# Tangential Flycutter



## Jim2 (Feb 10, 2015)

I made up a tangential flycutter a couple years ago.









using an idea that I copied from 

http://mikesworkshop.weebly.com/tangential-tool-flycutter.html


In use the flycutter is just, well, OK. . . .  If the metal is harder than mild steel, or rusted, or scaly it tends to dull very quickly.  I haven't noticed this problem with the tangential tools that I've made for the lathe.  They tend to last longer and not completely lose the point.  It also tends to take a fair amount of grinding to re-establish a good edge on the tool.  Heavier cuts tend to cause "hammering" on the spindle and bearings, and when I say "heavier", I mean 0.015" to 0.020".  So, it ends up being useful primarily for finish cuts.  And, it's not particularly well suited to that either because the bit has such a sharp point that it is difficult to feed it slowly enough to eliminate the ridges.  The tool has a larger radius than the cutting edge, so there can be clearance issues with some setups, also.  

For these reasons, I finally broke down and bought a carbide face mill for roughing.  It's a cheapy from Shars with integrated R8 shank, 2" diameter.  It seems to do the job, anyway. . . .

I'd been making some tangential lathe tools recently with round HSS bits, which I posted on another thread.  Here's the latest one:






It occurred to me that, borrowing from this design, an improved tangential flycutter could be made.  Now that I've got the carbide to handle roughing duties.  A tangential tool with a round HSS would be better suited to a light, finish pass because the rounded tip would leave a better finish.  So, here's the plan











Here's the body of the tool ready to drill the holes for the toolbit and the "flex".






Here's the setup to drill the hole for the toolbit






The holes are in place, and I've cut the facet for relief behind the cutting edge.  Setting up to remove the metal where the bolts will be drilled





Well, that's as far as I am for now.  

Jim


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## Jim2 (Feb 11, 2015)

I made a little more progress on the flycutter last night.  I milled the 45 degree flat for the fastening bolts first.







Then added the bolt holes, with tap hole and clearance hole.  Counterbored it with a 1/2" endmill to 1/16" depth and tapped the holes 5/16-18 tpi.






Next up is making the slot.  











I could only get 1.100" depth with that slitting saw, so had to finish up the slot with the portaband.  I inserted an old 1/4" bolt in the hole to prevent accidentally marring the far side of the hole when the saw broke through.  Here's the results after a little deburring:










I see there's a bur at the bottom of my clearance holes for the fastening bolts.  I must not have gotten quite deep enough!  That'll have to be cleaned up with the dremel.  

If anyone's interested in the drawings, you should be able to see them full-size by going to photobucket.  Click on any of the pictures, and your browser will take you to photobucket.  Once there you can hover your mouse over the picture and then expand them to full size by clicking on the little magnifying glass icon in the upper right corner. 

Jim


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## cjtoombs (Feb 11, 2015)

I would be interested in seeing a demo of it in action...


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## Jim2 (Feb 12, 2015)

Finished up the fly-cutter last night.  I did a little de-burring, trimmed the fastening bolts to length, and then it was time to make the fly-cutter a little more symmetrical so that it would be somewhat balanced.  I cut off some of the excess material with the portaband, then it was time to get the face mill out:






Here's the final result:






I had a little time left, so found some scrap and took a few test cuts.  I ended up taking a total of 4 cuts all at 0.003" DOC.  Each successive cut was done at progressively higher speeds working my way up from 110rpm, to 200rpm, to 340rpm, and finally at 650rpm.  The test piece was about 2" square.  Here's what it looked like after the final pass






It's maybe not quite as smooth as I would have hoped.  It certainly doesn't have the mirror-like finish that some folks can get with carbide.   I might be able to do a tweak the angle on the tool-bit, or take an even lighter cut.  All in all, I'm still happy with how it turned out.  The tool-bit can easily be removed for sharpening and replaced while the fly-cutter is held in the mill spindle.  Sharpening is easy because the bit is so small there's not much metal to grind.  I'd say there aren't any downsides compared to my other fly-cutter, and it was easier to make, too!

Jim


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## Jim2 (Feb 12, 2015)

cjtoombs said:


> I would be interested in seeing a demo of it in action...



:whiteflag:

I don't have a YouTube account, nor have I tried making any movies with my camera.  I guess I should get with the times, but hopefully pics alone will satisfy your curiosity!

Jim


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## brino (Dec 22, 2020)

@Jim2 

Great build thanks for sharing this!
I don't know how I didn't see it before.

-brino


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## courierdog (Dec 22, 2020)

Great built, really enjoyed your article.
I have sent you a PM, hope to hear back from you.


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