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The 3/4 inch steel bars for my forms arrived cut in two 6 foot lengths but each was bowed about a half an inch over the total length.  Using a couple of 2x4s and my 220 lbs I was able to bounce the bars almost straight.  I used cap screws and dowels rather than shoulder bolts.  I  have a lot of binding in my forms, my dowels are not loose even with the screws removed but the forms seem to work very well.  Clamping the bars together prior to filing and hole drilling insures alignment but introduces binding on the dowels after the clamps are removed.  I think binding (ie. being unable to hand tighten the shoulder bolts) will be the norm.  A way to check for alignment would be use a straight edge across the surface as the forms are opened and closed and look for misalignment.  But in my limited experience of making a few rods over the past six months, I find the forms are not opened very far so misalignment may be a minor problem.

This lack of straightness of the original bars coupled with bending during two dimensional clamping prior to filing and drilling is the reason that machine shops have such a problem with setup and milling of the tapered groove.  It is amazing but I believe hand scraping and filing is the most accurate way to make the 60 degree groove, the actual straightness of the form is not important.  (Bob McElvain)


Not being much of a metal worker, I managed to mess up my forms.  I have been plinking away at them since last August (I know they are only supposed to take about 20 to 30 hours to make, but I have managed to put in more than 60).  Well, somehow I managed to mess up the shoulder bolt holes so that the bolts won't go all the way into the holes.  Almost all of them get stuck because the screw in a little bit crooked, making the shoulder jam against the side of the hole.

I don't know if I drilled the holes at an angle or if I messed them up during the tapping.  When I drilled the holes I tested my drill press by drilling some scrap wood and measuring the entry and exit holes.  They matched, so I figured the holes were straight.  I also tried to keep the tap straight, but I often noticed it canting to the side.  Thinking that the tap would follow the hole, I just assumed it was me and my eyes that were off.

Anyway, now that I have this thing mostly finished, is there any way to salvage them?  I have collected all my other tools, and just need the bamboo before I can get started.  So, needless to say, I'm a bit deflated by this problem.  (Jason Swan)

    No doubt you tapped the holes at an angle. You might be able to go to the next larger screw size. If you used a fine thread screw you might be able to drill out the holes and tap for a coarse screw, A coarse thread takes a larger hole.

    Another alternative is to redrill another set of holes.  To tape straight. Square up the form under the drill bit. Drill the proper size hole. Get a spring loaded tapping pin at your tool supply house. Harbor Freight had there for about 3.00 on sale. Put the pin in the chuck.

    Lower the drill shaft and lock it down when you have taken up the spring extension.  This pin has a centering point on it and that point goes in the recess in the top of the tap handle. This keeps the tap in line with the hole you just drilled. The point had an internal spring the puts pressure on the tap handle to keep everything in line.  If you need a photo of this set up let me know, I can get one to you.  (Tony Spezio)

    To keep the threads straight when taping, keep the two bars together and use the one bar where the shoulder goes to act as guide for the tap.

    As an example I drilled my dowel holes then using a #7 bit I think, drilled a hole for the shoulder bolt through both bars.  I then switched bits to a 5/16" and drill through one bar and a portion of the other to accommodate the shoulder of the bolt.  Drop the tap in the larger hole and it aligns it perfectly with the #7 hole.  (Tim Wilhelm)


I started drilling on some scrap steel today and when I measure with the calipers from the inside of the hole to the outside of the forms on top and bottom, I'm getting differences as high as 10 thousandths.  What is the allowable error on this?  Also, on Penrose's instructions it says to drill the 1/4" hole all the way through and then drill the 3/8" hole about an inch and I am wondering how I could possibly change the bits without moving the forms or the drill press table.  If there isn't a way to do it, then how do I ensure that my 3/8" drill will be on same alignment as the 1/4" drill.  Thanks a lot for your help guys.  (Kris Fox)

    I don't think being off ± .010" top to bottom will matter all that much in the operation of the forms. As far as changing bits without moving the setup, you can't, unless your drill press has more than 2" travel.  (Don Schneider)

    When you set up the drill press with the 1/4" bit. only put the bit into the chuck enough to hold it securely, not all the way , and tighten it right up. Set the table height so at full depth, the 1/4" bit is just thru the bottom of the form. You should then have enough room to change to the 3/8" bit, if not, shorten the shank  on the 3/8 bit until it fits, it doesn't need to go to the bottom of the forms anyway. When using dial calipers, roll the jaws in until they just firmly touch, if you overdo it, you will get a false reading. As you use it, you will get to where you can feel the same amount of pressure each time.  (John Channer)

    You can swap your drill bits out without moving the forms.  Simply take a Dremel with a cutoff wheel and make the 3/8" the same length as the the 1/4" bit, or at least adjust the length so that you can insert it  after taking the 1/4" bit out.  I've done it and its not hard at all.  If you have the little 40-50 dollar drill press from the cheaper (ehem, 'discount') tool houses, you'll have to cut the bit pretty short and open the chuck all the way up to swap it out, but it can be done.

    I agree that if you can stay within .010" you should be O.K.  (Rick Crenshaw)

    I think you are well within the allowable error.  Remember, you are also using dowel pins to align the two sides of the form.  If you weren't using the pins, then being off the true center would potentially cause the bars to torque or rotate.  That would cause the grooves on one side to be greater than 60* and the other less than.

    But again using the dowels should keep the bars in alignment.  For a better fit on the dowel pins, drill the holes slightly undersize and then use a ream to enlarge the hole to the diameter of the pin.  (Tim Wilhelm)

    If I can add my 2 cents worth to what John mentioned.  When you put the drill bit shank in the drill chuck, you want the entire length of the chuck jaw in contact with the drill shank, IE if the shank is 2" long and the jaw is 1" long then the maximum length of shank you should have outside the chuck would be 1".  The jaws of the drill chuck SHOULD be parallel to each other over  their entire length to provide the most secure clamping of the drill shank, anything else is courting danger of drilling oval instead of round holes.  Although we often assume a drill will produce a round hole, in reality they generally don't, but the eccentricity for our purposes is generally within acceptable specs.  A round hole is generally produced by a drill being followed by a reamer.  If I need an accurate hole produced by a drill only, I will  chuck the drill bit in a collet or drill chuck mounted in a milling machine (usually this is going into over kill).  (Mike Shaffer)


I am building and gathering tools and eventually hope to build a rod or two. My questions are: Is a drill press accurate enough to drill the holes in final planing forms that I expect to last over the next three generations or so? Can an average craftsman drill holes accurate enough with a drill press and a vise or angle plate? Any suggestions? Can a bench top model handle this task? I have a machinist buddy who is offering to build the whole thing on a CAD machine. I have heard that machinist, traditional, manufacture less than ideal planing forms, creating forms that are not as accurate as they need to be. Fact or fiction? I want to build the forms myself and in the event I can't then I would at least like to know the person who does create them. Do you think I would be better off buying a set of forms?   (Dean Davis)

    Yes, you can drill planing forms accurately with a drill press. Make sure the table is level, and take your time. The problem I had was too much pressure, which caused the drill bit to wander a bit. Everything turned out fine, but several of the bolts were difficult to turn due to misalignment.  (Jeff Schaeffer)

    I'll take a shot at answering some of your questions.

    Is a drill press accurate enough to drill the holes in final planing forms?

    Yes, however there are drill presses & there are drill presses. Most DP can be adjusted/tuned to drill perpendicular/accurate holes to the work, some can't. Spindle runout can be a problem. The less expensive small table models are more apt to have these problems in addition to having minimal spindle travel and being able to run at slower speeds. Suggestion: Buy a DP that has at least 3 1/4" of spindle travel and run at 140 rpm.

    I have a machinist buddy who  is offering to build the whole thing.

    I'm sure there are a lot of machinist that can do the job well as long as you can explain exactly what you want done and the precision you require. IMHO a combination of the above is the cause of the stories you have heard.

    I want to build the forms myself.

    I think it is a good idea. You will learn a lot and what do you have to loose? It is a little time consuming but when you are done you have the satisfaction of saying "I did It !" If you get into trouble and need some answers there are enough of us on the list to help you out.  (Don Schneider)

    Well, if you are building and gathering tools, you're doing more than hoping to build a rod.  :^)

    With an angle plate firmly attached to the drill press table, and the form attached to the angle plate, you should do all right.  It isn't so much that the individual holes are drilled accurately as much as it is all the holes need the same error in them.  (hopefully a minor error though)

    The other thing that I don't hear spoken of much is supporting the ends of the form.  When you are drilling station 1, station 15 is hanging out in the air 6 feet away.  That puts a lot of torque on the table and there is a good chance the drill press itself will turn over.  Support the form in some what that you can keep the bars square to the drill bit and the table.

    "planing forms ... to last over the next three generations"  Sounds like you and your offspring are planning to make more than a rod or two.  :^)  (Tim Wilhelm)


A few months ago I picked up my steel bars to make my own forms.  Labor day weekend my wife got me a drill press for my birthday.  Since then I have come to one conclusion, I am not a machinist.  My grandfather, who was a retired machinist from Caterpillar, apparently did not pass on any genes that would allow this process to proceed without problems. 

Let me tell you my difficulties and see if anyone has any solutions.

I was following the instructions from Tom Penrose's web site.  I have all the dowel holes drilled and the dowels in place.  Then I drilled all the holes for the shoulder bolts and the set screws.  I then tapped the hole for the first should bolt.  Here is where the problems started, I did not drill the 3/8 in hole deep enough for the shoulder bolts to fully seat.  In hind sight I should have just used some washers.  But no, my brilliant mind said, "just put the bars back in the vice and drill deeper".  Which is what I did to all the holes.  Well most of you probably realize how hard it would be to find the dead center of an existing hole.  I thought, "the dowel pins are keeping the bars in alignment, so if I am off a hair, who cares" (just imagine what my rods will look like with that attitude).  What I did not realize is when the hole is a hair off center, the shoulder bolt is put into a bind and will not tighten down.  The first bold did tighten down because the bars could shift, but bolt # 2 will not tighten down.  I have not tapped the others.  The rest may work fine once I tap them, but I have a feeling the same thing will happen. 

I plan to tap a few more holes today and see what happens.  My other thought is to leave the dowels, and drill new holes, 9/16" on the other side of the set screws.  It would be unsightly, but should still function the same, correct?  Or would the bolts be too close to the dowels and cause them to bind.  This time I would drill my 1/4 in hole, and the 3/8 in hole, then tap with a spring loaded tap wrench, all before moving to the next,  to make sure everything is lined up.  The last option is scrap them and start over, not what I want to do with the cost of steel today.

Anyone out there have any suggestions to get me out of this bind (pun intended)?  (Matt Fuller)

    If you are going to drill new holes, drill the "Pull" screw holes on one side and the "Push" holes on the other side. This makes it a lot easier to set the forms.  (Tony Spezio)

      Yes, that is how I did it.  Pull on one side and Push on the other.  (Matt Fuller)

    Did you redrill the tap drill holes also? If your tap drill locations are not changed then you should be fine. Just finish tapping all the holes and use cap screws instead of shoulder bolts. If you have dowels you don't need the shoulder for alignment.  (Mark Wendt)

      I have started drilling new holes.  This time I took a bit more time in my setup and changed my process.  Now I am tapping as I go.  I am about half way done and things are going fine.  (Matt Fuller)


I've run into a weird problem just now as I was drilling holes for dowel pins in my planing forms.  I've drilled 14 holes with ease, but one sucker will not drill  more than about 1/4 inch into the steel.  I've changed bits, tested bits on a bar leftover from my first attempt at forms (my "learning experience"), and I've sat down and pondered my drill press, which is an old standup Craftsman.  I've tried other, smaller bits just to see if I could slightly nibble into the metal, but I get nothing. 

I'm suspecting there's something about the steel in this particular area of the bars, that maybe the metal in this area is somehow much, much harder than the rest of the bars. 

The rpms on my drill are not set very high.  In fact, the friend of mine who gave me the drill is a former machinist and he recommended the setting for cold-rolled steel. 

Anyone have any advice?  Has anyone ever run into this problem before?  (Alan Boehm)

    It is not unheard of for a bit of harder steel or even a foreign material entirely to find its way into a batch of steel and end up in the bar.  It is rare in quality steel but I have had this problem with some imported material.  The good news is that it is probably small and very localized.

    One option is to try a carbide tipped drill or even a carbide end mill but the chances of ending up with a round hole of the proper size for a good fit to the pin are small.

    The dowel pin locations are not critical.  You could abandon this hole and move over a little and try another spot.  If you run into the same problem in a hole for one of the screws, thats a big problem.  (Rick Hodges)

    You didn't tell us how the test hole in the scrape piece of material turned out. It could be localized hardness of the steel, bits also get chipped and stop cutting. On at least one occasion I had the depth stop on the drill press vibrate down during use, and halt production, boy that took some time to find the first time. Quite embarrassing.

    Then again another time I was working on one of the automatic boring machines when it quit turning the boring bits, I had the thing half way apart before I realized that the air supply for the pneumatic controls had been shut off, at least it wasn't expensive to fix. Now I try to look at everything before jumping in.  (Greg Shockley)

      The bit went through the test scrap like butter.  It seems to be a very hard spot in the bar, so I figure I'll move the dowel pin hole an inch, as a couple of folks have suggested.  And I'll also keep my fingers crossed that I can drill the neighboring shoulder bolt holes without a hitch.  (Alan Boehm)

        Have you tried using a Cobalt bit and cutting oil?  (David Dziadosz)


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