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Messages - mp2008

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11
General Mach Discussion / Re: Need help with Basic 3-Axis Router CNC.
« on: October 21, 2013, 09:29:23 AM »
Here is a picture of the machine:

12
General Mach Discussion / Need help with Basic 3-Axis Router CNC.
« on: October 21, 2013, 09:25:40 AM »
Hello everyone, My name is Mike and I'll start off by telling you my situation.  When I was first hired to run this CNC router it didn't even run and I had no experience on one, just knew a bit about electronics and computers.  It was purchased off ebay from a company going out of business and came with incomplete software, etc.  Before I came along someone else got the machine almost to working condition but Mach3 would not move the machine.  It turned out the XML file and Mach 3 needed some minor tweaking and was achieved thanks to people like you on this forum.    Since then I also added a smoothstepper.  The person I had fix the XML file said there was a lot of extra junk code in the XML file and it would take weeks to take it all out and said the machine should run right but with thrown together software and a iffy XML file who knows. 

Since then the machine has carved hundreds of carvings but not without it's mistakes.  Most the time the problem will be the Y-axis lags and shifts the carving in the middle of a carving up or down.  After troubleshooting, just by looking at the machine it looked like one of the screws for the Y-axis was spinning faster than the other side.  But that was just to the naked eye.  After attempting another carving it did the same thing, bumped the carving up a half an inch.  I did some more troubleshooting and tried rotating one of the screws by hand, it would not turn one way but would VERY easily the other way untill it got ahead of the other screw, which showed that the machine was ahead/behind on one side and cocked at an angle.  I did measurements from the machine to the motors on both sides of the machine and the machine was ahead .25 inch on one side.  Seeing how days before this troubleshooting I cleaned and adjusted the whole machine so that it was straight, level, and all measurements were perfect, it seems to me one side/screw of the Y-axis is spinning faster/slower than the other. 

As far as what would cause this I could only guess...  I know it has been messing up a little more lately so could a motor be going out?  Any way to adjust and calibrate each particular motor using Mach 3?  Any help would be appreciated. 

Mike

13
I've been researching and trying different bits for the waterline finish pass and the pencil finish pass and can't get quite the quality I want.  I'm sick of spending time and money and would appreciate some help.  At the moment for about a 15in.x10in. carving I use a 1/4 in. Straight 2 flute bit for roughing, 1/8 in. round tip bit for x and y finish pass & waterline finish pass, and a V shaped bit with about a 1/32 in. wide tip for pencil finish.  The V shaped gives the carving nice detail but leaves noticeable grooves and dots throughout the carving. 

Anyone have any advice on bit selection?

Thanks,
Mike

14
Mike,
(FROM another Mike) I too use MeshCAM Art. To critique your work (although VERY Nice!) I have learned that Pine is pretty much a waste of time, and material. It just doesn't hold up for much carving details without chipping, splitting, cracking, or breaking off. Oak is a much better material to work with. And regarding speed- even though a machine may be capable of faster speeds, this does not necessarily improve things.

But can instead, make it even worse -even if cutting Oak. The reason is, the cutter needs TIME to do it's thing. Sure, you can speed things up to 60 IPM feed rates, with a router running at 27,000 RPM, but it will result in the cutter just Knocking the wood instead of actually cutting it. (Think hitting it with a 27,000 RPM hammer!). I usually do my roughing cuts at about 40 IPM, with a 1/4" straight flute bit. And the finishing cuts at about 22 IPM, with a 1/8" single flute round tip bit. And for really fine details, a 1/16" carbide tile cutter bit.


Patience is the key to getting good results with MC Art. Most of my carvings average about 5 hours total cut time, depending on size, depth of cut, complexity of the shapes edited, etc. I have just finished the tool path for a carving which measures X=21 Y=10 Z=-.75 and the estimated cutting time for that piece is over 12 hours! Have a look at the Marine Corps logo for an example of my work (approximately 9x10).


Thanks for your critiquing and advice because I was really clueless on optimal feedrates, bits, and total time of carvings.  I have been actually looking to get higher feedrates to do more carvings in less time because I'm looking to use it for decorating cabinets, doors, and other things we do in our construction business.  I'm not sure how much value the carvings would add to these cabinets, doors, etc. and if it would be worth the labor at these lower speeds?  But after hearing what you had to say I realize lower speeds are best for wood routers, which is pry why the router machine I have only has single start screws and low oz. motors. Well, again thanks for the advice and nice carving, my brother just got out of the marines not even a year ago.

Mike

15
That's a pretty handy tool there Rich.  I think you've definitely helped me out more than I expected on here so I greatly appreciate it!  I'm going to have to commit a day or so to some research to better understand everything because like you said, each part of the system must compliment each other.  I don't want to replace one thing and then find out another major part of the system has to be changed to compliment the first change and so on.  I'm sure you'll be hearing from me soon  :D

Mike

16
Thanks for taking the time to explain all of that Rich because I was definitely confused with what I've been reading for the past couple days  :D .  

So from what I understand the screws I have now are more for precision rather than speed and because mythe motors have to spin at such a high rpm to go fast feedrates, they do not do not have enough torque?  

So you suggest that a option is to replace the screws I have now with multi-start screws, which would allow me to lower the rpm of the motors to achieve the same distance or feedrate as with the original screws?  This would also give the motors more torque and make the machine more reliable?

I've been researching Acme Multi-start screws and notice they have some as high as 8 start that move 1" per turn.  What would be the difference between a 2 start and a 8 start?  I understand one moves farther in one turn but I'm not sure what are advantages and drawbacks of each and which would be best for my machine and motors?

Mike

17
-Wood: 1in. thick Pine
-Toolpathing software: Meshcam
-Carving size: 10"x12"x.65"
-Bit: .125" ball nosed single flute
-Stepover: .09 in roughing and .03" during finish pass(I'd like to do somewhere around .01(or anywhere 7-10% of bit width) or so to minimize tool marks but I need to be able to go faster before that's an option)
-Depth per pass during roughing: .2" (can i do deeper passes?)
-Feedrate: 50in./min (trying to fix problems to go faster at the moment :-\ )
-Spindle Speed: 11000 rpm (I imagine this is too fast for the slow feedrate I'm doing but not quiet sure, especially in pine)

I figured I'd post my first real attempt at a really nice carving and I do wish it would have turned out a little better.  Choosing pine as my wood wasn't really a good choice and I didn't quite get the detail on the eagle like I wanted. I did use the same bit throughout the whole carving cause that's one thing I haven't tackled yet is tool changes and using different bits for roughing, finishing, and pencil finish passes.  Would really appreciate any advice or suggestions on improvement! Enjoy ;D

Mike





18
Thanks for resizing my images Overloaded. I'll remember to resize any future images I post.

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Just making a pit stop on the forum so maybe get back tonight ( boys monthly night out takes precedence). ;)
RICH
Haha, alright Rich, I'm in no rush now, as you can see I've been carving away just at low feedrates.
Mike

20
I do have more pics including some of my geckos, power supply, etc. if needed.  Sorry about the big sizes, that was probably why I was having problems, I'll have to remember to resize them.

Mike

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