Bit optimization

[mikechip]

Hi folks,

OK, I got this month's news letter and promptly glued up 2 nice pieces of Cherrywood to carve it. I made sure the design had bit optimization on "optimal" and also that the machine was on "optimal". Ran the project and I got a piece that I would rank as 75% good. I've included a photo to show what I'm talking about. There are tracks where the 1/16" carving bit appears to have gone "low resolution" on me. If you look in the picture, which is the piece straight off the machine by the way, you can see sections that are as smooth as baby's skin, then right next to it, it's all choppy and out of whack... it's not the grain of the wood either, you can see that clearly in the photo... half way through when I noticed this, I opened the shield and wiggled the bit - it was tight as a gnats behind sitting on a lemon wedge. So I closed the cover and completed it.

Any suggestions? Did I do something wrong or is this the best I can expect? I've read people claim that their projects run on "optimal" in many cases only require some scotchbrite and they're ready for finishing...

[cnsranch]

it was tight as a gnats behind sitting on a lemon wedge.

That's funny, I don't care who you are:mrgreen:

Double-check and see if your bit is loose in the adapter - that's my bet.

Looks like it's dragging along the carve without spinning.

[Digitalwoodshop]

First post.... Makes me ask if he knows the 7 inch rule of wood....?

The machine has 2 rollers 3.5 inches from each end of the bit making the 7 inches... When the board is being held by BOTH rollers and FLAT to the table the carvings were smooth. When the end of the board came out from under the roller, the messed up carving started 3.5 inches from the edge of the board in length. Hence... The 7 inch rule of WOOD....

A Sled with a block of wood keeping the project under both rollers would help... I design all my projects with a 4 inch waste block on the right side of Designer. I either tape a block on the end or use a carrier board.

Lots of GOOD Pilot Error stuff in Tips and Tricks.

Welcome and Good Luck,

AL

[buffybuttons]

The problem does not seem to be with optimal quality since other parts of the clover are still very smooth.I would bet some sawdust or small chips of wood got caught in the z axis belt and gears. Push up and down on z truck and see if it gets hard to move anywhere along its travel. inspect z belt and pulley gears thoroughally behind z truck for sawdust buildup. Sawdust buildup is hard to see in this tight area but every gear tooth must be checked. After having a similar problem I carefully used a dental pick and compressed air to get my z belt sprockets very clean. On the first cleaning try i missed a spot and of course that is where the lump of sawdust was hiding.
also recheck bit for up and down looseness in the chuck as well as bit adapter. it should not move even a pin head in width or it will hurt resolution.

[Digitalwoodshop]

To expand on my answer.... Question? Your board size is the same size as the project? Your not staying under both rollers? The board only being held by one roller can move up and down toward the bit making the marks.

OR.... Every new bit, you should remove the Allen screws from the bit holders and apply blue lock tite. OR the bits can come loose in the bit holder and move up and down... Or the Allen screws come loose and Jam the bit holder in the QC.

OR..... With the machine off, grab the bit tip and pull in 4 directions... A loose Y or Z Bearing or bad QC or Bit Holder can cause this....

But back to my first post.... If the bad carve starts 3.5 inches from the end of the board then that is when it popped out from under the roller and was FLOPPING around.... Like riding a bike with one hand.... Sometimes it works just fine.... Other times you CRASH.

2 Rollers and it will carve just fine...

We all had to learn the same lesson. I was new once too.... And I asked for help.

AL

[rjustice]

Sure looks like a tool runout, or slipping problem to me too... I would also suggest checking the setscrews to see if you had one or both back out...

To answer your question though, No this is not the best you can expect at all... Given a tight machine, chuck, and true workpiece, I too have carvings come out with hardly any prep work before finishing...

Let us know how it works out!

Ron

[rjustice]

One other thought hit me... I havent carved this pattern yet, but is the area that has the bad finish flat, and the rest on a slope??? If so, you may have a chipped carving bit right on the tip. Check that out carefully!

Good luck!

Ron

[AskBud]

Since these lines seem to only appear on the top-most surfaces, I would suspect the Z-belt & gears may have some dirt hampering the upward movement.
AskBud

[PCW]

Since these lines seem to only appear on the top-most surfaces, I would suspect the Z-belt & gears may have some dirt hampering the upward movement.
AskBud


Does sound like sawdust in the z belt or gears from looking at the picture.

[Digitalwoodshop]

Another thought..... Sawdust buildup on the top of the board and a loose bolt holding the bottom smooth rails. Riding over the sawdust raising the head.

AL

[mikechip]

Wow.. thanks for all that great info - you guys (and I mean that in a non-gender specific way) rock!!

OK - here's some more info;

For every project I run, I build a sled. It consists of a 1/4" MDF bottom which measures the full L x W of the project with the 7" rule applied (I'm a little OCD so I use an 8 inch rule with 4 inches on front and 4 on back). Then I will take two rails of 3/4"-1" wide wood along the full length of the sled. Then I place a slab of 4" long wood on the leading edge and the trailing edge. I place my work piece snugly in the middle (it's all held down with carpet tape - I love that stuff, but yet I hate carpets... weird). Then I pass it through the 36" wide belt sander so the height is DBA on all surfaces.

I think that the entire paragraph above was the really long way of saying "yes I understand the 7inch rule".

The tip of my bit is not chipped. It's as beautiful as the day I drove it off the lot.

I will periodically blast the sawdust off with the air hose. While visual inspection revealed that there was no dust or particles stuck in the truck belts or anything, I suppose it doesn't eliminate the possibility that there was some transient pieces throughout the carving.

And there is NO wiggle in that little 1/16" baby either. The set screws on the bit are tight (I already used the gnat's-*** joke so I'll spare you the redundancy) and the QC fitting was snug up inside the chuck.

In the absence of anyone finding a second gunman in the grassy knoll on this perplexing dilemma, I guess what I'll do is give the entire machine a good once-over and get everything that even resembles dust or chips out of it. Then I'll ensure proper travel on all axes, then re-run this project... but not in cherry, I can't afford it so I'll use poplar and give it to someone as a gift (hey - poplar grows in Ireland too, so it's not inappropriate to use for a gift).

If any lightbulbs go off in anyone's heads, or if you can find something wrong with what I did, please feel free to school me up...

Mike from Foster Rhode Island

[gumbo]

I may be way off here but I had a simular thing happen to me. My problem was the heigth senser on the back side of the z truck was dirty. In the back of the z truck motor there is an optical wheel and a sensor, the wheel had dust on it and the sensor could not tell where it was. But in my case the bit kept climbing higher during the cut. maybe something like this is happening here but with dust just on a portion of the wheel.

Just a thought.

[cnsranch]

It just seems so weird that there appear to be "scratches" on the carve - looks like something is being dragged along the board (that's what caused me to think it was a loose bit). Could the cut motor be cutting out (no pun) occasionally, resulting on the bit not spinning while it's being moved along the carve?

[mikechip]

As far as the motor "stalling out" I didn't notice any pitch changes in the motor during the carving (and I was in the shop for the 4 agonizing hours it was cutting). But then again - who knows...

After checking all the things you guys suggested, I just went to do another run (in poplar and smaller scale) and after I insert the bit during the intiation phase of the project, it stalls with "Error 313 Z axis stall" or something to that affect... does this shed any light on the "sitch"?

I mean, I guess it solved the problem of doing a shabby job with the bit optimization because it's not doing that any more... it's just sitting there... silently... with an error code...help me.

[dbfletcher]

As far as the motor "stalling out" I didn't notice any pitch changes in the motor during the carving (and I was in the shop for the 4 agonizing hours it was cutting). But then again - who knows...

After checking all the things you guys suggested, I just went to do another run (in poplar and smaller scale) and after I insert the bit during the intiation phase of the project, it stalls with "Error 313 Z axis stall" or something to that affect... does this shed any light on the "sitch"?

I mean, I guess it solved the problem of doing a shabby job with the bit optimization because it's not doing that any more... it's just sitting there... silently... with an error code...help me.

I might have missed it from your earlier posts, but what chuck are you using on your machine? The LHR QC or the Rock.. or another chuck?

Doug Fletcher

[AskBud]

The Z-Axis is the up & down movement of the truck.
AskBud

[mikechip]

I might have missed it from your earlier posts, but what chuck are you using on your machine? The LHR QC or the Rock.. or another chuck?

Doug Fletcher

I'm using the standard QC type that came with the machine...

I can't get the thing to even work anymore. I keep getting a 313 z axis stall error no matter what I do. I'm so exhausted with trying to get this machine to work, and so tired of sending parts back and forth to LHR.... I don't know what do at this point...

[dbfletcher]

I'm using the standard QC type that came with the machine...

I can't get the thing to even work anymore. I keep getting a 313 z axis stall error no matter what I do. I'm so exhausted with trying to get this machine to work, and so tired of sending parts back and forth to LHR.... I don't know what do at this point...

Thanks. The only reason I bought it up is after I first switched to the Rock i was using collars on my bits. 95% of the time i would get a z-axis error would check the bit on the keypad side of the machine. Apparently with the collar and the insert, the bit lenght was too long on that check and would almost always stall there. After removing the collar, all was well. This obviously wont apply to you since you are using the QC, but that was what prompted me to ask.

Doug Fletcher

[chebytrk]

Thanks. The only reason I bought it up is after I first switched to the Rock i was using collars on my bits. 95% of the time i would get a z-axis error would check the bit on the keypad side of the machine. Apparently with the collar and the insert, the bit lenght was too long on that check and would almost always stall there. After removing the collar, all was well. This obviously wont apply to you since you are using the QC, but that was what prompted me to ask.

Doug Fletcher

Hey Doug... on the flip side I put collars on mine (using Rock Chuck). When I don't use collars I can never place the bit it at the exact same spot as when it first measures. Even though some say to ignore it and just hit continue, it kinda bothers me. Also, in your case how far up do you put the bit in the sleeve? I even thought of maybe drawing a line with permanent marker on the bit to use that as a "set" point for the bit in the sleeve.

[dbfletcher]

Hey Doug... on the flip side I put collars on mine (using Rock Chuck). When I don't use collars I can never place the bit it at the exact same spot as when it first measures. Even though some say to ignore it and just hit continue, it kinda bothers me. Also, in your case how far up do you put the bit in the sleeve? I even thought of maybe drawing a line with permanent marker on the bit to use that as a "set" point for the bit in the sleeve.

I had the collar just above the top most cutting flute.. probably within a 1/16 of that. With out the collar, I need to insert the cutting bit so the top most cutting flute is about 1/8" from the sleeve. Anything more and I get a stall. I am one of those users who just hits continue on the bit measure/match prompt. I dont even bother changing bits on the first "pre-use measurement". For now... it seems either method works fine.

Doug Fletcher

[Digitalwoodshop]

Some more possibilities:

The screws on the back of the Z Truck holding the belt are loose.

The screws holding the Z Motor to the Z Motor gear box are loose.

The screws or bolts holding the smooth rods that the main head slide up and down on are loose under the machine.

AL