Dovetail cutters ?

T

Taximanny

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Jul 27, 2015
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As I search for my best way for a nail nick I'm now looking into the Dovetail cutters.

I'm pretty happy with the fly cutter at the moment but can't rule out other methods until I try them.
So for those of you that are using the Dovetail method please chime in with pics if possible.

So what I have gathered so far is I need a 60 degree cutter.
Questions are mainly
Diameter 1" or 3/4" or bigger ???
12 teeth 8 teeth ???

Carbide tipped ?
HSS ?

They do seem to range from $50 to $100 so would like to see what works .

Thanks for any input and pics.
 
hello, i was following your recent thread about the nail nicks. one guy mentioned that the farther the flycutter tip was from the center of the spindle, the harder it would be on the machine because of the increased leverage. that made sense to me since i have a mini mill. so i bought a 1 3/8" 60 degree HSS dovetail. these are my first three tries at nicks this morning. i ran it at 900 rpm, i dont know if that is too fast or too slow.
 
For cutting speeds: (cutting speed x 12) / (pie x diameter of cutter). You could use 60-65 for the cutting speed of most knife materials using HSS, some are much lower (less machinable) but for general: (65 x 12) / (pie x 1.375) : (780) / (4.320) = 181 RPM.

900 RPM will be hard on that cutter. Lower RPM with tools that have a high number of flutes is hard for less rigid machines (the more number of cutting teeth the greater rigidity of the machine required, more cutting edges = more chip engagement = more torque required per revolution at a constant feedrate).

It's partly why flycutters exist, to give small machines the capability of milling larger diameters with only a single point of engagement.

That said, a dovetail cutter is a more rigid tool than the fly cutter. I would just run it as slow as your machine is capable of otherwise you will lose the corners of the teeth rather quickly. Cutting oil would be ideal as well. Form tools in general create much higher stresses than single point or plane tools.
 
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the largest nick is 13mm long, and 2mm tall. a 45 degree would give you a nick that is not as tall.
 
Very nice...
I'm thinking for me 13mm is not long enough...
So one I guess I could move a hair left or right but than would lose the nice arch bottom.
But I don't think it would be that noticeable if only moving maybe 1/8" inch.

Have you tried increasing the length of the nick??
And about how long does one nick take to mill ?
 
thanks for the formulas kuraki, i probably run all my cutters too fast ! taximanny, the 13mm length depends on how deep you go, those cuts were three different depths, so they are of different lengths. . just by eye, the largest 13mm x 2mm one looks to be about 1mm deep. if you buy a larger diameter, it will get wider and more shallow.
 
hey, if you tell me what length you are looking for, i will cut one and measure its height and guess its depth. that will help you decide on what diameter and angle you are seeking.
 
OK, I just measured the fly cutter I use for cutting nail nicks - it's 3" diameter which cuts a nail nick .70" to .75" depending on depth of cut. I typically try to cut about half thickness of blade for the nail nick (I think that's what I was told to use). I use about 300 to 400 rpm for cutter speed on a Grizzly G0619 desktop mill.

My understanding is a nail nick should be cut with a cutter of the diameter that will give the correct length of nail nick by just feeding into the blade, without having to travel down the blade. This travel into blade gives the desired arc to the nail nick.

I took a 1/4" carbide tool bit and ground the required profile using my 2X72" grinder. I tried HSS but they didn't last as long, and I was just learning also.

Ken H>
 
With linear travel you'll lose the arch on the bottom, with a flat bottom the length of the distance traveled. However with a little math or experimentation you could resolve that by moving out in the depth axis and up in the Z axis and making another plunge cut in the center of the flat.
 
i have been trying , but i am having trouble loading photos. i made one 5/8" long. it is 3mm tall, and guessing 1.75mm deep. it looks way too tall for my taste. , i will buy a 45 degree and use that. i cannot comment on the time, as i said today was my first time using it so i used aluminum to test it. i did notice, with a slower speed the finish inside the nick was smoother and more consistent. i will continue to try to add the pic.
 
I see
I've found some cheap sets in eBay not the 60 and 45 degree.
I'll have to pick up a set and see.

Thanks for the info...
Pictures are worth a lot
 
You could buy some drill rod and design your own cutter. Even O1 at Rc63/64 with oil would hold up ok. Once you get a shape you like, get some HSS.
 
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