Re: CAD experiment entry

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Peter Homann" <groups@...> wrote:

>
> Hi Brian,
>
> I think that this is why it is good to have a discussion here. There are
> all sorts of CAD/CAM users here so hopefully we will get some really good
> and honest reviews of various option.
> I've only progressed to creating 2d dxf files and feeding them through
> sheetcam to produce the separate processes.
>
> That's how I'd do the T-nuts. A separate layer for;
> 1. milling the height
> 2. drilling the hole
> 3. milling the relief
> 4. milling the outside rectangle
>
> Cheers,
>
> Peter

When I moved from using a 2D approach to using 3D models and CAM that uses solid models it was a revolution in productivity.

This would be my approach if I had to do a t-nut in the mill. Obviously this is machinging technique and not CAD.

1 - Start with a piece of stock that is at least 1/8" taller than the finished nut.
2 - Clamp in the vise on parallels with 1/8" being held.
3 - Face off about .010" to give a clean and true surface.
4 - Profile the entire part neck first and then the flange.
5 - Spot drill with a 90 deg spot to a depth that will also create the chamfer in the hole.
6 - Dill the hole.
7 - Tap the hole. (OK so I am using a Haas with rigid tapping)
8 - flip over and clamp on the neck with what will be the top surface of the flange on the top of the vise jaws.
9 - Face off the top hat left from OP10 until the face intersects the already profiled flange walls.
10 - Debur and tumble

I reality we do it in the lathe with live tooling from a round bar. All the steps up through 8 are the same. Step 9 would be part off at the proper flange thickness and step 10 would be automatic bar pull and repeat. For the small sized Tuff nuts we make it is 75 - 140 nuts per 4 ft bar and 2 - 4 hours a bar. Far more efficient than using the mill and doing only a couple at a time.

In the mill the top hat work holding approach is a valuable techinque. I was taught this by the first real machinist I hired. While never heard of it as a hobbyist, it is pretty much the standard approach in machine shops. A very useful technique regardless of what size machine you use.

Tim Goldstein
A2Z Corp
A2Z CNC division
3955 S Mariposa St
Englewood CO 80110
720 833-9300
Toll Free 877 754-7465

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