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.

[roney c]

Whatever method you choose to do DON'T WAIT 12 years like I did before installing this X & Y proximity switches. They're so easy to install even a legally blind person (given enough time) can do. They are soooo worth it. I'd smack myself upside the head for waiting so long before installing them, but my surgeon advises against further damage.
Roney

[Thom Dudley]

Wow, thanks for the great advice everyone! I'm definitely feeling better about this....
Our background is that we just bought a PRS Standard 48x96 after feeling like we were outgrowing the 18"x32" laser engravers we usually work with. We have 8! Eight! It was time for a bigger machine. We are primarily a jewelry/accessory company, but my department gets a lot of orders from our retailers for custom signs & retail display stuff, and I was losing patience with having to scrap together big work from small parts. I'm really excited about getting as familiar with the CNC as I am with laser engravers, it is very liberating.

[Thom Dudley]

Roney, where in Brooklyn are you?