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  1. #1
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    06-21-2010
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    Can you make this?

    OK guys. I've looked everywhere on the net to find something like the attached. Nobody makes it but it sure would be nice to have. Could you do it at a reasonable price? to +/- .0001" tolerance?

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    This is what I had in mind. the 2” X 2” (or 3 x 3) square could also be used for set-ups... like in 1-2-3 blocks if heavy and milled to 0001” square/flat. The spindle could accept the various tips available for standard dial gages which would allow it to reach longer. The 1” long spindle could retract within the square allowing for a standard 1” travel with .0001” markings (?). Ideally, the spindle itself would be interchangeable for a longer one so that the unit could also function as a depth gage when needed. This would require a hole in the base of your perfectly flat face for it to fit through. The stem is 3/16”...(?)

    This dial gage would fit under the drum sander, which has a maximum height of 3". It would allow setting the drum parallel to the bed quickly, instead of the onerous, trial and error, cumbersome task it currently is.

    The shortest dial gages available are 3 1/4" long. Too big for this application.

    Any takers?

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    Elizabeth
    I think, therefore I'm more confused than when I began.
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  2. #2
    Join Date
    06-15-2010
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    Re: Can you make this?

    You're trying to make your drum sander parallel to the bed?


    I assume that only one end of the drum is adjustable (up/down).


    Get two pieces of hardwood about 1" wide by 18" long.


    Tighten everything up on the sander and feed both pieces of hardwood through the sander. One at the left edge and one at the right edge. Measure the thickness of each piece after going trough the sander. Now you know which edge is high or low and by how much. Adjust as appropriate.


    Hint: It is best to start with the adjustable end high.


    As you lower the adjustable end keep feeding the scrap through, but only at the adjustable side. When you have the two pieces of scrap at the same thickness, lower the drum, lock everything down and test the scrap again. Both pieces should measure the same thickness. (Use a vernier caliper to measure. It can be a pure vernier, a dial or a digital read out.)


    Hint 2: Every full turn of the adjustment nut or screw will move the drum the same distance. Put a mark on the nut or screw so that you know what fraction of a turn you have adjusted. Write down with a marker on the sander how much adjustment for a full turn. There is nothing wrong with making 1/8 or 1/16 of a turn adjustments.


    Chinese hint: If you machine is made off shore it is probably metric. Each adjustment full turn will give you some weird fractional increment. Just use the metric side of the vernier. You don't have to understand the metric system, you just want the thickness of both pieces of scrap to be the same number.
    Last edited by rrich; 01-24-2015 at 3:08 am.
    Rich
    Huntington Beach, California

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  3. #3
    Join Date
    06-19-2010
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    Sundance, Wyoming
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    Re: Can you make this?

    to set my drum sander I used two round solid steel shafts my dad had from his mechanic shop (I think they were from some front struts). I lowered the sanding drum to fairly close, loosened the adjustment bolts and let it down till it just touched both, then I used a feeler gauge of .010 and set it under the outside edge of the drum sander. Tightened the bolts, raised it up and down to check again.

    The reason I did this is because mine is a 16"-32" open end drum sander, 16" sanding drum, for boards wider than 16" I was having some issues with it sanding to low into the center of the board when I would turn the wider boards and feed threw, the slightly higher outside helped me eliminate that problem. Essentially I have a slight crown in my wider boards (I finish sand with a quarter sheet sander which pretty much flattens it out) but on the smaller boards it's not an issue as I just turn the board and run it threw again.

    ~Mike
    Last edited by autobodyman; 01-24-2015 at 5:38 am.
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  4. #4
    Join Date
    06-19-2010
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    Re: Can you make this?

    Elizabeth,

    Making that square and flat to within +/-.0001 - that is a total of 2 ten thousandths of an inch would be near impossible to be "milled" as you say. That is precision ground by a highly experienced machinist specialized in grinding. You would NOT get that at a reasonable hobby price. Making that bloch to that accuracy would cost several hundreds of dollars, just for the block.

    You would also have a very difficult time finding a dial indicator with a 1" travel and .0001 graduations. If you could find one - add another 100 - 200 dollars.

    Standard stem diameter on a u/s made dial indicator is 3/8 per AGD standards.

    You don't need anything more precise than +/-.002 on the block, which could be milled, and a .001 graduation dial indicator, which can be had with 1" or more travel.

    There are "other" kinds of dial indicators whereas you could get into spaces less than 1".

    For what you want - I would suggest a magnetic base indicator holder with a .001 grad and 1" travel. This does NOT need to be "under" the head in any way.

    What you would do it get the sander to be touching the top of the wood being sanded - that would be your reference point. Setup the indicator to touch the top of the sander (any movable part) Zero the indicator at the .500 mark or anywhere on the dial that will allow enough movement for the job to be performed.

    When you adjust the head - the dial indicator will register the movement.

    ---------------------------------------------------------------------------------------

    WHAT LEO DOES:

    When I am sanding something to thickness I can get to within .002 without failure.

    I start out by using a digital caliper and I measure the piece I am going to sand.

    I then run it through the sander - measure again.

    I know my sander will sand a certain amount per one full turn of the adjust handle - say .03 per one full turn.

    So half turn would be .015

    A 1/4 turn would be .007

    It's actually quite accurate and no guess work.

    When I am getting really close I will measure the wood and adjust accordingly.

    One thing that is really important - when you are moving up to the size - you need to be sure you are turning the adjustment screw only in one direction - you cannot back off and come back down - due to backlash in the screw. Well you can, but there is a procedure for it.

    The other thing is, there is a lot of variables between the movement of the adjustment and the actual thickness of the wood, which would negate the accuracy of adjusting the head to regulate the wood thickness. For example - you can change the thickness by .001 or .002 just by running the wood through 2-3 times with no adjustment.

    These sanders are just not that accurate to begin with.

    Besides - the accuracy of woodworking doesn't need more than about .005-.010 accuracy in most precision cases.

    I have dial indicators with a .0001 grad accuracy, as well as .001 grads and 1" travel and I have magnetic base indicator stands, but I would not use indicators for the purpose you are describing for a variety of reasons.
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  5. #5
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    06-21-2010
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    Re: Can you make this?

    Quote Originally Posted by rrich View Post
    You're trying to make your drum sander parallel to the bed?

    Hint 2: Every full turn of the adjustment nut or screw will move the drum the same distance. Put a mark on the nut or screw so that you know what fraction of a turn you have adjusted. Thanks! It never occurred to me to mark the adjustment knob! That's great!
    Quote Originally Posted by autobodyman View Post
    to set my drum sander I used two round solid steel shafts my dad had from his mechanic shop (I think they were from some front struts). I lowered the sanding drum to fairly close, loosened the adjustment bolts and let it down till it just touched both, then I used a feeler gauge of .010 and set it under the outside edge of the drum sander. Tightened the bolts, raised it up and down to check again. The round shafts are perfect for this. It's hard to find the lowest part of the drum with a flat piece.

    Essentially I have a slight crown in my wider boards (I finish sand with a quarter sheet sander which pretty much flattens it out) but on the smaller boards it's not an issue as I just turn the board and run it threw again. I get a crown too because I try to compensate by turning the piece.

    ~Mike
    Quote Originally Posted by Leo Voisine View Post
    Elizabeth,

    Making that bloch to that accuracy would cost several hundreds of dollars, just for the block. Ouch!

    You would also have a very difficult time finding a dial indicator with a 1" travel and .0001 graduations. If you could find one - add another 100 - 200 dollars. Double Ouch! I meant one thousands.... silly me typed an extra zero...

    Standard stem diameter on a u/s made dial indicator is 3/8 per AGD standards.

    You don't need anything more precise than +/-.002 on the block, which could be milled, and a .001 graduation dial indicator, which can be had with 1" or more travel. This is what I meant.

    There are "other" kinds of dial indicators whereas you could get into spaces less than 1". There are?

    For what you want - I would suggest a magnetic base indicator holder with a .001 grad and 1" travel. This does NOT need to be "under" the head in any way.

    What you would do it get the sander to be touching the top of the wood being sanded - that would be your reference point. Setup the indicator to touch the top of the sander (any movable part) Zero the indicator at the .500 mark or anywhere on the dial that will allow enough movement for the job to be performed. But to measure from the top you'd still have to place the indicator under the cover of the sander, no? I can't remove the cover...

    When you adjust the head - the dial indicator will register the movement.

    ---------------------------------------------------------------------------------------

    WHAT LEO DOES:

    When I am sanding something to thickness I can get to within .002 without failure.

    I start out by using a digital caliper and I measure the piece I am going to sand.

    I then run it through the sander - measure again.

    I know my sander will sand a certain amount per one full turn of the adjust handle - say .03 per one full turn.

    So half turn would be .015

    A 1/4 turn would be .007

    It's actually quite accurate and no guess work.

    When I am getting really close I will measure the wood and adjust accordingly. This is what Rich was saying too. Good way to do it.

    One thing that is really important - when you are moving up to the size - you need to be sure you are turning the adjustment screw only in one direction - you cannot back off and come back down - due to backlash in the screw. Well you can, but there is a procedure for it. I think this is why I messed up my initial adjustment.

    The other thing is, there is a lot of variables between the movement of the adjustment and the actual thickness of the wood, which would negate the accuracy of adjusting the head to regulate the wood thickness. For example - you can change the thickness by .001 or .002 just by running the wood through 2-3 times with no adjustment. It's what I'm doing now. Like Mike.

    These sanders are just not that accurate to begin with.

    Besides - the accuracy of woodworking doesn't need more than about .005-.010 accuracy in most precision cases. You're right. I just need the boards flat enough so they squish together under clamping pressure, so I can do the box or dovetail joints.

    I have dial indicators with a .0001 grad accuracy, as well as .001 grads and 1" travel and I have magnetic base indicator stands, but I would not use indicators for the purpose you are describing for a variety of reasons.
    You are all right. Feeling is the best way.

    Thanks for your replies.
    Elizabeth
    I think, therefore I'm more confused than when I began.
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