table is not in tram with the movements of the machine and the head in tram with the table.
    Hi Colt45 thanks for the reply,

    thanks for your suggestion regarding the indicator tip. I understand that you suggest repeated measurements, offset either side of the center of the test bar, that would prove if any deviation is tilt or nod, right? I was under the impression that flat bottomed indicator tips were the tool of choice for such measurements, similar to picking up a taper on the the lathe, since are relatively immune to small deviations off the perperdicular direction.

    Regarding tooling, I should have mentioned that I have a Deckel test bar (Actually had two and got an extra from a dear friend from here. My guess is that they came with the mill, the indexing head and the spiral attachement, so you seem to be able to easily find them with used machines) so utilizing it seems the easiest/fastest method.

    Closing, correct me if I am wrong, I understand that milling flat has nothing to do with table orientation, or part mounting on the table/vice. It's the parallel/square thing that's affected by how the part is supported with respect to the axes of the machine, right? In this context, I would prefer the direct measuring method over the indirect, which, to my understanding, is generally a better practice, avoiding error accumulation, right? I mean, my table has, if not anything else, some rocking right to left. I would not want to mix all the issues together, it would be difficult to reach a conclusion this way. I think that isolating parts and assessing their state/ fixing them will introduce less errors. My plan is to find out the compromises of my head (if any), then introduce Y axis as a next step (that is, remeasure nod for different Y axis points). After knowing what I am dealing here, I can tram the table as per the required job at hand (referring to the tilting table). Please share your thoughts on this.

    BR,
    Thanos

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    Some notes:
    First off as to indicators....Best choice here is to use a "test" style indicator...which to the best of my knowledge all have spherical contact points....
    Test indicators will allow easier and lighter (important when trying to hold the indicator stable) setups the are also easier to position in different positions....(more universal)
    The issue of having the plunger being on,or reading on an arc is easily handled by traversing or moving the axis the indicator is clamped to till you get the highest reading....its the way its done every day for
    precision work.....

    Not a big fan of the teat bar for this type of testing...
    First off there will always be error or run out on the bar, so you must compensate for such which introduces another source of potential error...
    The sweep method as outlined above gives direct readings...no compensation needed.
    Further using a teat bar will require movement of two axis (vertical to test along the bar and moves in "Y" at multiple positions to test the "Y" slide move) this introduces more error...slide vrs. slide...

    I would suggest , if set on using the teat bar, that you start by mounting the bar in the horizontal spindle......
    It seems unlikely that the original factory alignment of the vertical head to the "Y" slide ways have changed....Very little chance of wear or damage where the vertical head makes up with the "Y" either at the protractor or base mounting dovetail....
    As such the vertical spindle should still be perpendicular to the horizontal spindle.

    Mounting the teat bar in the horizontal spindle and testing it for flat in two planes (Y,Z and X,Y ) should give a picture of how the slide is moving along its full travel.

    Once you have a good picture of the slide and any possible wear, you should be able to verify using the teat bar that the vertical head is OK....If your slide (Y) is worn and pointing down for example, you should be able
    to calculate the induced error that would be seen on the vertical test bar....
    Remember that testing the bar in the vertical spindle introduces the truth of the "Z" slide into the measurement...Something that is not really present when surfacing with the vertical spindle having the tool set to one height...



    Might want to obtain a copy of "Machine Tool Reconditioning" by Connelly...
    Lots of good info there on accepted practices for testing the geometric "Truth" of a machine....

    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    Some notes:
    First off as to indicators....Best choice here is to use a "test" style indicator...which to the best of my knowledge all have spherical contact points....
    Test indicators will allow easier and lighter (important when trying to hold the indicator stable) setups the are also easier to position in different positions....(more universal)
    The issue of having the plunger being on,or reading on an arc is easily handled by traversing or moving the axis the indicator is clamped to till you get the highest reading....its the way its done every day for
    precision work.....

    Not a big fan of the teat bar for this type of testing...
    First off there will always be error or run out on the bar, so you must compensate for such which introduces another source of potential error...
    The sweep method as outlined above gives direct readings...no compensation needed.
    Further using a teat bar will require movement of two axis (vertical to test along the bar and moves in "Y" at multiple positions to test the "Y" slide move) this introduces more error...slide vrs. slide...

    I would suggest , if set on using the teat bar, that you start by mounting the bar in the horizontal spindle......
    It seems unlikely that the original factory alignment of the vertical head to the "Y" slide ways have changed....Very little chance of wear or damage where the vertical head makes up with the "Y" either at the protractor or base mounting dovetail....
    As such the vertical spindle should still be perpendicular to the horizontal spindle.

    Mounting the teat bar in the horizontal spindle and testing it for flat in two planes (Y,Z and X,Y ) should give a picture of how the slide is moving along its full travel.

    Once you have a good picture of the slide and any possible wear, you should be able to verify using the teat bar that the vertical head is OK....If your slide (Y) is worn and pointing down for example, you should be able
    to calculate the induced error that would be seen on the vertical test bar....
    Remember that testing the bar in the vertical spindle introduces the truth of the "Z" slide into the measurement...Something that is not really present when surfacing with the vertical spindle having the tool set to one height...



    Might want to obtain a copy of "Machine Tool Reconditioning" by Connelly...
    Lots of good info there on accepted practices for testing the geometric "Truth" of a machine....

    Cheers Ross
    Hi Ross,

    it's a bit hard for me to find workshop time midweek, but I reserved half an hour to be able to report something back. So:

    - regarding DTIs, point taken. I am more used to dial indicators but this can change.
    - regarding measuring along a cylinder, you're all right, no big deal to find the high spot, I was overthinking about this.

    - regarding use of the test bar...I tried two bars and they both showed around 0.02 mm runout (just less than a thou roughly), mounted on the horizontal spindle and measuring mid-length. I was expecting better. I measured the spindle's internal taper in two depths and got practically zero runout (plus some surface noise). I did not have the time to set the bar on Vblocks and see what runs out.

    - After all this, I did a couple of tests with the DTI on the test bar quadrant closer to the operator and moving the Y axis back and forth. I got a move of around 0.04 mm on the DTI, which seems to me both high and strange. The way I think of it, this kind of measurements can only show if horizontal spindle axis is parallel to the Y axis, right? Since I cannot see how these two might have stepped out of alignment, I am guessing that I am seeing something else. I think I'll have to make sure Y gib adjustment is proper. Can't think about something else at this point. Any ideas?

    - also, it the use of rapids recommended for such measurements? In my case I saw the measurement being affected possibly by DTI plunger drag when starting/stopping the rapid. So, I used the handwheel nice and slowly.

    BR,
    Thanos

    ps. Thanks for the advice on the Connelly book. I had read so much about it in this forum that I found it online and got it printed. I try to go through a paragrah or two whenever I find the time...

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    more notes:

    As to indicating. If using a DTI, then best if the finger is aligned to the direction of travel when indicating.
    Be sure angle of contact is in range..the accuracy of the indicated change will vary depending on the finger angle.
    Most indicators want to be between 12 and 16* off flat to the surface.

    Best accuracy obtained when doing the test always in the same direction. I generally prefer to move so that the finger is dragging relative to the movement.
    Pushing (rotation into the finger) generally gives more flutter from surface noise.....

    Test bar ...as i said before, not surprised that you have runout....0008" is not bad at full length.

    Indicate the bar closest to the taper. Mark any deviation that you see using a sharpie on the bar....with a dot at the + point.
    Indicate the far end same way and mark as before.

    To get accurate test of the alignment...Extend the "Y" axis to the end of travel, back it off slightly . Set DTI at the horizontal spindle end of your test bar....find the high spot or crown of the bar by using the "Z"
    (you are testing the alignment of the slide in the X,Y plane) Indicator sits at the mid point of the teat bar vertically

    Set the bezel of your DTI so that the zero is in the middle of the run out sweep on your indicator. Be sure you are not at the end of the travel in either direction.....

    Move the "Y" slide back letting the indicator read the bar...make a full move (total travel) and back off slightly from the end stop.
    Rotate the test bar and note the dial travel...At the highest point, check (by moving vertical) that the indicator is still reading at the bar center line. If the slide droops or climbs you will have to correct the
    indicator height

    Read the indicator travel by rotating the bar...Be careful not to add any force to the bar...best to rotate by grasping at the spindle..The algebraic sum of the indicator movement relative to "zero" on the indicator dial is the
    error of the move and direction...

    Example...if the indicator reads "Plus .010" on one side of "Zero" and "Minus .003" opposite then your real error is that the slide moving toward the plus direction and the magnitude is .007" over the length of travel that you indicated...

    If you see error in this move check the gibs, but be careful not to over tighten ...must test for freedom of movement over the length of the slides travel...
    Anything is possible with machinery this old...no telling what has happened to this machine over time...

    Cheers Ross
    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    more notes:

    ...

    Read the indicator travel by rotating the bar...Be careful not to add any force to the bar...best to rotate by grasping at the spindle..The algebraic sum of the indicator movement relative to "zero" on the indicator dial is the
    error of the move and direction...

    ...
    Cheers Ross
    Great Ross, got it (had to read twice but I got it), thanks for the detailed tutorial.

    One question, wouldn't it be ok if I rotated the bar by the handwheel at the back of the machine? Select a gear in the speed 'box and rotate without disturbing the bar, no?

    (I am in the middle of workshop reorganization due to replacing my lathe, so I might not be able to test today...)

    BR,
    Thanos

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    Sure...hand wheel on the gearbox input shaft would be fine...Could also use the draw bar tightening nut with the gearbox in neutral...
    Right at the spindle nose is fine as well.....Might be hard to see the indicator well if you are reaching to the hand wheel....What ever works, its your call.
    The object is to reduce the sources of potential errors or false readings...

    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    Sure...hand wheel on the gearbox input shaft would be fine...Could also use the draw bar tightening nut with the gearbox in neutral...
    Right at the spindle nose is fine as well.....Might be hard to see the indicator well if you are reaching to the hand wheel....What ever works, its your call.
    The object is to reduce the sources of potential errors or false readings...

    Cheers Ross
    Clear, thanks!

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    Quote Originally Posted by thanvg View Post
    Regarding CI surface scsle, I am aware, and feared it especially on this crappy casting. That's why, I, initially, took the part yo a friend with a huge shaper and had it roughed out.
    BR,
    Thanos
    Hi Thanos,

    I think that you can put this down to the Greek word "agon".

    I would have used the shaper to finish off the casting and have the machining marks uniform instead of zig zagging over the top. If you look at the surface finish on your FP2 table top you can see that this was machined on a planing machine which was the grandfather of the shaping machine and still used today to machine tables and slideways.

    There have been a lot of posts by the "names" but everyone has probably been looking too far forward and have not really considered the basics of the problem. In your original post, you mentioned that you used an old magnetic chuck to hold the work down! Have you considered that the casting was not held down completely and could have moved during machining or distorted due to the high temperature that you say was incurred?

    Of course, you have an old machine, this could contribute to your problems.

    I just dashed this post off before going to the workshop.

    Alan

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    Quote Originally Posted by bentley1930 View Post
    I would have used the shaper to finish off the casting and have the machining marks uniform instead of zig zagging over the top.
    Presuming Thanos' friend with the shaper would have done the best he could do with it, I don't think Thanos was left with the option of going final-final on the shaper they had to work with.

    Shapers may stroke linearly as planers do, but there are fundamental differences in the planer's fully-supported table, no ram droop, and an astonishingly low rate of asymmetrical wear. Those allow a planer to live long and stay capable of producing VERY "plane" surfaces.

    Shapers have higher wear rates, they have ram droop, they have more flex than planers. "plane"' surfaces are not as easy to generate on a(ny) shaper as on a planer.


    ... you mentioned that you used an old magnetic chuck to hold the work down! Have you considered that the casting was not held down completely and could have moved during machining or distorted due to the high temperature that you say was incurred?
    +1 There is certainly cause to wonder about stability on a chuck more common for light grinding loads - where the force from the wheel has no "flutes" or inserts but is exerting nearly constant force and not as much of it, than for heavier milling loads, where the flutes or inserts are also successively "hammering" at the the magnetically restrained workpiece. Hard to NOT expect movement.

    Then, too what of the the shape and contact "quality" of the backside - in contact with the magnetic chuck.

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    Hi guys, thanks for the replies,

    see my answers below:

    Quote Originally Posted by bentley1930 View Post
    Hi Thanos,

    ...

    I would have used the shaper to finish off the casting and have the machining marks uniform instead of zig zagging over the top. slideways.

    ...
    Have you considered that the casting was not held down completely and could have moved during machining or distorted due to the high temperature that you say was incurred?

    Of course, you have an old machine, this could contribute to your problems.


    Alan
    Hi Alan,

    well, finishing on the shaper was not an option. Apart from the physical limitations that thermite mentioned (that I had not think about of course) the main issue was the operator: dear friend but old school, probably a bit tired to give a damn. For example, for the roughing, he put the plate on a huge vise and used some old chuck jaws as parallels. The he squeezed the heck out of it (of course the 'parallels' stopped being in contact with the work. You see the picture...And if you say something, then it's "it's ok, it does not need anything more, we've always been doing it this way". My intention was (and still is) to do a little better in terms of accuracy (screwing up at the first take does not say anything about the intentions, does it... ). Also, it's a slow process and I would not want to use but my own workshop time to do it.

    Regarding the mag chuck, thanks for the input, I'll consider it and I can run some tests with a couple of indicators that will show if there was any kind of motion. However, as the forum has already suggested, there have been so many serious issues so far, that seem much more possible to be the cause of my problem than part moving. However, I have to check, thanks.


    Quote Originally Posted by thermite View Post
    Presuming Thanos' friend with the shaper would have done the best he could do with it, I don't think Thanos was left with the option of going final-final on the shaper they had to work with.



    Shapers have higher wear rates, they have ram droop, they have more flex than planers. "plane"' surfaces are not as easy to generate on a(ny) shaper as on a planer.

    +1 There is certainly cause to wonder about stability on a chuck ....
    Hi thermite,

    thanks for the shaper/planner advice certainly makes sense!

    Regarding the mag chuck, as I said above, I feel that it was robust enough (holding on to practically the entire surface of the iron part) but I need to check in order to prove it. I also think that, had there been any movement there, I would have seen something random in terms of final outcome, not the consistent straight step I got. I would expect the part to rotate or something like this.

    Thanks for all the input and sorry that I am not in a position to work in faster paces in order to sort this out soon. My workshop at the moment is as if was bombed, full of new (to me) lathe tools and parts, brushes, cleaning agents and machine moving carts....can't tell when I'll sort the mess out and be operational again...

    BR,
    Thanos

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    Quote Originally Posted by thanvg View Post
    Hi guys, thanks for the replies,

    see my answers below:



    Hi Alan,

    well, finishing on the shaper was not an option. Apart from the physical limitations that thermite mentioned (that I had not think about of course) the main issue was the operator: dear friend but old school, probably a bit tired to give a damn. For example, for the roughing, he put the plate on a huge vise and used some old chuck jaws as parallels. The he squeezed the heck out of it (of course the 'parallels' stopped being in contact with the work. You see the picture...And if you say something, then it's "it's ok, it does not need anything more, we've always been doing it this way". My intention was (and still is) to do a little better in terms of accuracy (screwing up at the first take does not say anything about the intentions, does it... ). Also, it's a slow process and I would not want to use but my own workshop time to do it.

    Regarding the mag chuck, thanks for the input, I'll consider it and I can run some tests with a couple of indicators that will show if there was any kind of motion. However, as the forum has already suggested, there have been so many serious issues so far, that seem much more possible to be the cause of my problem than part moving. However, I have to check, thanks.




    Hi thermite,

    thanks for the shaper/planner advice certainly makes sense!
    Thanks, hope so, or I'm going daft too rapidly! I do still have a shaper - modest 12" Sheldon, and was blessed it came out of a school system that hadn't used it much. The first I used was a Gould & Eberhardt - former lineshafter - around 1959-60. I've only ever tooled and operated one planer, a 20-footer on which I ganged-up Lee-Norse mining machine chain guides, and not much else. Those had been repaired with a "corncob" pattern of stick-weld which tore the hell out of milling-cutters trying to cut it back to dimension.

    Given my choice, I'd trade several dozen shapers for one large planer, the difference in "flatness" is that much more righteous.

    Regarding the mag chuck, as I said above, I feel that it was robust enough (holding on to practically the entire surface of the iron part) but I need to check in order to prove it. I also think that, had there been any movement there, I would have seen something random in terms of final outcome, not the consistent straight step I got. I would expect the part to rotate or something like this.
    No, what it CAN do is creep. Slide in the direction of applied force. A mag chuck actually does have "some" force that tries to center a part over the individual poles and the net-net center of the sum of its magnetic poles. But we don't want it to do that, so the designers have done their BEST to reduce its tendency to move anything laterally so the choice of position is ours, not a choice of the magnets.

    What is wanted is "straight DOWN" force. Into the chuck. Mostly, we get that. Now - depending on the surface shape of the part that is in contact - the bottom or back, if you will, we also have friction, sometimes not enough of it. This is where we add fixtures and use a "fence" at an edge of the chuck for initial alignment and to resist sliding or creep. A grinding wheel CAN fling a part off the chuck, and at a high velocity.

    So just keep in mind its downforce may be very strong, but it is NOT as good at lateral consistency as clamps, most especially when the loading comes from changing directions, as your zig-zag path with the facemill represented.

    Not saying it cannot be done.

    Just that you need to "get to know" that chuck better, recognize how dependent it is on intimate contact for friction, and re-assess whether it is even the most appropriate workholding AT ALL for milling operations in general.

    Were it my plate, it would have gone off for Blanchard grinding after milling or planing or shaper "best effort" that at least got the skin off it. Or so one hoped it had!



    Thence to scraping.

    Or not.

    Ordinarily, decent Blanchard ground - imperfect, but "not VERY imperfect" - is all I need for a "working" Iron or steel surface. I have blessed myself with plenty of good granite for metrology use.

    My workshop at the moment is as if was bombed
    Ah well, you'll have to let me know how you arranged for a precision air-strike, then!

    "Bombed" puts you some months or even years ahead of me. Can't yet MOVE in much of mine for all the machinery my gluttony has crammed into the space whilst I renovate two adjacent rooms.

    Running a front-end loader - even a small rubber-tracked one (Toro Dingo) - over yerself clear up to the gut sorts of sets the good intentions back, so far by nearly a full year. And I was slow and lazy to begin with - "procrastination" the best-preserved of my waning skills?

    I may yet have to brush-up on my biotechnology, kidnap some unsuspecting microbes, and teach them how to "just grow" nice paint jobs for my machines, the needle-scaler and media blast gear sitting idle!

    Lazy, Iyam!



    Carry on!

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    Missed the part about the mag chuck.....Sort of skimmed this post to start
    Additional things to be wary of when using magnetic holding tooling..
    That is that any surface out of flat on the side against the "chuck" will tend to be straightened out under the pull of the magnet..making the working surface
    distorted to match the back..then you machine the top flat...Once you release the magnet the finished surface springs back to its relaxed state...and becomes automatically out of flat.....

    Grinder hands deal with this all the time and spend careful time shimming parts to compensate for out of flat surfaces that are against the magnetic chucks and do so before the magnet is energized.
    Careful checking using an indicator on the top surface will show the action of the magnet pulling the part down when energized....
    Its a bit of a catch 22...by shimming to correct pull down distortion, you inevitably reduce the holding friction on your part.....
    As has been pointed out already....this is why you need stops or chocks....

    Another reason for hold downs....placing risers or parallels right below the contact point of the clamp....

    I might suggest some form of "Edge" clamp hold downs if you can't tolerate conventional hold downs/clamps.....Lots of ways to hold that part that would give more effective results .

    Mill wedge clamps - Google Search

    Cheers Ross

    .

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    Dear Bill,

    Quote Originally Posted by thermite View Post
    Running a front-end loader - even a small rubber-tracked one (Toro Dingo) - over yerself clear up to the gut sorts of sets the good intentions back, so far by nearly a full year.
    I read over this without absorbing what you meant. But then caught myself, read it again, and cringed.

    Every few years I do something stupid and injure myself. I try to learn from these mishaps. But this sounds beyond my range of experience. What happened?

    Cheers,
    Bruce


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