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IndustryArena Forum > MetalWorking Machines > Tormach Personal CNC Mill > Spiral Fluting A 17" Rifle Barrel With 4th Axiz
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  1. #1
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    Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I have the 4th axis unit for my Tormach 770 but I haven't used it in about four years. The last time I used it was to make some reamers but that was only cutting straight lines in the X-axis. I have a rifle re-barreling project that I'd like to use my 4th axis for cutting those spiral flutes but for the last few nights I've been unable to figure out how to set it up in SprutCam. I'm still using Version-7 of this CAM software so many of you guys have probably moved on to newer versions.

    This request for guidance is mainly for those of you who still use this older version of SprutCam. I've watched several YouTube videos on the subject but being that I'm dyslexic when it comes to learning this kind of stuff I was hoping for some pointers from you more advanced Tormach/SprutCam machinists. If I were cutting barrel flutes in a straight line in the Z-axis I think I'd already have this project done but being that I decided to get a bit fancy with this re-barreling/re-chambering project, the spiral flutes have brought this particular project to a stand still.

    The tutorial vids I alluded to all seem to be coming at this subject from a few different ways. Some of them use the engraving method, others use 2D or 3D contouring and still other show the use of 5D machining. My mistake may have been watching to many of these videos because right now I'm suffering from information overload. I'm not really sure which method to use. I'm thinking as long as I can get one method to work I don't really care which of these machining methods I use but, I'm looking for maximum simplicity. I don't know if that's even possible.

    The barrel in question isn't tapered. It's just a seventeen inch long straight 1.062" diameter bull barrel. The reason I'm asking here instead of the SprutCam Forum is because the folks that inquire there are usually no more knowledgeable than I am. I'm sure there are some pretty sharp SprutCam users here too so, here I am. A little help please. If I can't turn up some good info here I'll probably go ahead and post in the SprutCam page of this forum as well.

    MetalShavings

  2. #2
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    Feb 2014
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    6

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I’m interested in doing this too. I’m still in the middle of installing my 1100, but this is high on my priority list of things to experiment with.


    Sent from my iPad using Tapatalk

  3. #3

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I've done it but it has bee a while. I can go back and look to see if I can dig it up and see what I did.
    RAD. Yes those are my initials. Idea, design, build, use. It never ends.
    PCNC1100 Series II, w/S3 upgrade, PDB, ATC & 4th's, PCNC1100 Series II, 4th

  4. #4
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    664

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    write it by hand

    G0 Z5
    G0 X0 Y0 A0
    Z1
    G1 Z.5
    X10.0 A360 F15
    Z1
    G0 Z5
    X0 Y0

    this would give you 360 degree spiral in 10 inch

    just change "A" start to index and add the amount of degrees of spiral you want for "A" end , "A" start + spiral degrees = "A" end

  5. #5
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    Apr 2013
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    1788

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Adding "G92A0" to the beginning of the program from holbieone will set the initial angle to zero (regardless of the state of the 4th axis) and avoid having to "unwind" your rotary back to zero after each pass.

  6. #6
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    458

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I know that you guys who have taken the time to post a reply all know what you're talking about but one of the reasons I use SprutCam is because this software is my work around for not knowing how to manually write G-code. When I look at code like the code that holbieone was nice enough to post, it's like trying to interpret Egyptian hieroglyphs. I can't read those either.

    R.Desjardin; taking a look at how you were able to do the project you mentioned would be helpful. In the past when I've run into problems figuring out how to use SprutCam for certain milling operations I've watched YouTube videos on the subject. From those vid I've been able to eventually figure it out. Not this time; this time there are to many vids coming at this from to many different angles. I think that perhaps if the help I need is coming from someone like yourself who may have had to figure it out on their own, it may make a little more sense to me than what I've seen in these video tutorials.

    I thought I'd be able to use the same 4th-axis methods I used to cut my straight flute reamers but that didn't turn out to be the case. I don't want to sound un-grateful to those of you guys how have taken the time to post comments. I really do appreciate it. Unfortunately for me, it hasn't quite clicked in my brain yet. I hope you won't give up on me. I was thinking that tonight I'll go back into my SolidWorks CAD software and tweak my model to where my barrel has only one spiral flute. If I can figure out how to set it up in SprutCam with one lone spiral flute maybe from there it will help me to figure out how to do multiple flutes. Heck; if I can figure out how to cut that one spiral flute I may be able to just use the same tool path to do all five flutes I had originally planned on doing on this barrel blank. I'd just have to re-zero my index on the 4th-axis to get the same result as if I were actually able to figure out how to do all five flutes in one job assignment. We shall see.

    MetalShavings.

  7. #7
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    Nov 2007
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    2151

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I don't know how to get much out of Sprutcam without a cad model of the machined results to import and position. With that the machine scheme in sprut is setup with the 4th axis option. You then Import model and position as desired, Then select rotary or other machining operations and set all the parameters like tool, surfaces, feeds, speeds……………………………………� �……... and your on your way.

    Its not simple even if you have lots of experience

    If what you want is one off and you don't have a good accurate model. Your best choice is some math and some coding.

  8. #8
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    458

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Quote Originally Posted by mountaindew View Post
    I don't know how to get much out of Sprutcam without a cad model of the machined results to import and position. With that the machine scheme in sprut is setup with the 4th axis option. You then Import model and position as desired, Then select rotary or other machining operations and set all the parameters like tool, surfaces, feeds, speeds……………………………………� �……... and your on your way.

    Its not simple even if you have lots of experience

    If what you want is one off and you don't have a good accurate model. Your best choice is some math and some coding.
    Yea; that's exactly what I though too and it may very well be the case but I haven't been able to figure out exactly which "Machining Scheme" will work. I've actually tried them all and the closest I've come thus far is using the Pocketing feature on the A-axis. I stumbled onto another YouTube video featuring this method and it seemed like the simplest of all the vids I've watched thus far. I watched it and wrote down each step along the length of the vid and I actually got some results in my SprutCam window but the simulation came out all screwy so I figured I must have missed something.

    I plan on sitting in front of my desktop computer with my laptop computer booted up in front of me too showing my SprutCam set up and just following along step by step to see if I can figure it out that way.

    https://youtu.be/j4Yip6vW7mE

    I was really happy when I first attempted this method cause it looked promising at first. I'll try to take a screen shot of my CAD model of this spiral fluted barrel. Maybe if you guys see what I'm working with it will fire up your problem solving intuitions and you can help me come up with a solution here.

    MetalShavings

  9. #9
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    458

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Eureka!

    I think I finally figured it out using the video tutorial I previously posted. It took some tweaking of the numbers and text fields but I think it's going to work for me. I'll let you know how it turns out in a couple of weeks when I attempt to spiral flute my rifle barrel.

    MetalShavings

  10. #10
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    Apr 2011
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    720

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Really interested to hear how this goes.

    Not knocking you skills in any way, but it it was me, I;d be chucking up a broom stick first! LoL
    Terry

  11. #11
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    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Quote Originally Posted by MFchief View Post
    Really interested to hear how this goes.

    Not knocking you skills in any way, but it it was me, I;d be chucking up a broom stick first! LoL
    Terry
    I know exactly what you mean. In fact I have a length of one inch diameter Delrin rod stock that I dug our of my stash box the day before yesterday for that very reason. No sense in taking any chances.

    MetalShavings.

  12. #12
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    May 2016
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    316

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    If it's at all possible with your particular tailstock to put tension on the barrel when cutting the flutes, do so. Make a barrel thread adapter (assuming you have threads) and use it to to pull the barrel tight once everyting is centered and in parallel with the X & Z axis. If no barrel threads, then a collet or homemade clamp attached to the tailstock ram.

    The tension will reduce deflection and likely chatter dramatically.

    An alternative is to set up a 'steady rest' under the part for the barrel to ride in. A block or two on the table which reaches up to the barrel and cradles it in a groove will also cut down on chatter. You could get fancy and make an adjustable height thing, or clamp some V-blocks in a vise and shim them to the appropriate height.

    The V-blocks or whatever you make will act as bearings and stop your end mill from pushing the middle of the barrel away. Frankly, both V-blocks/bearings AND a tensioned barrel should result in a nice finish and very little chatter.

    I certainly wouldn't want to spend hours with sandpaper on a stick to smooth out chatter marks in the flutes... that sounds like too much work.

    -Spumco

  13. #13
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    458

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Quote Originally Posted by spumco View Post
    If it's at all possible with your particular tailstock to put tension on the barrel when cutting the flutes, do so. Make a barrel thread adapter (assuming you have threads) and use it to to pull the barrel tight once everyting is centered and in parallel with the X & Z axis. If no barrel threads, then a collet or homemade clamp attached to the tailstock ram.

    The tension will reduce deflection and likely chatter dramatically.

    An alternative is to set up a 'steady rest' under the part for the barrel to ride in. A block or two on the table which reaches up to the barrel and cradles it in a groove will also cut down on chatter. You could get fancy and make an adjustable height thing, or clamp some V-blocks in a vise and shim them to the appropriate height.

    The V-blocks or whatever you make will act as bearings and stop your end mill from pushing the middle of the barrel away. Frankly, both V-blocks/bearings AND a tensioned barrel should result in a nice finish and very little chatter.

    I certainly wouldn't want to spend hours with sandpaper on a stick to smooth out chatter marks in the flutes... that sounds like too much work.

    -Spumco
    I agree.

    In this case, since my barrel is only 17" long and the work envelope of my Tomach mill is only 14" in the X-axis (if I remember correctly) I plan on doing one end at a time. What I mean is that I'll flute the chamber end first and then turn the barrel around and do the muzzle end second. The way that I've modeled the spiral flutes also has alot to do with this. My Spiral flutes don't run from end to end. The muzzle end has about eight and a half -inches of flutes from front to back. The shank or chamber end of my barrel has about 4 inches of spiral fluting. In between the two lengths of fluting is a 1 1/2"gap that has seven straight front-to-back flutes.

    The point I'm trying to make is that because the amount of exposed barrel coming out of the jaws of my 4-axis will only be about 8 or 9 inches max at any given time, I don't think that the added support will be necessary. I'm still going to use my tail stock but I really don't think that a support will be necessary in this case. I do see how it would be necessary if I were fluting longer sections of a barrel. You make a good point.

    MetalShavings

  14. #14
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    May 2016
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    316

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Well done on the work envelope workaround. With the stickout half of what I thought it would be I think you're correct in that 8" of barrel (between 4th and tail) should be plenty stiff.

    Food for thought...

    Assuming you have the table length, you can do continuous flutes. If you clamp a flat reference surface (or use the dog) to the barrel at both ends you can indicate that horizontal and set A0.

    Model the flutes continuously, and cut all to the edge of your work envelope. Turn the barrel around, re-indicate it and cut the other half (or 1/3, more or less). It would help if you model it so that the end point is 0/90/180 rotation from the start point - i.e. the helix is a full, half, or some other easily indicated division.

    It would be easy enough to do a sanity check on your setup for the 2nd Op. Just set a sharpie in the tool holder and run the program with the marker just touching. If the 2nd Op flutes line up with the 1st op, you're in business. If not, clock the part in the chuck a hair or adjust the 4th axis on the DRO to compensate for the flue timing mismatch.

    And now you're back to supporting the center...

    Good luck, sounds fun.

  15. #15
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    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I had everything figured out in regard to milling the spiral flutes. My simulations looked good. They looked like I actually knew what I was doing. This was with a 17" bull-barrel with a diameter of 1.063" the full length; but then I got to thinking about it some more and I decided to take some weight off of my barrel blank by turning a straight taper onto it so that my chamber end would remain the full 1.063" diameter and the muzzle end would be whittled down to 7/8" diameter.

    I did this, which lowered the overall weight of my barrel blank from 4 pounds to 3.7 pounds. After I ream the chamber that should bring the weight down to just under 3.5 pounds. Then, when I cut the spiral flutes I'm hoping that it will bring the overall weight of my 17" barrel blank to close to an even 3 pounds if all of my flutes are about .125" deep.

    Here's where that previous SprutCam learning curve comes to a screeching halt. Figuring out how to spiral flute that cylindrical model took me a couple of weeks of online research but I finally managed to do it; after about a dozen tries on the computer. Now I've thrown a monkey-wrench into the mix by having a tapered barrel rather than a straight cylindrical barrel of the same outside diameter. I may have to go back and maybe start from scratch to figure out how to spiral flute a tapered barrel. I thought about just running my already established spiral flute tool paths on my newly tapered barrel and just living with spiral flutes that were deeper at the chamber end of the barrel than at the muzzle end.

    In my CAD renderings, doing it this way didn't look half bad but, in order to get the weight down as low as I can without compromising the rigidity of the bull-barrel, which is what I was after, I want my spiral flutes to have the same depth on both ends of the barrel blank. Another thing I have to consider is the overall balance of the rifle. At 3.7 pounds that 17" barrel has a balance point that's about two inches ahead of the center of the rifle's factory balance point. If I can get the weight of the barrel blank down to a bit less than 3.5 pounds the balance of the rifle is right near the balance point of this same rifle in it's factory configuration. I'm thinking that if I can get my spiral flutes to be .125" deep from front to back, that will be ideal.

    This means that I'll have to not only figure out how to do it in SprutCam but I'll have to figure out how to draw these same .125" deep spiral flutes on a tapered barrel or cylinder in SolidWorks as well.

    I'll be reaming the chamber tomorrow; then I'll worry about tackling the next learning curve. If I remember correctly, in SolidWorks there's a way to draw tapered threads when drawing threaded screws. I think I may be able to use the same feature to model my spiral flutes on a tapered cylinder. Wish me luck.

    MetalShavings

  16. #16
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    Apr 2011
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    720

    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I'm far from expert on this subject, so take this with a grain of salt. LoL

    In fusion 360 when setting up a milling operation to specify the bottom of the cut, there are a number of ways, one of which is selecting the model top, then specifying an offset to determine the depth of cut. I've never tried this with a tapered surface, but it seems to me that it should keep a constant depth as the top surface changes?

    If Sprut has an equivalent selection it might allow you to keep the depth constant over the length of the taper.

    Terry

  17. #17
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    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    I haven't been closely following this discussion and I'm not a Sprut user but...
    Cutting a tapered spiral is just a coordinated move of the X, Z and A axis which is a single gcode move command (g01 with appropriate X, Z and A values). Surely this would be easier than trying to do it in Sprut.

  18. #18
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    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Quote Originally Posted by kstrauss View Post
    I haven't been closely following this discussion and I'm not a Sprut user but...
    Cutting a tapered spiral is just a coordinated move of the X, Z and A axis which is a single gcode move command (g01 with appropriate X, Z and A values). Surely this would be easier than trying to do it in Sprut.
    THIS.

    Try coding it by hand and use the sharpie. I know you want to learn how to do it - at least not knowing something in CAD drives me nuts - but I think kstraus is right on the money.

  19. #19
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    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    It turns out that the CAD part of newly tapered barrel blank wasn't that hard after all. I was able to figure out that part last night. I got my chamber reamed this morning so now I'll try to figure out how to work up the SprutCam end of this project. With any luck it will be as easy to figure out as the SolidWorks modeling was. With my SolidWorks modeling, I remembered coming across a YouTube video on the subject of threading a tapered screw. I re-watched that video yesterday and used what I learned to draw up my tapered barrel model and then applied the same tapered threading method to the spiral fluting.

    After reaming my chamber I re-weighed my barrel blank and it's now down to 3.4 pounds. That will put the balance point back near the center of the rifle where it should be. After Fluting the barrel it should drop the weight of my barrel blank to just about perfect to put the balance of the rifle to right near the front of the magazine well once I've mounted the scope back on. That will be just about perfect as far as I'm concerned.

    I don't know enough about manually writing G-Code to write out the code myself. To those that have learned to manually write their own code these problems I'm dealing with must seem like child's play but for me, I have to rely on my CAM software to do this kind of stuff. That means alot of trial and error in front of the computer. I did plan on doing that Sharpie-Dry-Run thing. Originally I was going to just use a piece of Delrin rod stock for my test run but I didn't want to go through the trouble of tapering it to match the taper on my barrel blank. First things first. I want to figure out how to work up some G-Code in my SprutCam software first.

    Incidentally, I'm rebarreling a factory Tikka Rifle that was chambered in .223 Remington. Because I wanted to install a shorter barrel to make this rifle a little more compact and maneuverable, the shorter barrel would have meant a substantial loss of velocity with whatever loads I were to fire through it. To counter some of this loss of velocity I decided to rechamber it in .223 Ackley Improved. If I calculated correctly, the Ackley Improved chambering should keep my velocities at least close to standard .223 Remington velocities out of this shorter barrel. It will be shot suppressed so any time I use the suppressor it should add just a bit more velocity on top of the velocity I get from the new chambering. I'll just have to wait and see how it turns out.

    MetalShavings.

  20. #20
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    Re: Spiral Fluting A 17" Rifle Barrel With 4th Axiz

    Finally got it all figured out; I think. Among the things I figured out was the fact that the little 3-jaw chuck I've been using on my 4th-Axis unit will not allow me to dial in the exact center of my Z, X, Y and A axis'. It didn't really matter to me before because I never really need to dial in any closer than "Good-Enough." I've had to order a small 4-jaw chuck in order to be able to index my barrel blank properly for cutting concentric spiral flutes all of the same depth.

    I took some of the suggestions eluded to my some of you good folks and decided to cobble together some other things to help this project along. I built a rudimentary adjustable "Steady-Rest" that I could use to support my barrel blank as it's being held in my incoming 4-jaw chuck. I wasn't really worried to much about chatter but since I have the time while I'm waiting for that new chuck to arrive I thought I might as well take precautions and build this "Steady-Rest." I cannibalized one of the Steady-Rests that came with my gunsmithing lathe. It wasn't a permanent alteration of that Steady-Rest. I just borrowed the rollers off of it for this project. They can be easily replaced back into my lathe's Steady-Rest once the project is done; and I can also swap those rollers back and forth if I ever need to use them again in the future.

    Another thing I cobbled together was a Spring-Loaded felt-marker holder. I'll be using this to test my tool paths first; just to make sure that my Spiral-Flutes will be cut just like they were in the simulations. I made this felt-marker holder out of some old copper pipe I had out back. I made a light spring out of some music-wire I had laying around and the plug that fits up into the 3/4" collet of the mill is made of some old Delrin rod stock I also had laying around. I'd hate like heck to have a major catastrophe this late in the project so I thought I'd run the felt-marker test first.

    That 4-jaw chuck is coming from China. This means it won't be here till early April some time. Such is the life of a budget-minded home machinist. In the mean time as I wait I've been drawing up some CAD models of an extended magazine for this same rifle. If they come out as I hope I'll be able to 3D print this magazine on my 3D printer. The factory extended magazines are outrageously high priced. I've already designed and 3D printed extended magazines for my Swiss K31 rifle and my Lee Enfield rifle. I'm hoping that this new Tikka Extended magazine design will work just as well. The factory magazine only holds three rounds. I'm shooting for at least a five round extension with some carrying capability of extra rounds on the outside walls of the magazine. First things first though.

    If you'd care to do so, I've uploaded the extended magazine designs to my Instagram account. You may have to scroll down a bit to find them but they are there for all to see. I even included a short vid to prove that they actually work. (@umarex_tim)

    Thanks alot for your help and input guys. I really appreciated it.

    MetalShavings

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