SB Link User Poll

[Gary Campbell]

Link Users: How do you Zero your Bits?

[alister]

I do spoil before and material after...but intend to swap to Kenneths separate zero spot setup.

[Gary Campbell]

I now notice I didnt add the version I will use. To the spoilboard AND a separate zero block.

You can select more than 1 answer

[ken_rychlik]

Is this a trick question?

[Gary Campbell]

Kenneth...
Yes... I didnt ask if your zero block is at spoilboard or material level :D

[dlcw]

My current eCabs design strategy doesn't require me to change bits, but I would like more flexibility in this regard.

I will be adopting Kenneth's version soon. My zero plate is already installed. Now I just have to modify my tool change files to zero at this location after a bit change.

[jdervin]

I use the method that Bill Palumbo taught at the Camp ShopBot I first attended: whichever way is best suited to any given project.

[thewoodcrafter]

I am surprised to see so many options to do the same thing, zero your Z.
Thermwood designed the system to zero to the bed.
Works really well.
Who is writing your tool changing routines to zero elsewhere?
Is SHopBot sending out these files? Or are you guys doing the modifications?
How do you get your joints to fit correctly by zeroing to the material?

[Gary Campbell]

Roger...
Unless someone adds a separate zero location, (read as Cost, expertise, wiring and programming) which all users are not able to do, how would a 4 by 8 machine be zeroed after a toolchange if not to the top of the material? And if you are going to make subsequent zeros to the material top, why not the first one? As usual, the options and methods are as varied as the ShopBotters that are using the tools.

All of us that zero to bed... always... know there is an accuracy advantage, but all dont have that option.

I have just finished some testing on the new machine, and it looks like my answer is..... zeros are not needed. Since I zero to bed for all files, and the SB ATC files keep track of all bit heights to the zero plate and the plate to table surface, all I have to do is keep a surfacer in the rack and voila! no more zero plate. I rewrote my surfacer routine to update the plate offset to table... and I am stylin'!

It took a little work to get the zshift implemented and havnt heard from SB for the final word, but looks very promising. Tomorrow I will be testing Vectric posts with the z shift added.

[thewoodcrafter]

I guess if you have to change bits in the middle of the file you are stuck zeroing to the material. I forgot about that. I don't have to change bits.

The best way is a separate zero location. That is how Thermwood does it on there machines. A little work to get that up and working but I would think would be worth it.

[benchmench]

Another option, would be a collar around the bit such as the one provided by Precise Bits. Once zeroed, the collar maintains the same distance from the collet to the end of the bit and consequently to the zero reference point. Changing bits is simple and easy without having to re-zero.

I don't know why this isn't an option on all bits.

[thewoodcrafter]

That sounds like a good idea Dan.

Have you done this?
Is it accurate enough?

[bleeth]

After those who jumped all over me just a few short weeks ago for saying that I zeroed to the top of the material I would like to thank those of you who now have acknowledged that there are good reasons to do so.
Since the poll was just for "link users" and as yet I am not I have not voted, but I do see how many of you recognize top registering is also a viable option.
As my granddad used to say-"There is more than one way to skin a Cossack". Whoops-I mean cat.

[Gary Campbell]

Dave...
I can only hope that I was one of those that jumped all over you for the top of material zero. I will tell you the same thing tomorrow.

The "viable" reasons I give above do not apply to you. You have the budget, and experience in all of the aforementioned areas. I have seen your work, you also care about quality.

There is no question about much greater accuracy with zero to bed, especially if doing blind dados. I am sure, that if polled, all that zero to bed have tried it both ways, few, if any that zero to top have tried zero to bed.

There are viable reasons for not zeroing to the bed, most are attributed to either lack of experience with the system, use of a non professional oriented design software, especially those not aimed directly at cabinet making, or use of a machine that holds a single tool. If you use butt joints, it doesnt matter.

Even the popular CAD/CAM software packages give the zero to bed option, even tho seldom selected.

My personal reasons are as follows:

My own cutting has produced MUCH better results with zero to bed. Especially with blind dados. With most CAD/CAM software you can hardly design the joinery, let alone cut them accurately.

I know there is as much as .040" thickness difference in some sheets. Even more if all sheets of a given batch are checked. What I dont know is... what the thickness is where I zero the bit! (when on top) ;)

[wberminio]

Separate z plate set at top of spoilboard works best for nested cabinet parts!

[Gary Campbell]

Erminio...

I agree, but there is no need to have it at the exact height of the spoilboard. Just like the zero plate, the difference is just a number that can be used in the zero routine. Doesnt matter if the plate is above or below. You just have to know the difference to the spoilboard.

[wberminio]

That's true Gary,
There is a clear advantage to having a z plate located to the side of the spoil board.Before I set mine up,if I had to rezero to the spoilboard,I had to remove the sheet material
rezero and relocate the material exactly.I believe that is why some might want to zero to the top of the material.
In any case, accuracy in parts and jointery is what's important.It saves time in the long run.

[thewoodcrafter]

Erminio...

I agree, but there is no need to have it at the exact height of the spoilboard. Just like the zero plate, the difference is just a number that can be used in the zero routine. Doesnt matter if the plate is above or below. You just have to know the difference to the spoilboard.


Garry,
Isn't that what the "spoil board thickness" number is for in the Link?
For changing the bed surface height relative to the zero pad.

[Gary Campbell]

Roger...
The wasteboard variable is not really intended for that, and im not sure that it would work. The wasteboard is usually a piece of 1/4" MDF used on toop of the spoilboard.

The heigth difference between the plate and spoilboard would be best added to the C9 along with the other offsets.

[englert]

Since Thermwood methods are often referred to here and you are referring to your "block" for touching off to get zero. Our tool length sensor is mounted to the side of the table. The surface of the sensor is usually mounted below the table surface, but it could be mounted above, as well. During our tool measurement operation, a variable called "switchspoil" is either added or subtracted from the measured value to surface of the sensor. So if the sensor or "block" is below the table, the "switchspoil" variable is subtracted from the overall Z distance automatically to compute the final daylight value for that tool. That adjustment would make Z zero the surface of the table. As mentioned in some of the previous posts setting Z zero to the table's surface helps ensure joinery accuracy despite variances in material thickness.

Dennis L. Englert

[bleeth]

Regarding the "off-field z-zero block". I assume this is located off the spoil board and therefore off the normal cutting field. That means, for example, that you need an extre inch or so in either the minus y or minus x direction to mount it. Now if you have a 4896 then you have very little extra room in the minus y direction but could have some in minus x. so my assumption would be that you would put this plate (if you happened to be doing some mods to your bot) at minus x and probably below the actual spoil board so when you were replacing and milling a new one it wasn't in the way. This, of course, could also be a good location for a set of x-zero stop pins or a stop bar that might be air activated to be located as well.
Does this seem like the right track to you guys or is there something I'm missing?

(BTW Gary-still looking for that assembly file for the DF)-Let me know when you are going to be in the neighborhood.

[Gary Campbell]

Dave...
You are right on. Dennis explains it well. On my machine that same variable is called "&plateoffset", but works the same.

Check your mail.

[bleeth]

Thanks for both replies. Next: When ya'll gonna be around?

[Gary Campbell]

Hoping to make a trip south by the end of the month, but not sure. Depends on how Jr is doing and a few other factors

[bleeth]

10-4. Keep me up to date.