Tiny dovetail 3

[TheTick]

We're machining a dovetail onto a set of mass-produced small aluminum (6061-T651) parts. It is a 60° dovetail, 5.5mm [.216in] wide x 1.25mm [.049in] deep.

The original plan to CNC mill the dovetail seems a no-go. The tolerance is ±0.05mm, which is way too much to maintain a decent sliding fit at that small size. At LMC, parts may even disengage and fall apart. Sliding fit tolerances for a Ø3mm hole are in the range of ±0.02mm.

Is it possible to reach these tolerances with a CNC mill? It is a high-volume production part, so they are not in a hurry to do something more exotic. But, it seems we need something better.

 

[dgallup]

Does the dovetail go all the way through the part? If so then I think it could easily be fineblanked. There is up front tooling cost but with high volume that is easy to recover. Much cheaper than CNC. Depending on other features, you may need to finish the part on CNC.

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[TheTick]

Blind dovetail (for now).

 

[KENAT]

There are some medical device micro machining places that I've seen at events like

http://mdmwest.mddionline.com/

who might be able to do this kind of thing at reasonable volume.

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[ornerynorsk]

What you have described is not a particularly difficult operation for a decent CNC shop. These kinds of dovetails are produced by instrument manufacturers (think dial indicator mounts) in high volume on a relatively economical basis.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[capnhook]

Small broach, perhaps..?

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[TheTick]

I like the notion of instrument makers doing it. Sets a nice precedent.

I have limited power in this situation. The manufacturer is a client; I am a contract designer.

 

[MikeHalloran]

See

http://www.charles-supper.com/en/page/product.cfm?idProduct=22

Note that the pictured product comprises two _arcuate_ dovetails,
in about the size you want,
with their rotation axes at right angles
and intersecting.

They make straight dovetails, too, and their stuff is not as expensive as you might imagine.

You might order a few pieces just to get some design/ assembly/ construction hints and to get a hands-on feel for what they can do.





Mike Halloran
Pembroke Pines, FL, USA