Lesson Cutting Male and Female Dovetails in 6061-T6?

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seal killer
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Lesson Cutting Male and Female Dovetails in 6061-T6?

Post by seal killer »

All--

I have been thinking of making my life a little easier regarding the little machines I build that run around the floor . . . and sometimes outside, as well. Construction, cosmetics, and flexibility could be improved if I had some kind of modular system from which I could build frames. So, I am thinking about using 6061-T6 cross-pieces with male dovetails and female "connectors."

Too bad I've never cut a dovetail!

Here is my preconceived notion of how to do it. (I've read about it a little and should have read more but can't find what I read then, NOW.)

The slot should be cut with a regular end mill to depth. The dovetail cutter then cuts first one side of the slot to produce the dovetail and then the other.

How big a bite do you take with, say, a HSS dovetail cutter? Do I use the same cutter to create the male portion by taking material from opposing "outsides" until they look like the female, only different?
Thanks!

--Bill
You are what you write.
Jose Rivera
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Post by Jose Rivera »

I leave some 1/32 per side on the width for finish and go some .015" to .020" deeper.

The final dove tail will be the same amount less deep.
That will leave clearance in the center for debris to be in and the friction area much smaller than the whole bottom surface.
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gangel99
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Post by gangel99 »

I made some quick change tool holders - female dove tails - and broke a dove tail mill learning to take smaller bites than one takes with an end mill. It is a lot more like side milling than end milling. :oops:
Jose Rivera
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Samples

Post by Jose Rivera »

Here are some sample pictures of a dovetail cut out of a piece of 4140.
Attachments
DSCF4335.jpg
DSCF4340.jpg
DSCF4350.jpg
DSCF434-5.jpg
There are no problems, only solutions.
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Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa
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seal killer
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Post by seal killer »

gangel99 and Jose--

gangel99, thanks for that advice. I will remember it!

Jose, great pictures! Of course, you make it look easy. I will let you know how many cutters I go through. :)

--Bill
You are what you write.
JackF
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Post by JackF »

Bill,

If you plan to use a gib of course you will need to mill one side or the other more to accommodate the gib. I didn't on my first cross slide table but will fix that on my next go around.

Jack.
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Post by JimGlass »

Bill;

I figure the less work the dovetail cutter does the better for two reasons.

First, the less work the cutter does the longer it will stay sharp.

Second, Dovetail cutters seem to like pulling out of the collet or lifting the workpiece thus changing the depth and ultimately the size of the dovetail.

I have machined a lot of dovetail assemblies. Dovetails are just about the most challenging thing to machine. The depth is critical, width is critical and straightness is critical. I have ground a few dovetails but that is not always an option.

Vise I made with dovetail slide.
Image

"Y" axis of my CNC mill.
Image

Jim
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

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seal killer
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Post by seal killer »

Jack and Jim--

Hmmm. It is beginning to sound like my first attempt may not achieve perfection. :)

Thank you for the advice!

--Bill
You are what you write.
JimGlass
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Post by JimGlass »

Bill;

Machining dovetails takes a little practice but it is excellent experience. They usually end up a hand fit.

I usually use a black felt tip marker and ink up one of the dovetails. Try to mate the two dovetails then examine places the ink was removed to identify interference. File, stone or mill the high spots then try to reassemble. Watch for interference in the sharp corners.

Take your time. You may attempt mating the dovetails 15-20 times before they mate.

The problem with dovetails is you can remove more material but you cannot put more on. :roll:

Jim
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

www.outbackmachineshop.com
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seal killer
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Post by seal killer »

Jim--

I appreciate the help.

I was THINKING that it might be best to make the male portion first and then cut the female to fit?

Using ink is a great idea. Glad you thought of it!

--Bill
You are what you write.
Jose Rivera
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Post by Jose Rivera »

If you need a dovetail that need a better fit than what the cutter can give, then consider lapping the two parts to fit.
You can lap the gib as well. Lots of elbow grease !!
There are no problems, only solutions.
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CANINDUST
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Post by CANINDUST »

When working to a print with tolerances on it I always like to cut the female first so I can measure it with dowel pins and gauge blocks. I guess fit is more important than size to you unless you want to interchange you're parts you make.
Last edited by CANINDUST on Wed Feb 10, 2010 6:15 pm, edited 1 time in total.
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