Bit length in Rock

[want2b]

Got my Rock and was lucky, the QC came off without heating. My question is exactly how much of the bit should be exposed below the Rock?? Have read everything I could and found a post where someone cut the shipping plastic tube to 1.25 inch and used it to slide the bit into the Rock. Same thread several people mention the bit cutting into the plastic behind the brass wheel. Don't want to create a problem having to much bit exposed. Sorry if I missed the answer but really want to be sure of the bit length before I carve.
Thx, Rich H

[DocWheeler]

Rich,

Keep in mind that this is just my opinion.
I have the 1/2" Rock so the adapter to 1/4" adds length to the chuck.
In my case, I am setting the bits so that the 1/4" length shrink tubing is right at the ends of the flutes so that the flutes start 1/4" from the chuck insert.

My thinking is that the further below the bottom two bearings on the Z truck the bit tip is, the rougher the carve will be because any "slop" or runout there is, the more it will be magnified. It would also have more "mechanical advantage" to create wear and other problems.

[sk8nmike]

I agree with Doc about the shorter the better. Keeping this in mind, the length of the bit has little to with the depth of the carve as the machine measures the start of the bit (the tip) before it starts the carve. So, 1.5" of exposed bit or 2" pf bit, then machine will only cut 1.5" deep. As for cutting into other parts of the machine, if you only have .5" of bit exposed and the machince decides it's time to cut into the plastic it's going to happen.

[mostlycold]

I agree with Doc about the shorter the better. Keeping this in mind, the length of the bit has little to with the depth of the carve as the machine measures the start of the bit (the tip) before it starts the carve. So, 1.5" of exposed bit or 2" pf bit, then machine will only cut 1.5" deep. As for cutting into other parts of the machine, if you only have .5" of bit exposed and the machince decides it's time to cut into the plastic it's going to happen.

I have another question, when I do a more complex carve, the machine asks me to insert all the bits I'm going to use in the carve before I start. When it gets to the point that it wants a particular bit, how do I know that I inserted the bit to exactly the same depth as when it first asked for it? Does this matter, or does the CW measure it again after each bit goes in? If it's doing that, then why does it ask for all of them before you start?

[dbfletcher]

It does measure again... and that is why most of us with the rock ignore the bit change request at the beginning. When the project starts, it will prompt for bit changes... remeasure.. and then give u a warning that the bit doesnt match what was first measured. After you put the correct bit in, just select continue on the keypad and off you go.

Collars (shrink tubing, vinyl tubbing, drill collars, etc) will also allow you to switch bits and be assured the measurement will be the same if yiou do want to do the bit changes twice.

Doug Fletcher

[Digitalwoodshop]

The only bit I had a problem with was the 1/8 inch cutting bit. I made it TOO Long at first and it was just above the bit plate as it arrived at the bit plate and then it drilled the plastic that holds the brass roller on it's left side dip.

See how I choke up on the bit with my locking ring.... One for length and the other to keep that FLAT spot from being at the rock Locking Pin.

The 1/16 inch endmill was cut shorter after this picture.

AL

[Wilbur]

If you are using the 1/4" rock you can use the tube it came in. Cut it to 1.5" and let that be your guide. That will give you a 1.5" of bit from the rock to the tip of the bit.
If you use the 1/2" rock with the 1/4" adaptor this will drop the bottom of the chuck down 1/4" and you will need to account for that. In that case you would need to cut the plastic to 1.25" instead of the 1.50". This is what I do.
Now when using different bits. I let the machine go through each step but I don't change bits. I use the carving bit to measure each one but I do change bits into the carving when I am asked to do so.
I will get a message that the bit is not the right length so I mash continuer. The machine will measure and cut. When I use the router bits I don't use the plastic tube to measure. I slide the bit all the way up and go.

If the bit is to long it can cut into the roller but I have not had this happen any by using this method of measuring. I did have the cutting bit to become loose enough that the bit dropped down and did cut in to the sand paper roller.

For proper bit exposure you can measure the exposed bit on the CW QC with the bit holder on, to get that.


Wilbur

[liquidguitars]

It does measure again... and that is why most of us with the rock ignore the bit change request at the beginning. When the project starts, it will prompt for bit changes... remeasure.. and then give u a warning that the bit doesn't match what was first measured. After you put the correct bit in, just select continue on the keypad and off you go.

I need to try this more but if i get a bit depth mix match i will be cutting at the first Depth measurement location right?


let say i need the bit to index off a guitar body at the center of the board
the bit sticks ot 1" if i set the same bit the second time to 1.125 cut will be wrong right? The idea is to use the indexing features of the CW like different landing points for each job. I think each bit needs to be in the exact place each time. But I could be off base here..




LG

[eromran]

If you are using the 1/4" rock you can use the tube it came in. Cut it to 1.5" and let that be your guide. That will give you a 1.5" of bit from the rock to the tip of the bit.
If you use the 1/2" rock with the 1/4" adaptor this will drop the bottom of the chuck down 1/4" and you will need to account for that. In that case you would need to cut the plastic to 1.25" instead of the 1.50". This is what I do.
Now when using different bits. I let the machine go through each step but I don't change bits. I use the carving bit to measure each one but I do change bits into the carving when I am asked to do so.
I will get a message that the bit is not the right length so I mash continuer. The machine will measure and cut. When I use the router bits I don't use the plastic tube to measure. I slide the bit all the way up and go.

If the bit is to long it can cut into the roller but I have not had this happen any by using this method of measuring. I did have the cutting bit to become loose enough that the bit dropped down and did cut in to the sand paper roller.

For proper bit exposure you can measure the exposed bit on the CW QC with the bit holder on, to get that.


WilburHow does the bit drop down enough and cut into sandpaper when it is not even below bit?

[want2b]

Thx to all, the feedback is helpfull, my guess on the cut sandpaper issue was from a router bit which is larger in diameter than the space between the rollers and since the machine has to be able to cut lower than the top of the belts to do a 'tab cutout' something was either wrong with the MPC or a problem with the machine. As noted in above post someone had a bit loosen, like a router the bit will surprise you in its choice of travel.
Rick H

[eromran]

Thx to all, the feedback is helpfull, my guess on the cut sandpaper issue was from a router bit which is larger in diameter than the space between the rollers and since the machine has to be able to cut lower than the top of the belts to do a 'tab cutout' something was either wrong with the MPC or a problem with the machine. As noted in above post someone had a bit loosen, like a router the bit will surprise you in its choice of travel.
Rick HHe said it was the cutting bit that came loose not a larger router bit. I would under stand a router bit since its wider.

[TIMCOSBY]

to cut the belts with the 1/8" cutting bit even if it was 4" long.

[sk8nmike]

It's physically impossible for the cutting or carving bit to cut the sandpaper belts. Maybe come out of the holder and nick the belts.

Here's a photo of my fix for setting the depth of a bit.

FYI and 12" tube of .24" brass tubing at Home Depot cost $1.75 and will give you 40+ rings. I can also still use the bit in my router.

[Creekwood]

Cutting some large letters out, I change from the carving bit to the cutting bit and when the CW started measuring the bit length it came up with Z Axis error? Did not write the code number down.
Could this be having the bit to long in the Rock?

[Wilbur]

It was a cutting bit that hit the sandpaper.
I have always just snuged the bits up in the Rick but in this case I must have not tighten enough.
The cut started at the top of the carving and mover to the left working itself to the end with the key pad. When it got there I saw sparks coming from under the board and stopped the cut.
Took the board out and could see that the bit had moved down in the Rock enough that it was rubbing the paper as it went around the roller.
The bit did not go through the paper but it did cut the paper at the curve.
I have also had the cutting bit to go through the board and hit the rod that goes across between the rollers and broke the bit.

Now, in both cases this was my fault, Not the machines fault at all.

Wilbur

[Wilbur]

After looking much closer I must have been wrong about the bit hitting the sandpaper.
It sure did look like that was what happened at the time and There was sparks and a place on the sandpaper that looked like a cut but after looking closer it was something else.
This I do know , the bit did hit something and after very close look I just can not see what it was.

Wilbur

[Chief38]

the rod that the sliding plate moves on. I had the same thing happen when a bit slid down from the chuck. (Sparks & all)

[rjustice]

the rod that the sliding plate moves on. I had the same thing happen when a bit slid down from the chuck. (Sparks & all)

Hi Chief,
When this happened were you using the 1/8 cut out bit or the carving bit? Also were you using a Rock Sleeve?

Thanks,

Ron

[Chief38]

Hi Ron,
Was using the 1/8 bit in sleeve in the 1/4 rc. Also 1/4 carving bit had slid down slightly, half way through the carve just prior to the cutting bit problem. Looks like I had a slight burr or saw dust in the clamping nut channel & clamp had not pulled in far enough although the screw felt tight. Cleaned & oiled and have not had any further problem
Herb

[rjustice]

Im not sure if you guys have seen these pictures or not, but to get optimal clamping force with the Rock sleeves, be sure to turn the slit in the sleeve to point towards the hex in the clamp screw (where you insert the "T" handle to tighten up the tool).

To keep from mis-clamping on a flat when you arent using a sleeve, face the flat towards the same place (hex in the clamp screw) see the pictures...

The burr you described is what can happen when you get the clamp nut located in a flat... You do not want this to happen... You want to clamp on the smooth part of the shank

Hope this helps...

Happy Carving,

Ron