Registration & alignment

[Thom Dudley]

Hi! I'm new, so do forgive if I've put this in the wrong place...
This might seem like a daft question (a search brought up very little, so I'm likely missing something, somewhere...), but how does one machine a piece of specifically-sized material on a very specific spot on the board?
My specific example: I have a 3.375" square block, which I'm trying to cut a 3.125" disc from. I set the material origin in Part Works at the lower left corner with no offset (and sized at 3.375), then moved the tool tip to that corner, centered ON the corner (or as close as I could, which seemed to be very close), but the part cut off center - probably because I was eyeballing it. So: is there a better way of registering parts? What is the preferred method? I'm learning this form an all-laser background, so I may simply have some bad habits to shake off, but if I need tight registration for machining on a specific piece, is there an "easy" way, or is it a trial & error process?

[steve_g]

Thomas...
There are no Daft questions...
Different folk do things differently, often based on their previous experiences.
Personally, I always design with an area the size of my table (48 X 48) and 0,0 is always lower left. I move my projects around my table to try and not have all my spoil board cuts at the 0,0 area. To locate my project, I create a perimeter toolpath that just barely skims the spoil board, I call this path "locate" I've been known to chase the bit around with a magic marker as it is a very slight cut.

Hope this helps...
Steve

[Rick W]

Thomas,

Why don't you origin from the center in partworks, and use a v bit to zero

your project (in the center). Should be pretty accurate, I think.

Rik

[beacon14]

Welcome to a wonderful new world. What type of machine do you have?

Many people use proximity switches (which I thought came standard with new machines?) to "zero" the X and Y axes. Once you get them set (use the Tools/Setup command with the tool located exactly at your 0,0 point) they are pretty reliable.

Some Shopbotters have mounted laser crosshairs on their gantry to help with manually locating the corner of the workpiece. Search the forum for 'laser' or 'laser pointer' or something similar.

Another technique is to screw a couple of pieces of plywood down in an "L" shape, and use the machine to trim one edge of each piece, to create accurate reference surfaces to register the part against.

It can often be helpful if you can make the blank oversized so you can concentrate on other issues and not have to worry so much about the registration - although that's not always possible.

Good luck with your new machine!

[dana_swift]

With most of my "utility" cutting where I am making something out of some scrap left-overs, I just move the bit over the center of the clear area and hit Z2. I dont have to be exactly in the center, anywhere close will work, as the last cut frees the part from the stock and will never know how close it came to some other holes from previous projects.

Z0 is critical, and the ZZero needs to be reset anytime you change bit or material.

Beyond that its pretty easy, much to learn of course!

Hope that helps-


D

[feinddj]

Tom,

I screw a length of ply to the right side of my table. I move my z2 in at least 3 or 4 inches in x and y. At 0,0 I start a 96 inch long line in x, and then a 4 inch line in y. add a filet in the corner to let square pieces rest there. then cut to the inside of that line. you now have a registration for 0,0 on your table. Holding down a small piece is another story.

D

[bruce_taylor]

I mark the center of my piece and secure it the the machine, then I put a v-bit in the machine and set it on the center manually. I record the center location and go into my design software and place the part I want to cut out at the location of the center of the piece that is secured on the machine. Then I put the correct bit into the machine and cut the tool path above the part so to be sure the tool path will cut correctly. I normally try to leave a little more meat around what I'm cutting but what you want to do is possible but may take a little work setting it up. You could also pocket out or area clear the 3.375 in a piece of sacrificial material mdf etc. and place the part you want in the middle and then place your material into the pocket which would help hold the piece while you cut it. Hope this helps, Depending on the material your cutting you just have to make the machine work for you.

[rww]

For small parts like blocks I like to fasten a piece of plywood on the table. Then cut holes the size of the blocks, Insert blocks and you know exactly where center is.

[myxpykalix]

Without having gone back to reread all answers to see if it has been said...here is what i do.

As you see in the picture i have a jig with a 90 degree corner that sits at 0,0 on the lower left corner of the table.
I put my material in and fasten it down by screwing scrap plywood or mdf butting up against it and a small lip to hold it down.

I ALWAYS set my x,y Zero in the center when creating the file

I ALWAYS make my material X,Y Zero in the Center of the material. see pic

I always set my Z zero to the top of material.

Now when i want to set my Table X,Y Zero I do a C3 and bring the tool to the 0,0 lower left corner.
I then manually move the router to the red X being the center of my material.

I then take and write down the coordinates in the X and Y boxes on the screen.
I then Zero my X,Y at that spot on the table over my material center.

Now if i loose settings or anything all i have to do is go back and do a C3 and take those setting i wrote down earlier and do a MX and a MY and insert those figures.

Thats what i do and if i ever loose any settings for any reason i can right back to my X,Y Zero with no problem.

[tlempicke]

Here is a super accurate way to do this easily.

Do a C3. This will zero your table very precisely. Within a couple of thousandths

Pick a spot on your table where is is convenient to have the zero point. For an example x+14, y+18

Do mx14 and enter. Do MY18 enter. Do Z2.

In partworks open a project the size of your table. Draw two lines along the origins for X andY. Make them about ten inches long

Mount up a V bit or an engraving bit.

Run the drawing you just made as a quick engrave and about .015 deep.

You now have a corner on your table at a very exact location. If you screw down a couple of pieces of scrap you have a fence that you can pocket your work in to.

Because the stops on the shopbot are accurate to within a couple of thousandths you can come back to the corner in just a few seconds with great accuracy.