Lining up double sided carves, measuring boards

[karossii]

I have been having more and more problems with double sided carves not lining up for me. My biggest issue is that frequently, the machine will measure the same board as slightly different sizes on being flipped. Sometimes this is an issue, sometimes it does not seem to be.

I rarely have a specific board planned for a project before the project is designed. Often, I will design a project thinking, "I'll get a 1x12 for this" or "I should try to make this fit a 1x10" or etc. So I will design the project at .7" thick, 11" or 9" wide, and however long I feel is needed. Then I will make sure the physical board is cut 7-8" longer than my project, and have the machine center it. This seemed to work the first few times I did this.

Then I started having issues. Things would get slightly misaligned, or completely off kilter. Sometimes I could salvage a carve, sometimes it was scrap and I had to start again.

So I culled through the forums, looking for other solutions. A sled seems to be the way to go, but I haven't had time to build a sled in the past couple of weeks; and with many of my carves a sled wouldn't really be practical. Today, for instance, I carved a 1x12x45" board. That would require a massive sled, and add a lot to the weight the belts are having to move.

I saw several other suggestions. I tried adding 4" to one end of the board in designer, then place on end. Except it seems I added the 4" to the wrong side of the board (left side of the front in designer), as it placed the *other* end on the end of the board, meaning that project came out from under the rollers. So the next time I switch to the right side of the front of the board in designer. And again, it did the opposite of what I expected, and placed the un-padded end on the end of the board, and again came out form under the rollers. The third time I tried this, I went back to what seemed natural, and designed the space on the left side of the front in designer. And again, the machine insisted on doing the opposite of what I hoped/expected. So I think I will likely never place on end again. Not with only one end 'padded', for sure.

I have designed boards in designer with the extra 7" or 8" added, and centered, and placed on end. It seems to work about the same as not adding any extra padding with the centered choice, and while it works better for placing on end, it still will not center across the width of the actual board. Meaning I have extra wood on one side of my project.

So then I thought I should use the carvewright to measure a board, adjust my project specifically for that board (which can be as involved as completely redesigning it, sometimes), and everything will work out perfectly.

Except that it doesn't. The machine will measure a board at different widths, lengths, and thicknesses if I remove it and replace it. And if I flip the board, it is almost always slightly off from the measurement it gave on the first side. So how do I pick what size to put? If I make the board too big in designer, I am forced to scale the project down at the machine. But if I take the smallest of each of the differing measurements and say that is the size of the board, then I am back to it being slightly offset from one edge or another.

So aside from making an adjustable sled which could accommodate small to large projects, or multiple sleds for each project, neither of which seems realistic for me to do in the next few weeks... does anyone have any suggestions on how to improve the accuracy of the machine's measuring abilities, and or the alignment of double sided carves?

[DickB]

In my opinion the optical sensors are just not accurate enough for good double-sided carves. I have the best luck using Jog to center. With this method, the optical sensors are not used to center the board - you do the centering yourself.

Use a sled, or an actual board that is both longer and wider than your actual project. When you design your project, use a virtual board that is the same size as your actual board. Before loading your actual board into your sled, mark the center of your board on both sides. I like to use a sliding square and reference the marks from the same edge of the board on both sides. That way, even if your marks are slightly off center, they will still match up on either side - does that make sense?

When you run your project, because your virtual board is smaller than your sled, you will get the scaling prompt. Of course you will say no to scaling, but then choose the jog to center option. You will be prompted to load the 1/16" carving bit, to be used as a "pointer". Then use the arrow keys to position the bit over your center mark. (If you are prompted to enter an X position, press Stop to switch to the jog with arrow keys prompt.) After running your project on the back side, flip your board as usual in the sled, and run the front side in the same manner, using jog to center.

(BTW you will be limited in the distance that you can jog to find center. Let's say your sled is 8" longer and 2" wider than your virtual board. When you jog to center, the machine will move the spindle to within 8" and 2" of center, as it will not let the virtual board overlap the edges of your sled. You will be able to jog at most 2" in y and 8" in x to get to center. Make sense?)

Another source of offset error is that the sled has a tendency to move away from the keypad-side rail as the sled moves in the x direction. This can skew the sled so that it is no longer square under the head. Even a fraction of an inch can cause problems. I've had this happen even when I thought I had the moveable rail tight against the sled. Watch for any drift away from the rail as the board moves in x while being measured, and gently push it towards the rail as it moves in x.

For even better accuracy, when your project permits, drill a 1/8" hole in the center of the board from the back side. Now, when you jog to center on the front side, use that hole, and not a mark, to find center. You can even manually lower the bit into the hole when jogging to make sure it is dead center. I use this technique whenever I can.

73549

[Alan Malmstrom]

Excellent advise DickB. I usually make my board size in Designer smaller than the board I feed into the machine, and use "Actual Size" and select "Stay under Rollers" NO. But I then center it to the marks using "Jog to Center" or sometimes "Jog to Edge". Jogging to the marks you make on a board gets much better accuracy than letting the machine measure. At least that's my experience with my machine.

[cestout]

I find that the closer to the accrual width the better it works. If you need a 7" width, use 7 1/16, not 7 1/4.
Clint