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I am in the process of designing some steel planing forms but I don't understand the purpose of the dowel pins.

If the dowels allow enough movement back and forth, doesn't that also mean that there will be enough room for the steel bars to move up and down?

Also, if anyone can describe the best and/or easiest way to cut the slope on my long forms using a mill machine, that would help tremendously.  (Matt Baun)

    Welcome to the list, not sure where you got your plans from, but check Thomas Penrose's site for a couple of different sets of plans. 

    As far as milling the taper, from what I have read on the list it does not work well, or at least the person doing the milling does not understand the need for exact tolerances. The dowel pins are a reinforcement for keeping the two sides of the forms perfectly lined up. Once again if they are off alignment slightly you will not get a good groove and therefore your strip angles will be out of whack.  All strips need to be as close to the same and perfect as possible, otherwise when you glue up you will get gaps and other unwanted blemishes.  (Pete Van Schaack)

    I have made several sets of metal forms and have not used dowel pins. Instead of dowel pins I use counter sunk flat head Allan screws. This keeps the bars centered and no screw heads sticking out the side to grab your knuckles. In issue 16 of Power Fibers, I had part 1, This covers smoothing, drilling and tapping.  Part 2 is in the issue 17. It covers making the groove.

    It might help you in making your forms.  (Tony Spezio)

    The dowels are made such a good fit that you will not get any movement up or down they will keep the faces of the forms true as they are opened and closed.  I put dowels every 10 inches but if the forms are made to produce dramatic swelled butts the push/pull screws are every 2 1/2 inches over the swell distance the dowels every 5 inches.   I mill or grind the angle on the forms.  To mill I use an end mill with the angle of 30 degrees ground on.  I find it best to machine about 12 to 18 inches at a time blending in at each stage.  On the surface grinder the angle is put on the grinding wheel and the same steps as milling is done.  I measure the angle with an optical scale to get the right depth.  (Barry Grantham)

      Barry made me a set of forms (and a few others whom I know).  Not sure how they were made but they work just fine so I believe we can safely say he knows a' just a little 'about machining planing forms.  (Paul Blakley)

        I make my forms with dowels midway between all stations. The holes are precisely drilled and reamed for a close fit and still operate without binding. In addition, I use countersunk pull bolts for two reasons: One, for additional self aligning and Two, so there is nothing protruding from the sides of the forms to catch your fingers.

        I also use 1 x 1 stock for a wider  platform to work with while planning. Using larger stock also allows one to use larger push-pull hardware for additional stability. The larger stock adds 1/3 more material/weight, which I view as an advantage. (They don't move as easily in use) Disadvantage - more work to make, but you only have to  do it once.

        Cutting the groove is done with the setup aid of a spreadsheet. I believe the Spreadsheet is on Todd's web site. If your present forms are off at any/all locations, the spreadsheet can be used to fix the problem. If someone wants a copy and can't find it, let me know and I'll send you a copy off-line.  (Don Schneider)

      I forgot to mention that I do not machine the angles on the forms with them fitted together.  I do each side of the vee separate.  To get the taper a dial indicator is used and to get the correct size of the groove is a simple job if you use one of those 10 times optical scales.  By careful set up you will find all angles are the same when fitted together.  Of course the top faces must be flush and doweled before you start.  (Barry Grantham)


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