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  • #46
    Originally posted by BaronJ View Post
    ................. Once you start talking "Side & Face" mills you also need the horsepower to drive them, most hobby mills struggle with a 20 mm drill !
    I have a mill with a 1/4 HP motor. I run 2" slabbing cutters, and 2" shell end mills with it, and get fine results. I do not take off mere shavings, I get the cutters stuck right in, like a 3/4" wide convex milling cutter to full depth. Have not yet run out of power.

    The problem with modern hobby mills, and modern hobby lathes as well, is that they are set up for high speed, small cutters, small work. The lathes cannot in many cases be used for full diameter parts, due to the speed limits.

    Older equipment like mine, is happy to cut spinning a cutter as low as 35 rpm, or a lathe spinning a full diameter part at 40 RPM. At that point, it does not take "that much" power to get work done in a reasonable time. Sure, 5 HP would do it faster,but the point remains.
    CNC machines only go through the motions

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    • #47
      OK ... I made it. I did offset the arbor to get more steel behind the cutter, per BCRider's suggestion. I intended to offset it 0.125 (3mm) to have 0.375 (9mm) backing but due to a brain fart I only offset 0.062 (I set up the 4-jaw for 0.125 difference - the difference should have been 0.250). So I have 0.313 (8mm) behind it.

      I tried on my "new" Rusnok head & I love it. The head was only half-assed trammed, but good enough for a trial. Quite a different experience for this horizontal mill owner.

      For dian: I used a 3" piece of 1-1/2 sq bar that I got from the dump & 2 SHCS that I have dozens of. The cutter is shared with the lathe. So there is the opportunity cost for the steel, but this is the first time that I've used any of it & there's 12-15" of it left. So there really was no cost to me. And I had the no-fee entertainment of building it.

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      • #48
        Originally posted by dian View Post
        i have been trying to understand the obsession wih flycutters for a few decades. still dont. why dont you get a facemill for $40?
        Speaking in broad, and general terms here, not carved in stone. A face mill tends to be the tool of choice for heavy stock removal in production environments where the spindle is rugged enough to make it cost effective. High quality high capacity face mills, and their required inserts, are not cheap. The flycutter is an inexpensive way to do the same task, but with some compromise in time required. Then there is the additional feature of an appropriately sized fly cutter being hard to beat when ultra fine surface finish is of primary concern. Many's the time I've horsed the material off, roughing the part a bit oversize with a face mill, and then gone back and finished things to size and surface finish after the parts have cooled down and the smoke has cleared, using a simple fly cutter to make those delicate cuts.

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        • #49
          this is getting a bit weird. so nobody buys on ebay/banggood/aliexpess anymore and used is out of the question as well? everybody has 1/4 hp mills?

          if you get a mill you need a drill chuck, collet chuck, vice, facemill and a set of end mills. so which of those do you start making yourself? i have over half a dozen facemills that i got used and none of them was over $100 (incl. a 250 mm one and bear in mind swiss prices). i bought two (new) 50 mm facemills off aliexpess for $20 each recently. even if you decide you need brand name inserts, they are available for $20 for a set of 10 if you have a bit of patience. also, if you so desire, you can shim an insert higher in the facemill, feed it slower and you get the action of a single tooth cutter being able to take deeper passes.

          and i understand the geometry to make a successful cut appears miracuously by itself? no, your going to experiment untill you get it right. the idea to use a lathe tool for milling is courageous. why do you think insert manufacturers have two sections in their catalogues: milling inserts and turning inserts? because they are the same and they decided to pull your leg?

          but to each his own, of course.
          Last edited by dian; 04-23-2021, 11:24 AM.

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          • #50
            I buy on eBay constantly. Mostly German, American, and Swiss tooling. I refuse to waste my money at banggood etc. Have already done so, will not do it again. You *might* find a used 50mm face mill on eBay. Or build a flycutter that can do 150mm for zero cost other than the time.
            25 miles north of Buffalo NY, USA

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            • #51
              This thread started with my query about using square stock for a fly cutter. But it evolved into a discussion of many things fly-cutter'y. And was so much more useful than a direct answer about using square stock. Members lament about the deterioration of HSM, but I think that this thread is a fine example of its health.

              Thanks to all who contributed.

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              • #52
                Originally posted by dian View Post
                ......................................

                and i understand the geometry to make a successful cut appears miracuously by itself? no, your going to experiment untill you get it right. the idea to use a lathe tool for milling is courageous. why do you think insert manufacturers have two sections in his catalogues: milling inserts and turning inserts? because they are the same and they decided to pull your leg?

                but to each his own, of course.
                Dian, the tool does not know what machine it is connected to. The tool responds to the angle with respect to the material, and the speed of movement, etc, etc. These things are true in any cutting situation, because the interface of tool and material is essentially the same.

                It would be odd if one could not somehow improve the cutter for absolutely maximum cutting efficiency and maximum possible cubic cm of material removal per minute. But those things are refinements for high speed factory production. They are not determinants of function vs failure.

                YOU may have never done flycutting. Many of us have. It works well, and one can use the same tool grinds used on a lathe, in general, with the same results. It has been done for a hundred years, and that did not happen because it did not work. It works quite well.
                CNC machines only go through the motions

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                • #53
                  I understand where Dian is coming from. I guess most of us have facemills if we take this hobby seriously . I have two 3 inch face mills and a 2 inch one. I also have a small flycutter which I made as an apprentice designed for a 8mm square shank. I burnt a square hole through it in my downtime using a spark eroder. Damn ,one can even use a boring head as a fly cutter.
                  But I dont have a big sweep flycutter that would do large cleaning up sections on flat plate or a cylinder head.

                  It would be quite useful to have something like this even though it would be seldom used. For its cost and simplicity its hard to beat a simple flycutter and they work well.
                  Living where I do all my stuff is second hand. But i have noticed its harder to get quality unbeat second hand stuff where I live. Ebay generally doesn't deliver to S Africa and banggood seems to be hit and miss. Coupled with our corrupt useless postal service one would be lucky to receive your parcel at all.

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                  • #54
                    Originally posted by plunger View Post
                    I understand where Dian is coming from. I guess most of us have facemills if we take this hobby seriously . ..............
                    Maybe.... Take the hobby seriously? Not everyone who takes it seriously has equipment to use such a thing. Or they may have sufficient equipment to take care of the need a different way.

                    I have a few flycutters that have accumulated, and I DO have two arbors, for 1" and 2" (maybe 2 1/2") shell end mills. I have a large 4" shell end mill that needs an arbor made for it.

                    I do not own a face mill of the type you mean, and have no plans to acquire one in the foreseeable.

                    I find that the horizontal mill, with a slabbing cutter, does pretty well with surfaces. And I could theoretically get one of the shapers operating and use it. The flycutter would be fine too. I would not use anything but the 1" shell end mills on the Benchmaster, but I would have no issue using the 4" shell mill on the horizontal mill, taking a decent cut. That small motor geared down to the appropriate SFM, has eaten anything I can throw at it.

                    Face mills? Why for?
                    CNC machines only go through the motions

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                    • #55
                      The age old fly cutter is a great tool for finish work, but a machine like Bridgeport or smaller you can distroy the bearings with heavy cuts. Guy in my shop was milling H-13 with one . Bearings were kaput in 3 days. Machine was only 5 months old. You learn the hard way !

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                      • #56
                        Absolutely -- they are not meant for "hogging out material" not even plastic,,, one tooth hanging way out is a recipe for disaster if you think your going to remove large quantities of material, interrupted cuts play hell also - they are for truing up large surfaces that would otherwise have to take multiple passes with a "lesser tool"....

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                        • #57
                          Originally posted by J Tiers View Post

                          Dian, the tool does not know what machine it is connected to. The tool responds to the angle with respect to the material, and the speed of movement, etc, etc. These things are true in any cutting situation, because the interface of tool and material is essentially the same.

                          It would be odd if one could not somehow improve the cutter for absolutely maximum cutting efficiency and maximum possible cubic cm of material removal per minute. But those things are refinements for high speed factory production. They are not determinants of function vs failure.

                          YOU may have never done flycutting. Many of us have. It works well, and one can use the same tool grinds used on a lathe, in general, with the same results. It has been done for a hundred years, and that did not happen because it did not work. It works quite well.
                          think top rake and relief angles.

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                          • #58
                            Originally posted by dian View Post

                            think top rake and relief angles.
                            Why do you think (apparently) that those are so different for a flycutter?
                            CNC machines only go through the motions

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                            • #59
                              flat and round.

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                              • #60
                                To be fair to dian I did find that trying to use lathe tool bits on my shaper (round to flat) didn't work out well. Rough galled looking surfaces resulted. It wasn't until I reviewed my shaper book and saw a couple of videos on YT on shaper specific cutters and tried these that my fortunes and surface finishes turned around. Now my roughing cutter leaves as smooth a finish as my previous best attempts at smoothing. And my shear cut finishing tool leaves a surface that looks like it came off a fine stone surface grinder.

                                These little things DO count. I got similarly rough results from using a brazed carbide bit on a fly cutter. And the HSS lathe tool wasn't any better but wore out faster on the alloy I was using at the time.

                                So I'm looking forward to the next use of my own fly cutter where I plan on seeing if I can translate the shaper angle information to the fly cutter in hopes of getting similar results to that from the shaper.

                                The basics still apply of course. But for best results the angles need to be seasoned a little in regards to how the work moves past the cutter or vice versa. I was truly gob smacked at what a difference a couple of degrees made. And moreso by the effect of a more generous top and side rake than typically used on a lathe.

                                With that in mind I do like the idea of a round flywheel disc that has a well tuned HSS or insert off a face mill as an option. A cross or single stick out arm would work too but I like the idea that a flywheel like rotor won't kick my chip brush or air nozzle across the shop, make stick in the far wall and go "BROINGGGG!".

                                It's a lot more work to cut multiple pocket saddles for inserts so they all cut at the same time. But surely even the most ten thumbed of us can cut ONE pocket for a single face mill style insert to make a somewhat more modern fly cutter? Although, so I can play with the angles more easily I'm keen on the style posted by BaronJ eariler with a hole. I can angle the hole for the side rake and rotate the tool bit in the hole for the top rake and just grind the end and side and use a nice generous radius....... I think I got that right since the tool is vertical and work horizontal, but you get the idea.

                                Or since fly cutters are only really supposed to take at most .01 at a time I might even be able to use the shear cutting geometry....
                                Last edited by BCRider; 04-23-2021, 03:50 PM.
                                Chilliwack BC, Canada

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