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Thread: Milling a flat straight edge on an aluminum sliding table saw table

  1. #1

    Milling a flat straight edge on an aluminum sliding table saw table

    So who ever the prior owner of my Griggio sc3200b slider was, they apparently ran the blade or something into the right edge of the sliding table a few times. It made that edge rough on almost half the length of the sliding table.

    This is making it difficult for me to set up the sliding table parallel with the saw blade as I canít very easily get my dial indicator to read perfectly throughout the travel of the table because the edge is so rough. It bounces the tip of the dial indicator and messes up my reading. Tried going really slow and it is worse that going fast.

    My solution is to mill a straight edge on the aluminum sliding table on the blade side. I am thinking about using my Bosch Colt trim router with a .25Ē shank 1/4Ē straight bit and making a wide base with a fence or guide of sorts to register off the opposite side and slide all the way down the length of the table. Itís aluminum so this should work.

    Any thoughts from you guys would be much appreciated.

  2. #2
    If you have to take much off you might want to build back with JB weld or similar before trimming to the original line. Your plan should work but has the potential for varying from a straight line. I would probably use a straightedge clamped to the table as a guide to insure against divots. I would want the new edge parallel to the table slot.

  3. #3
    Join Date
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    I do not have a sliding table but I have used JB weld and a strip of high density Pionite to re create the surface on a standard fence. Could you use the saw its self to do the milling?
    Best Regards, Maurice

  4. #4
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    Your plan sounds good. You could also make something to ride in the slider’s slot. I am planning the same thing on my old Felder combo rebuild project. I aim to re-install the slider closer to the blade to compensate for the 2-3mm of lost material. I am not quite clear on what technique causes the blade to deflect that much into the slider.

  5. #5
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    Wow...someone must have "done a number" on a blade for that to happen...and i'm with Maurice on this one. Repair the edge with JB Weld and some flat sanding blocks/sticks, maybe aluminum angle with the abrasive on the inside, to make the fixes parallel to the real slider edge. Getting it machined would be a really big row to hoe.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
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    This happens when a small offcut gets jammed into the throat opening and deflects the blade into the sliding table. Its why a zero clearance is a good idea. Its also why Martin designed their tables to have a replaceable aluminum strip closest to the blade.

    Do you have a long straight end you can clamp to the table as a reference? If you get the table .001-.002" over 48", then id call that 'good nuff' and move on to squaring the crosscut fence.

  7. #7
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    I agree with Pattrick. Clamp on a good straightedge of something and use that as a reference. The actual edge on the table does not matter.
    I assume this is a set once and forget deal that does not require periodic adjustments. At the very least do the clamped edge bit for now and verify no slide ways or bearings need replacing and readjusting before committing to machining the table edge.
    Bill D.

  8. #8
    Quote Originally Posted by Bobby Robbinett View Post
    So who ever the prior owner of my Griggio sc3200b slider was, they apparently ran the blade or something into the right edge of the sliding table a few times. It made that edge rough on almost half the length of the sliding table.

    This is making it difficult for me to set up the sliding table parallel with the saw blade as I can’t very easily get my dial indicator to read perfectly throughout the travel of the table because the edge is so rough. It bounces the tip of the dial indicator and messes up my reading. Tried going really slow and it is worse that going fast.

    My solution is to mill a straight edge on the aluminum sliding table on the blade side. I am thinking about using my Bosch Colt trim router with a .25” shank 1/4” straight bit and making a wide base with a fence or guide of sorts to register off the opposite side and slide all the way down the length of the table. It’s aluminum so this should work.

    Any thoughts from you guys would be much appreciated.
    Couldn't you just use that other side with some sort of jig to hold the dial indicator?

  9. #9
    I know aluminum can be cut with normal woodworking tools, but you may want to use a router with a 1/2” collet.

  10. #10
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    +1 with Dan. Assuming your table has no slot to measure from, I would try the other side edge of the slider table.
    Rick Potter

    DIY journeyman,
    FWW wannabe.
    AKA Village Idiot.

  11. #11
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    Seems to me you should have the indicator on the slider, and align its travel to the blade.

    A perfect edge, not aligned with the linear bearings, will never show as straight with the indicator on the table. And even if perfect, tells you nothing about its alignment to the blade. Which you true up by shifting the table.

  12. #12
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    The problem with that, Wes, is he is limited to the travel of the table across a 12-18" blade. .001-.002" across a 12" blade plate means his actual error could be 5-10x worse over an 8-10' stroke. Also, blades arent perfectly flat etc at times so they arent an ideal reference surface. To your point, he could put a 4' machinist straight edge up against the blade and then reference that edge with the indicator base on the sliding table.

    Personally, i didnt go nuts over calibrating the parallelism of my sliding table over the entire length. Its very close, and it has zero impact over crosscuts 36-48" wide. My table is only 80", and i havent yet had to marry up two pieces of that length yet where i would discern any error in my cuts. If its really out of whack, then you will chase your tail forever when calibrating the crosscut fence, but practically, i dont think you need it to be exactly dead nuts perfect over 8-10'.

  13. #13
    I've never cut into a sliding table, but every one I've used had some divots in the edge. My neighbor has one that occurred as a result of the blade getting pinched while crosscutting reaction wood, heating up and deflecting enough to ding the table. The blade was ok to use after cooling down.

    I like a continuous edge as I often use it as a reference when lining up cuts, measuring out to the workpiece edge with a 6" rule.

    You do want the table travelling parallel to the blade, which may or may not line up with the fixed table edge. If it is out by much it will cause tearout at the back of the blade as the teeth come up through the kerf.

  14. #14
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    Quote Originally Posted by Kevin Jenness View Post
    I've never cut into a sliding table, but every one I've used had some divots in the edge. My neighbor has one that occurred as a result of the blade getting pinched while crosscutting reaction wood, heating up and deflecting enough to ding the table. The blade was ok to use after cooling down.

    I like a continuous edge as I often use it as a reference when lining up cuts, measuring out to the workpiece edge with a 6" rule.

    You do want the table travelling parallel to the blade, which may or may not line up with the fixed table edge. If it is out by much it will cause tearout at the back of the blade as the teeth come up through the kerf.
    Same, and my table is virginal, but ive had a dozen experiences of offcuts getting pulled through the throat plate and exploding against the dust chute under the table. It makes a god awful noise. One of these days ill make a zero clearance insert.

  15. #15
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    Make a wood jig to allow the dial indicator to slide in the table groove, make it snugÖ.Regards, Rod

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