Calibrating Z-Axis with Rock Chuck

[hotpop]

I just received my machine back from CW a week or so ago. I then installed my new Rock Chuck. I noticed my vector cuts were cutting deeper then they should and decided to check my Z-Axis calibration. During the cal. process it requires the 1/8" cutting bit to be installed. Then the truck comes back to the brass roller end and descends into the the pocket next to the brass roller. The problem is that the cutting bit bottoms out in the pocket and I get a Z-motor stall.

The Rock Chuck assembly is longer then the CW QC Chuck.

Do I need to reinstall the CW QC to check depth calibration?

Is there a specific tool length recommended when using the Rock?

[dbfletcher]

Basically you want to put the bit as high as you can go before getting to the cutting flutes. I had this problem too and had to remove the collar I was using and have the cutting bit with about 1/16 between the bottom of the rock chuck collar and the cutting flutes. I only have issues with the 1/8 cutting bit, the 3/8 straigth bit, and the carving bit.

Hope that helps.

Doug Fletcher

[Jeff_Birt]

It would do you no good to install the QC and calibrate. When you reinstall the Rock Chuck it would not be calibrated correctly again. The machine expects that the bit's length will fall into a small range due to the design of the QC and holders. The automatic setting of tool height offset by the machine saves the user from the difficult task.

If you use an aftermarket chuck then you have the freedom to install the bit with as much protrusion as you want (for good or bad). Since the machine has no way of knowing that you have an aftermarket chuck on it is up to you to get it set up correctly so your bits only protrude within the same range as they would with the QC. If your not using some sort of depth setting ring on the bit with your Rock Chuck then you have the potential of creating problems with every bit change as the machine expects the bit length to be within the small range as the original QC.

[hotpop]

Thanks Guys,

That makes sense. It sounds like I got my stop collars set a little to high.

[Pratyeka]

That's funny, because I never used collars and have been inserting all kinds of bits at different lenghts in the Eliminator chuck and never had any problems. Before 1.152, I just eyeballed them, but now I just press "continue" when the machine check the bit lenght. I must have used the ogee bit at different lenght over a range of 1/2" without problems.

Even with the QC, the lenght of the bit in the adaptor can vary, depending how the bit is installed in the adaptor after replacing it. Are you saying the calibration routine of the machine is programmed to be calibrated with a specific bit with a specific lenght?

[dbfletcher]

The only instance I have run into that might be related to what jeff said is when i use the keyhole bit. I select the 3/8 straght bit in the designer gui... and it works fine with the much shorter keyhole bit. However, what i did run into today is when I was keyholing a board ON A SLED... when it tried to touch down on guide plate, it acted like it expected the bit to be much longer than it had measured. it wouldnt go all the way down to touch the plate and would give me the message to make sure the sliding plate was slide to the board.

I just stick a small piece of 1/2 material on the guide plate where it would attempt to touch. this made it happy and it carved the keyholes just fine at the correct depth. My other keyhole projects where not run on a sled and I didnt have this problem.

Althought today was the first time I did keyholes on 1.153 too so that may have something to do with it.

Doug Fletcher

[liquidguitars]

Hotpop,

With your "Rock" chuck installed run a depth calibration " keypad 06" using the 1/8" cut bit. The bits need to be seated very tightly in the "Rock" and at the same indexed hight every time you change a bit during the check bit process.


Are you saying the calibration routine of the machine is programmed to be calibrated with a specific bit with a specific length?

I do not think anyone is thinking this.. a minimum size is expected. Its the milling stock top z indexing thats most important like in most CNC's. I stop the indexing process as the bit drops down to the deck Hit Stop, "03" and jog to a location that accounts for thicker or thiner wood. That will zero out the z for that bit. The trick is to find the same hight when replacing the bit the second time :) the way the bit adapters do and not hit "continue" indicating an error .
LG

[Pratyeka]

I have the modified Eliminator installed. Anyway, the last discussion on the matter of bit height, if I recall correctly, stated that pressing continue instead of retry told the machine to use the reading it just made and go with it (latest software). I don't remember ever calibrating the Z. I'm getting totally confused now.

This weekend I will run some test and make my own conclusion. Not to criticise, but everytime this subject comes up, I seem to get more confused:confused:

[dbfletcher]

I also recall it that way pratyeka.

Doug Fletcher

PS. Can you try your keyhole bit to see it it reacts that same on a sled (.75 sled with .75 board)

[liquidguitars]

Hmm, now yo have me confused :) anyone ready to put this to bed?

let say the second time i install the same bit this time 1/4" lower, it still will be ok to run at the exact place i indexed it in the first time?


LG

[dbfletcher]

If I am understanding you LG, then yes. When I do a project and it first prompts for bits, I normally just ignore all the bit change requests and leave the carving bit in.. since that is where it normally starts. then when i have to change bits during the project, i swap em out.. get the message the the bit depth doesnt agree with what it measured at the start of the project, select (2) continue from the menu and it happily goes off and performs as expected.

Doug Fletcher

PS. By the way, my understanding of the "double measurment" philosophy is just another way to try and make the machine more idiot proof. It assumes you put the right bits in the first time, and if the measurements dont match the second... it serves as a "hey dummy.. r u sure you put the right bit in" kinda message. Also, my understanding is the first measure ment is only used for that "rror check" and the second measurement is what the machine really uses for the operations.

[liquidguitars]

OK I think i know what the confusion is have you index all your bits the same depth as the carving bit?

I use some shorty bits so everything has a different hight to it in relation to the carving bit..


so the second time i install the same bit but let say a 1/4" lower, will be at the exact place I indexed on the wood surface? This would be a good test for Ron J to look into.


LG

[dbfletcher]

For me, no... I use the full bit set.. and they are all of very different lengths. At first i tried to do what you are suggesting, but there is just no way to make the short bits 60/90 degree v- bits, keyhole bit, etc come even close to the carving bit. For example.. since i leave the carving bit in for all of the first measurement in all the bits... this is generally an inch to an inch and 1/8.... and then on the second measurement when i put the real bit it... it could be as small as 1/2 inch to closer to 2+ for the 3/8 straight bit.

Doug Fletcher

[liquidguitars]

Good to know.. Looks like I could been wasting time tring to get them all the same durning the bit check. ARG! :)

LG

[RMarkey]

Neither the chuck nor bit matter when calibrating depth, so as long as the bit doesn't dig into the board, does not slip and it can touch everything it needs to.