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Thread: Hammer K3 bowed rip fence spec

  1. #1
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    Hammer K3 bowed rip fence spec

    I was a bit surprised (and annoyed) to learn that there is a tolerance for the amount the fence can bow on my K3 and that I'm within it per Felder. The amount of bow in the fence is between .002 and .005 depending on where you check on the fence. The picture here is around .004. While this doesn't seem like much, it's enough to play tricks on my eyes when cutting a piece. When I see a .005 gap between my workpiece and the fence it causes me to instinctively push the workpiece more against the fence which messes up the fluidity of my cut and is a distraction. The piece itself is riding against the bottom of the fence which sits true, so the finished result is fine. Anyone else see this on their machines? Maybe its the universe telling me to stop using the rip fence and make that fritz and franz jig that I've been putting off for ages.IMG_6683.jpg

  2. #2
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    You might get it flattened at a machine shop. It is a quick job, and easier than arguing with the manufacturer.

  3. #3
    If it is aluminum you can sand it flat fairly readily with a hard block or an accurate edge sander.
    Last edited by Kevin Jenness; 08-02-2021 at 10:57 PM.

  4. #4
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    Quote Originally Posted by Jamie Buxton View Post
    You might get it flattened at a machine shop. It is a quick job, and easier than arguing with the manufacturer.
    That's a great idea, I definitely don't see felder budging as it is within their spec. Now to find a machine shop near me.

  5. #5
    If you sand it you will more than likely remove the hard coat anodizing, just something to be aware of. Btw, my k940 rip fence extrusion has a twist in it and I don’t care what they say their spec is they will replace it in due time…

  6. #6
    I have read, off and on, for quite a few years now about slightly dud extrusions on Felder machines. I used to own a 2000 build CF731 which I sold in ‘08. After recently returning to woodworking I now have a pair of BF6 combos-both of their fences are within my ability to flatten and true to the tables. Sometimes the ability to measure thou creates it’s own issues.(I can measure microns and have OCD…imagine my distress!) I used to struggle with the fact that measurable error could fall squarely within a manufacturer's stated tolerance for a component. Best advice: read up on machine tool reconditioning, how to flatten extrusions, how to work around your machines to sneak up on the dimensions you need for a first-class result. Chasing zero error in our machines is only as good as getting the next most expensive dial indicator.

    Greg

  7. #7
    Quote Originally Posted by Greg Quenneville View Post
    I have read, off and on, for quite a few years now about slightly dud extrusions on Felder machines. I used to own a 2000 build CF731 which I sold in ‘08. After recently returning to woodworking I now have a pair of BF6 combos-both of their fences are within my ability to flatten and true to the tables. Sometimes the ability to measure thou creates it’s own issues.(I can measure microns and have OCD…imagine my distress!) I used to struggle with the fact that measurable error could fall squarely within a manufacturer's stated tolerance for a component. Best advice: read up on machine tool reconditioning, how to flatten extrusions, how to work around your machines to sneak up on the dimensions you need for a first-class result. Chasing zero error in our machines is only as good as getting the next most expensive dial indicator.

    Greg
    That's good advice Greg, I work in a precision industry and am expose to machining tolerances that we struggle to even be able to measure, in reality the manufactures spec should be derived from actual real world results and if it falls within an acceptable outcome of the end result.

    I am not actually stuck on the specs provided only the result, I think I readjusted my table above their spec because I prefer it this way, the only reason I checked the fence extrusion was because I was getting inconsistent results over a period of a month or two. at first I thought it was the adjustment to the fence bar (its a bit fiddly to get right) then I realized after two adjustments that it was the position of the extrusion that was causing the variability

    In my case with the twist I can make it work by positioning it in different xy positions depending on what I am doing but why should I (or anyone else), this is a new saw under warranty. basically I need to have it set with a toe out of 0.006 - 0.008 so I don't pinch the cut on the way out.

    As far as tolerances go I suspect it is dependent on the equipment/time they are willing to invest into that particular part and how important that part to the overall end result- e.g. more time and money spent on getting the Arbor machined with very little run out is more important than getting say the extrusion perfect, an operator can potentially make the extrusion work with a bow, cup or twist buy learning idiosyncrasies of that fence, but with runout in an arbor you are stuck with that and it is potentially a big headache and expense for the manufacture to replace under warranty.
    Last edited by Mark e Kessler; 08-03-2021 at 8:45 AM.

  8. #8
    new or used dont expect all to be true. Thats out a lot. The last small adjustment I made was on a 30 year old shaper fence. The SCM fences are heavy and well made but im pretty sure a design flaw in them. On this fence it was out of square by .002 but only on one side. I put stick down 3M auto body paper and guide coat sharpie and sanded to .000. Id see putting a guide coat on your fence then stick 3m paper two rows on a flat surface and hand lapping it using care with hand pressure as you go. If there is some fancy finish on there you will loose it but if you do some finer grits after what you start with at least smooth it up. Id be happier with a fence that is true than having a consistent pretty finish. You still have to maintain square to the table, not sure how the base is on that fence.


    P1110965A.jpgP1110967A.jpg
    Last edited by Warren Lake; 08-03-2021 at 11:03 AM.

  9. #9
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    I don't recall ever checking mine before, but I just looked and it's bowed by probably the same amount. That being said, I leave my fence in the "down" position about 99.9% percent of the time anyway, so this bow really doesn't affect me.
    And there was trouble, taking place...

  10. #10
    My fence is in the low position as well most of the time, it is where I first discovered the issue. Attached is a pic of what I settled on for now, with the fence all they way forward I am about 0.004 toe out….

    As far as using it for a bump stop I pull the fence as far back as I can then recalibrate against a stop that I made and it’s close enough…kinda…next step is to make a small “bump” of wood or aluminum to attach to the fence and recal after that just haven’t done it yet…

    And no the recal isn’t a pain, literally takes 2 sec to do with the dro …ok well maybe 4 sec’s ��

    FAC260FA-E787-4BBC-AF84-824DE4C42E4A.jpg

  11. #11
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    Quote Originally Posted by Mark e Kessler View Post
    My fence is in the low position as well most of the time, it is where I first discovered the issue. Attached is a pic of what I settled on for now, with the fence all they way forward I am about 0.004 toe out….

    As far as using it for a bump stop I pull the fence as far back as I can then recalibrate against a stop that I made and it’s close enough…kinda…next step is to make a small “bump” of wood or aluminum to attach to the fence and recal after that just haven’t done it yet…

    And no the recal isn’t a pain, literally takes 2 sec to do with the dro …ok well maybe 4 sec’s ��

    FAC260FA-E787-4BBC-AF84-824DE4C42E4A.jpg
    Moving my fence to that position would likely help me as well. My issue isn't with my cut quality as I got the fence, very tediously, dialed in and can make . It's all around when i'm making a cut and I see a gap between the wood and the fence that makes me react.

  12. Well there's no shimming that, it's cupped. Machining it is a coin toss, removing the anodizing or even just machining the metal could release internal tension and make matters worse. I'd probably attach (shimming the cup) a known flat surface. Not sure if you can get ground fixture plate in that dimension but that's likely what I'd look at first.

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