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Rule

Quick question for you accuracy types.  Since I am waiting to receive my 60 degree points for my depth indicator, I thought I would try the drill rod method to see how far over I went on the tip side.  Tried three drill bits and came up with three different depths (all within 1 hundredth).  Smallest gave the smallest depth and largest gave the largest.  Any ideas?  (Jason Swan)

    The rod needs to be about 1/2 the depth of the groove you are trying to measure I think.  There was a discussion on this a while back, you might search the archives.  Three measurements within 1/100th of an inch is not what you are after, you need to get down to 1/1000ths.

    What size rods are you using and what is the estimated size of the groove?  (Kurt Clement)

      I assume you meant .001, not .01. What the differing measurements are telling you is that your angle may be a bit off, assuming your measurements of the drill rods and the heights above the form are accurate. Use short lengths of rod, to make sure you are measuring a specific spot. Make sure there are no burrs on the ends of the rod. Finally, plane a short section of cane and check the angle you get. If necessary, carefully file the groove to correct the error. (Make sure the file is 60 degrees)  (Tom Smithwick)

        I did the tip side first, and found that my measurements on the first station (using three sizes of drill bits from small to large): .041", .049" and .054".  So, I figure that I have room to make that my butt section side.  If I can get it consistent.  I was hoping the depths would be closer to my target .025", but I still haven't gotten far enough on the other side to take any metal off the tip end.

        I used a mill bit plane, and I conscientiously shaved the forms as opposed to trying to hog the stuff off.  I reset the bit at each station, then as I got closer to removing metal from the tip side of the form I reset the tool bit every half station.  I was running the tool so that I would get some resistance for the first two or three passes then smooth for another five just to make sure I didn't have any high spots.  I touched the whole thing up with a triangular file.  I suppose the file might have messed the groove up, but I only took maybe 6 or 8 light passes with it, and I wasn't removing much.

        What would be the best way to try and shore up the groove?  I was using a triangular file, and I have a Starrett 60 degree check that says it is OK. Any tips?  (Jason Swan)

          I used a triangle India oil stone, inletted into a block, to smooth the groove. Use oil with the stone.  (Martin-Darrell)

          Ditch the drill rods, close the forms completely and plane a full length strip of something, bamboo, pine, maple, it doesn't matter. Actually, pine or maple might be better because there won't be any kinky nodes to mess you up. When you get your test strip absolutely flush to the forms (plane, scrape and sand if necessary), then mark and measure it at every station, then you will know for sure what you have done. Yes, I know it is not at all scientific, but it is a real-world test for the real world. I imagine that you are using your dial caliper to check the actual size of the drill rods you are using, so why not just check a strip with the same instrument, it is what you will be doing your final measuring with after all. OK drill rodders, flame away.  (John Channer)

            Great idea John!  No variables of drill rod size or calculation errors.  I would think that maple might be best because it would be harder and less likely to crush when measuring the strip.   Any fine grained hardwood (cherry, walnut, poplar, basswood) would be better than pine which would still work.

            I still like drill rods for setting the form though....(Kurt Clement)

              To each their own. Math makes my head hurt (even with a calculator), so I avoid it whenever possible. (John Channer)

                I've been using test strips in this manner for many years and find they work great. I use cane test strips rather than other woods because the results are directly applicable to what I do for planing my ugly rods.  (Bill Fink)

      I don't believe you are that far off. I think you are using drill rod that is way too big. The drill rod must touch the inside of the groove, not sit on top of it. Grind a section out of a needle or pin of about .025 diameter and see what you get.  (Tom Smithwick)

    Are you sure you are getting your caliper flat on the bottom of the forms?  Also, are you making the comparison measurements in exactly the same place on your forms?  (Mark Wendt)

Rule

I am using drill rods and a depth gauge to set the station depths on my quad forms and was wondering which way I will get greater accuracy:

1) using the  absolute smallest  drill rod  possible for  each station, i.e., one that would minimally extend above the forms, like 1-2 thousandths.

2) or use different drill rods for each station that extends about the same amount each station. i.e. drill rods that would always extend 25 thousandths over the form

3) or use a large drill rod that minimally fits in the groove yielding a large amount extended above the forms.

My belief is that 3 would be the least accurate and unacceptable and that 1 would be the most accurate.

The reason I asked the question is because at some stations I was getting different depth readings (2-3 thousandths) using two different diameter drill rods.  I would have expected them to be much closer.

I'd appreciate any input.  (Bob Williams)

    It should not make a difference if you use large or small rods, as long as the sides of the rods contact the sides of the groove. A rod so large it sits on the groove won't work. First be sure that the rods are truly round. I hope they aren't, because the next most likely explanation for the variance is that the angles of your form are wrong.

    You might also try using very short pieces of rod, or precision ground steel balls.  (Tom Smithwick)

Rule

A while back there was a thread about setting planing forms. I don't have a depth gauge yet and was wondering if there was any method for setting planing forms for final taper without one. I think something was mentioned during that thread about using a drill rod (whatever that is), but didn't catch if that was for rough taper or finish taper.  I have every thing ready for my 1st rod (finally) and I'm getting antsy. Also any info on purchasing DIGITAL depth gauge would be appreciated.  (Will Price)

    If you have your calipers already, you have a pretty effective depth gauge built in.  The length of the thin tail piece that extends out when you open the jaws of the caliper is exactly the reading that shows on the dial.  The only problem is that it doesn't have a 60 degree point on the end. 

    You can easily get around that by using your center gauge.  Measure the length of your center gauge with your caliper, then stand the center gauge vertically in your planing form with the 60 degree point in the groove.  Then using that tailpiece, measure the height of center gauge above the face of the forms, and subtract that measurement from the length of the center gauge.  The difference will be the depth of the planing form groove.

    Now, having said all that, I can say, you don't have to worry about setting  your  forms  at  all.  Just  use  them  as  a  set nonadjustable forms - like your roughing form.  Just lay the roughed out strip on your form and take a few passes with the plane.  Pick up the strip and mic (measure) it, take a few more passes with the plane and measure again.  As you get closer to the final measurements just mic more often.  Take a roughed out strip and give it try.

    Adjustable forms will save you some time, but you can certainly make perfectly acceptable, and accurate rods without them.  The most important thing at this point is:

            JUST PUT THE PLANE TO THE CANE

    and don't worry so much -  your first rod is going fish like a dream!  (Mike Biondo)

    There are a lot of ways to set the form without a depth guage And although I do use one, I still do not trust it.  Garrison gave a great way of doing it.  You take this very precise digital machine God put on the ends of your arms and use your fingers to detect slight differences in a planed strip set  in the planing form.  Then with a micrometer or caliper you measure the strip at that point.  It is as accurate as almost anything I know of.  I never could figure out the drill bit way, but then I am not very smart and I will always take the easiest way of doing things.  (Ralph Moon)

    The drill rod method is, without question, the most accurate method for setting a planing form. Drill rods are blank drill bits and are available at most tool shops. If you can't find them, use the unground end of a drill bit. Five drill rods sized from 1/32" to 5/32" will handle most rods from 6 to 9 feet in length. Check the diameter of the drill rods with a micrometer for accuracy and use one that fits most of the way into the V-groove. The dial indicator reading = half-diameter minus 1.5 times the drill rod diameter.  (Ron Grantham)

      Do the drill rod thing like Ron suggested.  There's another cool thing you can do with that method that will be helpful if you're using a new set of forms.  You can verify that the bevel in your forms is a true 60 by doing the drill rod calculation with two different size rods in the same location (don't assume they're true because they're new).  If they're a true 60, you'll get the same depth with both rods.  I'd check the bevel at each station on a new set of forms.  If they're not true - well, that's another subject.

      I don't check every station when I'm setting my forms, but I do set a couple stations with the drill rod before setting the forms for another rod.  Then I double check the calibration of my depth gauge at those stations, reset it if necessary and use the depth gauge to set the rest of the stations.  I know that sounds like overkill but it only takes a few minutes to set the first couple stations.  Setting a couple stations with a drill rod will also save you the cost of a "standard" if you could actually find one at a reasonable price that will accurately calibrate your depth gauge.  A couple drill rods will be much less expensive and more accurate.

      Here's a sample of the calculation I use:

      (Drill Rod Diameter .123) X 1.5 = .1845

      (Form Depth with Drill Rod .799) - (Form Depth .745) = (Drill Rod above Form .054)

      Bevel Depth = .1845 - .054 = .1305

      I think that's the same as Ron's calculations.  I just get there in baby steps.  (David Bolin)

        Never have understood why you supporters of the drill rod method of adjusting forms think it is so accurate. It just doesn't make since. Now that your hackles are up, let me tell you why.

        First of all; When you setup a taper in the forms the path from one end of the form to the other is not a straight line unless you are doing a straight taper. I will admit that the drill rod method will work as well as any other method on a straight taper.

        Second; most tapers are not straight tapers. Meaning there is a change of direction at each forms station, meaning you are no longer looking at a straight line over three stations, The groove at the between middle station is curved.

        Third; As far as I know, drill rod is straight and not flexible. So, there is no way a straight non-flexible drill rod can sit in a curved grooved station making full contact it's full length. As an extreme example: Tell me a straight drill rod will make contact it's entire length in a 90° change of direction in the groove or anything less than 90° for that matter. Impossible. Thus your depth measurement is less than actual. This is accurate?

        Fourth; You have the hassle and error possibilities of measuring the drill roll diameter and height above the form plus math..

        On the other hand; A properly calibrated DI with a 60° point will measure the depth of the groove at a precise point. The 60° point only makes contact with the form at the tangent of the curved surface of the sides of the point.  No math required.

        As far as a standard is concerned; A Dial Caliper set at .1155" is all the standard you need. A DI with a 60° point set in the gap of the DC should read .100"

        Am I missing something?  (Don Schneider)

          I switched to the drill rod method when I discovered that both of the expensive 60 degree points that I'd purchased from a well respected purveyor of rod making stuff were in fact more like 61.5 degrees.  If I couldn't get good stuff from these folks, then I had to wonder if it was really available at all.  (Bill Benham)

            Well, all I can say is, my 60 degree point matches the 60 degrees in my Starrett screw gauge as nearly as the eye can detect holding it up to a light.  Also, it's wide enough to set the caliper to .231" and double check the setting from the .1155".  The only problem I've had is I sometimes don't get the  base set flat on the caliper jaws.  (Neil Savage)

              I use Starrett 60° points, they are hardened and accurate. I've got into the habit of picking up the DI, Base and Point and moving it to the next station instead of sliding the point in the groove to the next station. Seems to me Points will last longer that way. Just a thought.  (Don Schneider)

              I had a reamer ground to .1155 and have made a couple of .1155 standards. That is what I use now for setting my depth gauge. It is a flat tool steel plate with the .1155 hole in it. The hole is drilled then reamed on my milling machine so I got a true .1155. This keeps me from setting the calipers each time I want to zero my gauge and gives me a flat surface for the base.  (Tony Spezio)

              "...The only problem I've had is I sometimes don't get the base set flat on the caliper jaws.  Neil Savage"

              And thus is the primary problem I have with using calipers to set my depth indicator.  The base to set your depth indicator on  (i.e. on the caliper “fingers”) is pretty small and I never feel as though I'm 100% flush.

              So method #278 1/2:

              I'll set my forms using a depth indicator "zeroed out" on a flat piece of glass (I believe that the glass is soft enough to not bend the 60 degree point on my depth indicator).  Then I'll re-calibrate the depth indicator using a combination of a standard (a flat chunk of aluminum with a fairly precise .1155" hole drilled in it) and/or the calipers method.  Measuring the forms again, I get pretty close readings between the three methods. 

              I want my forms to be as close to the measurement I desire as I can set them.  But when I get the final passes with the plane, I do a lot of measuring and can slide my strip up or down the form to get that fine tuning of the final strip. 

              By the way, I LOVE the saying that was written here last week:  Put the Plane to the Cane.  (Scott Turner)

                I don't trust math, standards, or voodoo.  I use a standard to set the dial depth gauge.  Set the forms to 1/2 the flat to flat measurement plus .003".  Plane strip one down to the metal from end to end.  Adjust the forms as necessary after carefully measuring strip one, then plane again.  From that point forward the strips are on the mark.  (Harry Boyd)

                  As an aside to all this, several years ago John Bokstrom did a test at Corbett Lake. He took ten strips of bamboo, each marked with a felt pen at certain locations, and three measuring devices: a standard digital micrometer, a Mitutoyo hand-held dial indicator with 60-degree anvil, and a Bill Waara-type digital caliper. Many attendees were asked to measure each marked strip with each of the three gauges. Not surprisingly, the results varied widely.

                  Which brings me to the point: it ain't what you got, but how you use it.  (Ron Grantham)

                  I'll admit to belonging to the Harry school of form setting, but I haven't quite gradiated yet. I just zero my indicator on the top of the steel form, as I have done with the same point for the last 53 rods, set the forms .002 shallow to allow for the groove in my plane and a bit of Epon between the strips and then plane and measure the first strip. If it comes out as hoped, I continue with the rest of the strips, otherwise, nudge the settings, plane and measure again. So far, I've never had to do a third adjustment. DISCLAIMER!!!!!!! This works for me, I'm not as hard to please as some, so it may not work for you. I think if I were making graphite rods with predictable material, I might get a bit more retentive  about the whole thing.  (John Channer)

                  While we're on the subject, other than the drill rod method, is there any other reasonably accurate way to verify that the bevel in a form is a true 60?  Just curious.  I thought my home made forms were out of whack until I checked them with a couple drill rods.  They're reasonably true so I had no choice but to declare the plane defective.  I'm sure it has nothing to do with my planing skills.  (David Bolin)

                  Harry has given us the final word on this. No matter what method you use the final thing you must do is to as Harry says "adjust the forms as necessary" Has anyone out there set his forms and not had to "adjust the forms as necessary"?   (Dave Norling)

                    Dave, I never had that happen!

                    I can set the forms by whatever method, and they ALWAYS require some tweaking in the process of finishing the first strip.

                    However, in defense of the accuracy of the method as a general principal in rod building, once the first strip is produced, albeit with a lot of check-measuring and form calibrating and tweaking, you can just let 'er rip and run all the other strips.

                    I have often wondered, so perhaps someone can tell us at this point - do those who use Morgan Hand Mills also have to do this "Adjust as necessary" thing?  (Peter McKean)

                      Yep!  (Winston Binney)

                      With the MHM, You don’t raise the bridge, you lower the river!  Since you are lowering the cutting blade on the plane, as long as the taper measurements are set correctly, it’s a matter of taking off cane until you are at the measurement you want.

                      The method I was shown on the MHM, was to get all the within a couple of thousandths – short, then take one final pass on each strip to bring it down to the final measurement.  So for good or bad, each strip is (in theory) essentially the same as the others.    (Scott Turner)

                      Yes and no. With the MHM you set the relative changes in the taper - the thickest part of the strip is zero and the thinner parts are lifted up by half the diameter measurement by a plastic taper rail called an anvil by Tom Morgan. The planing unit runs across the strip in a straight flat line cutting both sides of the apex at the same time. So generally you just plane away until you get the correct measurement on your strip, note the setting on your planing unit, and for the rest of the strips you plane until you you reach the same setting. The "no" part is unless you do something to the plastic anvil - flattening it or replacing it - the same setting of the planing unit applies all the time from then on, so you can set your taper and plane until the same setting shows on the planing unit and your strip will be just about perfect.  (Darryl Hayashida)

        The easiest way I’ve found is to set the Calipers to .1155.  Put the point in the .1155 opening with the block flush on the caliper and zero the gauge. All readings will be direct readings. On 60 degrees, .1155 is the width at .1000 up a 60 degree triangle.

        No calculations need to be made.  (Tony Spezio)

          You are missing something.

          1.  With a 60 degree point you are making the assumption the point and groove is exactly 60 degrees. Not likely.

          2.  With your dial calipers set to 0.1155 you are not likely to set them exact. Also, the contacting edge of the calipers must be exactly 90 degrees.  Again not likely. If there is any wear on the corners of your calipers your  off.

          Yes using pins takes a bit of math, it is more accurate than the calipers.  If the 60 degree point were so good, we would not calibrate thread gauges with wires. After a career that included 25 years in metrology, my pick is to measure over pins or wires.  (Jerry Drake)

            You are missing something.

            1.  With a 60 degree point you are making the assumption the point and grove is exactly 60 degrees. Not likely.

            Unless the forms are completely closed, you are not using the point to the DG, you are using the sides.  If the groove is not 60 degrees, the drill rod measurement is likely to be off too.

            2. With your dial calipers set to 0.1155 you are not likely to set them exact. Also, the contacting edge of the calipers must be exactly 90 degrees. Again not likely. If there is any wear on the corners of your calipers your off.

            As long as your DG base is sitting flush with the flats of the calipers, how would that not be likely?  You can also slide the DG point in and out on the mouth of the caliper blades.

            Yes using pins takes a bit of math, it is more accurate than the calipers. If the 60 degree point were so good, we would not calibrate thread gauges with wires. After a career that included 25 years in metrology, my pick is to measure over pins or wires.

            Ah, but threads, unless you are cutting pipe threads, are not tapered.  They "should" have the same major and minor diameters the entire length of the thread, no?  Therefore, the entire thread gauge wire is nestled in the thread, and not sticking up or down into the groove.  (Mark Wendt)

              It's been almost 50 years since I took geometry and trig has clouded my mind. I had mixed up the calculation for sine and tangent.

              The correct formula is as follows:

              (r - r tan(30)) / tan(30) where r is the radius of the pins.

              Here is a link to an Excel spreadsheet that shows the geometry and trig and a way to calculate depth for any size pins.  (Jerry Drake)

                If you massage that equation a little more, the expression will reduce to Depth = r x (sqrt3 - 1) or 0.732 x r, which is a little friendlier to work with.  (Ralph MacKenzie)

                  Some further thoughts  -  Diameters would be more convenient to work with in terms of drill rods and such, so make that relationship:      Depth = 0.366 * diameter of rods used,  and it is a little more useful, I think.

                  i.e. if you used two .250" rods, the point should be calibrated as sitting .250" x .366 = .0915" deep.  (Ralph MacKenzie)

                  Looks to me as if .005"  dowels (drill rod) would be the easiest to use for setting.  That gives a depth of .183013", no messing with .0005" on the D.I.  (Neil Savage)

            OK so what your saying no process is 100%, neither is mother nature.  So since we're using mother natures creation (BAMBOO) try not to sweat the .00000000001 difference in your forms and make a rod, use your head. Use what is the easiest and adjust for mistakes. Practice makes almost  perfect. Hell the first rod I made ..I did the taper by eye! Oh yea and a few adult beverages. The rod casts 40 yards. Put the plane to the cane!!!!!!!!  (Bill Tagye)

    I don't know what your budget is but you can get a depth gauge for about 20 bucks and the base from Golden Witch for 45 bucks and a point for 16.  (Bill Tagye)

    If you are in need of a loner, I have a Bellinger gauge and base. I would be willing to let you borrow it until you can get yourself one. The only thing you'll need is a standard. (and it's not required, just something to save the point on the 60 degree) Hope those forms work out for you, they got me through a few rods.  (Robert Hicks)

    The digital depth gauge prices are much lower now. Harbor Freight flyer (not on web) has one for $30, and Lee Valley has one for $38.50. The Lee Valley digital gauge (1/2" travel) appears to allow .0001 depth, though claims .001 accuracy, which is good enough. They also have a 1" travel version.  (Paul Franklyn)

    I make rods in all geometry’s between hex and trirods. It's reasonable that a hex-pointed depth gauge may be of help in setting a planing form for hex construction. But what about penta and quad? I learned long ago that cane test strips work well for all geometry’s, including hex. I never bother with depth gauges.  (Bill Fink)

Rule

Anyone out there using the drill rod/depth gauge method (like in George Barnes' book) to measure the groove when setting your forms?  If so, you might find this interesting. 

I switched to this method a coupla years ago,  after I got some bad, purpose made 60 degree (actually 61 1/2) points from a high end seller of rodmaking stuff.  I figured if they could screw them up, then I'd be better off looking for something more foolproof.  The drill rod method seemed to be working pretty well, though I had occasional problems with the settings seeming to drift - I'd set all stations, go back  and  recheck  them  and  some  would  be .001-.002 off.  I just chalked that up to the forms "settling" after being set.  Last night I was setting the final taper for the butt section on a 3 piece 7 footer.  The taper was such that I was only using one rod, a 2" piece of 3/32".  The problem with the setting changing was much worse than experienced before.  I couldn't seem to set the station and have it stay set.  It would seem to drift a thousandth or two one way or the other when rechecked.  After an hour of that crap, I pulled up my moaning chair and started to think about what was happening.  I took my micrometer and measured the rod.  It tapered slightly, less that a thousandth over it's length.  So if I used both ends of the rod on a station, I'd get different measurements.  Another little test showed that the depth measurement would change as I rolled the rod.  I can only conclude that the rod's not perfectly round or not perfectly straight.  As I moved the rod from station to station, the rod would be oriented differently.  It'd roll a little, or I'd measure off a different place on the length of the rod, or a different end.  The result was inconsistent measurements.  The fix was pretty simple, I put a black dot on the rod with a marker, and then made sure that dot was centered on the station and oriented up.  Surprise, surprise, the problem went away.  So much for foolproof.  Probably what I get for using cheapy Chinese drill rod.  Does make me wonder what the level of precision is like for drill rod, overall.     (Bill Benham)

    With apologies to any metrologists we might have hanging about...

    Typical tolerances for 1/8 rod are .0005" for the diameter and .005 per foot for length. For a two inch piece, that would represent approximately .0008 if the error happened to be linear.

    Add in the tolerance of your calipers (typically plus/minus .001) and it is easy to see that things can easily vary a thou or two in either direction, depending on individual circumstances, and that is without quality issues, Mr. Murphy, etc.

    Remember too that you are  bending your forms between stations, and then introducing a straight piece of steel into the resulting arc.

    The answer, of course, is to do things one way, all the time, and know the results you obtain with your tools and methods.

    Open any industrial supply catalog. You will typically see 3 price ranges; Made where quality is important, Quality Imports, and Imports. TANSTAAFL  (Larry Blan)

    Good suggestion.  I'm going to do mine as suggested.  FWIW, I modified my form setting procedure to include both the drill rod and depth gauge method.  It was taking to long to use the drill rod on every station and I was getting the differences you observed probably for the same reasons.  Also, I'm not comfortable with the accuracy of the depth gauge alone.  So, I set one station with the drill rod.  Reset the depth gauge at that station using the form as the standard.  And then use the depth gauge to set all the other stations.  I go back and check every station with the depth gauge one more time and then check one station with the drill rod on the opposite end of the form.  That's probably overkill, but I get consistent results every time.  It only takes a few extra minutes to start and finish with the drill rod.  (David Bolin)

    I think using a round rod is a great method, particularly for the four and five strip guys. To add a little accuracy, I would like to suggest the use of plug gauges. The gauges or standards are available from McMaster-Carr or equal in just about any size for the same price as a chunk of drill rod but have much tighter tolerances.

    If anyone would like to try this method, I have graphs for 4, 5 and 6 strip rods with all the indicator readings. I would be happy to e-mail copies out to those who could use them.  (Kevin Callaway)

      To add a little accuracy, I would like to suggest the use of plug gauges.

      I'm going see if MSC has these in the sizes I use.

      If anyone would like to try this method, I have graphs for 4, 5 and 6 strip rods with all the indicator readings. I would be happy to e-mail copies out to those who could use them.

      Also, I'd be willing to share a spreadsheet I developed for using the drill rod method.  You just plug in the rod dimensions, any deduction for varnish, and the sheet computes the strip height, correct size rod to use, and what the measurement is supposed to (the rod sticking up above the form) at each station.  It's got rough taper (+.025") for prior to heat treating, and final taper.  It really speeds up form setting when using this method.  (Bill Benham)

Rule

Just a question how many of you guys set the forms with the Depth micrometer and drill bits as opposed to the dial and 60 degree point method.  Do you find any more accuracy with this method?  I set my dial and point in a setting block to 100 thousandths this over comes the lack of accuracy when the point is lost.  Can I expect more accurate results buy changing over?  (Gary Nicholson)

    I use a 60° point and a standard.  I suspect that if you're reasonably careful with setting the dial you won't be able to tell the difference in a finished rod.  Remember, if you mic a "classic" rod you will most likely find variances from flat to flat at the same station.  Unless you have access to a makers intended taper, any rod you make from someone's measured taper is going to be a "best guess" or average of the flat-flat measurements.  The few old rods I have mic'd have had several thousandths difference, in a couple of cases as much as 0.010".  (Neil Savage)

      Yes Neil.  It's amazing how inaccurate the old classics are, someone said Garrisons were as much as 8 thousandths different from flat to flat.  (Gary Nicholson)

      I have a method I've never heard discussed before. It's given me the most accurate results I've ever had, and it's E-Z!

      I set all the stations, quickly, with the dial indicator. I don't obsess about their accuracy. I then drop a strip into the form so it's "set back" 15". That is, The place that SHOULD be at 0" is at the 15" position. I draw lines on the cane at every 5" for repeatable places to mic.

      I plane that strip as if I were making the final job, then I mic the stations on the rod. If any are off from their temporary stations (some usually are), I use the dial indicator to change the setting only by the amount a station is off - in other words, if the station is +.002, I place in the indicator and lower the setting .002. After doing all of them,  I slide that strip up 5" (so the 0 of the strip is at the 10" station) and redo it. I remeasure it and if all the stations are now "on", I do a second strip to see if they agree. If they do I check the new top station's setting on the first strip and repeat the above if necessary. If that needs change, I change it, do a third strip so that it's set back 5" from the end  (0) position. I redo all three.

      When they match, I slide up to the final positon, do the first strip, check with a second strip, and then do the third. I now have the CANE at exactly the dimensions I want - NOT the form!, and I also have three strips done.

      The only place you have to be reasonably accurate on its first try is the 0" one, as if you come in under, that strip will be under forever, or ruined, as you deem it. I therefore set the true 0" setting predictably large and sneak DOWN on it from above.

      It goes surprisingly fast and accounts for any irregularities in your forms and your planing, AND it gives you half the strips of a section by the time your forms are  set.  (Art Port)

        I do something quite similar.  I carefully set each station .003" oversized., then plane down to the forms.  I measure the first strip and readjust as necessary.  Succeeding strips come out right.  (Harry Boyd)

          Art and Harry, these are great practical ideas. I usually plane a couple of strips for the tip section to test the form settings for the butt section. In addition to getting the forms set right, it's good practice, especially if you haven't planed for a while.  (Tom Bowden)

        When Art put this method up a few weeks ago I thought it sounded fairly easy and also very logical.

        I tried it today, and it is very easy and logical. It also showed that my usual method of setting forms was not giving me the correct result and explained a "weak tip" in a recent rod I had made!

        Thanks for the suggestion Art , and I would really recommend  to anyone this as an accurate way to set forms.  (Ian Kearney)

    I use a combination of both methods.  I'll use a drill rod and my calipers to calculate the depth of my forms at two random locations.  Then I set my depth gauge to the calculated depth at one of the two locations.  Move it to the other location and make sure I get the previously calculated depth with the depth gauge.  Effectively, I use the forms as a standard.  I then proceed to set all the stations with the depth gauge.  (David Bolin)

Rule

Could I get the formula and method for using a drill rod and digital caliper to set my form?  I know I’ve seen it on the web somewhere but I’m not having any luck finding it this morning.  (Mike Monsos)

    The depth of a 60-degree V groove is equal to 1.5 times the drill rod diameter. Your dial indicator reading would be (Rod Diameter/2)-(Drill Size x 1.5)  (Ron Grantham)

Rule

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