Fly cutter - first try

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Feb 25, 2018, 02:54 PM
Canobi

Fly cutter - first try

Hi folks :)

I've got a toolpost grinder project waiting for me to get a vice for my mill. I also need some specific tooling to perform some of the operations and felt inspired enough to have a go at making one or two of them.

The main body of the grinder will need squaring up but I don't have a fly cutter in my shop yet, so I chose to make the fly cutter first.

I wanted a relatively chunky fly cutter so I grabbed some 1.3/4" mystery alloy steel bar I have (that's as much as I know about it, chips turn a very pretty blue which is my only clue to it being an alloy) and cut a piece off about 82mm in length:
https://i.loli.net/2018/02/25/5a92c0c682674.jpg

I then chucked it up in the lathe and faced the end, then measured a 30mm section on the faced end for the shaft and turned it down till it was just a shade over my target size of 17mm. I then flipped the part round, gave it skim cut to clean off the rust and faced it.

At this stage I figured I would make it a round head fly cutter as it's my first attempt and there being less milling operations involved.

I then worked out at what angle I wanted the cutting bit to be positioned and cut a taper on the end of part to match my chosen angle.

After the taper was cut, I flipped it round to give the shank it's finishing cut, which I then polished with some oiled 250 grit wet n dry and finally buffed with some fine scotch bright:
https://i.loli.net/2018/02/25/5a92c0c712a1a.jpg

My next move was to make the hole for the cutting bit. This I did on the lathe due to lack of a milling vice but had to get creative with the setup to achive the required angle and offset:
https://i.loli.net/2018/02/25/5a92c0c5d2d18.jpg

Once it was set up and ready, if not a bit sketchy, I chucked up a 10mm carbide slot mill to make a flat for the spot drill:
https://i.loli.net/2018/02/25/5a92c0c37f13e.jpg
https://i.loli.net/2018/02/25/5a92c0c3e4feb.jpg

I then used a smaller drill bit, the size of which was chosen at random, to make a pilot hole and then switched to a freshly ground 10mm drill bit to bring the hole to it's final size:
https://i.loli.net/2018/02/25/5a92c0c06c533.jpg
https://i.loli.net/2018/02/25/5a92c0c45136c.jpg

With that job done, I indexed the head 45° and repositioned the setup to 90° in order to drill and tap an M5 hole in the side for a grub screw that will lock the cutter in position. Since the hole was on centre this time, a flat for the spot drill wasn't needed:
https://i.loli.net/2018/02/25/5a92c0c497480.jpg

I then chucked up an M5 tap and put my lathe in backgear for a bit of power tapping. To get a proper feel of things I feed the carriage by hand and utilise the VFDs forward and reverse function to break the chips as I go.
https://i.loli.net/2018/02/25/5a92c0c681df5.jpg

Once the tap started slipping in the chuck (which they always seem to do), I released it from the jaws, backed the carriage away with the tap still in the work, then indexed the part another 45° so I could finish tapping by hand:
https://i.loli.net/2018/02/25/5a92c1288d0ae.jpg

After the hole was tapped, I removed tge piece from the ER chuck and used my cordless and a countersink bit to chamfer the edge and neaten it a little while it was clamped in my bench vice:
https://i.loli.net/2018/02/25/5a92c129a1961.jpg

After that was done, I put it back in the ER chuck which I put on the lathe spindle to give the rest of it the same polish and shine treatment I did on the shank:
https://i.loli.net/2018/02/25/5a92c12805d8b.jpg

I still need to get some tool steel to make the cutting bit with but all in all I'm quite pleased with how it came out. If it actually works on testing, I'm going to knock out a couple more in different sizes to make a full set :)
Feb 26, 2018, 07:58 AM
Paul Jones

Canobi,

The fly cutter looks good and thank you for taking the time showing all the excellent photos and descriptions.

Regards,
Paul
Feb 26, 2018, 10:57 AM
Canobi

Not a problem, and thank you for the compliment :)
Feb 26, 2018, 06:16 PM
ncollar

Canobi
Very nice work and a tool you can be proud of. Please do not take it wrong but if you spin your countersink by hand it will produce a much smoother finish. I am convinced that you will make the set because of how good it works out.
Nice machining and keep it coming
Nelson
Feb 26, 2018, 06:48 PM
aphilipmarcou

Hi Canobi,
Any specific angle for the cutter hole to be at?.
Feb 26, 2018, 08:18 PM
ncollar

Canobi
I just made a big facing cutter. I need a cutter for it and not really sure what size I want to use. My thoughts were to put 4 cutters on it but to get then all in perfect setting would require a tool and cutter grinder. My dis was from 1 inch thick cool roll 5 inches in diameter. I cut the drive pin from an old bar bell weight bar. Cut down to .750 and bore the hole in the disc .004 smaller. I heated the disc on my turkey roaster until it was red hot, nice and slow. When it got there I took the pin out of a glass of frozen water and dropped it into the hole and gave one tap for good measures. When it got cold I put it in a ER32 .750 collet and it had warpped some but not much. Turned it and trued it up and it looks nice. I can not wait to slip a cutter to it. I'll get a pic tomorrow.
Nelson
Feb 27, 2018, 01:49 AM
rossbotics

Turned out nice
Feb 27, 2018, 02:37 AM
Canobi

Quote:

Originally Posted by ncollar

Canobi
Very nice work and a tool you can be proud of. Please do not take it wrong but if you spin your countersink by hand it will produce a much smoother finish. I am convinced that you will make the set because of how good it works out.
Nice machining and keep it coming
Nelson

Thank you for the compliment :)

I went real slow with the cordless drill for chamfering but will take your advice and make a handle for the countersink so I can chamfer by hand. The finish never seems to come out well with the cordless anyway.
Feb 27, 2018, 02:51 AM
Canobi

Quote:

Originally Posted by aphilipmarcou

Hi Canobi,
Any specific angle for the cutter hole to be at?.

I didn't choose one, I just went for an angle that was useful but felt wouldn't put too much strain on the cutter as it was spinning (I chose to use a 10mm bit for this one as it would be more resistant to flexural forces). However, since you asked, it piqued my curiosity to find out and the angle is 40°.
Feb 27, 2018, 02:52 AM
Canobi

Quote:

Originally Posted by rossbotics

Turned out nice

Thank you :)
Feb 27, 2018, 07:26 AM
DIYer


Thanks Canobi! We've added your Fly Cutter to our Machining category,
as well as to your builder page: Canobi's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-fly-cutter-39"> <img src="/uploads/210958/homemade-fly-cutter-39.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-fly-cutter-39">Fly Cutter</a> <span> by <a href="http://www.homemadetools.net/builder/Canobi">Canobi</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/fly-cutter'>fly cutter</a> </div> </div> </div> </div>
Feb 27, 2018, 08:57 PM
Toolmaker51

To Canobi, real nice flycutter. Glad to see mention of the offset in conjunction with the angle. I'm not sure why, but conventional flycutters set the edge on centerline. If that is moved farther 'back' it creates some extra clearance, great for softer materials. On center, flat bits tend to slap. While the mechanics seem alike to lathe turning, clearance means more in milling. I've seen some try to generate a positive rake with inconsistent results.

When making a flycutter, the incline angle depends on the tool bit[s] you grind. Avoid acute cutting edges, they'll dig in and/ or bind. My common use of flycutters is clean fillets from a flat to adjoining wall, way better than a radiused endmill, when there is room. No laws are in place stating such cutters require a certain minimum diameter...

Quote:

Originally Posted by ncollar

Canobi
I just made a big facing cutter. I need a cutter for it and not really sure what size I want to use. My thoughts were to put 4 cutters on it but to get then all in perfect setting would require a tool and cutter grinder. My dis was from 1 inch thick cool roll 5 inches in diameter. I cut the drive pin from an old bar bell weight bar. Cut down to .750 and bore the hole in the disc .004 smaller. I heated the disc on my turkey roaster until it was red hot, nice and slow. When it got there I took the pin out of a glass of frozen water and dropped it into the hole and gave one tap for good measures. When it got cold I put it in a ER32 .750 collet and it had warpped some but not much. Turned it and trued it up and it looks nice. I can not wait to slip a cutter to it. I'll get a pic tomorrow.
Nelson

ncollar; hand set multiple HSS bit cutters easily when mounted in the spindle. Use gravity and two feeler gauges at a time. Then a sharp bit doesn't bite sliding shim.
Sometimes you can get good results with them 'stepped' in Z axis height from cutting plane. Only need a couple thousandths variation, whichever is highest is the 'rougher'. Common to multi-flute cutters, RPM can be reduced and feed rate increased.
Feb 28, 2018, 02:43 AM
Canobi

Thank you for your kind words and advice toolmaker51 :)

The offset measurement was a bit if a fluke this time. My dividing head's centre point is a little lower than the lathe spindle and I normally use a specially made shim for it to line them up. I actually forgot to include the shim when I raised it for the offset but it wasn't till after that I was happy about that as I'll be using round bits so the extra I will need to remove from them should be enough to make a decent flat. If not, a 10mm bar is enough to make a seat for a carbide insert, so all won't be a total loss if the flat ends up too far back from the cantre line.

I can't wait to start grinding the cutting bit actually, tool geometry is something I'm keen to get down pat. I've only just started grinding tools for the lathe after making my own mini toolgrinder (WIP still, needs some refinement but it's usable) so it'll be an intersting challenge finding the right geometry for the Fly cutter bit. If I've got things right, the cutting edge radius is small for hard materials, large for soft?
Feb 28, 2018, 04:26 AM
Toolmaker51

Canobi; you are welcome. Applying radius to softer materials is correct, available RPM's are a factor, including depth of cut, etc. As mentioned, it's lathe like in most respects. Envision clearance as if looking down flycutter's centerline, eyeball = to spindle.
10mm tool shank will carry an insert. I find making insert tools tedious; try silver soldering carbide on instead. All told, HSS seems to have lost prominence, where it can be applied hasn't changed. Perhaps tool grinding has declined in practice because carbide has become more widespread.
Whoever our shop's buyer/ specifier practically ignored HSS for tools in general, and no bench grinder at all. I imagine a salesman's heyday with his suggestions to a neophyte. Trying to get carbide to perform is like starting a race in the wrong direction. One of today's projects is correcting those deficiencies.
Feb 28, 2018, 06:10 AM
Canobi

Well, despite my suggestion of inserts, I hope to keep the old "artisan" aspect of engineering going as I have much love and respect for the old school machines, tools and techniques from back in the day.
Feb 28, 2018, 06:15 AM
Frank S

Whoever our shop's buyer/ specifier practically ignored HSS for tools in general, and no bench grinder at all. I imagine a salesman's heyday with his suggestions to a neophyte.
How is it even possible to keep the doors open in just about any business without one?Ok, maybe a Hospital normally wouldn't need one for patient care. I've seen bench grinders in the back room of restaurants and in dress makers shops.
Carbide inserts are great, but only a seasoned professional will know the best insert size and profile and grade for every application. Cemented (silver brazed) carbide tools can be shaped for a wide range of specialty applications. Straight out of the box their usually lacking in performance for many tasks. Not all HSS is created equal but in the hands of seasoned veteran machinist/ tooling grinder person it can be shaped to do varying operations nearly impossible to do with inserts unless those jobs are done on a CNC machine.
I personally like the fact that Canobi's fly cutter has a slightly off center set to it for the same reasons already mentioned by Toolmaker 51.Nice job even if it was as you say an accident.
Mar 1, 2018, 05:32 AM
Canobi

Thank you Frank, if I can get half as good as you at making stuff I'll be a happy man :)
Mar 24, 2018, 07:53 AM
Canobi

Hi folks :)

I finally got my hands on a milling vice, some 10mm diameter tool steel (10% cobilt mix) and happily, a work colleague has lent me his bench grinder for a couple weeks, so it was time to make a bit for my flycutter and test it out, after a quick mini build session knocking together a grinder stand out of parts that came from a discarded shop display unit first:
https://i.loli.net/2018/03/24/5ab63f7bdb573.jpg

With that complete, I set about grinding a short length of one end of the bar of tool steel down to the halfway point using the side of the wheel and then ground a relief behind the cutting edge, after putting the radius on the corner.

Grinding done, I then honed the flats and radius with a medium stone, then a fine stone to get the cutting edge really crisp.
https://i.loli.net/2018/03/24/5ab63f2bace51.jpg
https://i.loli.net/2018/03/24/5ab63f5ae117d.jpg
https://i.loli.net/2018/03/24/5ab63f7a4586e.jpg

I got carried little away once I'd finished and I forgot to take footage of my first cut but I was well surprised at how well it performed. Admittedly the cutter was slapping at first and the finish wasn't all that great:
https://i.loli.net/2018/03/24/5ab5647a9076d.jpg
https://i.loli.net/2018/03/24/5ab5647d25993.jpg

But after adjusting the cutting angle from vertical to slightly positive, it went very smoothly and quietly indeed, making a light peeling noise as it cut chips, much more akin to the sound metal make when cut with a shaper but on a smaller scale and faster.

The finish also vastly improved too, so I'm well chuffed to have managed a good grind on my first try:
https://i.loli.net/2018/03/24/5ab63f27e3d56.jpg

My next move is to grind the other end for aluminium, then cut the bar to get the correct length bits for the cutter. I chose to do it that way as I found it easier to grind with a long shank as I could make finer adjustments carving the business end, probably as I've done wood turning before and the feel of it was much like sharpening a chisel.

I do still have one issue though and that is caused by my mills slightly bent quill. The flycutter bites in the work material again with the trailing end of the cutting radius and ruins the nice finish made by the lead cutting radius (which technically should be the only one to do the cutting). I have yet to address that issue until my skills catch up, mainly as I want to make a new quill but with a few changes and that will be quite involved.

As a way around the problem for now, my plan is to make an adaptor for the cutting bits that will bolt onto my lathe's face plate to bodge a large disc style flycutter together.

Until then, stay safe, have fun and keep those chips flyin' ;)
Mar 24, 2018, 03:46 PM
Canobi

Hi again good folk :)

Here is my grind for aluminium I did eaeliear. Basically the same steps as i did before, I just made the radius a lot larger:
https://i.loli.net/2018/03/25/5ab6c55e7e50c.jpg
https://i.loli.net/2018/03/25/5ab6c55df178e.jpg
Mar 24, 2018, 10:36 PM
Toolmaker51

That 'bent quill' is far more common than you'd suspect. If the machine has a adjustment, it's not perpendicular. Only takes a tenth [.0001] to mark the backside of cut. Part of the marks can occur from the figurative opposite rotation as cutter passes over. The semi-circular pattern is identical to a vinyl record disc. When cutting travels over the pattern, it disrupts the peaks. Feed rate and a bit of tool radius reduce it. If tilt is forward/backward, the cut is flat but angled to the table X axis. If side to side, a very large concave/convex arc is formed along the X.
With out adjustment, any displacement of quill-spindle-casting will create that double cut. Achieving no marks is difficult, including chips of material carried by cutting edge over the previous cut, scoring the pattern.
If you really want a stoned edge, use marble, a ceramic tile or glass plate and wet silicon carbide [wet or dry] paper. Mark bit with Sharpie, Dykem etc. Dress radius, rake and clearance along selected surface [away from edge if possible] not around it. Works on HSS and carbide alike. Magnified inspection will show the result.
Jul 20, 2018, 08:00 PM
Ronj

For anyone interested in old school info and techniques, check out Your Old Time Bookstore. They have a large library of books from the old days. They send out e-mails regularly with 75% off discounts. Very good information and very cheap. Ronj.

Quote:

Originally Posted by Canobi

Well, despite my suggestion of inserts, I hope to keep the old "artisan" aspect of engineering going as I have much love and respect for the old school machines, tools and techniques from back in the day.
Nov 7, 2018, 05:02 PM
ncollar

Quote:

Originally Posted by Toolmaker51

ncollar; hand set multiple HSS bit cutters easily when mounted in the spindle. Use gravity and two feeler gauges at a time. Then a sharp bit doesn't bite sliding shim. Sometimes you can get good results with them 'stepped' in Z axis height from cutting plane. Only need a couple thousandths variation, whichever is highest is the 'rougher'. Common to multi-flute cutters, RPM can be reduced and feed rate increased.

Toolmaker51
I did not think about what you said. But letting it sink in I could also rotate the fly cutter around to a fixed point and adjust all cutters with the feeler gauge. Almost like tramming the head but the cutters.
Thank you for your wise intervention.
Nelson
Nov 7, 2018, 05:53 PM
Toolmaker51

About wise intervention, I'm not so sure. Just doing what it takes, that way a boss keeps handing me checks on Fridays IYKWIM.

There are all kind of small bound notebooks. I plant them all over; so when inspiration strikes, a trick gets discovered, or reminder to purchase so & so, it gets recorded.