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I plan on building Penrose's forms out of 1" stock. In his plans I believe he is using 3/4 " stock although he did mention 7/8 and 1" stock.  So, if he used 3/4 stock and his shoulder bolts had a 1" shoulder, (according to his materials list),  that means that the shoulder bolt extends into the second form by 1/4 ". So if I use 1" stock, do I need to have 1 1/4 " shoulders on the  bolts I use. I guess what I'm getting at is this, is it critical to have the shoulder extend into the second form or does it just need to clear the first form. Anyone know of a good outlet for shoulder bolts, the local ACE has them for 2.50 apiece. Yikes. (Mark Bolan)

    Go to Enco's web site.  They have what you need. And, yes, if you are going to go to the bother of using shoulder bolts, it is most necessary for them to go at least 1/4" into the other side. I think it might be easier to just use regular bolts and a dowel pin at each station.  (John Channer)

      Regular bolts might be OK if you're using 1" stock.  I made mine from 3/4" bars and glad I used shoulder bolts because I nicked the bolts with the triangular file while forming the grooves.  If this happens to regular bolts, you'll foul the threads.  (Ed Riddle)

        Nicking the bolts should not be a problem with 1" bars, but 1" bars will not flex nearly as well as 3/4" so you will have a harder time adjusting the forms for changes in the slope of a taper.

        I used 3/4" bars with cap screws and dowels and had no problems with nicking the threads while filing the grooves.  The cap screws are smaller in diameter than shoulder bolts so you are less likely to hit them.  If I make another set, I think I will use cup head Allen bolts and countersink them. Check out Tony Spezio's forms and Morton Lovstads' forms like this on Todd Talsma's tips site.

        They are flush on both sides.  (Robert Kope)

        I had no problems with nicking the bolts when I made my forms, but I do have a problem of being able to only make a rod butt section in  a maximum dimension of .368, since the apex of the strip will strike the shoulder bolt. The bars I used started life as 3/4" bars, but after all the draw-filing they ended up somewhat less.  I'd opt for 7/8" or 1" bars, even if it does take more  effort  to  adjust  the  forms.  (Martin-Darrell)

    I used both shoulder bolts and dowel pins.  I made mine with 7/8" CRS.  I've forgotten the length of shoulder bolts I used.  It will be easier if you leave only 3/8" to 1'2" to be threaded.  The threading is the bear so don't thread more than is necessary.  (Onis Cogburn)

    When I made my forms there were lots of stories about the problems of tapping the thread. I therefore used slightly longer bolts and did not tap the form  for the pull action. The bolts extend out the other side of the form and are closed by tightening a nut. This works well for me. I did include dowels and tapped the push side of the form.   (Ian Kearney)

    When using 3/4" square material just move your drilled hole's centerline off center of the bar's centerline by .04".  You won't clip the shoulder bolts and will be able to get .44" across the flats.  Just remember that the shallow side is for tips and the deep side is for butts.  (Brad Love)


The new metal forms are complete, finally, and have had a butt section and two tip strips planed on them. The cup head allen screws align the forms and get out of the way at the same time. I highly recommend there use for anyone making new forms. I have to thank Tony Spezio for this tip. I don't know if just hearing it would have inspired me to try this but I saw Tony's forms and examples of the rods he was planing with them. I knew that the process would work, didn't know if I could get it to work.

I highly recommend this type of setup! No more busted knuckles and the forms set up easily! Thanks again to Tony Spezio, my hat is off to you!  (Steve Trauthwein)


I decided (first mistake) to take apart the "inherited" planing form I'm using and now am having a devil of a time getting all the differential screws to cooperate and pull together, as I'm reassembling the form. Looks easy, but.  Hmmmm....!

Is there a technique or trick? Have tried a few "obvious" steps and sequences, but seem to end up with a couple of outliers, or the forms closing unevenly. This is worse than raising 5 teenagers!

I suspect there was a good reason that Mr. Catalano invented those new-fangled "push-pull" forms!  (George Deagle)

    It has been a long time since I disassembled my forms.  I used to have a sheet that helped, but it is long gone.  What I do remember is that the forms must be shimmed apart about an 1/8". Then all screws have to be started and turned the same number of turns until they just come through the near bar.  Then count each turn until each catches the far bar, release your shims and tighten it up.  It may not be perfect, but I think you might make it.  I really love the ease of the push pulls.  (Ralph Moon)


A fellow from Pittsburgh called me this afternoon.  Seems he picked up a set of differential screw based forms at an antique store.  In seeking to understand the forms he removed one of the screws.  Now he cannot get it back in...

How do you get them back in?  Someone here is bound to know. Guess I could call him back. (Harry Boyd)

    "The trouble with one piece differential screws is where they start"

    I've built two set of forms with one piece differential screws.  The best way to get them to start is to open the forms up to the point where you can start the two halves at the same time.

    I quickly learned that that I couldn't tap the two halves so that the screws started in the same place.  I converted the screws to three piece screws that are started individually and then locked together.

    If anyone needs more info, let me know.  (Ron Larsen)

      Don't forget to remove the shims.  (Ralph Moon)

    I don’t have an answer for the problem like Ron does, but I can assure you that you have a big problem removing one screw.  What I generally do is completely disassemble the form.   Then shim the two bars apart with an opening of about .025  (not sure about this dimension) then replace all the screws with only about a half turn  no more starting at one end and going to the other.  When the shoulder of the screw comes through the near bar very carefully attempt to feed the small end of the screw into the far bar.  If you are lucky you can again tighten all of the screws  again by half turns until the bars are locked.  If you are lucky the same amount of screw will extend on the far side at each point..  If not go to square one and repeat,  Good Luck it has taken me more than a day to reset my forms..    Once properly set they are great forms, but if not they can be a bear cat.  (Ralph Moon)

    I have made my forms with differential screws and they are very tricky if you unscrew any of them. They all have to be removed and then all have to be started again.  They all have to be tightened from one end to the other just a little in progression down the line until the forms are drawn together. No one screw can be too far ahead of the rest. I guess that doesn't sound too good but that is about the best way I can explain the situation which I was also faced with when I put the forms together the first time.  (Jack Follweiler)

      I knew there was a reason to use push-pull screws.  Garrison sometimes seems to have made things difficult just because.  (Neil Savage)

        Well, he never met Channer to ask him "Just how hard do we want to make this?"

        ........Here I go again, sometimes I'm the only one I amuse :>)  (Joe Arguello)


If your forms are pinned together with precision pins, what do the shoulder bolts do but add extra effort. The pins will keep everything in alignment.

    I agree.  And a box of shoulder/stripper bolts costs about 4 times as much as a box of hex head cap screws.  (Larry Swearingen)

      I use Counter Sunk screws, for the "pull" screws, no pins needed, The counter sunk screws center themselves and there are no knuckle busting heads exposed. The screw heads are flush.  (Tony Spezio)

      Cap screws are a nuisance too, unless you like beating your fingertips to death. If I were going to go to the trouble/expense of having the holes put in with a mill, I'd be on the phone with Tony Spezio asking him about his method with CS screws and no alignment pins.  (Larry Blan)

      If you use the hex head screws 10-32 you have 32 threads / inch and get much better control of your adjustments.  (Bob Norwood)


I have another question that someone might be able to answer. Don Schneider's instructions state to drill the pull holes 5" apart the length of the form, but the push holes are drilled 1/2" to the right of the pull holes from one end and 1/2" left of the pull holes from the other end. Why are the push holes drilled in this manner instead of them being the same (right or left of the pull holes) the whole length of the form?  (Ron Delesky)

    I'm not sure I understand exactly what you are asking.  Also I've never seen Don's instructions but the usual planing forms has a precision steel dowel at each station with one pull screw half an inch to one side of the dowel. This screw goes through a clearance hole on the near bar and into a threaded hole on the other bar. Pulling the bars together. The Push screw is obviously half an inch on the other side of the dowel.  It goes through a threaded hole and butts into the other bar.

    Pushing it away.

    Each station covers 1" + with a dowel in the center and the push and pull screws on either side of it.  (Larry Swearingen)


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