sinumerik 808d threading problem

zirconium · Dec 31, 2014

First at all:

Happy New Year for all of You!

I have a trouble with sinumerik 808D control (mounted on a L28 cnc optimum lathe machine), when programming threading cycles (Cycle 99 or G33) the tool remains quiet no operation is performing and a "wait for first thread cut" line is displayed. This kind of messages have no mention in manuals of 808D. I keep the outmost care in programming parameters for cycle99 and with g33 but I can´t solve this question so I ask for help.
Facing, Profiling and Turning cycles have no problems.
Thank You.
:confused:

J_M · Dec 31, 2014

Uhm, just throwing quick thoughts in air, but from memory id say thats normal message with G33 threading (Gives it always when you start threading cycle), did you try to punch more feed than 5%?, maybe use atrans to move starting point so you can cut in air, and/or try again without skp/sbl turned on.

G33 X Z K ?

zirconium · Jan 2, 2015

Thanks

JM thank you for your response.
I'm going to try and I'll tell you . By the way, what kind or brand of machines have you in machine shop? My specialty is the machining of very small parts for dentistry.

J_M · Jan 2, 2015

Normal machines, wide variety of milling machines & lathes, two with similar control as yours. As for products ground/rock drilling tools for example. Could you paste a sample of your program, most interested in where you command spindle & feed and thread cycle line?

Feed says 0.000 even when your feed is at 6%, though it might be right when it's in stop state.

zirconium · Jan 2, 2015

g18 g90 g71 g40
g95 g54
g0 x80 z40
t4 d1
s500 m03
g0 x2 z2
cycle 99 (0.00, 2.0000, -4.0000, 2.0000, 2.0000, 1.6000, 0.24000, 0.5000, 30.0000, 45.0000, 4,2,0.4000, 300103, 0, 0.0000,0,0,0,0,0,0,0,1 , , ,0)
g0 x80 z 40
M2

zirconium · Jan 3, 2015

How are you JM?
I follow your direction, put more %feed exactly 85% and it works but only I obtained one cutting pass. The line "waiting for first cut thread" is still displayed. But I notice that going down a little with the spindle speed potentiometer and raising then to the first position really works but the thread is a mess. What do you think about it?

J_M · Jan 8, 2015

Sorry, few days off from computer access, and that's a small part indeed.

// Clipped (Edit2)

Been on vacation last 3 weeks, i'll head to work tomorrow again, so i can check cycle99 with retranslate on machine with graphics to help with parameters.

Edit: External thread apparently, not that i can even think parts that small being made.

Edit2: Ok, did some more digging about cycle99, and it seems reference point should be same, unless your trying tapered. I think the reason for single cut might be parameter 8, finishing allowance is set to 0.5, while your parameter 7, thread depth is 0.24

pcasanova · Jan 8, 2015

https://www.youtube.com/watch?v=502CFOkrbbw&feature=youtu.be that might help
and j_m just posted what I saw. The FAL is .5mm and depth of cut is less.
change the FAL to .05mm and change the the IANG to 29 or -29(alternate between to front and back of the cutter on passes)

zirconium · Jan 9, 2015

pcasanova thank you.
But I saw this vid many times and I found no clue to solve question, but We notice (my old son and I) that set speed differs for more than 15% of actual speed. We are sure this is the problem core, but how to fix it?

zirconium · Jan 9, 2015

Hi JM, still on vacations? That's good idea because life is short.
You are ok all parts I make are machining from 0.125" and 0.175" round stock. Need to machine screws from 1.40mm diameter up to 2.30 mm.

J_M · Jan 12, 2015

Hmm, that screenshot is bit weird on that spindle speed, can't remember which was actual speed / commanded, but in either case, they should be same if override is at 100%.

Your current gear is selected for 3, is that right one for 500rpms?, just to be sure id try G97 if css is on from previous tool, don't know if that's even possible though, looking some of my programs, none have it, just G96 when turning, and nothing when drilling for example.

Try rpms near 650, and 300, and see if the rpms still differ?

pcasanova · Jan 12, 2015

I noticed your in your pic the SBL was solid at not greyed out. Do you have single block on?

And in MDI if you go

g95 s500 m3

does the RPM on the screen go to 500 rpm +/- a few rpm with the spindle over ride at 100%

zirconium · Jan 13, 2015

weird? a bit

Threading is possible only if you "play" with speed control potentiometer, example in 100% position you go down to 90% wait for a second and raise again to 100% that's the only way the things go on. Or when coolant pump is turning off. Can you explain this behaviour?
Thank You. :confused:

industool · Jul 14, 2020

Did you have any luck with the threading issue? I seem to be having the same issue. Makes parts just fine can't thread.

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