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Is This Normal? Hitorque Mini Mill Table Is Not Straight

Discussion in 'MINI-LATHE & MINI-MILL INFORMATION' started by edojan, Feb 16, 2016.

  1. edojan

    edojan Canada Steel Registered Member

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    Hello folks, a couple of months ago I purchased Hitorgue mini mill (3990 - fixed column model) and only now was able to complete its installation (putting it on a removable base clamped to my workbench, tramming and DRO install). I am new to milling and not sure about what kind of precision to expect from this mill.

    Here is what I noticed: When trying to use my vise with the key slots (not to tram it every time) it was not sitting straight (DTI was showing about 0.05 mm (0.002") difference over 3" (75 mm ) of the jaw length of the vise.

    I put DTI over the front of the table (x axies) and it seems to be acceptible at just a 0.01mm (0.0004) over the table length - about 15 inches measurable distance.
    Here is the pic
    hitorque_side_of_the_table_is_straight.png

    Then I measured the slot and lo and hehold - it gives 0.10mm difference
    hitorque_table_is_not_straight.png

    The back of the table is straight too (this is why I didn't notice this during the DRO installation) but both slots are crooked about the same amount.
    Both the indicator and the holder are quality and all of the results are repeatable.
    The question is this normal? To translate metric into inches 0.1 mm (10 notches on my metric DTI which has a 0.01mm resolution) equals to about 0.004 of variance over the 15 inches. My question is if this is to be expected for hitorque machines or should I ask for a replacement table?

    upload_2016-2-16_21-8-27.png
     

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    Last edited: Feb 16, 2016
  2. David VanNorman

    David VanNorman United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Lets get this straight, the front and back of the table are parallel and the slots are not. Thats goofie. I have not herd of that one.
     
  3. edojan

    edojan Canada Steel Registered Member

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    Let's get this straight... like literally? How?
     
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  4. wrmiller

    wrmiller Chief Tinkerer H-M Supporter-Premium

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    It doesn't surprise me that the hold down slots are not parallel to the ways. They were not parallel on my little LMS mill either.

    Just my perspective, but on a mill in this price range, I would literally make a skim pass on the inside of any and all slots that I want to be perfectly parallel to x-axis travel. Then make some t-nuts that register only on the newly machined surface in the slots. Just my $0.02 :)
     
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  5. edojan

    edojan Canada Steel Registered Member

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    After using the crooked table for a while I have decided to replace it with (hopefully) a straight one so I wrote to LMS. They have promptly sent me a replacement free of charge! All I can say is that I am very pleased with the way LMS deals with its customers.
     
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  6. JimDawson

    JimDawson Global Moderator Staff Member Director

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    I have never checked the T-slots on a mill, but I never considered them to be a precision surface. Maybe I've been doing it wrong all these years. :) 0.004 in 15 inches seems to me to be within reason, I normally use an indicator to tram in a part or a vice if I need accuracy.
     
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  7. wrmiller

    wrmiller Chief Tinkerer H-M Supporter-Premium

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    It is however, handy when you're back and forth between a vise and a rotary table (for example) to be able to just lightly snug it down, give it a couple of soft taps with a dead blow to register against the (in my case the slot surface closest to the column) registration surface, and go. Or maybe I should just plan my work better so I don't have to do as much back and forth? :rolleyes: :confused:
     
  8. Tony Wells

    Tony Wells United States Vice President Staff Member Administrator

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    Like Jim says....those are NOT precision surfaces. In the manufacturing steps involved in a machine table, the tee slots are machined pretty early. This is to allow the material to stress relieve, among other reasons. Because of this, they are a little over-size for fit allowance of the nuts, which are also NOT precision surfaces. Frankly, I am surprised they are as close as they are. And I will be surprised if the replacement table is as good or better than the existing one. Please let us know.
     
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  9. 62Scout

    62Scout United States Iron Registered Member

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    I would think that the slots could be 0.100" off across the table, and it wouldn't matter, as long as the table surface itself is flat and true, as that is what the work/vise/whatever will be registering against for flatness when it's snugged down, not the underside where the slots are.

    I would also think that measuring along the top of the vise jaws wouldn't matter either - the key measurement would be the base/bottom that faces the spindle, as that's what the work/parallels/sine bar/etc will be registering against, not the top of the jaws. Of course, I could also be misunderstanding what you're measuring on the vise, so this won't matter anyways :p

    Did you also check for parallel between the jaw base and the bottom of the vise? It's possible that you have a bum vise too....
     
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