45 degree miter joint jig-sled for BT3x using SMT

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  • LCHIEN
    replied
    Here is the spreadsheet I use for making frames.(actually page 3 of the spreadsheet) to calculate the exact outside dimensions for a frame to fit a given picture size given the frame member width, the rabbet size and allowance.

    Frame Calculator Size and Foot 4.xlsx
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    Attached Files
    Last edited by LCHIEN; 05-12-2022, 01:41 AM.

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  • Dedpedal
    replied
    Nice jig! I’ve been thinking about making a new one. I have a sled but it’s limited.
    Click image for larger version

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  • LCHIEN
    replied
    This is a continuation of the frame making exercise from the previous post in this thread.

    The First test was a mess - I used some good pine, my Bessey miter clamps were not able to open enough So i used some older classic miter clamps and the problem was getting the whole shebang level.... I did two corners and then the two opposite corners and the result of a 19-3/4 x 12-5/8 frame was about 1/4" not flat. But laid out on a flat table the pieces looked perfect.

    So I decided to change and use my DIY odd angle miter clamps which work at 45/90 as well. The advantage is that they can lay flush on a table.
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    DIY miter clamps post number 2 in this thread: https://www.sawdustzone.org/forum/di...u-made-part-ii

    I did two opposite corners. I could only get one clamp on the short side even though I had enough clamps. The other advantage of the DIY miter clamps is that it conforms to the exact angle of the joint rather than attempt to make it fit 90.

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    When I placed the two halves together it was perfect... on both sets of frames I made.

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    I completed the glue up doing the remaining two corners with the frame perfectly flat on the workbench.
    Note that while I cut everything with the back side up I assembled and glued face side up so I could make sure the faces lined up perfectly. I used a rubber mallet to tap them perfectly flush. And could wipe off any excess glue with a damp towel. I use a piece of wax paper under to prevent gluing to the table.

    From long experience, I apply and spread thoroughly a film of glue on both end grain surfaces and wait about five minutes for it to be absorbed. Then apply another layer of glue. Otherwise the joint will most likely end up dry. The first coat of glue absorbs rapidly into the end grain of the wood (even at 45 degrees) and starves the joint of glue. The first coat skins the pores and the second coat makes the adhesion of the wood.

    I have to say these two final frames I made were the absolutely most perfect coming together with the least adjustments that I ever made.
    Here are the four corners before finish sanding, they'll look better after that:
    Notice the grain even matches as much as possible wrapping around (at least 3 of 4).
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    All in all the miter jig did live up to expectations of making perfect 45/90 degree miter joints as I expected.
    Using the complementary angle technique, cutting top and bottom together, and having the planned order made it fast and non confusing - just four cuts and the frame came out with perfect joins and lays perfectly flat.
    After the first one I made two more with red oak 1x3x 6 foot from the box store and both came out perfectly.
    Attached Files
    Last edited by LCHIEN; 04-27-2023, 01:56 AM.

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  • LCHIEN
    replied
    After a break I finally got around to using the jig.

    You recall that the object of this jig is to make very square 90 corners with two complementary 45's. The basis being a very 90.00 degree square that is set ~45 to the blade so that the two angles cut on either side add up to 90.0.

    Here is a example from the last Mitered frame I made, I glues up two corners and then glued the remaining corners, all using a Bessey miter clamp.

    You can see the last two corners are not completely closed.
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    Here is a plan of the jig, how to cut the frame of sequential pieces so that the grain matches, and how to fit the pieces together.
    I mark all the pieces so I know which is which and don't swap or reverse similar looking pieces. T,L,B,R are top, right, bottom and left as viewed from the back side. The miter cut edges I numbered 1-8.

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    I cut the board between the 4 and 5 marks leaving a little extra space for two 45 kerf waste (allow W+L+1/2" from the left end). This allows me to cut the Top and bottom rails at the same time since the lengths are identical and the L & R at the same time, stacking them. The rabetted edge is up and hard to see in this picture but matches my paper plan.

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    Stack the boards and make the first cut on the close side of the jig. All the odd numbered edges are cut on the close side and all the even cuts are on the far side of the jig... so that even and odd are mated to be complementary. Note the rabbet edge is away from the jig. This is cut for edge number 1 & stacked with number 5.

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    How to get the cut line set
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    This is set up to make the second cut - edge number 2 on the far side of the jig, also stacked with number 6.

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    The third cut is edge number 3 stacked with number 7, again , odd cut close side.

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    And measure off the side height, and made cut number 4 (stacked with 8)

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    Four cuts and done! It goes very fast!

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    In the next post I will show the assembly.
    Attached Files
    Last edited by LCHIEN; 05-12-2022, 01:27 AM.

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  • LCHIEN
    commented on 's reply
    I looked at it for a really long time. One arm is fixed to the handle and the other arm pivots around its pivot point. But regardless the travel is an arc and not a line.

    I would have cut off the tip on the fixed arm so that the handle would stay motionless and in fixed relation to the fence as the movable arm moved to clamp the workpiece. But alas the movement is an arc rather than linearly in and out meaning I can't clamp thin stuff If I cut off the pivot and go to a simple straight jaw. That's why you only see these wide arm locking pliers with point ends or swivel ends, no flat ends, to accommodate the arc.
    Last edited by LCHIEN; 03-22-2022, 10:59 AM.

  • nicer20
    commented on 's reply
    Great. Of course .

    Hopefully one day I may be able to think of something that Loring hasn't implemented yet ;-) ;-)

  • leehljp
    commented on 's reply
    I still think a modified vise grip pliers would do well; just don't cut the wrong arm off!

  • LCHIEN
    commented on 's reply
    Thanks. Sandpaper face Already done - look at post no. 25 in this thread.
    Last edited by LCHIEN; 03-22-2022, 02:05 AM.

  • nicer20
    replied
    Great jig and equally great step by step documentation.

    Regd. holding the pieces against the miter fences - how about gluing some 120 grit sandpaper strips on both faces? I have glued this on my sacrificial miter fence and they provide excellent holding without any sliding movement.

    Just my $0.02

    NG

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  • LCHIEN
    commented on 's reply
    Partner? Like A consenting adult?

  • LCHIEN
    replied
    Thanks for everyone's input and suggestions.

    After quite a bit of tracking down and buying a locking clamp of 6" I pretty much decided it won't work, although I had high hopes. The jaw opening was too limited and the jaw angles would not have been right after doing some modifications. Among other things as the jaw opened the clamping point swings in an arc (as opposed to in and out in a line) and when widest would have been too high for thin pieces. I was not looking forward to hacksawing the Cr-V jaws either.

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    (OK, I just realized I drew it reversed with the wrong movable jaw but I'm not going to redraw it.)

    I looked at 4", 6" and 11" locking clamps physically in my hand at the jig and none really fit the bill even with modification.

    I finally cut down a F-clamp and also glued some sandpaper on the fence faces. And drilled a hanging hole. Slotted the new end of the clamp so I could do a screwdriver assisted tightening if needed with the short handle. With the 4" F-clamp I can clamp 3-1/2" wide workpiece.

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    Somewhere soon I need to make a frame and see how this works.
    I have a couple of 8x15 photo prints I brought back from a vacation my wife has been wanting me to frame.
    Attached Files
    Last edited by LCHIEN; 03-22-2022, 10:48 AM.

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  • LCHIEN
    commented on 's reply
    Yeah, a panel under the jig that provide a support for a vertical clamp and also serves as a cut line reference has been running thru my mind. Didn't want to add a lot of bulk and size to it but yeah that's surely a possibility.

  • mpc
    commented on 's reply
    If the jig was mounted to a flat panel that in turn attached to the SMT via the dowel pegs, the panel would serve as the clamp mate for the stock SMT clamp. And it would serve as a ZCTP of sorts. You could make the plate a little wide so the blade trims it to size initially, forming a nice reference edge to line up your desired workpiece cut line. In effect you would be making something approximating the typical table saw miter sled but turned 90 degrees.

    mpc

  • LCHIEN
    commented on 's reply
    Capn', you are correct that the jig is held in position by the two dowels pegged into the pivot holes. and captured by the knob and bolt in the center slot.

    An you are right that the downside of downward clamping from the 45 square fence is that it pushes against the saw table and not against the SMT base as the Ryobi miter clamp does. The SMT is limited, though in upwards travel by the slides.

    So I Have to think about it some more.

  • capncarl
    commented on 's reply
    I don’t think that the SMT clamp will work because there is no bottom of the angle jig to clamp against.

    When I went back to look at the sliding miter table I noticed that the 45 jig appears to be positioned by a dowel on both sides of the SMT, is this correct LCHIEN?
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