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Thread: Car parts

  1. #1
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    Car parts

    Working on some car parts for a friend (an antique, 'wooden' body car). The pieces I am trying to replicate were joined with a 'finger' joint. But the fingers arent tapered, they are all square.

    The pieces to be joined together are about 2.25" thick square (cross section), one about a foot long and the other about 4ft long - white oak. The fingers are 1/8" thick, and about 5/8 deep.

    Does such a cutter exist? ( have a router table and also a shaper) Else I 'might' be able to use a slot cutter and make a bunch of cuts raising the bit precisely each time (sounds tedious and prone to error...)

    Box joint cutter would work, if there was one with 1/8" fingers and could go 5/8 deep.... havent found it.

    One end might be doable indexing across a table saw blade (short stubby piece). The other part though is about 4ft long so would stick up pretty high in the air if I tried it on the table saw. Maybe a jig of some sort to hold it is the answer (I do have an incra fence I could put on it for the task).

    Other ideas? (will see about getting some pics...)

    (it may be acceptable to use a traditional finger joint bit... will consult with him on that option since it wont match the other joints and this is a resto)
    Last edited by Carl Beckett; 09-24-2018 at 6:08 PM.

  2. #2
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    I'd probably use the slot cutter in the router table. Make a bunch of 1/4 (or whatever is needed ) spacer sheets and just add one underneath the piece after each pass. 1/4" MDF would work for a 1/8 cutter and is nice and flat and uniform. You'll have to notch the spacers to fit around the bit, but no biggie.

    Edit: there will be a bit of fussiness lining up the first cut of the mating piece, so make some test pieces that you can use to adjust the height for the first cut of the mating piece. After that, the spacers will do the trick. If you can, cut the joints before final shaping is done so any minor misalignment can be flushed out.
    Last edited by Paul F Franklin; 09-24-2018 at 10:37 PM.

  3. #3
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    I would do those in a shaper. Stack of horizontal cutters and spacers. Or maybe a tennon jig on a table saw.

  4. #4
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    Carl, I'm sure that others here who have restored vintage cars (I restored one some years ago) will tell you that restoration must be exactly the same as the original. It is not enough to only make parallel fingers, but they must match the dimensions of the original. You would also be advised to use the same materials as the original.

    Regards from Perth

    Derek

  5. #5
    My father and stepfather restored old wood body fords and from what I learn is all the finger joints or box joints so to speak was cut and chisel by hand. Templates where made and transfer onto the wood then cut and chiseled.

  6. #6
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    A slot cutter in a router table would need a very long mandrel. It has to cut a slot at the top of a piece that is 2 1/4" thick.

    I'd cut the slots with a table saw. Yes, not tilting the 4' stick is an issue. Build a jig that holds the stick very firmly in the upright position. Think of the stick as the leg of a dining table, upside down. The aprons on the table hold the leg firmly, so it can be done. Okay, you don't want to cut mortises in your car part, but you can clamp it to a jig to hold it upright. Probably the jig moves with the workpiece as you index the part past the blade.

    If your restoration friends are really picky, use a flat-top blade so the slots ends are square. Many rip blades have flat tops.

  7. #7
    I think you could make those joints fairly easily with a pantorouter

  8. #8
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    I think some are missing the point here of what denotes "restoration work".

    If the original was made with hand tools, then that is what you need to use.

    Regards from Perth

    Derek

  9. #9
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    If I understand what you are trying to do, I think an Incra box joint cutter on a table saw would work. The width of the fingers is set by the width of the blade and the depth by the height of the blade. So you need a 1/8" thick flat bottom blade with the height set for a 5/8" depth of cut. Several shop made box joint jigs (like Matius Wandel's aka Woodgears) allow you to make any width of finger wider than your blade by indexing the blade using gears or a threaded rod so you could use a narrower blade with them.

  10. #10
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    Some good thoughts here. Did snap a few pics. I believe it is a 1939 ish Pontiac Woody... the sister to this car was completed and for sale at over $100k

    What I am suprised at is the relatively crude joinery (one in particular is a mess, and filler was used on a couple of them). I will find out how critical this is but the guy has done 3/4 of these cars and seems to be ok with it.

    The new pieces go on the straight end that is resting on the floor in the pic. And some closeups of the joints already done (not by me).
    Attached Images Attached Images

  11. #11
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    Quote Originally Posted by Bert McMahan View Post
    I think you could make those joints fairly easily with a pantorouter
    You know... I do own a Wirth machine... hmmm

  12. #12
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    While that joinery might look crude from a visual perspective, it does have a ton of glue surface and is likely very strong.
    --

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

  13. #13
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    I've seen a router bit but I don't think it would do the full 2 1/4". Pretty sure it was in the MLCS catalog. I also think CMT makes one. Do a search for "box joint" router bit. If I remember correctly they make 4mm slots, not sure if being slightly over 1/8" will matter for your project.

  14. #14
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    What kind of glue was used back in the day. Hide glue I would expect. Not very weatherproof. Do you care if the modern glue is not reversible like hide glues.
    Bill D

  15. #15
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    When it comes to restoration, hide glue wins every time because it makes it easier to pull apart pieces. There will be a finish, which will protect the glue.

    Regards from Perth

    Derek

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