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Tiny dovetail

Tiny dovetail

(OP)
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.

RE: Tiny dovetail

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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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Tiny dovetail

(OP)
Blind dovetail (for now).

RE: Tiny dovetail

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.

RE: Tiny dovetail

Small broach, perhaps..?

Proud Member of the Reality-Based Community..

To the Toolmaker, your nice little cartoon drawing of your glass looks cool, but your solid model sucks. Do you want me to fix it, or are you going to take all week to get it back to me so I can get some work done?

RE: Tiny dovetail

(OP)
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.

RE: Tiny dovetail

See

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

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

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