Thoughts on What We Do

[SPEEDRE]

I have a, K2CNC Gantry machine, that I purchased about five years ago, and quite frankly, has less than two hours use on it. I must admit this is due to fear!. I have made only two parts and both were, unmedicated failures. Both attempts were made using the same scenario, made the drawing and converted to code the night before, then ran it the next day. Somehow they seemed to have lost some steps and made some random moves, spoiling the cut.
This is somewhat off the track of my post, it's just an intro to my angst. I took a real hard look at that machine and said, I could have built one like that. A statement many of us have made I'm sure. Well, I've been designing many alternate ways of doing it since then. Many here on this forum are doing the same thing. I have seen some IMO that qualify as real, viable, quality, concepts. One is the belt drive idea, and the other is the use of 8020 extrusions. I have found that the way many machines are designed that they utilize linear shafting, all well and good. But mostly they are unsupported causing a flexing of the gantry at the bearing center points. So why not use the belt drive?. Someone here, has shown it is both economical and accurate. I may use it myself to strengthen my machine. And 8020, or t-slot extrusions, a great idea,strong, accurate, and economical. So, there it is, a little over long,obvious I know but often not considered. I also work alone. It's tough not having a colleague to experiment with.

[CarveOne]

Originally Posted by SPEEDRE I have a, K2CNC Gantry machine, that I purchased about five years ago, and quite frankly, has less than two hours use on it. I must admit this is due to fear!. I have made only two parts and both were, unmedicated failures. Both attempts were made using the same scenario, made the drawing and converted to code the night before, then ran it the next day. Somehow they seemed to have lost some steps and made some random moves, spoiling the cut. This is somewhat off the track of my post, it's just an intro to my angst. I took a real hard look at that machine and said, I could have built one like that. A statement many of us have made I'm sure. Well, I've been designing many alternate ways of doing it since then. Many here on this forum are doing the same thing. I have seen some IMO that qualify as real, viable, quality, concepts. One is the belt drive idea, and the other is the use of 8020 extrusions. I have found that the way many machines are designed that they utilize linear shafting, all well and good. But mostly they are unsupported causing a flexing of the gantry at the bearing center points. So why not use the belt drive?. Someone here, has shown it is both economical and accurate. I may use it myself to strengthen my machine. And 8020, or t-slot extrusions, a great idea,strong, accurate, and economical. So, there it is, a little over long,obvious I know but often not considered. I also work alone. It's tough not having a colleague to experiment with.

Errr, no, you're not working alone if you're on CNCZone but I know what you mean.

Building my machine(s) has been more fun to me than learning the software side of it. I'm more of a nuts and bolts kind of guy though I'm decently computer literate.

Design and build a small machine to test your mechanical ideas and then scale it up or apply it to your K2CNC machine.

CarveOne

[FandZ]

Originally Posted by CarveOne Errr, no, you're not working alone if you're on CNCZone but I know what you mean. Building my machine(s) has been more fun to me than learning the software side of it. I'm more of a nuts and bolts kind of guy though I'm decently computer literate. Design and build a small machine to test your mechanical ideas and then scale it up or apply it to your K2CNC machine. CarveOne

Designing my machine was more fun than building it for me. I had very little experience working with tight tolerances and marking and drilling metal. I'm really excited about my second machine, especially since my first one will help in building it.

SPEEDRE, I don't know what K2 cnc's were like 5 years ago but I know they make some nice machines now. If I had the coin I would pony up for one. Post some pictures if you don't mind. But only 2 hours on it within 5 years? That's a crime man. I've had to pack my cnc up because the only place I can use it is my breakfast nook inside my house. But I'm moving in September to a house with a patio and a little shop. Trust me, that puppy will get some use.

Regarding your fears, what are you afraid of damaging on your machine? Once you get all your limits setup and safe Z's it's pretty much fool proof.

[SPEEDRE]

Fear is , well I don't know. I'm not afraid of damage, I too have metal working experiences, I just can't put it to words. I self analyze way too much. I plan on getting the machine together and just doing it. Damn the cutter full cuts ahead.

[analogman]

I am curious, If I purchased a machine and it was losing steps, or being anything less than their stated accuracy, I would be calling the manufacturer. Did you contact K2?

Which model is it? Even their little machines should be pretty good.

What specifically was the problem? In lieu of close by buddies to play with, use your digital camera and post pictures here, along with your experiments.

[SCRAPWOTSCRAP]

Doubting it is a machine problem, Speedre talks of missing steps and random cuts, sounds like minor problems with the code, which might look like lost steps, not sure what he is using for software. As for fear.....Fear of the unknown? Unfamiliar? Fear of screwing up? Should be easy to overcome with Zone members at the ready. Show us what's going on with the K2, a lot of us have been where you're at.

[sonicwonder2000]

My perspective for what it's worth: I understand the fear thing when it comes to building these. I am also relatively inexperienced when working with tight tolerenaces. I have made many errors in my construction of my cnc that have been time-consuming and costly! Mostly the fear is a money-related thing. If time and resources were unlimited, then there would be no fear.

Regarding the belt driven cnc's, belts are not a panacea. My understanding is that belts rebound and flex with heavy cutting. While you may be able to produce very high rapids, your usable cutting speed will be limited by your acceleration settings which must be lowered with belts.

[SPEEDRE]

I was using V Carve Pro to generate the code for the piece. I imported a dxf. from Auto Cad 2000. What I don't get is how it happened. Picture this, you draw a part in Auto CAD, save as a dxf V 14, send it to V carve, do all that stuff, and then dry run it, with a pen in the collet, and paper to mark it. Sounds good so far, right? Then go to bed. Wake up the next day set it up, put the stock on the table, cutter in collet and run it. Up until now it's good, the it all turns ti s**t. It over cut the first piece by an offset of one inch to the right. Oh yeah, did I mention, I mirrored the part to get two from every blank I put on the table. How does the machine or the code or whatever you want to call it, go from what seems to be correct to, the next day being all messed up?????
The K2 ran expertly from the first time I started it up. No rubbing, quiet, smooth, and robust. For metal it will need to have the unsupported liner rods stabilized but I can't complain, I'm not running metal. I guess one could say the unknown is my fear. Will it run consistent?????

[ger21]

The next day, when you go to run it, does it still look correct on the screen in Mach3? It's virtually impossible for it to have changed. Assuming you turn off the machine at night, do you re zero it before cutting?

Also, always use v12 .dxf from AutoCAD. You'll eliminate future problems.

My understanding is that belts rebound and flex with heavy cutting. While you may be able to produce very high rapids, your usable cutting speed will be limited by your acceleration settings which must be lowered with belts.

That's kind of a general statement. Everything can flex, even screws. A belt stretching and bouncing depends greatly on the length of the belt, and, if it's the correct belt for the design. If I recall, Speedre's machine is fairly small, so he shouldn't have to deal with the issues you've mentioned. Also, here's a belt drive that eliminates the problems you mentioned. http://cnczone.com/forums/showthread.php?t=59570

[Med-Pac]

If you have the machine set-up, dry-run the part and everything works. Why wait until the next day to make the part?

Just my 2 cents
Mike

[analogman]

Hard to tell what the problem is (I am wondering about tool diameter), however, why not try some small stuff first? Then if you run into a problem post the gcode and we can have a look at it. It'll also help build your confidence in the software and the machine. It will also help with figuring out your feeds, speeds, vacuum, cooling, etc.

Which K2 machine is it? Anything is possible, but I bet the machine is not the problem.

FWIW when I finished my machine (based on datacut plans) it scared the crap out of me. So I just did a lot of small stuff - just for us to become friends together. I ran it slow, I triple check boundaries, I even did some explicit limit testing. Now after being operational for a few months, I just don't hesitate do draw something up in CAD, CAM it, then cut it. It is great - I LOVE it.

[SPEEDRE]

My machine is a K2CNC 2514, a good size to start I think. Well I didn't run the part because it was 2:00 am. The tool dia. is always, for the part type, is .250 in. @ 50 iim., a value set by V Carve. My controls are, Geckos 201's I think, and Mach 3. a cnc4pc unipolar bbw power supply. These are reliable good quality components. I think, that after all this though and consternation, it may have been a fluke. These things do happen when computers are involved. I plan on getting my machine up and running again by this week end and trying to run some good parts in foam first. Wish me luck!!!!