Re: [CAD_CAM_EDM_DRO] Tapered Threads?

Running a tapered thread requires moving 2 axes in coordination with the
spindle/each other. G33 (ie you must be using TCNC) only coordinates
one axis with the spindle.

I too need a tapered thread for a project I'll be working on in a few
weeks. I've written a canned cycle for turning non threaded tapers in
TCNC, ie a G77 cycle with a Tword for the taper, in inches per foot. (I
hate those units...)

Ie G77 Z-2 x0.5 T-0.1 I-0.05 F8 P2

Where:
z = endpoint of the taper
x = final radius of the NEAR point of the taper
T = taper per foot between the near point and the end point
I = the cut depth
F = feed rate
P = number of finishing passes at the final diameter/taper.

Note: *my* G77 will take the shaft down to the major diameter of the
taper and then turn the taper itself. Not all G77s are the same.

I've also written a canned cycle for TCNC for turning threads, ie G76.
It does the whole threading process, ie:

G76 Z-2 X0.5 K0.05 I-0.005 P2

Where:
z = endpoint of the thread
x = final radius of the thread depth
K = thread pitch
i = cut depth
p = number of passes at the final depth.

Note: the shaft has to be at the thread OD before calling G76. I'll
probably add an A parameter for the angle of the thread tool as it
affects the offset calculation.

What you/I want to do (ie tapered threading) requires that these two
canned routines be combined. First you'd have to cut the non threaded
taper using the G77 command with the appropriate parameters. (This can
also be done using a number of G01 commands.) Then we'd have to use an
enhanced G76 command with a T parameter to cut the TAPERED thread.

I will be writing such an enhancement to the G76 command in the near
future. I need to speak with Dave K and see if the MultAX command will
support spindle synch in TCNC. Right now the G76 uses the OneAX command
and it does synch.

There is another issue here: I don't have the right to distribute TCNC.
That belongs to Dave. We'd need his permission to share this
enhancement.

I hope this helps.

I'd like to thank others who have <patiently> answered some of my posts
over the last week or so.

Kim

On Wed, 2003-10-29 at 07:53, Linc Reed-Nickerson wrote:
> Hi,
>
> I'm new to lathe programming, I have a Bridgeport with a Microkinetics
> conversation and just converted my lathe.
>
>
> I need to turn some tapered threads for making studs for a steam locomotive
> boiler. 12 tpi, 1 in 12 taper... various diameters... all boiler threads
> are 12 tpi.
>
> I understand the G33 command to set the threads, but not how to make a
> taper... is that set in G33 or by a previous command?
>
> Anyone able to help with a few lines of G-Code?
>
> Linc Reed-Nickerson
>
>
>
>
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