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  1. #1
    Pete F is offline Stainless
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    Default Commercial cutting style knurling tool

    A recent couple of editions of the magazine Home Shop Machinist ran articles on making a knurling tool that cuts the knurl rather than forming it by pressure. I'm only familiar with the latter method of making knurls and this is the only tool I have for that process.

    I have no time or interest in making this tool as per the magazine articles but may be interested in buying a relatively cheap cutting style knurling tool to try. Until this article the only other ones I'd seen were, I think, Swiss made and very expensive.

    Is anyone able to provide a source for an inexpensive tool (local outlets here in Oz and Enco up there is the US has yielded only the form style)? I typically have more success from larger organisations in understanding where Australia is ... well unless your name is McMaster who feel exporting a part down here is a "national security risk" so won't do it.

    Also, I wonder what the disadvantages of this method are? As I understand the process it effectively cuts a multiple series of closely spaced threads on the piece and I would think it would be a far superior process to brute force and ignorance, but presume there must be some significant disadvantages for the form style to be more commonly found.

    Thanks.

    Pete

  2. #2
    Mud's Avatar
    Mud
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    Dorian has them, I have not seen one myself.

    dorian

  3. #3
    adama is offline Diamond
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    There was a realy good post around here. Some show off made one the cut a knurle on some skiny thin exhaust pipe. Disadvantage unlike conventional knurling is no increase in diamiter.

  4. #4
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    Quote Originally Posted by Pete F View Post
    A recent couple of editions of the magazine Home Shop Machinist ran articles on making a knurling tool that cuts the knurl rather than forming it by pressure. I'm only familiar with the latter method of making knurls and this is the only tool I have for that process.

    I have no time or interest in making this tool as per the magazine articles but may be interested in buying a relatively cheap cutting style knurling tool to try. Until this article the only other ones I'd seen were, I think, Swiss made and very expensive.

    Is anyone able to provide a source for an inexpensive tool (local outlets here in Oz and Enco up there is the US has yielded only the form style)? I typically have more success from larger organisations in understanding where Australia is ... well unless your name is McMaster who feel exporting a part down here is a "national security risk" so won't do it.

    Also, I wonder what the disadvantages of this method are? As I understand the process it effectively cuts a multiple series of closely spaced threads on the piece and I would think it would be a far superior process to brute force and ignorance, but presume there must be some significant disadvantages for the form style to be more commonly found.

    Thanks.

    Pete
    I've never seen a relatively cheap cut knurl, least expensive one I have seen over here was $1250.
    The are the only way to go fro cnc knurling, pretty much the only disadvantage is cost.

  5. #5
    Pete F is offline Stainless
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    Quote Originally Posted by TonyOW31 View Post
    I've never seen a relatively cheap cut knurl, least expensive one I have seen over here was $1250.
    The are the only way to go fro cnc knurling, pretty much the only disadvantage is cost.
    Cripes, maybe I should have kept that magazine!

    Sorry, I meant to put in my post that it would be used on a small manual lathe.

    As far as not increasing the diameter I would think that's often an advantage but good point, just like cutting threads.

    Why are they so expensive then? I've never seen one in real life but the one in the magazine didn't strike me as particularly fancy, sure as heck not $1250 fancy anyway!!

  6. #6
    David Utidjian's Avatar
    David Utidjian is offline Titanium
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    Pete,

    The one in Home Shop Machinist (March/April 2010 Part 1) is a bit over the top. The author does say he has never actually used a commercial knurl cutter before and only seen pictures of them.

    I have a Hardinge L20A knurl cutter that fits the L18 QCTP. It is MUCH simpler than the one in the HSM article. No bearings and bushings (the knurls rotate on simple shoulder bolts), no height adjustment (that is built in to the QCTP tool holder), no gearing for changing the angle of the cutter axles (just loosen a couple of SHCS and move em).

    Here's mine:
    Attached Thumbnails Attached Thumbnails dscn1713.jpg   dscn1714.jpg   dscn1715.jpg  

  7. #7
    L Vanice is online now Diamond
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    The cheapest cut type diamond knurling tool I know of is the Hardinge C30. I have no idea of the new price from Hardinge. They turn up on eBay for from $50 to $150 final price. They are designed such that they can fit a standard quick-change turning tool holder. I use one in my Swiss 40-position tool holder on my 12" Clausing lathe. I don't use it often enough to claim proficiency with adjusting it. Sometimes I think it is doing more crushing than cutting, but I think it is a matter of adjustment, work diameter and material.

    Here is a NIB Hardinge C30 that sold a few weeks ago for top money.
    BRAND NEW IN BOX HARDINGE C-30 KNURLING TOOL on eBay.ca (item 110485839050 end time 31-Jan-10 17:35:10 EST)

    Here is a link to the Hardinge catalog. The C30 knurling tool is on page 6. There is also a single wheel holder for cutting a straight knurl. Hardinge also makes the same type of knurling tools to fit their own quick change tool post.

    http://www.hardinge.com/usr/PDF/tooling/1318.PDF

    I have also cut thousands of 12L14 steel knurled parts with my Hardinge turret lathe. I used a Brown & Sharpe two wheel knurling tool with a 5/8" shank in the turret. The wheels have sharp edges and do a lot of cutting, as evidenced by the powdery chips in the oil I squirt over the tool to keep the wheels free to turn. The results were fantastic.


    Anyway, if you want a knurl to cut, you have to use sharp edge wheels, feed axially and have a very rigid machine and holder. Those requirements may be more important than the design details of the knurl holder.

    Larry

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    Pete F is offline Stainless
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    Thanks guys sounds like ebay may once again come to the rescue. Yes I did think the design in HSM was a bit "over-engineered" from what I could tell. Maybe appropriate if you're doing thousands of feet of knurls, but not for what I need. I use an AXA toolpost and couldn't see any reason the tool itself needed any ability to adjust to centre. I presumed the knurls were kept sharp simply by lapping the flat face that meets the work?

    So is the reason they're not used more because they need a very rigid setup? In using them is it correct to say you cut the knurl in one pass, so there's no ability to take multiple light cuts on a smaller machine? If so, that could be a show stopper for my little 9" SB.

    Pete

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    L Vanice is online now Diamond
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    One pass is not a problem with leaded brass and fine knurls on a small diameter. It is just a matter of scale, to make the work fit the machine's capabilities. In practice, it is possible to make several passes, but it is more efficient to get the tool set right with a short test cut at the end of the bar and do one pass.

    Larry

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    gr8life is offline Cast Iron
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    David Utidjian
    Your point about no adjustment points to the question that has been on my mind since reading that article in HS Magazine. Why would you need to adjust anything once the cutters are set on center? I do not understand. If the cutters are set to CUT once they are centered the center of any circle remains in the same place. I know I am missing something.
    thanks
    ed

  11. #11
    dp
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    Any time you have a question like this think Frank Ford. I don't know how a luthier gets into so much metal working problem solving as he does, but he does it in spades.

    For instance:

    HomeShopTech

    HomeShopTech

  12. #12
    Pete F is offline Stainless
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    Quote Originally Posted by gr8life View Post
    David Utidjian
    Your point about no adjustment points to the question that has been on my mind since reading that article in HS Magazine. Why would you need to adjust anything once the cutters are set on center? I do not understand. If the cutters are set to CUT once they are centered the center of any circle remains in the same place. I know I am missing something.
    thanks
    ed
    I imagined the angle of the cutters was designed to be adjustable to account for different circumferences so the knurling met itself. Not having ever actually seen one, or even knowing much about them, I can only guess just from looking at it. Am I close

    Frank Ford has a terrific site, I hadn't come across it before, thanks for that. It reminds me how nice it is that people take so much time and effort just to help the next guy out.

    Pete

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    hickstick_10 is offline Stainless
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    agreed ebays your best bet, as there is no cheap version of those knurls (but I imagine there eventually will be)

    I'm not a big fan of guy lautards book series "The Machinist Bedside Reader" but he was a good write up in one edition (i forget which one) on how he made a cutting style knurling tool holder, and just used store bought cutters (there about 40 bucks), it only did coining/straight knurls as far as I remember, but there were dimensioned drawings and everything.

    As far as adjustment is concerned, the dorian ones I've used have an adjustment feature that changes the orientation and spacing between the wheels to suit diameter, as well as verticle adjustment of the head itself. The adjustment is needed so you dont have those damn double cut knurls that look like hell, one setting will not fit all diameters.

    There is FAR less pressure needed to use these knurls, I wouldn't hesitate to use then on a smaller lathe, definitely a better tool then the old style ones.

    One thing I dont like about them is theres far less room for error in setup, both wheels have to be contacting at the same time or else that tool WILL self destruct. Your knurls are also SHARP very sharp.

  14. #14
    Mcgyver is online now Stainless
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    Quote Originally Posted by Pete F View Post
    I imagined the angle of the cutters was designed to be adjustable to account for different circumferences so the knurling met itself.
    No, the rotary adjust of arms the knurlers are on is so that different dia work pieces can be knurled....the position of the arms has to change for the dia of work. The serrations of the knurl wheel have to meet the work at close to a tangent....to much one way and you're not cutting and to much the other and tracking will be poor - resulting helix will look a drunk.

    over engineered? If you've not used a cut knurler, how do you make that judgment?

    over the top? imo its a better tool than the one David displayed in that it is a pita to get the two arms at the right angle because you can't see the bottom one very well. Having them move in concert makes use so much easier. Height adjustment? first off, not everyone has a QCTP, but even if you do, height adjustment there is a bit of a crude affair. I have a drehblitz which is a high end QCTP still its a lot nicer to adjust the head of the knurler without disturbing everything loosening the tool holder and the vertical dovetail is a much finer adjustment. Since the QCTP height adjustment requires it being released, its not conducive to fine tuning adjustments done with the machine running by gently bringing the tool to the work, noticing the pattern, backing off a quarter turn, adjusting height and coming back in, etc.

    Finally, there is always some backlash in gears so when you change the arm positions for a new diameter, its convenient to have a very fine height adjustment....as hickstick says its important to get the adjusted properly and this design makes that finicky task easy....but if a builder disagrees, simple, don't build the height adjustment part.

    I disagree with Larry on rigidity; the cutting knurling tool imposes minimal cutting force...that's why you can do a length of 5/16 steel and deflection isn't a big issue.

    David, maybe being better than the you one have makes it over the top . The style you have is similar to the Mark I which proved to be a pain to set up so a version with the adjustments followed. It's impossible to make everyone happy; if the design was simple, guys would be criticizing it for being a pita to use and not dealing with the tricky parts of a full function cut knurler. This design attempts, and it is sucessfull imo, at providing all the functionality in use of the expensive ones, at least that I've been able to see. There are notes on building a simple version, but imo, it is too much of a pita in use. If you build one, I hope you enjoy it....its engineered just right but that of course is an opinion that obviously varies

  15. #15
    David Utidjian's Avatar
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    Pete F,

    No one has mentioned "scissors" or "clamp" style knurling tools. They are still the pressure type of knurl but they do unload the spindle and the work effectively. Even more so than the cut style knurling tools.
    I use all three types depending on the work I am doing. I prefer the cut type because, so far, it has been so easy to set up.

    The cut style works very well for doing multiple parts. I recently had a job where I was making a couple of dozen banana jacks for some demonstration motors and generators for our physics classes. These were made from 3/8" OD 360 brass. Once I had the tool set on the first part I just noted the cross slide dial reading and for each subsequent part plunged in to the same reading, traversed the carriage, backed off, swapped in the next tool for the next operation. Got it to under 5 minutes per part for all operations. *Hugs his Hardinge L18* But I digress...

    gr8life,
    I find that I have to re-adjust the height for each diameter of work I do. Only takes a few seconds to make sure that both tools contact the work and start turning at the same time.

    Other than the height adjustment I have NO idea how these tools are to be adjusted.

    I have been using this tool for about a year with excellent results every time.

    I just compared how the knurl cutting wheels are oriented to the work at a given setting for different diameter work. The small diameters (3/8"-1/2" or so) appear to bear on the "outside" or rear edge of the wheels. Larger diameter work (1-1/4" and up) appear to bear on the "inside" or forward edge of the wheels. At the given setting of the wheel axle angle it would follow that there is(are) some diameter(s) of work where the wheels would not cut at all but simply press on the work.

    There must be some ideal angle (or small range) for these tools to work most efficiently for a given diameter but I have no idea what that is. I have looked for this information before with no luck. Now that this thread has come up perhaps someone who does know how they are to be set can tell us.

    -DU-

  16. #16
    David Utidjian's Avatar
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    Quote Originally Posted by Mcgyver View Post
    No, the rotary adjust of arms the knurlers are on is so that different dia work pieces can be knurled....the position of the arms has to change for the dia of work. The serrations of the knurl wheel have to meet the work at close to a tangent....to much one way and you're not cutting and to much the other and tracking will be poor - resulting helix will look a drunk.
    I haven't had a "drunk" one yet but I see your point.

    over engineered? If you've not used a cut knurler, how do you make that judgment?

    over the top? imo its a better tool than the one David displayed in that it is a pita to get the two arms at the right angle because you can't see the bottom one very well. Having them move in concert makes use so much easier.
    The Hardinge L20A is the only cut knurler I have ever used and only for about a year. It works very well.

    I see that setting the angle of the cutter axles WRT to the work is important. I also see that the one in HSM makes it pretty easy to keep the angles in sync. What has not been addressed (yet) is what that angle is supposed to be.

    For the HSMer who often is only working in onesy-twoseys the extra adjustments could definitely be an advantage over the Hardinge design which is almost certainly for limited production work.

    Height adjustment? first off, not everyone has a QCTP, but even if you do, height adjustment there is a bit of a crude affair. I have a drehblitz which is a high end QCTP still its a lot nicer to adjust the head of the knurler without disturbing everything loosening the tool holder and the vertical dovetail is a much finer adjustment. Since the QCTP height adjustment requires it being released, its not conducive to fine tuning adjustments done with the machine running by gently bringing the tool to the work, noticing the pattern, backing off a quarter turn, adjusting height and coming back in, etc.
    Whether the height adjustment is done at the tool head (HSM) or at the QCTP makes no difference to me. Whether I flip a clamp lever at the tool head or at the QCTP (about 2 inches away) and twiddle height adjuster screw... the other operations such as touching off on the work are the same. The height adjustment on the Hardinge L series tool holders is via a 1/4-28 set screw. The height adjustment on my own QCTP is 1/4-20, same on my lantern style tool holder (I made a screw adjusting base for my lantern tool post.) If I had the four-way style of tool post that required packing shims for each tool then the height adjustment at the tool head would be a definite advantage.

    Finally, there is always some backlash in gears so when you change the arm positions for a new diameter, its convenient to have a very fine height adjustment....as hickstick says its important to get the adjusted properly and this design makes that finicky task easy....but if a builder disagrees, simple, don't build the height adjustment part.
    Right.

    I disagree with Larry on rigidity; the cutting knurling tool imposes minimal cutting force...that's why you can do a length of 5/16 steel and deflection isn't a big issue.
    As do I. I have little problem using the cut style or scissors/clamp style knurling tool on my light and not-particularly-rigid Rockwell 10" lathe.

    David, maybe being better than the you one have makes it over the top .
    A bit better makes it a bit over the top

    The style you have is similar to the Mark I which proved to be a pain to set up so a version with the adjustments followed.
    I have not been able to reproduce your results yet. Perhaps I have just been lucky and mine just-worked-out-of-the-box. I can see that it will need to have the angles changed on the wheel axles for certain diameters of work, whatever that angle may be. I have not encountered that situation yet in a year of using mine.

    It's impossible to make everyone happy; if the design was simple, guys would be criticizing it for being a pita to use and not dealing with the tricky parts of a full function cut knurler.
    LOL Oh how I agree.

    This design attempts, and it is sucessfull imo, at providing all the functionality in use of the expensive ones, at least that I've been able to see.
    It is a nice design. And after having discussed it with its designer (I think you just outed yourself as the Michael Ward) I can see some of the advantages of your design over the commercial ones I have seen. All the Dorian tools have fixed angles and one just buys different tools for different ranges in diameter. Most all of the Dorian tools do include the height adjustment though.

    Perhaps my "bit over the top" comment was a bit over the top

    There are notes on building a simple version, but imo, it is too much of a pita in use. If you build one, I hope you enjoy it....its engineered just right but that of course is an opinion that obviously varies
    Yes, yes it does

    I may build one yet. I think I will leave out the height adjustment and, still IMO, the over complicated wheel axle arrangement. I will wait for Part II before cutting any metal though.

    In closing.... Michael "Mcgyver" Ward your design and your workmanship are beautiful and (almost) elegant.

    -DU-

  17. #17
    Mcgyver is online now Stainless
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    thanks very much David, I get that anything like that one does is only going to suit some people....just wanted to fill in some context as to why it is the way it is

  18. #18
    Pete F is offline Stainless
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    Thanks guys, however please consider my comments in the context in which they were written ie "Maybe appropriate if you're doing thousands of feet of knurls, but not for what I need." To make that even more clear, the demonstration of knurling a length of rod is probably more knurling, in terms of feet, than I envisage in a considerable time. Who knows however, maybe if I have an easy to use tool I will knurl other than small items, however that hasn't occurred at this point.

    While I have indeed never used this style of tool, there are countless other devices that I have purchased without using where a judgement call on whether the perceived level of engineering is appropriate for the intended task. As I recall in the article the author also hadn't actually seen nor used this type of tool before determining this level of engineering was appropriate for his (and possibly others) intended purpose.

    As far as why I made those comments, I couldn't see any need for the spindles to run in bearings for the amount of use I envisaged. Furthermore, while indeed not everyone has a QCTP, I do. While there are plenty of examples of "bad" engineering, that shouldn't be confused with "inappropriate" engineering, the latter only becoming "bad" if used in the wrong context eg. Man wouldn't be flying if aircraft were designed like battleships; a battleship wouldn't be capable of sea if it were engineered like an aircraft. In isolation, either example could be absolute engineering brilliance, but not if it's used in an inappropriate environment. Given that the design appeared in a HOME SHOP magazine I wonder if I'm the only person to be considering the design under similar circumstances, but anyway hopefully that's put that baby to bed as it's clear it was viewed by some as unintended criticism, which it was, of course, not.

    David, I was interested in this style of tool over the scissor style (notwithstanding the advantages you outlined) as I considered the results of a knurl cut as opposed to formed as looking (to me at least) superior. Maybe I'm just kidding myself, but to me I feel the cut knurls are sharper and more definitely shaped. Then again I have used knurls that were too sharp in practice, so maybe it's not an advantage at all

    While I described the path of the knurls in terms of circumference (as I was picturing the physical knurls themselves as they travelled over the work), of course in practical terms, work diameter is one and the same thing. However I am having a difficult time understanding what you mean by the term "drunken", as that suggests in my mind that the helix of the cut is not at a consistent angle, and if the work is concentric have difficulty in picturing why this would be so. It seems I was partially right in imagining the angle of the cutters needs to be adjusted to account for different sized work, but don't understand the consequences if they are not.

    In the meanwhile I'm not definitely going to ask for my copy of HSM back and save that article

    Pete

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    Quote Originally Posted by Mcgyver View Post
    If you build one, I hope you enjoy it....its engineered just right but that of course is an opinion that obviously varies
    McGyver, I thought your article was one of the best I have read in the last couple of years in HSM. I hope you write some more articles. It is an interesting read, a useful project and a good design.

    -Dave

  20. #20
    David Utidjian's Avatar
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    Pete,

    Far be it from me to guess what it is you need in a knurling tool. I can only speak for myself... so I will

    What I need is a tool that makes perfect knurls, clean crisp, perfect diamond shaped pyramids. There are a few applications where one actually wants a flat topped knurl (a hammer handle might be one.) I don't need to do knurls in feet, typically only an inch or so, more often even less. However, each time I want the knurl to be perfect and I don't want to spend too much time and bother getting the desired results. A good knurl of the right TPI looks good, feels good, and makes the item just that much more functional. I don't mean to say that every hand tool (or tool you put your hand on) should have a sharp knurl or, at times, any knurl. I agree that there are clearly applications where it is the wrong finish to put on a part. I had one of my students make a "crank yanker" (like a big socket) about six months ago so that one can use a cordless drill to crank the knee up and down on the mill. It needed to be held in the had and still spin free and yet have enough grip to push on and pull off easily with oily hands. A knurl on the surface would have been a really bad idea, yet leaving it totally smooth would also not work well. We ended up cutting two 1/4" wide grooves 1/16" deep and spaced 1/4" apart around the circumference. Spins easily in the hand and yet still has good enough grip to push on and pull off of the leadscrew hub.

    Most of what I do is prototype work for the Physics labs at a small college. I don't do production beyond a dozen or two parts and most stuff is onesy-twosey. Much of what I do is small mechanical and electromechanical devices that are used and adjusted by hand. I often make knobs and handles that need to be knurled. Even if for only 1/4" or 1/8" of its length. I have and still use all three styles of knurling tools (pressure, clamp, and cut) to do my work. When I need a knurl in a design I do not hesitate, when I start to make the parts I do not hesitate. I prefer to use the cut style knurler because it is so quick and easy to get a perfect knurl. Just drop it in the QCTP and get it done.

    Many people, especially HSMers, seem to dread knurling. (They also dread single pointing threads for some reason ) Nothing speaks "amateur" louder than a poorly done knurling job... even if all the other features are executed to perfection. Most are fumbling around with the crappy pressure type knurling tool that came with their import QCTP set. Even though with a good set of knurls and properly done a pressure applied knurl can be just as good as any cut knurl. After much frustration the determined ones will buy or make a clamp or scissors style knurling tool and get better results. Because of price and/or availability few move on to using a cut style tool. Until now... a moderately skilled HSMer can now make their own cut knurling tool by simply following Mcgyvers article. The material cost is trivial, the wheels are about $40/pair, and if they have the usual tools (lathe and mill) and tooling they can knock it out in a weekend or two. For a business it makes more sense to just buy the tool (new or used) but for the HSMer their time is their own. All the hard design work is already done for them by Mcgyver. All they have to do is read the articles and follow the directions.

    If you want to easily make perfect knurls on your not so heavy lathe and can't justify buying a cut style knurler then just make the one Mcgyver designed. If there are features you don't like just alter the design to suit your fancy. Once you are done I expect you will have many happy knurling experiences whether you measure it in feet or fractions of an inch. There is no down side to this.

    -DU-

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