StIffness in plane iron adjustment

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    Alexander Miller

    I’m puzzled when I see Paul adjust the depth of his plane iron with the effortless ‘twiddling’ of a single finger. My limited experience makes me doubt my eyes when he does this. My thoughts – probably somehow mistaken – are as follows:

    The cap iron must be set to clamp the blade quite tightly, otherwise the blade backs off when it encounters resistance; but this tight clamping makes adjustment very stiff and awkward; also makes it difficult to feel exactly when slack in the adjusting screw has been taken up.

    What am I misunderstanding and/or doing wrong?

    Larry Geib

    Assuming you aren’t referring to the backlash that is so common to older planes, how easily the adjuster works is mostly a function of the tightness of the lever cap , cleanliness and friction properties of the moving parts, and smoothness of the frog surfaces.

    The lever cap should be snug and click into place, but it doesn’t have to lock the iron in place. There should be an allowance for some movement in depth and lateral adjustment. Try easing it a wee bit on the screw tension.

    Clean the adjusting screw. A light oil coating on all the moving parts ( iron, frog ways, adjusting fork and screw, etc) helps.
    And, of course, the larger ( 1 1/4”) adjuster knob is easier to adjust than the 1” knob style, but both can be adjusted with one finger.

    Benoît Van Noten

    The iron/cap-iron assembly must be able to move without snag (hard point) between the frog and the lever-cap. Otherwise it is not possible to correctly adjust the lever-cap screw (it would be either too loose or too tight) .
    – the underside of the iron, including the long slot which might have a burr if stamped;
    – the top of the cap-iron;
    – the top of the frog;
    – the underside of the lever-cap both at the edge and under the spring leaf
    must be smooth and lightly oiled.
    Any arris on those pieces (except of course iron cutting edge and cap-iron edge) should be rounded.

    IMO it is normal that “the blade backs off when it encounters resistance”. When one has retracted the iron, one has to take back the yoke slack to minimise this.
    See Paul Sellers Instagram dated 25 October 2021 and 21 April 2021.

    Smooth doesn’t mean mirror finish. Mirror finish surfaces tend to stick together. Machine-ways used to be hand scraped which allowed the existence of small oil pools.
    google “Hand Scraping: the Last Bastion for the Blacksmith’s Art in a CNC World”


    This can also be an indication of the iron not being sharp so that excessive force is needed to get a shaving.

    For me, I can flick the knob to get rid of the backlash, which can be 3 or 4 flicks (I guess), but once the backlash is out, it takes more effort. On some planes, I can get enough friction with a finger tip to make actually move the blade. On other planes, it might take a finger and a thumb. I suspect what you are seeing with Paul is him flicking the knurled knob a few times to get rid of the backlash, but then it takes so little movement to actually move the blade that you’re not seeing that part.

    Alexander Miller

    Thanks Larry, Benoit, Ed.

    Yes, what I’ve been seeing is Paul taking up the backlash. When he then makes the actual adjustment, he is so quick/adept/subtle with his custom-tuned plane and strong fingers that I wasn’t seeing it happen. I’ve dismantled my own (old, acquired) plane for tuning.

    Matt Sims

    “The cap iron must be set to clamp the blade quite tightly, otherwise the blade backs off when it encounters resistance; but this tight clamping makes adjustment very stiff and awkward”

    That’s not quite right… You are correct that the iron must be quite tight to the blade for the reason you mention, to stop backing off against resistance, and this is also aided by taking up the backlash in the adjuster after taking the blade back to take a lighter cut… but this will have no effect on the easy of adjustment.

    The easiness/stiffness of adjustment is a function of how tight the lever cap is. It’s true this can be a delicate balance, but it’s helped by having a clean frog surface, lightly lubricated.


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