Y Axis Trouble....

[gwizpro]

HI all,

OOOPS, NEVER MIND. - I found the problem. The adjustment screw was loose on the y belt.

Well, maybe I screwed something up.
Replaced Y truck bearings and had the cables disconnect a bunch of times doing various maibtenance.

Well, went to do a carve after all the work and here is what is happening.

Start a project and after measuring and all the routines, when I get to the step where the Y truck goes all the way to the bit stop plate , the Y motor keeps running longer than it should and forces itself to jump three notches in the Y belt.
It is as if if it lost it's homing as to where the truck is.
It homes correctly tho on the keypad side.

Any help would be apprciated.

I could do a short video to show what it does if my expalination is not enough.

Thanks -- Tom

[bjbethke]

HI all,

OOOPS, NEVER MIND. - I found the problem. The adjustment screw was loose on the y belt.

Well, maybe I screwed something up.
Replaced Y truck bearings and had the cables disconnect a bunch of times doing various maibtenance.

Well, went to do a carve after all the work and here is what is happening.

Start a project and after measuring and all the routines, when I get to the step where the Y truck goes all the way to the bit stop plate , the Y motor keeps running longer than it should and forces itself to jump three notches in the Y belt.
It is as if if it lost it's homing as to where the truck is.
It homes correctly tho on the keypad side.

Any help would be apprciated.

I could do a short video to show what it does if my expalination is not enough.

Thanks -- Tom

Sounds like you did not tighten this screw after your repairs.

[Digitalwoodshop]

Tom,

3 Clicks at the Bit Plate is Classic "Worn out Y Gear Box Bearings".... The 2 bearings holding the big plastic gear have worn out. This lets the big plastic gear tilt toward the pressure or the center of the machine and away from the motor shaft. The Three Clicks are the Servo Motor shaft skipping 3 teeth. If you wait too long, the bearings jam up and then the shaft of the big gear starts to wear thin and this lets the big gear tilt further toward the center of the machine. Most people see the Y belt Loose and think it has stretched but due to it's design cannot stretch... The Slack was caused by the bearings and thin shaft....


I highly recommend replacing the 2 bearings when you replace the Cut Motor Brushes at 250 Cut hours. This is "Preventive Maintenance" as you should clean and lubricate the machine at this time. The Y Bearings take the MOST Abuse and you will be VERY PLEASED at the SMOOTHNESS of the Y Action if you replace them at 250 Cut Hours....

LHR sells the Big Gear with Shaft so you can replace it saving from having to buy the whole assemembly...

Here are the bearing numbers.

http://www.avidrc.com/product/1/bearings/170/5x11x5-Metal-685ZZ-bearings.html

Buy Local 685ZZ.....

Good Luck,

AL

[gwizpro]

Thanks AL, this time it was just a loose y belt adjustment screw at the bit plate end.

Here is a question for you. Will the y motor keep on turning for awhile if say the belt broke when the truck was heading to the bit plate?

Tom

[Digitalwoodshop]

Thanks AL, this time it was just a loose y belt adjustment screw at the bit plate end.

Here is a question for you. Will the y motor keep on turning for awhile if say the belt broke when the truck was heading to the bit plate?

Tom

If the belt broke on the way to the bit plate the Y Motor would still keep turning until the Encoder on the back of the motor was HAPPY.... Then most likely since the head was not at the bit plate would Bob down 3 times and fault out.

Still thinking that the tightening of the Screw was just fixing the symptom of the loose belt.... The Spring on the back side of the Y return is just like the one on top of the Z. It has sufficient spring to hold the belt tight... I would order the bearings now.... As you keep using the Y, it will cause it to become thin like my picture.... I ended up with 3 worn Y Gears before I realized there were 2 bearings inside the gear box.... One of my BLUNDERS.... My first time removing the big gear, the Bearing area was dusty and I thought that the bearings were BABBIT.... and that is why the Shaft was worn.... It was not until someone posted the pictures of the 2 bearings MORE THAN A YEAR LATER that I went back and looked at that gear box and then SAW the 2 bearings.... I was recommending for more than a YEAR to Lubricate the BACK of the Y Gear BOX shaft..... That is a long time to be giving bad or WRONG advice.... It Humbled me.... But like everyone, I am "Self Taught" on the machine..... I had even thought that the Q1 Transistor on X Termination Board was the DRIVER for the X MOTOR.... Thinking to move that much weight, it had to be a 115 Volt AC Motor.... I was also WRONG.... The Q1 is the On Off for the Cut Motor.... and the X Servo Motor is just like the Z Servo except a Serious Reduction Gear Set makes the little motor move HEAVY BOARDS.....


So order the Bearings.... They are most likely bad.... 3 Clicks.... That is the Motor Shaft.... Not the belt slipping.....


Good Luck,


AL

[gwizpro]

Al, I value your experience and read everything you write. But, in my particular case I actually watched the y motor spin and jump belt teeth 3 times. Numerous times while I tried to figure what was wrong, until it dawned on me that the belt was loosing tension. The screw that was loose was not the spring tension one, it was the other one on top that stabilizes the tension bracket. it was allowing the belt to get slack.
I did however pulled the y motor assembly last night and the gears and shaft are ok for now, they show little signs of wear on the teeth or the shaft. Will order them tho, as well as the x and y gears.
Getting more and more orders where the machine is needed to complete them.

PS. My background is in Teletype Machines for the Air Force, fixed them and also taught how to fix them. Then industrial maintenance for Rite Aid Wharehouses. I love electro mechanical devices and always take them apart more than I should just to see how they work. This machine for what it does , is quite a marvel in simplicity.... But, seeing as I keep forgetting that I am considered Old now (60). I always like to hear from someone else who delves into machines as I like too.
Tom

[Digitalwoodshop]

Excellent!!!!!!

AL:mrgreen: