Question
I am considering purchasing my first CNC machine in the near future. I've been looking at various manufacturer's web sites, and I have some questions:
1) When you take delivery of a CNC table, how do you square it up and level it, make sure that the travel is uniform in each axis, and make sure that the axes are truly at 90 degrees to each other, etc? Is it going to take me 40 hours to get up and running?
2) When you want to cut multiple sides of a work piece, how do you ensure proper absolute positioning once you've released it from the hold-downs and moved it? Do you just get out the trusty framing square and some gauge blocks?
3) Since adding a CNC router to your shop, do you find that you're getting more adventurous with the kinds of joinery you do, or do you just use the CNC machine to work faster?
4) What I'm hoping to gain from CNC, is to be able to rapidly render pretty intricate joinery (think Japanese-style). Anyone have specific advice about that?
Forum Responses
(CNC Forum)
From contributor B:
If you take delivery of a CNC that is fully assembled, it should be square, accurate and ready to cut. You will only have to level the unit on your floor. A transit is very handy for this purpose. The machine should have a leveling system.
If you purchase a machine that comes with "some assembly required," then you will easily spend one to two days installing and calibrating the system. Squareness calibration will depend upon what type of machine you have… moving gantry or moving table. However, I can't imagine a moving table machine coming any other way but fully assembled.
Moving gantry machines can most likely be adjusted to square by loosening mounting bolts on either transmission (ends of the gantry) and tweaking their position on the drive systems. Squareness can be checked by drilling four small holes (with the router itself) at maximum distance apart at the four corners of the machine. Checking cross distances as in any construction scenario tells the tale.
Multiple side cuts can be accomplished different ways. If the machine doesn't come with a positioning system, then you can easily accomplish this in your drawing software. One way is by creating indexing points (1/4" holes as an example) that are centered on the piece or its offcut area. The points would be in the same reference location on the part when it is face up and face down.
I can't speak to detailed furniture joinery, but I've been willing to take on some very tricky projects that I would have passed on if not for the CNC. One was a project of hundreds of about 2" x 3" dovetail joints for door casings that were visible in the face of the corner joints. Ugly as sin....but we don't design these things, do we?
1. Research all relevant issues, i.e. additional required items, programs, dxf file importability, availability of pneumatic reference posts (to aid in repositioning of materials/widgiting) (answers part of your question about turning material), height clearance from tool tip to tabletop/spoil board, large vacuum pump system for chip clearing, ability to control vacuum zones on the table/turn on and off, local maintenance, parts availability, service record of the manufacturer/dealer, footprint of machine and positioning in your shop (you only want to set this thing once), reputable local tooling dealer that stocks most of your tooling on hand, the list goes on and on.
2. Ensure that you have in writing that, before the technician that comes to set up your machine leaves, you will be fully functional, if the technician setup is included in the purchase price or pay the extra money and have them send a technician to set it up. It is worth it.
3. Squaring should not be a problem. My old machine was a flat bed router. I simply had a reference stop bolt that I adjusted and squared it up (kind of like the depth stop on old style drill presses). The first time I had to square it, the time was about 3 hours. But once that was through, the subsequent times were quick (10 minutes).All I had to do was completely shut down my machine, move the gantry by hand to the end by the reference stop, and break loose 6 allen head bolts on the stop side of the gantry, pull the gantry against the reference stop with an f-clamp, then tighten the bolts. This would get me to within 1/256 of absolute square on a 47x95 test. Plenty acceptable. If you go with a point to point like my new one, get good with a calculator.
2) I assume you are using a matrix table to first cut the parts and then want to run as a single part. Most machines have pop-up pins at the 0-0 reference point, so the individual part would be positioned against the pop-up pins. If it is an odd shaped part, an overhead laser which would outline the part profile can be used.
3) So many customers first purchase the CNC and have specific work or projects in mind, but once implemented, they expand their imaginations to do more and more. Software is key and the newest development is in niche software which contains galleries for MDF, entryway doors, windows, staircases, signage and engraving. Most images are copy and paste, apply the tool and create code for the machine automatically.
