Fly Cutter Attachment for Lathe Faceplate

A few years ago I first saw the design of this fly cutter attachment for faceplates in the book “The Shop Wisdom” by Rudy Kouhoupt. It looked like a great idea to try and it does machine very smooth surfaces. The cutter holder fits into one of my Unimat 2.7” dia. faceplates but the same idea could be applied to any lathe faceplate.

I made the HSS cutter holding part from 0.50” x 0.625” x 0.75” cold rolled 1018 steel. There is a 0.17” deep step milled around all four sides on the backside to allow the fly cutter to fit snugly into one of the slots in the faceplate. This part is held in place with a 10-32 cap screw and two washers. The cutter was ground in a semi-circular form from an old 3/16” HSS drill shank and secured with a 6-32 set screw.

The milled surface finishes created by the fly cutter are very smooth (almost mirror-like) and great for squaring blocks in preparation for other work. An added bonus is the faceplate can be used as an aide with a machinist square in setting up rectangular blocks at right angles to the cutter path (or set up to any other angle).

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Thank you for looking,

Paul Jones

Nice post, another idea to add to this group's collective knowledge.

Thanks Paul! I've added your Lathe Faceplate Fly Cutter Attachment to our Machining category, as well as to your builder page: Paul Jones' Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="/lathe-faceplate-fly-cutter-attachment"><img src="/uploads/100652/lathe-faceplate-fly-cutter-attachment.jpeg" alt="Lathe Faceplate Fly Cutter Attachment" /></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="/lathe-faceplate-fly-cutter-attachment">Lathe Faceplate Fly Cutter Attachment</a> <span> by <a href="/builder/Paul+Jones">Paul Jones</a></span> </div> <div class="tags"> tags: <a href="/tag/lathe">lathe</a>, <a href="/tag/fly-cutter">fly cutter</a> </div> </div> </div> </div>

Very good adaptation .. Thanks for sharing.

Since originally posting this article about the 3" swing Unimat fly cutter three years ago I discovered the original photos disappeared and have now been replaced.

I just purchased a Lathe/Mill combination and the first thing I seem to need is a fly cutter.
Still recovering from the cost of all the tools and measuring goodies I find this an brilliant idea, only problem is I did not receive a face plate with my machine.

Now my question can I take a 3" disk and clamp it in the chuck and use it as the face plate or will the side forces damage my chuck?:confused:

Is the cutter hispeed steel? How is the cutting edge ground?

Quote:

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Originally Posted by garage nut

I just purchased a Lathe/Mill combination and the first thing I seem to need is a fly cutter.
Still recovering from the cost of all the tools and measuring goodies I find this an brilliant idea, only problem is I did not receive a face plate with my machine.

Now my question can I take a 3" disk and clamp it in the chuck and use it as the face plate or will the side forces damage my chuck?:confused:

Is the cutter hispeed steel? How is the cutting edge ground?

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I don't think you need to worry about chuck damage.

You really don't need a disk to convert the chuck into a monster fly cutter. A length of steel, fitted with a spigot to grip in the 3jaw or gripped directly in a 4jaw will work just fine. Drill a hole in the bar to accept the tool holder (or a slot if you want adjustable radius). The tool holder can be cobbled together from a bolt and nut as I did here...

http://www.homemadetools.net/forum/i...y-cutter-58399

Depending on the stiffness of the steel and desired depth of cut, you may want to fix things so the back of the tool holder seats against the face of the chuck to make things more rigid.

Many years ago I made what I'm describing here. I'll try to find it and get a picture to make my description more understandable.

Quote:

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Originally Posted by mklotz

You really don't need a disk to convert the chuck into a monster fly cutter. A length of steel, fitted with a spigot to grip in the 3jaw or gripped directly in a 4jaw will work just fine. Drill a hole in the bar to accept the tool holder (or a slot if you want adjustable radius). The tool holder can be cobbled together from a bolt and nut as I did here...

http://www.homemadetools.net/forum/i...y-cutter-58399

Depending on the stiffness of the steel and desired depth of cut, you may want to fix things so the back of the tool holder seats against the face of the chuck to make things more rigid.

Many years ago I made what I'm describing here. I'll try to find it and get a picture to make my description more understandable.

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OK, I managed to find the tool I mentioned. I wrote a description which can be found here...

http://www.homemadetools.net/forum/f...943#post102905

I've reproduced the two photos from that post below. They may be self-explanatory...

https://s3-us-west-1.amazonaws.com/f...e/102905-1.jpg

https://s3-us-west-1.amazonaws.com/f...e/102905-2.jpg

What shape should the cutter be ground to?

Quote:

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Originally Posted by garage nut

What shape should the cutter be ground to?

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I've always had good results with a generous radius on the tool. Probably the profiles suggested for lathe tools will work well as a starting point. Experiment a bit and see what works for you.

With a tool like this you'll want to keep the depth-of-cut small and the feed slow. It's meant to clean up a surface, not take off large amounts of material, a process better done with endmills.

Need to square off some 30 x 30 mild steel I want to use for a power hacksaw project

Quote:

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Originally Posted by garage nut

Need to square off some 30 x 30 mild steel I want to use for a power hacksaw project

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There is a mysterious entity in the HomemadeTools.net wheelhouse. He senses issues we have with projects, and he brings out related posts. This appeared today...... http://www.homemadetools.net/forum/s...-17#post102983

How this mystery started is unknown, but is growing to legendary proportions, and we minions have all the fun.
Kinda like Santa Claus.......

I forwarded the cutting disc in angle grinder post to garage nut; unaware 30 x 30 was square bar stock. My picture was a sheet of plate, lol.

Quote:

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Originally Posted by garage nut

Need to square off some 30 x 30 mild steel I want to use for a power hacksaw project

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I assume you are using a lathe for this, if so its a classic use of a 4 jaw chuck.
U tube is the place to go for machining tutorials, example https://www.youtube.com/watch?v=qQp8zP1Q92s

Toughness maybe. Or hardness.

Quote:

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Originally Posted by mklotz

Depending on the stiffness of the steel

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But Youngs modulus tells us that pretty much all steels are pretty much the same "stiffness"

Quote:

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Originally Posted by 12bolts

Toughness maybe. Or hardness.But Youngs modulus tells us that pretty much all steels are pretty much the same "stiffness"

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True, but I was referring to the stiffness of the shape, not the material. Since I used a C-section, I was concerned about it deflecting while cutting. A stiffer shape would be better.

I probably should have worded it more clearly.

re questions about tool form.
Fly-cutters skim, so avoid a too-negative leading edge that pulls into the work. The face does most of the finish shearing, a radius or angled leading edge 'roughs' stock a few turns ahead of that.
A successful turning tool is not too far from a good fly-cutter.
As a side note.
Occasionally, I need minimal tool marks in a recess. I grind 1 flute off a new & proper diameter 2 flute end-mill.
Voila! Mini fly cutter.