Messages

1

General Mach Discussion / Re: Axis length movement profiling / mapping ?

« on: October 12, 2010, 02:34:00 PM »

Hi, Thanks for the replies and info.

I ran the numbers on the belt drive - surprisingly strong belt needed actually.  I was kind of surprised at the width needed compared to what people commonly use, so I am still double checking my calculations to see if they are reasonable.

I guess the alternative to the screw mapping approach is closed loop positioning from a linear encoder, but I have no idea how to approach that beast, or the budget impact.

Thanks

Harry

2

General Mach Discussion / Re: Axis length movement profiling / mapping ?

« on: October 12, 2010, 09:01:23 AM »

Please dont take this the wrong way but do you actually need such accuracy with a router?
Hood

Hi, you are absolutely right, that a wood router probably does not need higher precision than I could achieve with good quality components.  I am looking into this area for really several reasons:
- I am already well into a belt drive approach, and the belt needed is nearly 12 ft long.  The price of belt with "average" results is reasonable, and the price of belt for "good results" is much higher.  Belt for "great results" (better than I need) is not made.  I hope that make sense, but the point is, if I can profile the axis, I can use cheaper belt and pulleys.
- Over short distances, the belt specs are fine, but over longer distances, they are kind of marginal.  In an open loop, non profiled axis, a simple thing like drilled hole spacing could be off by 1/8 in over the length of a board, based on "specs".
- One of the goals of this "router" is to be able to drill fairly accurate hole and positions, using a drill, on 20 ft long boards.  Over 20 ft, there could be a rather large placement error, at least in theory.
- Longer term, I would ideally like to use the same ideas I have learned from this project to put cnc control on a mill, which of course has higher accuracy requirements.

Thanks for looking,

Harry

3

General Mach Discussion / Re: Axis length movement profiling / mapping ?

« on: October 12, 2010, 01:28:22 AM »

Hi Rich,  Thank you for that information, that is exactly what I had in mind.

Since it is perhaps not such a commonly used feature, I guess that means that an experienced machinist probably has a better method of improving their positioning than just relying on the open loop programmed steps on a rack, belt or screw ?

Does that mean that high precision work is all performed with linear encoders along the length of the axis with some kind of feedback to the software ?

Thank you,

Harry

4

General Mach Discussion / Axis length movement profiling / mapping ?

« on: October 11, 2010, 07:26:06 PM »

Hi,

I am in the build phase of a DIY wood router.
- Sized for 4 x 8 sheet
- model airplane wings
- sheet plywood
- Various other hobby things.

This is for hobby use for routing wood and foam. I have an idea to also use it to improve my drilling results as it also incorporates a drill in the Z axis. (not a spindle, a hand drill, so not perfection use, just better than I am by hand)

Drive Method
- Tried to do them all the same, but in the end, they might all end up different, but most likely belt and rack and pinion.

Motors
- At this point, steppers running open loop. I have some linistepper driver kits already, but am open to options if other methods are significantly better, and I have the budget.


Question

Regardless of what method is used, there are always imperfections and non - linear areas of a drive mechanism. For example, even high end ball screws have a rating for "accuracy per foot or meter", and a belt has even larger errors, most likely, not consistent over a 8 foot distance.

I read the mach III manual again last night (yes, I am a beginner) and found a setting to "fine tune" a local section of motion for a movement distance, but I wondered if there is a method to "fine tune" sections of the axis. Example, if I can manage to borrow a very accurate meter, can I somehow profile the axis for these imperfections continuously, or over say 10 regions of the axis ?

I realize that my work may or may not need this, it is partially for my own learning.

I am sure this has been asked before, I just could not find it in the many  pages of threads or the manual.

Feel free to just point me to the right section of the manual or an existing thread.

Thanks a lot

Harry

5

FAQs / Re: System Requirements - single vs dual core processors

« on: November 16, 2008, 02:34:13 PM »

Hi, I am in the middle of a hobby type home made cnc router build.

The plan is to use Mach 3, probably Lazy CAM, and perhaps gcam and GRZ Meshcam.  (still learning / testing)

OS will be either XP Pro or Vista - I am ok with either and use Vista every day so it is no bid deal either way.

Computer - looking at buying a used desktop as they pretty much all can do what I need to run the software.

Question of choices
- AMD 64 Athlon single core at 2.7 ghz and strong video card
- AMD 64X2 Athlon dual core at 2.2 ghz and mediocre video card
- More or less the same price

Is there any benefit to a dual core setup ?  I am pretty sure that in Meshcam, dual core is not a benefit (yet).  Does Mach 3 or lazy cam pro benefit at all from dual core vs single core processor setups ?

Thanks

HarryN

6

Feature Requests / Re: More axis for master / slave control

« on: December 30, 2007, 06:35:56 PM »

I think you need to re-think your machine or look at using a Fanuc 18Mi they are only 13 axis and $20000.

Graham.

Hi  Graham - you are probably right, but this is the "feature request" area.  Maybe the Artsoft programmers would be willing to come up with a version of mach / quantum with more axis.  6 for the $ 150 / price, and 10 or so for a premium price - just an idea.  $ 20 K is out of my range for a DIY project, but I am sure you knew that already.  Take care.

7

Feature Requests / More axis for master / slave control

« on: December 28, 2007, 01:14:02 PM »

Hi, I posted this in the Quantum area, but today saw that this is the correct place for feature requests.  Sorry for double posting.

I am designing / building a DIY router.   As planned, I am running up against the need for more than 6 axis for driving steppers.
- X = master / slave = 2
- Y = master / slave = 2
- Z = 2 (or more) independent Z spindles with independent Z motion = 2
- I would really like to use a stepper motor for one of the spindles = 1 or 2
- 4th axis - not yet needed, but I would really like to be able to add in the future = 1

All would be driven off of parallel ports.

Thanks

8

G-Code, CAD, and CAM discussions / Re: Going from Rhino 3D cad to G code for Mach III question

« on: November 05, 2007, 11:15:17 AM »

Thank you for the information Graham.

An alternative file format I was advised on was:
- Create 3 D drawing in Rhino
- Save the Rhino drawing in STL format
- Import te STL format file into Mesh CAM
- Create the tool paths / G code in MeshCAM, then view them in CUT VIEW
- Import the G code into Mach

Is there any particular advantage of using IGES vs STL formats for exporting the Rhino 3 D cad files ?

BTW, I have read through the Mach III on-line manual 1 X through now - what an amazing amount of programming and feature depth.

9

G-Code, CAD, and CAM discussions / Going from Rhino 3D cad to G code for Mach III question

« on: October 31, 2007, 03:58:46 PM »

Hi

I am building up a DIY CNC router which will be run from Mach III.  I do not have ANY CAD programs or experience, and am not ready to take this part on right now.  I am also new to G code.  Wow - sounds pretty lame when I spell it all out.

Anyway, a guy I know would like to take his 3D Rhino (cad ?) drawings (true 3D shapes, not 2.5) and have me cut them out in foam.  I told him that he should buy a copy of Mach III as well, import the CAD file to Mach III, and send the resulting G code to me to run on my cnc router.  I assumed I can provide a copy of my tool configuration information to him, and his exported G code would work on my router.

Now that I am reading a bit more about it, I am thinking that this advice is not sufficient - perhaps wrong.  After searching through the topics here and on cnczone, it seems that the steps are really more like:

a) Draw in Rhino CAD
b) Convert from CAD to CAM using Rhino CAM or similar
c) Post processor - no idea what that is ?
d) Have him import into Mach III at his site
e) Email the file to me for running
f) Run on my machine using Mach III

Is this right ?

It seems like perhaps Meshcam is easier ?


I tried searching and reading about this topic, but I am still unsure of how to go from drawing to part.

Thanks

HarryN