Problem- In Engineering Class, NEED HELP

[jturovskiy]

My class is working on machining a Jig to hold blocks of wood in order to make small toy cars on a Techno CNC Router. The Jig we need has to have abut eight 3/16" holes that we need to tap with 10-24 threading. If this doesn't really make any sense, I'm sorry since I hardly know what I'm talking about. We're using 6061 aluminum for the Jig and we have the tap for it, but we don't know what feedrate or what spindle speed we need to use for tapping the holes. Any help would be greatly appreciated!

[doorknob]

I don't have any direct experience with machine tapping, and it's not clear to me what type of machine you are proposing to do the tapping with. People have used everything from drill presses (with or without automatic tapping attachments) to lathes to milling machines to air-driven impact wrenches to do tapping.

Of course you could tap them manually. With a small number of holes, that may even be the easiest way to do it.

Perhaps someone with more direct experience can chime in with suggestions.

(BTW, 3/16" holes appear to be slightly larger than the hole size recommended in the usual charts for 75% thread with 10-24 bolts, but maybe that is by design)

Also see Tap and die - Wikipedia, the free encyclopedia for an introduction.

[jturovskiy]

Oh, yeah I forgot to mention that. We have a chart for tapping and if I remember correctly we needed to drill .1495" holes in order to tap them. We're just not sure what speed and feedrate we need to use when tapping.

Also we're using a Techno LC 3024 Tabletop Router.
The website is http://www.techno-isel.com/CNC_Route...C_TableTop.htm if that will help anyone that knows anything about tapping that could help.

[MMICKELS]

Does the machine have rigid tapping? If so you'll need to feed the tap at its pitch. 24 threads per inch is .0416" feed per revolution. So if your speed is 600 rpm then the feed will be 25. inches per minute.

[MMICKELS]

I don't see anything about tapping on that machine. Hand tapping is probably your safest bet.

[jturovskiy]

Oh! My fault. We're using the router for something else. For the tapping, our instructor wants us to use an EMCO Mill 55. Here's a link if it'll help.
Concept Mill 55 - CNC Milling Machines

Sorry, for the mixup. Again, thanks for the help

[doorknob]

Not to overly complicate things, but you probably need to figure out and then state what kind of tap you plan to use. For example, there are taps that work by cutting the threads into the material, different types of taps that work by pushing the material out of the way to create the threads, and still other types of taps that are actually specialized types of end mills, which require a completely different method of tapping the hole.

[MMICKELS]

Here is a tapping routine for bronze.

N5 G28 G91 Z0 M09 T5
M06
M01
G80 G90
M41
S500 M03
G00 X1.4246 Y-0.8225
G00 G43 Z1. H05 / M08
G98 G82 R-0.15 Z-0.23 P250 F5.
X0 Y-1.535 R-0.05 Z-0.11
X-1.535 Y0
X0 Y1.535
X1.535 Y0
M09
G80 G90