Dove Tail End Mill Speeds and Feeds?

[MetalShavings]

When setting up to use a small 60 degree carbide Dove Tail End Mill, which dimensions on that End Mill do you use to figure your Spindle Speed and Feeds?

The largest part of the Dove Tail itself measures about 3/8". (or there abouts) The the Dove Tail then tapers down to much less.

Which of these two dimension is used to calculate my spindle-speeds and feed rates? Do traditional mathematical formulas apply with Dove Tail End Mills?

MetalShavings

[Geof]

Use the largest diameter for the speed and for the feed be conservative and use a quarter the chipload, or less, that you would use for an endmill of the same diameter.

Also if you are doing a dovetail slot, don't try to mill the it starting from scratch with the dovetail cutter. Use an endmill to first cut a groove about 0.001" deeper than the dovetail cutter will go.

[Gerry Sweetland]

Hi Metalshavings,
I don't have a lot of experience using dovetail cutters so hopefully someone with more experience will come along and add to the topic.

You use a strait end mill to remove most of the material between the tails and save your dovetail cutter for just the sides.

I am not exactly sure but I don't think normal feed and speed calculations apply but I think I would go with the major Ø of the cutter to start with.
It's kind of a touchy feely thing, go slow and remove chips and swarth as you go.

There is a pretty good thread here that covers some dovetailing Swingup external threading tool
Read thru the thread as the part about dovetailing is a bit down in the thread.

HTH
Gerry

[MetalShavings]

Thanks for the quick replies gentlemen:

I've used Dove Tail End Mills before but, only on manual machines where I could control the Feeds and Speed by feel.

It's always good to be reminded too but, I knew about removing most of the material that needed removing with a regular End Mill. I've just never used a Dove Tail cutter on a CNC mill before.

On this particular project I'll be cutting the angled slots on either side of a pre-shaped rectangular protrusion that forms the foot that slides into a Dove Tail slot on a gun barrel.

I still consider myself a newbie to CNC milling and I'm still kind of leery about using my good Dove Tail End Mill and possibly breaking it and ruining my project in the process.

Is it possible to program the feed in the Y-axis to have the same kind of feed you get when Deep-Hole-Drilling? You know; like when your drill bit will feed a small amount and then retract to clear the metal chips off the tip and then dive right back in?

I think this may be a good way to feed the Dove Tail End Mill into my part to cut my slots. That's basically how I do it when using a manual mill.

MetalShavings

[Gerry Sweetland]

Hi MetalShavings,

Just off the top of my head... can you create multiple identical operations except for LOC in SprutCam with the same tool but each operation going deeper into the cut than the last operation. Since you're using the same tool there would be no stopping between operations, it would just finish one and and exit out and then go back in. I would like to setup a model and try this out but I am right in the middle of something else but when I get done later today I will give it a try, sounds interesting and fun I could use this method in other projects.

In addition if you knew G-code well enough you could edit a program to work?
Gerry

[Gerry Sweetland]

Sorry it so long to get back
This is in ref. to just nibbling away at the cut.
There are probably other ways to do this but this is one I came up with.
I have attached a zip file with SC project.
I also attached some screen caps.
I'm glad Metalshavings asked this cuz it gave me a reason to figure out to make a dovetail form tool in SC
There is a dovetail 2D geometry file and image file located in the SC installation folders, here is the path for my install C:\Program Files (x86)\Sprut Technology\SprutCAM 7\Supplement\Tools\Axial for the .s text file and C:\Program Files (x86)\Sprut Technology\SprutCAM 7\Supplement\Tools\Axial\Images for the image file.

I'm amazed that once you figure things out in SC it just gets to be a better and better CAM program for the things I currently do and plan on doing in the future.

HTH some folks
Gerry

PS
by the way, each operation is just a copy/paste of the first or previous operation and just editing the stock dimension in the Perimeters dialog.

[MetalShavings]

Thanks Gerry:

This is very useful information for me. In addition, I never thought of doing this until I viewed your screen-shots but, one of the Wizards I've been using alot lately is the "Side-Clean-Up" wizard.

For my application, I think perhaps it would be faster and easier to make my small Dove-Tail cuts using this wizard. In the mean time I can practice the steps you've described in my SprutCAM simulator so I don't ruin any parts or take the chance of breaking my Dove-Tail end mill.

MetalShavings

[BobWarfield]

Nice write up on "nibbling" with SC, as you call it.

I just did an update to G-Wizard so it does feeds and speeds for dovetails, and I also added a page to the feeds and speeds cookbook about various techniques such as the nibbling to help minimize the stress on these delicate cutters:

CNC Feeds and Speeds for V-Bits, Dovetails, and Other Cutters

Cheers,

BW

[Gerry Sweetland]

Thanks Gerry:

This is very useful information for me. In addition, I never thought of doing this until I viewed your screen-shots but, one of the Wizards I've been using alot lately is the "Side-Clean-Up" wizard.

For my application, I think perhaps it would be faster and easier to make my small Dove-Tail cuts using this wizard. In the mean time I can practice the steps you've described in my SprutCAM simulator so I don't ruin any parts or take the chance of breaking my Dove-Tail end mill.

MetalShavings

Your welcome!

Nice write up on "nibbling" with SC, as you call it.

I just did an update to G-Wizard so it does feeds and speeds for dovetails, and I also added a page to the feeds and speeds cookbook about various techniques such as the nibbling to help minimize the stress on these delicate cutters:

CNC Feeds and Speeds for V-Bits, Dovetails, and Other Cutters

Cheers,

BW

Thanks for the GW update Bob. The first thing I did when this was asked was go to your program and see if I could see feed and speed results for dovetails there. Glad that it is now in the program.
Gerry