Oversized Fly Cutter

[Richard Kirkman 1Participant @richardkirkman1]

I’ve been wanting the ability to face larger stock in my small milling machine. So I went about designing a Fly cutter.

I wanted it to use CCMT insert tooling, so I based my design to take an 18mm Lathe tool. My mill is relatively small so I wanted to ensure the body of the fly cutter had quite a lot of mass, and was relatively balanced. This meant I went for the longest CCMT Lathe Tool I could find, which was 25x25mm so would need machining down to 18x18mm

This was the plan, although a few dims may have changed slightly.

I started with making the washer, as the one provided with the MT3 arbor was not good quality.

Then began facing, cleaning up the outside of the material, then drilling and boring the screw hole and washer recess to size.

https://photos.app.goo.gl/pJJmvxxWsM7BtCVD6

Then I turned the part around and dialed it in the 4 Jaw to allow drilling and boring for the arbor to fit. I managed to get a nice slip flit which I was very pleased with.

From there I could turn the taper and the lathe work was finished.

At this point I had milled down the large lathe cutter to 18mm, but was held up by the mill gears eating themselves. So had to wait a while for replacements. I ordered two, one nylon and one steel for if the plastic dies again.

Unfortunately when fitting the new gear I found that another was broken, so I designed and 3d printed a replacement gear from PETG-CF which has held up since. It will be replaced when the real gear arrived.

From there I finished off machining the lathe tool down to size and started machining the key slots for the arbor. This went surprisingly well after my previous milling and having gears break.

From there I machined a t-nut to hold the fly cutter head down to the table so I could mill the tool slot, this also went surprisingly well!

 

 

 

 

 

[noel shelleyParticipant @noelshelley55608]

An interesting project but a small machine may well struggle to do the work of a big one ? Does the motor have the power to drive a large cutter ? Plastic gears will not like the shock loadings a flycutter will cause. Good luck. Noel.

[Richard Kirkman 1Participant @richardkirkman1]

Too many Pictures, so pt2.

Tool slot cut in.

Then I drilled and counterbored some holes for m12 grub screws

Counterboring Vid

From there I could assemble and test.

I’m very happy with the result. Thanks to the tool holder being extra long, i can keep the tool balanced and still have the cutter at 150mm dia.

Facing some 100mm wide aluminium was a breeze, leaving a very nice surface finish (where supported. I won’t be holding parts like this in practice, or will make some screw jacks).

One problem I’ve been having, which is consistent with my face mill, is struggling to get the mill head to be perfectly in line with the bed. There isn’t a proper adjustment so it’s just me hitting it back and forth and taking cuts/measuring bed distance. It would be nice to make an attachment for the side of the head to allow a more controlled way to tilt the head.

Anyway, very happy with the result, it will be suitable for my applications. Although it is quite large for the machine I am able to run it at whatever speed I want due to the mass and even stick out of the tool. It gives no signs of bogging the machine down, even with currently using a 3d printed gear in the head.

[Richard Kirkman 1Participant @richardkirkman1]

Noel, it’s a 750 watt motor which I fitted last year since the original smaller one died.
Seems to have plenty of power, but I’m not exactly hogging. 0.25mm cuts is as far as I’ve taken it so far.
Especially using carbide inserts for an interrupted cut, i won’t be taking it any deeper.

The new gear I’ve ordered is metal, and then the middle gear I already replaced is currently nylon, but I have a metal one spare so will put that in if i get any problems.

[howardbParticipant @howardb]

For tramming the head to the table on my WM16B mill/drill I made up a plate 4 1/2″ diameter with a recess to take the turned down OD of a soft blank end stub morse taper mandrel with a drawbar thread in the small end. Drilled and tapped the soft end M8 and secured the plate to the mandrel

I used an MT2 mandrel so I could then true the OD and the face of the plate mounting it in the MT2 headstock female taper in my Myford. I relieved the face of the plate by 0.010″ leaving a 1/2″land around the outer rim and then turned the face of the land true with a fine cut with a sharp tool.

To true up the head to the table, the assembly is mounted in the spindle, I had to use an MT3 to MT2 sleeve, drawbar nipped up, check the land face is running true, then slacken the mill head securing nuts until the head will just move, crank the head down until the land face of the plate is resting on the table, snug the head tilt nuts up and that’s the quick way to do it.

T

[David SeniorParticipant @davidsenior29320]

I assume you are aware that if you want to get a flat surface with a large cutter the tramming needs to be absolutely spot on.

Any error makes the surface that you are machining concave, and the bigger the cutting radius the bigger the problem.

You do normally however get a better looking surface than if you had machined it with a small cutter!

Dave

[bernard towersParticipant @bernardtowers37738]

Bring back the shaper!!!

[bernard towers]

On bernard towers Said:

Bring back the shaper!

Please make some assessment of the table travel on the milling machine shown. Couple that with the 150mm swept diameter of the flycutter and work out what size piece could be cut with the method shown.

Now think about what size shaper would be required to cut the same area.

[VicParticipant @vic]

Nice job on the Flycutter Richard, they’re hard to beat if you want a good surface finish.

Edit: I’ve actually generated, shall we say, a decorative effect on Aluminium by moving the workpiece under the cutter at a much higher speed than would normally be the case. I’d show an example but it’s a small part bolted under my Bandsaw.

[bernard towersParticipant @bernardtowers37738]

sorry but the way the part is fixed to the mill does not bode well for a flat surface, being only supported in the middle

[Richard Kirkman 1Participant @richardkirkman1]

David- Yes, very aware of needing to get things trammed in properly. Hence wanting to sort a mechanism for adjusting the head more precisely. Too many projects for now. Thankfully my machining is never that precise anyway, but always nice to make things properly where possible.

Howardb very interesting, a great solution. I had been thinking about some kind of fine-adjustment screw to be mounted to the side of the head, but yours sounds a lot simpler and easier!

If I had unlimited space and money then a shaper would be nice. The mill will do for now!

[howardbParticipant @howardb]

“Howardb very interesting, a great solution. I had been thinking about some kind of fine-adjustment screw to be mounted to the side of the head, but yours sounds a lot simpler and easier!”

I also have made an adjustable stop to the side of the head be able to return the head to approximately it’s original 90 deg setting before using “bigfoot” as I have christened it, to  fine tram the head to 90 degs.

 

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