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< Home < Tips Area < Tool Building < Planing Forms < Groove Depth
Tomorrow, I am going to build a 6 1/2 foot long planing form for one piece rods, I hope. My friend whom owns the machine shop says he has the soft steel. All I need, are some plans. Does anyone have a n idea on what depth the grove should be on the shallow end and the deep end of the forms. Probably a better way to put it would be, if the rod I was building, had a tip measurement of .070 then form would be set to .035 for final planning. Should I cut forms, so when they are closed together I would be at .030. And for the big end, 1/2 the final measurement minus .005? Or if I have everyone thoroughly confused, where would I get some info explaining how to machine a set of forms? (Jim Christman) I'd highly recommend that you look at the article that Don Schneider wrote and is posted both here and in Power Fibers (I'm not sure which issue). I'm not sure what measurements you'd want to use, but take a look at the article. Even I could figure it out. I made forms using maple, but it will work just as well with metal. It's a lot easier to understand than the Penrose instructions for me. (Todd Talsma) If the smallest tip you will ever make is .070", I would start with .035" at station 0 and end at .115" at station 16. You could start with .030" and end with .110". IMHO one of the most common problems we can create for ourselves is think that some day we will make a very small tip and not cut the groove deep enough for the normal rod. The groove should support at least 2/3 of the strip when planing. If it doesn't, you run the risk of the strip rotating in the groove while planning, especially tips, the measurements & angles of the strips will look OK but when you glue them up you will see a twist in the section. It is common to think the twist is caused by the binder when in fact it was caused by using a shallow groove form. Cut your bar stock to 82" and starting 1" in from the end layout the 17 Stations on 5" centers. Use the procedure in the article to setup and cut the groove which gives you a slope of .001"/inch. (Don Schneider) Don you are so right. Here is a tip that will help to keep the tips from being planed flat if they rotated. If it is noticed that the tip is rotating and the 60* angle is starting to change, Move the tip to a deeper part of the form and taper that area. When it lays in the groove like it should, move the tip up and plane the lower part of the section . Cut off the planing at an angle by sliding the plane off the edge of the strip to where it was planed to fit in the groove. When it looks even, then plane the full length of the strip. If I see the angle starting to flatten out, I sometimes just turn the form over and plane the strip to the larger size groove to get a good taper going then finish the taper on the tip side of the form. This only seems to happen to the tip sections when a wide strip is planed in a real shallow groove. If you have gone too far to where the strip will not go in the groove, plane some of apex off, it will drop in the groove and the 60* angle can be restored. (Tony Spezio) I don't know where all of the "Bit Planes" described in the article are out there. Who ever has them can make the following modification that makes it cut better. Here is the modification: On the sole of the BP starting about 1" in front of the bit cut a sloped slot as wide as the bit back to the face of the bit. The slot should be about 1/4" deep at the face of the bit. This gives a place for the shavings to go other than down between the bars, the bit won't clog up as fast and it cuts smoother. (Don Schneider)
I am in the process of building a set of planing forms, 90 inches long. I am using Penrose's method (tip site). The question is, what depth to start the tip cut and butt cut groove at? Would I also be able to use this same set of forms to make any standard tapers on? What depth of a groove could I cut on the reverse side to make this set of forms more versatile? (Jim Christman) I would think if you started off at either .020, or .025, and then let the groove deepen by .001 per inch, you would have a pretty versatile form for the tip side. Since you would be going from .020 to .110 on the tip side, you could start at say, .090 on the butt side and have a butt end measurement that would be .180. That would give you a pretty versatile set of forms. (Mark Wendt)
I am finishing making a steel planing form using Thomas Penrose's great info and Lawrence Waldron's design. I have a question regarding the groove depths though. It appears that groove depths are commonly prescribed, by Thomas Penrose and others as being around: Tip shallow end - 0.025 inches My question is how would you make a Leonard Catskill taper (referred to by Darryl Hashayida in a mail explaining stress curves) which has a 0.043 tip measurement and 0.265 butt measurement in such a planing form? The grooves would surely be too deep both at tip tip and butt butt. Would it not be better to make the grooves shallower than prescribed above e.g. tip shallow end at 0.020 and merely widen the form to achieve more conventional tapers. (Stephen Dugmore) Good question. Let me take a stab at answering the easy question first. Butt sections smaller than half the butt diameter are no problem, you simply use a different part of the form. Think about the mid section on a three piece rod and you'll see what I mean. I almost never use the widest stations on my form as the final stations for planing. With tips you have a coupla options. As you propose, one can make the forms smaller than is often prescribed but .020" is tiny, barely over one sixty-fourth of an inch. (Okay, one fiftieth of an inch for you math whizzes) As you accidentally shave the forms in final planing, that small groove can wear away in a hurry. Another way to handle this is to change the taper a little. Tips that small are likely to have a little bounce in them, throwing shock waves into the line. Tips at .050 are plenty small for even 1 weight rods. Third, you can do what I have done... Make a set of wooden forms and plane the groove down to the depth you want. When I make my two weight rods, I plane the last few stations in my old wooden forms. Fourth, and I'm not saying you should do this. Heaven knows I NEVER would <g>..... You can plane down the the forms as small as possible, then glue everything together and take the final few thousandths off with a scraper or sandpaper. (Harry Boyd) I made a form just as you and I made my smallest groove .02. I like small rods so I figured I need it and my form is extra long, so it handles the smaller grove with no problem. (Jim Lowe)
I was wondering how important it is to have an even progression in your forms. I presume it's pretty important, considering we're presuming an even progression in the rod from station to station. I'm building new forms and I've severely messed up the tip section. The progression on the left is what I have and the one to the right is what it's supposed to be: .015 .020 I guess I need someone to tell me it's pretty important before I do something stupid and try and it. Presumably I can still fix some of this and come up with something like: .025 .020 Should I try the fix or scrap the project all together? Stations 2 and 3 and 6 and 7 will be pretty messed up but presuming I can cut out the problem dowel pin the others should be OK. Presumably I can slid the rod up and down to avoid the problem spots? (Yes, I've already messed up the butt side, but I can work with that.) (Jim Lowe) My advice for what it is worth is to first fix the problem of the forms not opening/closing smoothly all the way. Once you have the problem fixed, close the forms and take accurate measurement at all stations. Yes, it is important to have a constant slope in the groove. Take your accrual measurement with the forms closed and insert them along with your target dimensions in this spreadsheet. The instruction on the spreadsheet are self explanatory. If one or more of the station setting displays "Red" the larger is how much you need to mill/file off the top surface. Any questions, give me a shout. (Don Schneider) The messed up station was due to an aluminum pin which must have been missed placed at the hardware store. It ballooned up when I tried to close the forms. It had a disagreeable encounter with Mr. Dremel this morning and all is fine. I've been able to work out the most of the stations so that it will be OK. One thing I noticed this morning is the tip on my dial indicator keeps unscrewing. This apparently happened when I measured station 7. (Thank goodness.) It actually measured out at .49. It looks like I'll be able to go from .25 to .85 with only one station being a problem. Thanks to those that reminded me that I can simply file down to make the groove smaller. (Jim Lowe) If you can come up with a way to take .05-.010 off the surface of each side, then you can re-cut the groove. I did something similar when I made my first set and took them to a local machinist who said he could take an even amount off and leave them smooth and flat. Needless to say, he made a royal mess of them. I have a Porter Cable door planer with a spiral carbide cutter in it and I set it for the finest cut I could take and in 3 passes had them back to workable. Don't try this with a regular power plane with straight high speed steel cutters, you will ruin them in the first couple of inches, only attempt this with the spiral carbide cutters, you might find one at a rental place, but don't tell them you are going to plane steel with them. (John Channer) If need be, I was going to just take it off with a file. Fortunately I won't have to. Everything has worked out fine, the stations are off by .002 but they are all consistently small, so I go from .023 to something like .087. (Jim Lowe) .002 is nothing. If you've got the top flat and the angles 60d on all sides you're set. That's the important thing. I'd hate to think you couldn't adjust them to the final .002". (Terry Kirkpatrick) Like you, I was having a heck of a time being consistent in the graduation of my forms. I made mine out of oak and the grain was rough. What I ended up doing was resurface the forms so that I had something to work with. Then, I got an angle gauge and set the table saw at 30 degrees. I then cut a vee groove on the edge of a piece of 4x10 hardwood. I cut 2" off of each end, wrapped a piece of sand paper around the block and sanded the groove in the form. Because of the long cutting edge I was sanding only the high spots. The forms came out perfectly graduated .0001 per in. I don't know whether something like this would help or not. (Larry Downey)
I am working on my metal forms and have a few questions. What size should I make the tip of the tip side? .025 or should I try for less? I like 2-4 wt rods and would like to be able to make light stuff without using the very end of the forms. Is this feasible? Also, should I keep the set screws and bolts on the same side for each side of the form? IOW, should I reverse ends when I flip the form over? Does this make setup any easier or does it matter? (Barry Janzen) I'd shoot for .020" on the tip side of your forms at the smallest station. That way when (not if) you overcut, maybe they'll wind up .025" :-) And I would make the big end of both the butt and the tip side the same end. That way you can use the butt side for knocking the bulk of the material away on tips without having to reset the taper. As for whether both bolts should be on the same side, well, there are proponents of each. I've never tried a form with both adjustments on the same side, but can see some advantages and disadvantages. For one disadvantage, the wrenches used to adjust the form will inevitably crash into each other as they work back and forth. (Harry Boyd) Well, my forms have all the bolts on the front as I plane from right to left. That's easier than having them on the back for one half of the planing/adjusting. If you're left handed, you'll want to reverse this. It's better to plane from butt end toward the tip, especially on the tip section. Trying to plane toward the butt on the tip section can cause considerable weeping and wailing as the plane snags, lifts the strip out of the form and breaks it. Of course, if you always have the plane iron razor sharp, I don't suppose this is a problem. (Neil Savage) All the bolts are on the front? Whether planing tips or butts? Hmmm, guess that means the wider gap is at opposite ends for butts and tips, huh? (Harry Boyd) Yes. I bought them, so no choice, but it's handy and if I were making a set I'd do it that way again. Sure beats reaching over to adjust them, especially if you use Tim Abbott's method which requires repeated adjustments. Just flip the forms end for end when going from butts to tips. You can still use the butt side to knock down the tip strips, it isn't a problem. (Neil Savage)
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