Z axis stall with hole in encoder *** shaft

[want2b]

Started a carve and got a Z Axis stall. Assumed it was dirt or something lodged so shutdown and did a clean and check. Some dust but nothing lodged while the truck moved easily with no play. Cleaned up and restarted with the same failure. Restarted again and watched carefully and it occurred when doing the surface thickness test. Watched the next time and realised that the bit was going through the 'shaft' at the encoder assembly shaft after I selected the 1/8 cutting bit.
Way back when with an earlier version the machine had carved through when the bit didn't slow down fast enough after the 'insert bit' step and I had plugged the hole with a piece of plastic and epoxy. Never had another problem till now with it. The only difference I see is that I rarely use the cut out option. Just prefer to save machine time by doing them myself. Found a plastic cap with a pin on it and inserted it into the hole(no glue). Reran the project and no stall. Watched the bit test and noticed it carved down into the plastic, not a pressure mark but cut a 1/8 inch hole approx 1/16 in. deep during the 1/8 cutting bit select test. Hole was not deepened by the carving bit when it ran after the cutting bit. Does anyone have an idea how to resolve this? Does the machine run the cutting bit longer during the test than the carving bit?
Running 1.187 - project is Zan29's Majestic Sun-- pics attached but original hole is hard to see.
Thx ,
Rick H

[henry1]

change cut motor brush did you check them lately

[want2b]

change cut motor brush did you check them lately

Both replaced about 50 hrs ago
Thx, Rick

[bergerud]

This has been and ongoing problem and controversy. Some think the the cut motor runs too long because of not enough friction from the flex and brushes to slow it down. I think it is to do with an internal burn through in the C1 capacitor on the x termination board. The capacitor has a lower breakdown voltage and lets the motor run longer. (The job of the C1 capacitor it to turn off the triac which runs the motor.)

My bet is that you use opening the cover to pause the machine. I believe this is what zaps the capacitor. I am waiting for someone with this problem to replace their x termination board so my theory can be tested.

In any case, your machine will probability keep doing it. Some have used a dime to cover the hole, but, I do not think nickel is too good for bits! Some have used epxoy. (There is supposed to be a spring steel clip on B machines and up. Not to good for bits either.)

[Digitalwoodshop]

I agree with both theories... I open my cover as I have over 1000 hours on most motors...

So someone who has this problem.....

If you replace a X termination board and it changes let us know.... or someone with a A and a new C want to put the C board in the A for a test....

Then swap the motor too and let us know....

AL

[want2b]

My bet is that you use opening the cover to pause the machine. I believe this is what zaps the capacitor. I am waiting for someone with this problem to replace their x termination board so my theory can be tested.


Only thing I can be sure of is I have never raised the cover to pause the machine. In fact I can't ever remmeber pausing it using the stop button, just never had any reaason to pause.

Rick H

ps Just ordered the X termination board, will post results when replaced.

[want2b]

Mystery continues. Received new Xterm board today and replaced it.
1. Put a new plastic plug in the hole and started a carve of the Sun face without the cutout so only yhe carving bit was involved. Bit touched down without any damage to the plug and went to Carving the Pattern. Stopped the carve.
2. Started another carve with the cutout in place. Inserted the 1/8 cutout bit and it went thru the touchdowns without any damage. Inserted the 1/6 carving bit and it again went thru all the touchdowns ok with no damage to the plug and started carving. I went in to dinner and came back about 1 1/2 hr later and found the insert 1/8 bit. Inserted bit and after it 'spun ' the bit and went to the side to touch down it cut thru the plug and pulled it out and up when it lifted. Stopped the carve at that point.

What is different between the first test of the 1/8 bit and the second one??? First thought of heat but my thought is the delay in my return should have lessened that. Guess my option at this point is to be on the ball and hit the Stop button after it starts spinning. Why does it spin at all?? Can the machine sense whether a bit is in place or look for a vibration from a loose one??

Appreciate any help.

Thx, Rick H

[bergerud]

Well, not too good. Too bad the problem persists. Strange that it worked for awhile before returning to the same state. I wish I had a machine with the problem to play with.

My theory of zapped x termination board is not looking good. If I was to try and uphold the theory, I would have to say that it is being zapped by the cut motor. (You never used the open cover current interrupt to explain the original zap so maybe it is the cut motor.) It is known that cut motors with problems can take out the x termination board. My theory, however, is starting to feel to me like a long shot.

It will be interesting if your machine now consistently continues to over spin.

I think what people do as a work around to this is simply open the cover for a second to pause the carriage and give the spindle an extra second to spin down. Too bad if that is what you have to do from now on.

Someone with this problem posted a video years ago and it seemed to show that the motor was powered for longer than normal. If true, that does implicate the x termination board. I will pay you for your old x termination board and shipping if you are into sending it to me. I feel bad that you bought a new one based on my theory. (Also, I would love to put it into one of my machines and finally test the theory!)

[want2b]

Decided to do a quick check. Had not even removed the board or turned off the carver so I put in a new plug in the hole and started the same carve over from scratch. Asked for 1/8 bit, I OK'd it, machine did the spin, went over and tapped the new plug without doing any damage to it. I aborted the carve.
Will run the carve again completely later today when I have time and post the results.

Berg, thx for the offer on the board. I'll keep it in my spare parts. Thx for the info on possible causes, helps me learn more about what controls what in the carver. Last problem was a power supply that Al helped me work through with success. I'm another one of those who actually enjoy digging into a problem.

Rick H

update:

Went ahead and changed the cut motor brushes just in case a weak spring or faster wear than expected, pic attached of old. Did a good clean & lube and ran the carve again. Initial ask for 1/8 and 1/6 bits went off without a hitch and not a mark on the plug. When it did the spin after loading the 1/8 cutting bit it again did not stop in time and made a small hole in the top of the plug. I watched carefully during the initial bit selections and during both bits 'spin' it was stopped about the time the head started lowering but on the second load 1/8 it obviously keeps on spinning.

Logic says the same motor, same sensors, how can it happen?? Open to suggestions. Know I'll probably end up settling for pausing whenever a cut is required but would like to find a fix.

Thx.

[Digitalwoodshop]

To me the copper armature getting smaller in diameter must come into play here too. A smaller diameter and the springs don't put as much pressure on the armature letting it coast to a stop slower.

My theory early on was the delay time waiting for the spinning to stop was designed for a tight NEW machine and if my theory holds true my older loose machine with a worn thin armature spins longer. It would be a great fix if LHR came out with a update that gave you a keypad option with a selection of normal and extended delay after spin up for us older machine users... But that will never happen and especially for 1.187 users like myself.... As 1.187 is the XP of the CW world and will never be upgraded.

So the lifting continues... Machine is happily pumping out Tag blanks today for a few orders including a Oil Refinery Fire Department in New Mexico. I have over $5K in orders in the works and it would be much more difficult WITHOUT the CW pumping sheet stock into tags.... So on a Happy scale of 1 to 10 today... the Machine is a 10...


Long live Version 3 and beyond...

Engage...

AL