proper length of cutting bit

[skeeterman]

What is the length that the 1/8th cut off bit bit can extend past the collar of the sleeve in rock chuck. having problems here lately with z axis stall, when checking bit length .I
can run the machine if i use the 1/16 carving bit on initial setup and when it comes time to do cutout i can change bit and all is fine.
I have went from 1 1/4" extended to 3/4" extended past sleeve collar with 1/8" bit with same results.
My tab where the bit touches down on hasnt got a hole in it, but i went ahead and tryed the dime trick, (didnt help)
steve

[skeeterman]

Also this is happening to two of the three machines i have. i can take same bit and sleeve out of the one that it works on and put in either of the two and it will z axis fault
steve

[lawrence]

I'll be honest, I struggle with this as well-- any info folks can give will be appreciated

Lawrence

[badbert]

I made a gauge... but unless we are using the same adapter... it won't help you. I have a split collet from my router. I saved a broken cutting bit. I wrapped the shaft in shrink wrap. I then cut off 1/4" from the edge. I put it in top of the collet and then slide the bit in from the bottom until they meet. This positions the bit in the collet repeatably. I then slide the collet in the chuck until it bottoms.

[skeeterman]

i use the sleeves that came with the rock chuck i purchased. (all three machines have rock chuck) thats why its weird that two machines will not accept the length that one will .

[bergerud]

Are your bit plates all the same height? I think there is a variation in heights and they can also get bent. Do the heads all crank down to the same distance from the board? If these distances are all the same, it really is a puzzle. Maybe crank down on a board under the bit plate and measure the height of the bit plate above the board.

Do you get the z stall if the board is 2 inches thick? Then the bit cannot touch anything but the bit plate and the board.

[Digitalwoodshop]

Time for a little SCIENCE here to solve this problem.....

Lets have a few users post some Scientific Results that will help us solve this.

We know the reason that the Z Stalls is because the Window or Length for the 1/8 inch CARVE TITE bit is OPTIMIZED and STANDARD for the CarveTite Chuck.

So in layman's terms, there is a window of length that the CW is EXPECTING. And to optimize the machine, the Z Current Feedback is turned off or NOT Monitored UNTIL the 1/8th inch bit reaches that window. At that time during THAT window of length of the bit, the Current of the Z is being monitored by the computer. At the MOMENT it senses a increase in current as in the bit HITTING the bit Plate, the Z Reverses Direction and the computer uses the ENCODER PULSE Count as the 1/8th Bit Length.

So the Good thing about this.... No more AIR CARVES, ok.... Less Air Carves.... A Air Carve happens when you have dirty Z Rails, Bearings, or even the Z Belt... the bit is going down to touch the bit plate and encounters a speed bump on the Z Path... That results in a Increase in current.... In the PAST if the bit was 1 inch away from actually touching the bit plate, FALSE DATA would be generated at to how long the bit IS.... The Result could be a AIR CARVE.


The Down Side.... IF as users of the ROCK we install a 1/8th inch Cutting Bit in the machine and the length WE Choose is LONGER or SHORTER than the Optimized CT BIT, then if the bit is LONGER it will HIT the Bit Plate BEFORE the Current Sensing is turned on and the machine will continue to FORCE the bit into the bit plate until the Z STALLS.... SO... we need to mount something on the 1/8th bit so we get CONSISTENT length.... Having this problem come up at the LAST Bit change and Stall the machine means more WORK doing some of the project over... As seen in the picture, I use 1/4 inch locking rings with a set screw.


So the TEST....

Install a 1/8th inch cutting bit in your machine and lift the Z Head all the way UP to the mechanical stop and turn it on. Option, Sensor Data and down to Z Data. It should be 0000 and since you put the head up into it's mechanical stop it is 0000 at Top Dead Center.

Now move the head over and gently down and touch the Bit Plate.

My reading was 0.866 to just touch and .909 at starting to deflect the bit plate.

This is using a Rock Chuck and a 1/4 inch Stop ring.

So lets hear your numbers.... Post what chuck and what numbers, touch and deflect...

Remember the bit plates can BEND over time DOWN. This could account with different machines in the same shop swapping a working bit to another machine that does not work... The Bit Plate is BENT on one....

I have NEVER got into the Calibration Data on any of my machines... So that number for each Axis could play a part in this too... the number of pulses to rotational motion... We called it Scale Factor in my Navy Analog Computer Days...

A Summery of the RESULTS of this thread should be made into a Tips and Tricks that will give new users the Number Range to mount a ROCK Bit.... It may be as simple as telling the person to mount your locking ring on the 1/8th inch bit at 0.900 and you will be GOOD....

Lets post the results.... And NON working numbers too...

AL

[lynnfrwd]

Two other things to know about your 3 machines, Skeeterman:
1. Do you have heavy duty traction belts or sandpaper belts on these three machines?
2. Do you have the new Board Tracker (metal piece) or the old Board Tracker (plastic piece that would eventually get a hole in it)?

[bergerud]

i use the sleeves that came with the rock chuck i purchased. (all three machines have rock chuck) thats why its weird that two machines will not accept the length that one will .

With what Al says, this begs the question: Are the two machines C and the other A or B?

[lynnfrwd]

Looks like two A and one B.

[skeeterman]

I have two A machines and one B machine, it is an A and a B that are giving me fits one of my A machines is working fine talked to Al this evening and will perform some test tomorro on all three.
all three machine have sandpaper belts , all three have the plastic touch off area by the brass roller, but they are in great shape no holes.
steve

[lawrence]

One more factor in our tests will be whether we are using the "dime method" to cover holes by the brass roller....

I'll try to do the test this weekend if I can

Lawrence

[lynnfrwd]

Rats. Back to the drawing board...

We have another customer not on the forum that is having an issue with his Rock and 1/8" cutting bits. Trying to figure it out, but we don't have one.

[brdad]

I know it probably doesn't help much because of all the other variables, but I have my 1/8" bit extending 1.32" from the 1/8" adapter, which adds another .246" from the rock chuck. I put a spot of superglue between the bit to the adapter to keep it from moving since it's the only 1/8" diameter shaft bit I use. B machine.

[skeeterman]

thank you all, we will try to figure this out? as stated before i did not have a wear spot but put a dime there just to see if that would help ( it didnt)
i will check the distance on all three machines with same bit with the sensor check Al sugested. and post info tommorro,
what i dont understand is how if i put the 1/16 carving bit in as the 1/8th and run it thru all the measuring cycles it will take it even though i can put same length on cutting bit and it will not
steve

[Old Salt]

I have had a similar problem with one of my C/W on 1/2 thick material. I know tape a thin board to bottom and make it come out to 3/4 in thick only then will it work.

[Digitalwoodshop]

I believe since LHR is the main source of the 1/8th inch cutting bits and the machine and software is optimized to the length of the CT bit then as ROCK users we just need to make our 1/8th inch bit in the ROCK the CORRECT length... And the only number that counts is the number of pulses from top dead center of the Z to the Bit Plate as that is what the machine program is looking at....

Because there are at least 2 versions of the 1/16th carving bit as seen by my own purchases AND there is a wide variety of V60 and V90 bit, LHR is being "NICE" to us and keeping the Window of LENGTH of Bits a bit WIDER.... As in a longer or shorter bit will still work without Driving HARD in to Designer and STALLING.

SO once a few post the DATA it will become a little easier to understand. The first measurement is the Bit Plate. That in my opinion is the Critical one.... If you are using the dime on the Brass Roller plastic Plate OR on the Right Side Guide does not mater as it all starts with the touching of the Bit Plate. Improper bit length of a 1/8th inch cutting bit will STALL the machine and it never gets to the Dime.

SO for anyone having a 1/8th inch ROCK problem my suggestion is to place a bit in the machine.

Move the head up to touch the pin on top.

Turn on machine with a card in it.

Select 0 or Options, 7, or Sensor Data, and use the down arrow to go down a few to find the Y and Z Data that is now 0000.

And the reason that I had you move your head to the top is that it makes 0000 position where ever the head is when you turn on the options and sensor data and z data.... 0000....

Now move the bit over to the bit plate and down to just touch it...

FOR ME... This was 0.866 to just touch. IF your numbers are not close to 0.900 then loosen the Rock Chuck and Adjust the BIT LENGTH until is is close to 0.900 on the LCD. Then move your locking ring up to the rock chuck so every time you install the 1/8th inch bit you get it installed at the same length as the CT. Try and see what happens..

I went to my shop and got readings on one of my 4 machines yesterday that has never Z Stalled stalled.

SINCE the CT is the OPTIMIZED version and everything else is NEEDED to match the CT... Please post some CT Z Readings.

And what can make this number different between C machines is a BENT BIT PLATE...

ALSO post the version of DESIGNER you are using as LHR may have different numbers for different versions of Designer....

I am still running a very old version of designer....

Good Luck,

AL

[bergerud]

But Al, Skeeterman has A and B machines. Is this data going to help him? Also, the programmed "window" for length must be bit dependent.

You know, I have used really short bits and really long bits and have never had these problems (my ER16 is as long or longer than the Rock). Something else must be going on here.

[brdad]

thank you all, we will try to figure this out? as stated before i did not have a wear spot but put a dime there just to see if that would help ( it didnt)
i will check the distance on all three machines with same bit with the sensor check Al sugested. and post info tommorro,
what i dont understand is how if i put the 1/16 carving bit in as the 1/8th and run it thru all the measuring cycles it will take it even though i can put same length on cutting bit and it will not
steve

When you make these two bits the "same length", is this the distance from the bottom of the rock chuck, including the adapter(s)? In other words, not just how far the bits extend beyond any adapters used.

[bjbethke]

Also this is happening to two of the three machines i have. i can take same bit and sleeve out of the one that it works on and put in either of the two and it will z axis fault
steve
This may have nothing to do with the bit lenght. The "Z" truck error maybe from dust building up behind the two 1/4 inch shafts, you need to take the dumb assumbley apart to fix that, it's a somewhat an hour enhanced job, but is a few hours of carving going to hurt you too much? With selling to the Arkinsas HillBillies you can't make more then $1.00 per hour, it's great traning. I make more money from my donactions then from my carvings. Most of them I give away.

[skeeterman]

here are results from a what i would call a controlled test
I used same card in each machine with same mpc to be carved and same bit and sleeve ( the bit length at bottom of sleeve was 1.075 and the sleeve collar is .244)
machine 1 which is a (A) Z data from dead top to bit plate is (.682 ) tried to run the simple cuttout and it worked
Machine 2, wich is an (A) Z data from dead top to bit plate is (.890) tried to run the same and it also worked
machine 3 which is an (B) Z data from dead top to bit plate is (.748) tried to run the program and it would not
yesterday only one A machine would run but had different cards and different mpcs.
steve

[skeeterman]

dont know how that smiley face got in there that was suposed to be an 8 (748)

[Capt Bruce]

Skeeterman,

It looks like your keyboard has been hijacked by a roque Smileyface
Bruce

[CarverJerry]

I have a B machine with a Rock chuck. Before I changed over to the Rock I made a gage from a plastic tube that a tool came in (the 1/4" tool slides in and out easily) I cut it to length from the old QC adaptor tool length. I use the gage on both the 1/16" and the 1/8" tools and have never had a problem. (KNOCK ON WOOD) My tool length is the same everytime I change tools. With in a couple of thousands of an inch that is. I call it my tool length setter.

[skeeterman]

purchased another machine over the weekend from a fellow forum member, this is a B series with carvetight and rubber belts and i did some quick measurments from bottom of z truck to bottom of 1/8th cutoff bit here are results of my meaurements between carvetight and rock chuck
bottom of ztruck to bottom of 1/8th cuttoff with the carvetight is 2.650
bottom of z truck to bottom of 1/8th cuttoff with rock chuck ( on my A models that seem to work at this length) is 3.070
a total of .420 difference
I still cant get my C model with the rock to not get z axis stall when touching the tab by the brass roller
And BJ what Dumb assembly are you reffering to. glad you are doing good with your donations, i did very well with these hillbillys around here during the holidays and still am

[chief2007]

A friend of mine has a rock chuck - when he puts the bit in the adapter, he lines it up so the flat end of the bit flush with the top if the adapter. He says this works best for uniform bit measurements and so far no stalls.

[Digitalwoodshop]

If you get a Z Stall going down on the left side look for a hole drilled into the plate on the left. Not sure if the "C" units have a metal plate.

What we need is MORE posts from the "C" Users with the Encoder Data to touch the Bit Plate... THAT is the important number that Designer is looking for and is the Tripping Point with chucks other than the CT.

Setting your bit to THAT number with a locking ring will solve the Z Stall Problems....

Would be curious if you could post the Z Encoder Numbers on your machine and also the LEFT side numbers TOO on the machine with a left side stall.

AL

[bergerud]

I think the machines are different. The software must know the machine is C and uses different criteria. For example, my bit plate on my Dust Cap is a good 3/8 inch higher than the normal bit plate. No problem on my B machine. Only a slight raise in the bit plate for my friends C machine and after touching the board asks to reload bit. Seems like closer tolerances.

[henry1]

I had that problem and the plate on the left side was drill out by the bit and would give you a bad reading, what I did I used a like a razer blade you clean windows to take paint off and broke a small piece off and glued it were the bit touch and let cure for a while and then your good to go, work for me

[skeeterman]

the tab by the brass roller on the c machine that i am having problems with has a metal cap on it, no holes in it
my two As has just a plastic tab, one had hole a couple years back and i put JB weld in hole and it has lasted.
Al i have posted the Z encoder numbers from dead top to bit plate in earlier post, not sure about the z numbers on tab side
steve

[skeeterman]

with my C version machine the 1/8 cutting bit has to be 1.0 from face of sleeve collar and no more than 1.06 in order for it to not get z axis stall so it is a very tight window.with this being said i now have problem with 3/16 carving bit bought from carvewright, it has the pressed on sleeve and when placed in the rock on my c version machine i have same problem, Z axis stall when touches the metal tab by brass roller.whereas it works fine on my version A machines with rock.
LHR is there any way we can get this length of bit issue on version C fixed .
steve