Fly cutter for use on lathe

[DPittman]

Hi,
I am wanting to learn to use a fly cutter on my small Asian 10" lathe. I have attached picture of small 3/16" fly cutter. Shouldn't the bit be flush with top surface of the tool holder? The other two holders I have seem to be flush or at least close to flush. I'm thinking this will cause problems with clearance or I will have to run the bit out with excessive overhang? Should I just shim it out?
If it isn't already obvious, I know zero about the use of a flycutter. I am trying to get into my head how to grind them but will likely be looking for advice on that here also.

DPITTMAN

 

[schor]

You would normally use a fly cutter on a mill and not a lathe. What are you trying to do?

And yes, you could either let the tool hang out or shim it if you want.

 

[DPittman]

Yes I am wanting to use a fly cutter on my lathe....I have no mill....so I've made up a vertical slide vise that I can use on my cross slide to do very basic milling. I bought a cheap set of fly cutters in hopes of being able to do some surface area milling. No project in mind, just wanting to try something new and learn sum-ting.

 

[kylemp]

Fly cutting on a non rigid machine is often done at low speeds, for something that small as far as shank you would probably want to make sure you didn't run it too fast and shim it out if you don't have a piece of hss that fits fully. Make sure that your angles are right and your not rubbing, doing that on a lathe is much more dangerous than on a mill.

 

[Dabbler]

Using the lathe for milling can be quite hard on the cross slide lead screws, so be careful. One way is to actually take a cut with the lathe in neutral to test everything and feel with your hand how much impact and drag on the tool there is. As far a clearance and holding the tool out too far, you can only take a slim shaving without causing lots of problems. It won't matter if the tool is out to give clearance if you take a very slim cut. I know this goes against the grain about holding everything rigid, don't let tools hang out longer than necessary, etc. The spring from the extra length can help a little bit.

info on grinding a tool for fly cutting can be found at: http://tomstechniques.com/wp-content/uploads/2014/03/Fly-Cutting-Bit.pdf

 

[Jwest7788]

Whats the benefit of fly-cutting on the lathe vs just taking a facing cut like normal?

 

[kylemp]

Hes using the lathe as a mill, but you're right.. Chucking it would be easier probably

 

[DPittman]

Well it's all theoretical on my part but....
I'm thinking of chunk that couldn't reasonably by mounted in a chuck might be able to be held in vertical vise/slide and a larger surface area could then be milled off. Am I dreaming?

 

[PeterT]

I've seen pictures of lathe setups where people do milling operations in lathes. Flycutting is a somewhat lighter version of that. Usually its those crazy Brits on Myfords who seem to take particular joy in making a tool, to make a jig, to make a tool, to make a part

The challenge is having a rigid & upright table & all the strapping/vise to secure the part. The cutter location is fixed in the lathe jaw of course, so that means the table/part assembly has to be able to travers forth & back & up & down to mill a part of any size. So the part cant extend much below the lathe bed unless a small portion inside the gap. If you have a face plate for your lathe, you for sure can accomplish the same finish or better. The lathe capacity (swing clearance) and part shape / dimensions will dictate max size. If its a big irregular chunk, one needs to consider counterbalancing. The other thing about the lathe milling table kits is those days of inexpensive casting kits that model engineers could buy are long gone. Those kits are spendy & shipping them from far away is spendy. Typically they were unfinished cast iron & leaving you to machine & source leadscrew & such. (And then that circular problem - how to mill something in a lathe, that is going to make a part... which will allow you mill something in a lathe I'm sure you can flange something up, but do some net research & just be careful.

 

[DPittman]

Thanks for the input. I have made up my own version of milling attachment for my lathe and have done a little bit of successful milling on it so far but haven't tried fly cutting yet.
Here is a picture of some milling I did in steel for a ball turner I'm making.