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LotharSys
06-13-2011, 10:20 AM
I am looking to build something similar to mini tent poles, and need help building a prototype.

What I am going to need are around 15-20 100mm long metal dowels about 5.2mm in diameter. They will need to be hollow, with a 2mm diameter hole running through them, and have unthreaded male and female ends on each piece that mate.

This is my first time RFQing here, so if I didn't do it quite right, I apologize.

Regards,
LS

abcmojave
06-13-2011, 12:09 PM
LS,

A diagram would help. Along with tolerances, surface finish, timeline, etc.

LotharSys
06-13-2011, 03:02 PM
The timeline is just a general as soon as possible. Within a month would be nice.

The surface doesn't need to be finished, but there can't be spurs and such along the interior or the mating surfaces.

As for tolerances, whatever allows each piece to mate. The only inviolate rule is the outer diameter can't exceed 5.2mm, and the inner diameter can't be below 1.8mm. I'm not sure what tolerances are normal in this kind of work.

Attached is a screenshot of a simple SketchUp of the rod, to give a general idea. The other end is merely the female counterpart to the male end shown.

LS

Dualkit
06-13-2011, 08:04 PM
Drilling a 4" deep .078 hole isn't a lot of fun in most metals. First you need to select a material, it would be nice to use brass, or if steel is needed 303 stainless. Another thing t.i.r. or runout is an issue drilling deep with a small drill, that is how far the drill ends up off center. That will need to be spec'd out. This is a part where it is critical to let us know what the machinist can get away with, that is the difference between $10 parts and $100 parts.

LotharSys
06-13-2011, 09:39 PM
303 stainless sounds fine.

If the length of each piece needs to come down from about 4" to about 3", that's not a huge deal.

As for centering the hole, its not a huge deal with this prototype, but the male female ends (I'm envisioning about a 3.6mm diameter for the male part) need to mate.

The main thing is keeping costs down while still allowing each piece to mate, the overall length needs to be about 40" (or at the minimum 20"), and a central vein about 2mm in diameter throughout.

LS

Excelmachine
06-14-2011, 03:56 PM
If these are for purely prototype purposes, why not just find the right sized tube, have someone machine some plugs with the step and then glue them into your tube? In production, you might want to look into having a tube swedged down to provide the stepped diameter, would be really cheap to do in quantity. Just an idea.

Control Engrave
06-14-2011, 04:01 PM
Hi All,

I'm new to this forum, so I'm going to aplologize up front for asking a totally off topic question. Heres the question: How do you start a new forum/thread on the CNC Zone? I don't see the tab anywhere.

Thanks

LotharSys
06-14-2011, 04:17 PM
That makes total sense, but I don't know where I can find 5.2mm diameter hollow metal tubing. Honestly if I could find that I could probably fake the whole thing well enough to show it off.

Any ideas on how to find the tubing? Or does someone have something similar and can make the 10-15mm long plugs to make a quicky male end (with half in, and half exposed)?

LS

LotharSys
06-17-2011, 09:36 AM
Ok, this is closed. Thanks for the quotes.

LS