Making a flycutter

R

rzw0wr

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I have some cheap looking fly cutters that came with my mill.
I trammed the head to the table got to about .0005".

When I run my fly cutter over the metal the back of the cutter will touch the surface sightly.
This happens in both directions.

I am thinking that these cheapies are maybe bent or at least not rotating flat to the table.

I am going to make a new fly cutter on my lathe.

Does the angle of the cutter to the cutting surface make a big difference?

Thank you,
Dale
 
That's normal if your head is trammed in well. Making a new fly cutter or with a different angle won't change that. Some people will set their tram slightly off so that the fly cutter will cut slightly more on the trailing end than the leading end.
 
It will be a fun project none the less & in the end you will have something nice. You could always just skim cut the fly cutters you have now to make em more purdy. Assuming that's all that's wrong with them.
 
I have made 2 of them now. One with a 2.5" body made from a pulley hub and a 3/4" shaft, and the other made from a grade 5 1"x4" bolt with an integral shaft.

The smaller one cuts very well, but that may partially be because I set it up to use 1/4" HHS cutters and 1/4" carbide insert mini lathe cutters. The larger one uses 3/8" HSS and I have to grind the cutters which I haven't mastered yet.
 
I made mine from a chunk of CRS I had laying around.

It is about 1 3/4 dia. with a 3/8 bit.

Grinding a bit looks just like a lathe bit but right handed. Use a radius.
Once you get the hang of it you can then improve the grind.

Getting read to try mine out today.
 
rzw0wr said:
Grinding a bit looks just like a lathe bit but right handed. Use a radius.
Once you get the hang of it you can then improve the grind.

Getting read to try mine out today.
Click to expand...

Most fly cutters use a LH bit. Typo maybe?

Also, be careful with big nose radii. They leave a nice finish but if you try to take a big cut they will deflect and chatter. Better to keep it down to about a 1/32" radius and boost back rake a bit to improve the finish.
 
OK mikey.

I think we may be saying the same thing.

When I grind my fly cutter bit and look at them bottom up the cutting edge is on the right.
As if cutting on a lathe from the head stock to tail stock.

I do agree about the radii on a cutter. Mine is about 1/16"

BTW, my new fly cutter works great. My first mill cutting tool that I have made.
 
This is just a nomenclature thing. A lathe tool that cuts toward the tailstock is called a LH tool. What you call it isn't important but it can cause confusion when advising others, that's all.

Glad the tool works.
 
darkzero said:
That's normal if your head is trammed in well. Making a new fly cutter or with a different angle won't change that. Some people will set their tram slightly off so that the fly cutter will cut slightly more on the trailing end than the leading end.
Click to expand...
I do that! BTW, a bent fly cutter will not cause any issues. The cutter still rotates on the spindle axis.
Robert
 
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