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Kerfage & Snappage

Discussion in 'The Grumble' started by shayla, Mar 12, 2019.

  1. shayla

    shayla WOW Framer

    Ordered a big piece of museum acrylic, pre-cut, and was told that because the saw blade is 1/8" wide, they can't guarantee it'll be the requested size. (And then there's the way it can break wider at the back than the front.) I suppose we can route the frame out if this comes too big, but really don't want to. What they said makes some sense, but I sure wish they could adjust for kerf when cutting. Is it that inexact?
  2. framah

    framah PFG, Picture Framing God

    No, that makes no sense at all.:rolleyes:

    A wood worker is able to measure the distance between the fence and the blade, I know I can, I'm sure they can as well.:confused::rolleyes::rolleyes::confused:

    No idea what they mean by it breaking wider at the back than the front?! It should be the same size all the way thru the saw.:rolleyes::rolleyes::confused::confused::rolleyes::rolleyes:

    At what that stuff costs, they da** well better make sure it is cut to the size ordered!!:eek::eek::eek:
    I would tell them to hold off until they can explain WHY they are that inept at cutting things. :rolleyes::rolleyes:

    Then consider finding someone else to get it from.o_O

    Not a believable excuse for sloppy work.:mad:

    Yeah, that's about the right number of emojis!!:D
    Dave likes this.
  3. Larry Peterson

    Larry Peterson PFG, Picture Framing God

    They don't know what they are talking about.

    I cut acrylic every day on my table saw and can cut to a 1/64" accuracy up to 52" which is the limit of my table saw fence.

    There has to be another reason they are telling you this.

    No emojis needed for carp like that.
  4. Larry Peterson

    Larry Peterson PFG, Picture Framing God

    BTW, a properly setup table saw takes into account the kerf (1/8" or whatever the blade thickness is) so that the cut you set is the cut you get. If I set the table to cut exactly 16", exactly 16" is what I get.
  5. artfolio

    artfolio SGF, Supreme Grumble Framer

    So the blade is 1/8" wide? It doesn't matter what the width of the cut (kerf) is. The saw's scale needs to be set so that the waste falls on the offcut side of the material and the workpiece comes out exactly as ordered.
    shayla likes this.
  6. David Waldmann

    David Waldmann SGF, Supreme Grumble Framer

    I agree with the others. There's no excuse for the size to be off more than a reasonable tolerance of say +/- 1/64" when using a saw.

    As for a scored and snapped cut, yes, I can see the result being off a bit on the back side. Depending on the thickness it could be more I suppose, but I couldn't imagine it being more than 1/32".

    Sounds like the phone answerer doesn't know what they're talking about, or you need a different supplier.
    MATTHEW HALE likes this.

    MATTHEW HALE CGF II, Certified Grumble Framer Level 2

    I call b.s. Someone is making bad excuses for poor workmanship. If you know how to use a saw, you know how to account for the saw kerf. If you aren't using a saw, you're scoring and snapping which may result in a slightly wonky cut, but -like David says- not enough to make a difference. But you can't have it both ways. if you're snapping it, you have no kerf wastage.

    What they may have been trying to say was that you can't get two perfect 24" pieces from a 48" sheet because you do lose 1/8" to the saw blade. But that shouldn't be your problem. There's no reasonable reason you shouldn't get what you ordered.
  8. munnframeworks

    munnframeworks CGF, Certified Grumble Framer

    We use a panal saw to cut our plexi, and can cut to 64th accuracy
  9. Lafontsee

    Lafontsee CGF II, Certified Grumble Framer Level 2

    I could see this being an issue if you were trying to get two 48" squares out of a 48" x 96" sheet. The kerf would come into play in that case.

    Is it also possible that they are trying to cover in case the acrylic expands thermally? Maybe their facility is cold and the acrylic might expand when brought into a warm environment?

    Otherwise, it sounds like BS to me.

    shayla likes this.
  10. shayla

    shayla WOW Framer

    Could be this? In which case, maybe I should have ordered a tad smaller? It's a regular supplier, and the phone helper is great, so was just being honest about the results out of the warehouse. We usually cut Museum acrylic ourselves, so this is the first time we've ordered it pre-cut. We figured that since it's bigger than our 3100 can cut, we'd let the experts do it. I really hope it's good, but do know that it's probably better than I could have managed.

    A point of clarification: While writing the post, I added the thing about it breaking unevenly at the back. Had told Hubby about the call, and was thinking about what could happen when a thicker piece is scored in house.
    It didn't cross my mind that, with their saw, that's not an issue. (Which just makes this weirder). It really does seem like one should be able to plan for kerf width and adjust accordingly.
  11. artfolio

    artfolio SGF, Supreme Grumble Framer

    A lot of these problems arise from the "perfect world" theory.

    In a perfect world you would expect to get two 48" squares out of a 48" x 96 " sheet of material but in my world several things would go wrong:

    The sheet would be out of square - not by much but probably enough to make sure the two squares would not fit the frame.

    There would be some chips around the edges which may or may not show in the finished product.

    The kerf waste would ensure the two sheets would be undersized when put into the frame.

    Always a gremlin in there somewhere.
  12. shayla

    shayla WOW Framer


    To be clear, the sheet I ordered was not 48". It was under 46", by over 62". The 48" thought mentioned earlier, and again here, is a good point, but not the size of our piece.
  13. wpfay

    wpfay Angry Badger

    On the out of square thought. Don't assume any stock sheet is square. I check it all carefully with a square before cutting. I had a sheet of Museum Optium that was 3/16" out over 48". That would have been a very expensive mistake.

    Where I get my regular acrylic and OP-3 they will cut to size for free. If I have the lead time I will provide them with dimensions and cut patterns and save myself a bunch of labor costs. They are within the 1/64th" allowance.
    shayla likes this.
  14. David Waldmann

    David Waldmann SGF, Supreme Grumble Framer

    Interestingly enough (it sorta seems related to some of the comments) prefinished "4 foot by 8 foot" plywood is generally 48-1/2" x 96-1/2". I think it's because of the possibility of the finish being janky at the edge, but it sure makes it a lot easier to get full inch/foot pieces out of it.
  15. shayla

    shayla WOW Framer

    I just learned a new word. That's delicious.

    Your note brings to mind something that an employee of Hubby's once did. Measured a bunch of lumber with a tape that had a tang bent in 1/8". The whole train car load of wood was 1" too short, and he learned not to do that again.
    (The nice thing about working there was, he really did learn not to do it again. Wasn't fired, and learned.)
    alacrity8 and David Waldmann like this.
  16. wpfay

    wpfay Angry Badger

    That is probably more applicable to cabinet grade plywood than to construction grade. If construction grade was that far off, the third panel in a row would miss the 16" OC framing. With cabinet grade, we rarely used the factory edge, so the extra would provide for a fresh cut and a full measure of product.

    I did get an order of 10 sheets acrylic once that were 50" X 98" each. Amazing how much more yield I got from those sheets. It's like Murphy has a law that says all orders will use slightly more than half a sheet of whatever sheet goods you are using, and I beat it for once.
    shayla likes this.
  17. David Waldmann

    David Waldmann SGF, Supreme Grumble Framer

    Absolutely, construction ply has to be 48 x 96 (I think some products may be 1/16 or 1/8 undersized to allow H-clips to be installed without messing up the 16/24 OC spacing).

    From the two suppliers we've dealt with, all unfinished cabinet ply is exactly 48 x 96. It's only the prefinished that's oversized by 1/2".
  18. Pat Murphey

    Pat Murphey SPFG, Supreme Picture Framing God

    Score and don't worry about a kerf. :D
  19. JFeig

    JFeig SGF, Supreme Grumble Framer

    I think that the response by your vendor is just an excuse. A picture frame distributor should be able to give you an exact size for cut-to-size acrylic. Can you imagine if they did that to your order of moulding chops or matboard cutting?
    TurnerAssociatesdy likes this.
  20. shayla

    shayla WOW Framer

    Good news! After scaring me on the phone, they followed up by sending a perfectly cut piece. Guess that's better than the other way around. lol....
  21. MarkyW

    MarkyW SGF, Supreme Grumble Framer

    That brings up an interesting question. When a supplier is cutting it, do THEY check that the sheet is square or do they just push it through the saw?

    I say this because they don't necessarily have the time to be extra diligent with so much customer stuff to do - or so it would seem. And I said that because I once got a chop moulding that had an allowance sticker right in the middle of it. Now, a chop is supposed to be checked to be sure it doesn't have a ding or scratch. That's what you're paying extra for, besides the fact that they are cutting it for you. But it doesn't take much checking to see a sticker right in the middle.
    shayla likes this.
  22. shayla

    shayla WOW Framer

    Was it a Waldo sticker?
  23. MarkyW

    MarkyW SGF, Supreme Grumble Framer

    Yes. It was a "Here's Waldo. Right here. Don't miss him." sticker.
    Also, it was a white sticker.
    On a black moulding.
    shayla likes this.

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