Cutting bit losing orientation, carving bit skipping large lines - see pics

[PSQRD]

So last week I decided to carve a Navy Chief anchor with a few cutouts out of a piece of sapele. (1/16 carving bit) Carving went smoothly and beautifully, I changed out the bit (1/8 cutting bit) and on the machines last pass it cut the top of the pattern straight through the center of the plaque and ruined it. Asked a few people and talked to LHR checked head pressure, seemed a little high (92 lbs) so I went through the steps of lubing the clutch assembly with white lithium grease according to directions underneath the crank handle and went through calibration steps entirely. Carved another plaque which I've done before, silhouette of Louisiana with some details in sapele, went well. Today I loaded a piece of cypress to cut out some car show plaques and noticed during the carving portion that there was a "skipped" spot where raised lines were not carved (see pics), I figured I'd let the carving finish running it's course and when it was all said and done I'd re-run just that area to clean it up. I loaded the 1/8 cutting bit to do the cutouts and at the end of the project found the first and second plaque completely ruined due to the same pattern "misalignment". Any help to keep me operational would be GREATLY appreciated. Just trying to find a solution! My machine specs are as follows:
C Machine
CarveTight Chuck
25 hours on the machine when I started this carving
the last maintenance was described above as well as replacement of the x drive gears a few weeks back
I have rubber drive belts
and I'm using the large harbor freight dust collector with the DC Insert installed

[mikemi]

Paul,

My question to you would be, are you using tape on the back side edge of the board so that the brass wheel has something to bite into? I won't use any kind of board and/or sled without using the tape.

Mike

[PSQRD]

I have not been, in fact the only time that I've used tape up until now was the carve I did last night that actually went relatively well but I noticed the tape kind of bunching up where the brass roller bit into it. I was under the impression that the tape was just for visual purposes to the sensor on dark pieces of wood. Do you think something that simple could really be the problem? (I will kick myself if it's the case) Like maybe it not biting the board and the machine thinking it's further along then it is?

[Iron Mike]

I supposed you already checked your design layout with a "Show All" command to see if any of the errors might be due to misplaced or forgotten cut paths! I had a project that stumped me for awhile because of that issue.

[Digitalwoodshop]

In my opinion it is the Brass roller loosing contact with the board. That is when the board is lost... from that point on all cuts will be off... When you first saw the skipped area.... I would have shut down the machine and gone back to the computer and first re named the project. Then deleted the messed up plaque from that file. Then delete JUST the Carving leaving you with a file with just 2 cut paths... Don't change any locations.... run that file and save the 2 good carves...

Something that saved me over the years is to put one or 2 strips of masking tape on the under side of the board along the brass roller path. This gives the Brass roller teeth something to bite into... It makes a poor man's Rack and Pinion on the board..... Because like I said above... The board lost contact with the brass roller and a real smooth hard wood can let the brass roller slip....

Honestly if I were doing this project with really good wood like this... I would do them one at a time.... AND I would do them with a Scrap Board sled.... See the picture... Hardboard with a 4 or 5 inch head board the same width and thickness of your good wood. Cut a blank slightly longer than the carving. Add another scrap board 5 or 6 inches longer to the end of the scrap sled. I put Masking tape on the bottom of the hardboard base ans 2 strips at the brass roller.

I tape the good wood blank between 2 scrap pieces. I use PLACE ON END and in my artwork I know the top of the screen is the brass roller end of the project. I draw a box the length of my scrap on the 2 blocks and put the art between the blocks on designer. Remember you can draw a box like a ruler and lay it on the board to aid in setup.

Even the Cut Out or Cut Path will work with a Scrap Sled if you make the correct settings. OR do it without the bottom backer board like the clock... Masking Tape is your friend...

AL

Retired Navy FCC(SW) E-7

[myshop1044]

Paul from looking at your post, it seems the x orientation was lost. I hoped you used the masking tape on the bottom side on the brass roller side of the board.
My next suggestion and it my not answer all your questions, but for a large project I would break them up into separate projects and used the 3/4" foam insulation board that you put in the walls of the house. This is a good test material and you don't waste good wood. I use all the lime to make sure the carvers goes smooth.

[PSQRD]

I think all my issues are pointing to tape on the bottom of the board. Floyd sent me a message stating the same thing - something so simply overlooked. Lets hope it's the issue, I'll be doing another carving this evening more than likely if not, then tomorrow. I checked for extra cut paths, didn't have anything there. Al, you're right about not wasting wood, especially good wood. This is my first time working with cypress, guy at the lumber yard talked me into it instead of poplar since it's a local wood and offered to sell it to me for the same rate since I'm a Marine lol. It cuts a lot like pine, a lot of pitch, the grain looks really nice when finished though. I've been planning on making a sled, just haven't got around to it, and already had a bad experience with the really heavy shelf particle board material. Sled making seems a little overwhelming when you look at the good ones and on the flip side when it comes to taping things up I've always been worried about a jamming issue under the compression rollers (Al, in your second pic the 1/2" tall piece of scrap looks shorter than the overall workpiece that won't jack up the rollers? I'll tell you what, this community is awesome when it comes to leveling frustration. I appreciate everyone input and assistance, I'll follow up hopefully with better news. Thank you everyone!
Paul

[Digitalwoodshop]

You are correct, the 2nd picture shows a thinner 1/2 inch board on the right side of the sled. The left side of the board is the head of the project and I use place on end and set the board length to just past the carving. The board will stop long before the 1/2 inch board.

Another option is to leave the board long and just put one scrap block at the end of the board and when the carving is done cut the project off the end of the long board using place on end.

I almost always use place on end... Center on board measures the board twice.... more wear and tear.... Tear as in belts...

AL

[cestout]

The rubber tires on the brass roller (O Ring) do ware. I am about to replace the one on my B machine because I was 1/8" off on an 8.5" carve between the raster carve and the vector carve. Did have tape on it.
Clint

[bergerud]

Check that the brass roller is not touching the front rubber belt when pushed down by the board. Looks to me like the x drive was trying to "catch up" to the brass roller as the brass roller was being driven backwards by contact with the belt.