On Sunday 20 January 2013 11:28:00 Dave Caroline did opine: Message additions Copyright Sunday 20 January 2013 by Gene Heskett
> On Sun, Jan 20, 2013 at 2:49 AM, Gene Heskett <[email protected]> wrote: > > Greetings all; > > > > Has anyone cut any threads with g76 lately? > > yes and I checked the change log looking for updates to see if any > changes were made > > > I fired off a routine that 4 months back worked great, carving a > > 1/4-28 thread for me several times last fall. Tonight, without any > > changes in the .hal file that would affect threading ops, still set > > to make a 1/4-28 SAE thread, and it came out at about 24 tpi. And I > > haven't a clue. My encoder still has 39 slots. Etc, etc. I am on > > the bleeding edge development branch. > > > > If someone could go cut a thread with this 2.6 code and check it for > > true tpi, it might help me find whatever dumb effect I've put into > > this in my spindle servo tuning. > > > > Thanks folks. > > > > -- > > Cheers, Gene > > -- > > I believe the docs need updating to show some problems inherent in the > code I'd agree, but what I've found sure wasn't the show stopper this is. > The acceleration and deceleration time is not mentioned in the docs > and also does it fire off an error > if the acceleration and deceleration is programmed IN your desired > thread drive line > also if you set your spindle at a speed where your Z needs to run at > or above its maximum velocity no error is given Already noted. I've not seen an error of that nature, and in any event, the spindle speed in this example code, 100 rpm, is well below any accel/maxvel limits. I have run that same code at 750 rpms & the only thing that seemed to change was the left/right registration of the cut thread, it slides to the left as the rpms go up because the actual sync point is late, internally delayed from the index pulse by the accel time from a dead stop. X accel's for the leadout cut were at one time chosen to be about 1/2 turn of the spindle but the spindle was turning about 400 revs when I did that calc. At 100 revs, z has probably a 10x or more headroom, it can run 39 ipm steady state. Current settings are: [TRAJ] DEFAULT_VELOCITY = 0.250 MAX_LINEAR_VELOCITY = 0.65 [X axis]: MAX_VELOCITY = 0.60 MAX_ACCELERATION = 5.50 STEPGEN_MAXACCEL = 11.00 [Z axis:] MAX_VELOCITY = 0.3765 MAX_ACCELERATION = 3.00 STEPGEN_MAXACCEL = 6.00 Z is slower, its a 2/1 geardown to the screw, both motors are 430 triple stacks, x is 8 wire series, z is 8 wire parallel wired, amp wide open to get better accel's. Screw is 16tpi, but will eventually be a 16mmx5mm, its on a boat by now I hope. I probably won't change the gearing as creep speeds now aren't even worth calling a surveyer to set stake & measure it later... And it is geared, not belted, using the old 'change gears' gears. > I believe to get good threads with the current code run more slowly > and have a good entry and exit time That code I posted has a start point at +.200" from the start of the thread itself, lots of time to steady the motion. > There is also a strange path seen when making a left hand thread with > an entry taper Not tried yet. :) > I do a tool change, the next move is to the start point, except it > seems to have two parts to the move, the first going to the drive line > rather than the taper start. Thats correct. With separate homing operations in my setup, I did the x home to that gage when I switched to the single tooth, a cutoff tool blade suitably sharpened, and it appears I need to fine tune the code, the thread is about -0.015" undersized, but thats my problem because that code never before had a known home setting to work from, the tpi it cut is the real problem. In fact, the next thing I did after seeing that was to put a 1.050" travel dial indicator on the carriage to see if a 1.000" move was actually 1.000", and it was. I haven't figured out a way to home the Z with that tool as the broad side of the tool holder would hit the Z side of gage first. I should make some measurements of the offset & put it in the tool table, but haven't gotten to that point just yet. One thing at a time lest I overload my now ancient wet ram. :) > Your question has made me say something before I did a bug report. > > > Dave Caroline > Thanks for looking at this Dave. Thinking out loud, would it be possible to include the ChangeLog in the package I get 2-4x a week from the buildbot? That would tend to give us enough we might even be able to point a bit more specifically when a problem pops up. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> I bought some used paint. It was in the shape of a house. -- Steven Wright I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. 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