Max recommended cutting Depth?

[jpitz31]

Hello All,

I did my first "real" cutting last night. Making the top and bottom plates for the dust collector, as discussed in the Dust Collector thread.

Question on maximum bit depth for cutting. I was cutting MDF and did a maximum cut depth of .125 per pass. Machine labored just a bit in the tight corners. (this would be cut path with 1/8" straight bit)

Wondering what others have found to be the optimum bit depth per pass for soft and hard woods.

At .125 per pass am I babying the machine or can I go deeper per pass?

I know that on harder woods you want to make shallower passes.

Just want to get a feeling on what others are using for production cutting.

Thanks

Joe

[cnsranch]

I broke a cutting bit taking one pass on 3/4" ash - my fault - way too much to take on.

It scared me enough that I don't take more than .25" per pass.

It would be great to have an option on the machine to set the type of wood you're carving - that way it could default to the proper depth. Easy to do, but I wouldn't want to take on the liability if I were LHR, had set the parameters, then had guys breaking bits.

[SteveEJ]

I broke a cutting bit taking one pass on 3/4" ash - my fault - way too much to take on.

It scared me enough that I don't take more than .25" per pass.

It would be great to have an option on the machine to set the type of wood you're carving - that way it could default to the proper depth. Easy to do, but I wouldn't want to take on the liability if I were LHR, had set the parameters, then had guys breaking bits.

And change the feed rate!;)

[jeff412]

When I first got my machine I could easily cut all the way through southern yellow pine. I have even cut all the way through on Red Oak, but I wasn't afraid of breaking a bit at the time. A couple of months back I started breaking bits. I don't know if it was the software or the QC.(It started when I went to 1.134) I broke 5 cutting bits, even at .10 depth. I then changed the QC. It improved, but I still broke two more bits. I have since gone to the Rock chuck and haven't broken a single bit. I guess what I'm trying to say is that if everything is working correctly you should be able to cut all the way through SYP, but if something is even a little off you will be spending $40.00 on a new bit. I was actually ordering two bits at a time there for a while. I haven't gotten the guts to go back to a full cut through yet, but I am back up to .25".

Jeff

[jeff412]

And change the feed rate!;)


Amen!

Jeff

[liquidguitars]

I use .32" max pass.

LG

[ChrisAlb]

For me it depends on the wood and the length of the board. I use a single pass for "most" woods but will sometimes reduce it on things like Brazilian Cherry and other very hard woods. Most of my carves are in pine or poplar though so a single pass works fine.

The length thing for me is just an accuracy issue. If the project is over 3 feet I like to use one pass to avoid the "possibility" of it not tracking the same path accurately multiple times. For the most part, my CW tracks accurately but I have had times when it didn't.

[mtylerfl]

I use a single pass 99% of the time (I carve/cut Select Pine).

However, a couple months or so ago, I started assigning a Max. Pass of .3" for cutouts through 3/4" thick stock on projects that will be distributed to others.

NOTE: Even on projects for distribution, I still use single-pass for cut outs on stock that is 1/2" thick or less, or cuts within carve regions that are 1/2" thick or less - the end user can always customize cutpath assignments themselves at any time via the Cut Out Control window (with a cutpath selected, click on the Scissors icon or go to Tools/Edit Cutout in the menu bar to customize the settings). More details about the Cut Out Control window are described in the Tips & Tricks - ISSUE 12 - September 2008 "Designer 1.131 New Feature Highlights " (http://www.carvebuddy.com/PDFs/CW_TipsandTricks_Newsletters/CarveWrightTips&Tricks_Sept08.pdf)

[jeff412]

Since my last posting, I have made several cutouts using the single pass. All of the cuts have been in select pine. If you are breaking bits, there is something wrong. In my case it was the chuck. Even though I changed the chuck I was still breaking bits. When I went to the rock all of that stopped. I have not had a single project fail for any reason since swapping chucks. (knock on wood) Projects used to fail frequently before. Coincidence? Don't know, but I am finally happy with my CW machine.

Jef

[Digitalwoodshop]

If you are breaking bits then I believe there are 2 main causes....
A bad QC or Bit Holder with BB Marks making the 1/8 inch cutting bit flutter it's way through the cut and breaking.

The second is loss of contact with the brass roller. The bottom of the board must be perfect with no missing wood in the brass roller edge. For hard wood that the brass roller has a hard time gripping a strip of masking tape helps.

$40.00 will buy a lot of masking tape....

AL

[Kenm810]

Haven’t broken a bit yet,
Part of the reason, I owe to what I learned from “Al” and his Masking Tape.
(The brass roller has a hard time gripping hard or smooth surfaces,
a strip of masking tape really helps.

$40.00 for One Bit -- will buy a lot of Masking Tape....
I keep a good supply on hand! :cool:

[rickyz]

I just broke a bit from cw that I have had for less than a week. and it was in a rock chuck to boot. I was using select pine at optimal setting trying to cut out the bow for the christmas wreath project which was also purchased from cw. I used the 1/8 cutting bit from rcjustice and other parts cut fine but the bit really screams. I wanted to try out a cw cutting bit to see if it made any difference in the noise level. It sure did! once the bit broke, it was real quiet. lol I will never buy another bit from cw again. long live the rock chuck!!!!

[Jeff_Birt]

Was the bit new? Was it mounted properly? I've worn out a few cutting bits and even dropped one and chipped it but have never broken one. Typically a bit breaking is an indication of too much run-out, hitting a knot, having the board tip due to it coming out from under the rollers or maladjusted out feed rollers.

[bergerud]

My original cutting bit broke because of "climb milling". I was cutting out a carved pattern in pine and as the bit rounded the corner and the board changed feed direction, the bit started a climb mill and just broke off. I think it is important to keep the bit in the interior of the wood with the same amount of wood on each side. If the bit has to mill only one the side, make sure it is not climbing. Below is a picture I found of climb milling.

[Digitalwoodshop]

Thanks Ken.....

I would look at the board slipping in length or loss of contact with the brass roller as the most common reason for a broken bit.

AL

[rickyz]

I hate it when I am completely wrong and have to rant. I noticed on my next carve that my board doesn't seem to be tracking correctly and is starting to come off the brass roller. That would explain the problem with the bit breaking. it wasn't following the cut path and was trying to a full pass. but in select pine with no defects, it should have been able to do this shouldn't it?

[cnsranch]

AW ALWAYS says it's all about the brass roller - and he's right.

If he doesn't own stock in 3M yet, he should - I'm buying as much masking tape as he is, and placing it along the bottom edge of the board to ensure it tracks well along the roller. I typically put two or three thicknesses of tape on the board.

One interesting thing - if you run the machine thru the board measurement process, stop it and pull the board, you can see ridges along the tape where the roller was hitting it - if it skips, you see no lines, you've got a problem.

If your board is perfect, and you have the tape on it, etc., and you're still having problems, I'd say the only thing that could be wrong is the head, and the rollers not being level - that could be forcing the board down opposite side of the keypad, and as a result, slightly lifting the board up on the keypad side and off the roller.

[HighTechOkie]

Well, I think the evidence speaks for itself :). When the board looses contact, the feed rate of the material into the bit changes as the machine tries to move the board, but does not register X movement since it is not seeing the pulses from the brass roller.

Personally, I'd like to see the brass roller done away with and just use the X motor data. Has anyone every had a board slip on the traction belts? I sure would doubt it.

Rob