If you’d like to get in touch with Michael about having a custom guitar made he can be reached at mikdavhil1 [AT] yahoo.com . Either way, enjoy the photos:
The first is the cost of support. About a year ago I added a phone number where users can get a hold of me directly- not a low level guy reading from a prepared troubleshooting guide, but the guy who wrote MeshCAM. This has been well-received but it does have a cost. To be honest, if I could find a way to offload this function to a third-party and maintain the quality of support then I would. Unfortunately I haven’t figured out how yet so I have to factor this support cost into the product.
The second reason is that the features have expanded greatly since the last time I raised the price. I think the last time the price was increased was in the late version 2 or early version 3 era. MeshCAM has gone thru a huge evolution since then and I think it’s fair to say that only thing that MeshCAM 2 and MeshCAM 5 share is the name.
From a competitive view, there’s nothing that offers the features that MeshCAM does for anything near the price. The range of toolpaths, toolpath options, and toolpath accuracy is well beyond all competitors below $500 to $1000.
Finally, price tells a customer what a product is worth. I can go on and on about what MeshCAM has and compare it to competitors but many people will assume that there’s something wrong with MeshCAM, or that it’s not suitable for their application, because it’s “too cheap”. A corollary to this is that I’ve found myself cringing lately when I speak to other software developers and I explain my pricing compared to market norms. I cringe because the next questions is almost always, “Are you selling a substandard product or you just ignoring the market?”
In the end the price is now $250. For corporate customers this is almost nothing; for individuals the cost might be much more siginificant. I’ve always tried to sell software that provides value well beyond it’s cost. I still belive this to be the case and I’ll continue to work to add additional value/features even after you buy.
]]>This release also has new a new change to reduce memory use in the “Offsetting” stage of the toolpath calculation by up to 75%. This is obviously a huge improvement and it should go a long way to reduce out-of-memory errors that can occur when using MeshCAM in larger applications.
If you need a code to try the new release for 30 days then you can go to the download page to get one.
Let me know what you think.
]]>The forum is still on the old server until I know what to do with it. From a security point-of-view, it’s unlikely that I’ll be running anything like that on my main server ever again. VPS hosting is cheap and reverse proxies can hide the fact that you’re running multiple servers so why risk it?
I hope that you’ll find the new site to be faster and with fewer random outages. If you come across anything that’s broken, please send me an email and let me know. Right now the only problem that I know of right now is the video on the MeshCAM Art page.
]]>If you’d like to get in touch with Michael about having a custom guitar made he can be reached at mikdavhil1 [AT] yahoo.com . Either way, enjoy the photos:
I’ve had a love/hate thing with Wordpress. On one hand, it’s capable of doing almost anything and it’s the blogging standard almost everywhere. On the down side, it’s bad on shared hosting, even with caching plugins, and I never did anything really advanced with it so I never got the full benefit. You also have to worry about security since Wordpress is the target of a lot of hackers.
I could address all of these concerns by going to a better hosting environment and server configuration but hosting websites is not the focus of GRZ is so it would never be worthwhile.
I had been eyeballing Octopress for a while and I finally got it switched over late last night. Octopress is a static site generator so I can write a post and run a command locally to generate the whole site. Now when you view a blog post there is nothing being rendered dynamically on the web server- it just sends down a raw HTML page. This is a huge win for security, speed and backups. And it’s one headache that I don’t have to deal with anymore.
I do need to get the theme more inline with the main site but that’s not a huge priority now.
While my experience with Wordpress was mostly-good, my experience with phpBB, the forum software I use, has been mostly-bad. I was looking for competing software to install locally but I’ve come to realize that I’d prefer a hosted solution to get it off of my server. I haven’t found a good solution to export everything from phpBB to a new system so I may just have to save the current forum as a read-only archive and just move to a new empty forum from here.
Right now I’ve been looking at Ning and Vanilla Forums. Ning is looking like the winner right now but I’m open to suggestions.
There have been a number of V5 updates that have gone out lately that have not been announced here. The big V5 features have not been implemented yet. Unfortunately, they require big UI changes and lots of trial and error. I haven’t had a good idea about how to tackle these in a way that I’d be happy with them.
In the past week or two I’ve had a couple of ideas about how to move forward. Implementing these ideas requires major architectural changes in parts of MeshCAM that I don’t ever touch because they work well. I’ve spent several days cleaning up 8 years of monolithic code into something more modular. I’m not done yet but the progress has been good.
If everything works out as expected then this new setup will enable me to rapidly implement a number of features that I’ve been stuck on for a while. It will also enable a lot of new possibilities.
]]>http://anthromod.com/blog/?p=98
Chris appears to have tried a number of rapid prototyping technologies and has started using the CNC/casting approach outlined at http://lcamtuf.coredump.cx/guerrilla_cnc1.shtml . That happens to be one of my favorite pages so I always look for reasons to link to it. You should check out both pages if you’re not familiar with the casting process.
]]>http://www.kwartzlab.ca/2011/08/creating-3-dimensional-objects-taig-mill-rotary-axis/
He’s got a much cleaner work area than I do.
]]>64 Bit Support
A new “Automatic Toolpath Wizard” in the main toolpath dialog
I have been using only this version for about a month and it seems at least as stable as V4 although I’m sure there are plenty of bugs in there. I would like some feedback on the new toolpath wizard if you have some time. The main purpose of it is to analyze the geometry and then enable a “sane” set of toolpaths so new users don’t have to know what the difference between waterline, pencil, and parallel finishing are.
I am already getting upgrade questions so I just want to reiterate the upgrade policy- if V5 is released within one year of your purchase (either a new purchase or an upgrade from a prior version), you will get it as a free upgrade. I can guarantee that it will be released in less than one year from today, hopefully much sooner.
]]>We’ll use the part below to show how we can do a DXF to g code conversion with minimal effort:
This files contains a good combination of arcs, line segments and bezier curves. Also, these is nesting where the rectangle and circle are within the outline curve. MeshCAM will have no problem finding this hierarchy and generating a toolpath automatically.
The first step in the DXF to g code process is the DXF file. The DXF format has suffered a long evolution that makes it a less-than-ideal format to move CAD data between programs. The “most compatible” version of this format was way back in Autocad Release 12, and that’s the one that MeshCAM likes to see. Future MeshCAM releases will probably support newer DXF versions but V12 is the best one to use for wide compatibility with other programs.
Most CAD programs will have a list of DXF options available when you save the file. In this example, we’re using the excellent Rhino CAD program but the lessons apply to almost any CAD program that can save 2D DXF files.
After saving clicking “Save As”, select a file type of “DXF”. You’ll be shown this window:
Select the “R12 Lines & Arcs” option and you’re done.
Click “File” then “Open 2D DXF” and load the file saved above. The file will be opened like any other 3D file with the exception of the new “Extrude” window:
The setting entered here will tell MeshCAM how thinck to make the new geometry. If you’re just trying to cut flat stock then you should make the distance equal to the thickness of your stock. For the example here, we’ll use .125”.
It’s worth noting that this extrude command was added in MeshCAM V4. V3 users will not have this command available.
The stock in MeshCAM is used to define the area in which the tool is allowed to move. By default it is set to the size of the geometry you load (you can see it as the white box around the part). In this case, the stock is touching the geometry so the tool would not be able to move completely around the part to cut it out. We’ll enlarge the stock using the “CAM->Define Stock” command.
Since we just need to add a little room around the part, enter “.2” for the “Right” and “Back” values under the “XY Position” area. All other defaults are fine.
In the screenshot below, you can see that the white box representing the stock has been enlarged.
The current settings would be fine if you’re going to hold the stock down with double-side tape or something similar. What if you need to add tabs or other supports to hold the parts in place for machining? Use the “CAM->Set Geometry Supports” command and enter the settings below:
Click at a few spots around the part to automatically place supports. Don’t worry if you get one or two of them wrong, you can right-click to remove the last support. When you’re done it will look something like this:
The only part left is the toolpath, and there’s not much to that. Since we’re just looking to cut out a profile, we can skip the normal roughing and parallel finishing passes. We’re going to use the waterline and pencil finishing only. As a quick refresher on those two, waterline makes a series of profile passes around the part, each a little deeper than the last. The only thing it does not do it attempt to find the “final depth” of the part to take a last cutout pass. The pencil toolpath is used to trace the outline of the part one file time a full depth and ensure that nothing remains around the part.
We’ll use a .125” endmill for both toolpaths and a stepdown of .03” for the waterline pass. The rest of the settings can be seen below:
Click “OK” and after a couple of seconds you’ll have a toolpath ready to go:
After you do this the first time, I think you’ll be agree that this is “way faster” than a traditional 2D CAM program that requires you to select vectors to cut or one that just does a straight DXF to g code conversion where no tool offsets are calculated.
A couple of other options for advanced users:
1) If you want to plunge to full depth and cut the whole thing in one pass then skip the waterline and use only a pencil pass.
2) You can tell MeshCAM that the waterline tool is a little bigger than it really is. This will cause it to offset the tool more than it should leave a little extra material around the part. This lets the pencil pass cleanup the final surface in a single pass with a better finish. For example, if you tell the waterline pass that your .125” endmill is actually .135”, MeshCAM will leave .005” for final cleanup. This is one way that lying to MeshCAM can get you additional features that were never programmed into it. Don’t worry, it’ll forgive you.
]]>All of that being said, it’s worth noting a few “quirks” about SW that make it slightly trickier to get a file out of than a program like Rhino.
MeshCAM Accepts 3D files as STL or DXF (using 3D Faces). Of the two, STL is preferable since it is a more robust format and it is faster to read into MeshCAM.
STL is a file format originally developed for the 3D printer market that represents your models as a bunch of triangles. Some users worry that some accuracy will be lost in the triangulation but this is not really the case. As shown below, you can create the STL file to almost arbitrary accuracy- generally well beyond the accuracy of your mill. Second, most CAM programs that take SolidWorks files natively do this triangulation in the background, it’s just hidden from you.
The first thing that many users note when taking the output from SolidWorks to CAM software is the orientation of the parts. As someone planning to machine a part after designing it, it’s tempting to build the part by extruding out from the “Top” plane.
When you load the resulting STL file into MeshCAM you’ll see the following:
Obviously, this will require a rotation before machining it. Within MeshCAM you can use the “Rotate Geometry” command to get the correct orientation. You can enter an X rotation of “-90” or, if you’re running MeshCAM Version 5, click the face button below:
The simple option is to always extrude from the “Front” plane in SolidWorks. If you do, you will always be able to load the STL directly into MeshCAM without rotation.
[EDIT] Randy just filled me on another technique that I never knew about- reference coordinate systems. Under your Insert->Reference Geometry menu, select Coordinate System. Place it in whatever location you want but align it so that the Z axis is parallel to the Z axis of your mill. When you open the STL Options window, pick that new coordinate system using the pull down shown here:
Your STL will now have the proper orientation without any need to rotate it within MeshCAM. Thanks Randy!
Here’s a really frustrating thing in SolidWorks (if you don’t know about it)- the units of the STL are not necessarily the same as your part.
After you click “Save As” and select STL as the file type, click the “Options” button shown below.
When you get the options window open, note the “Unit” setting:
The unit value selected here will be used in your STL file no matter what units are used in your part file. If they differ, the part will be converted to the STL units when you save it.
The other major setting that affects the STL output is the “Resolution” setting defined in the “Export Options” window shown above. The resolution values define how accurately the STL represents your original part file.
SolidWorks predefines a “coarse” and “fine” resolution and these will be fine for most users. Unless you have a very large model I would usually recommend starting with the “Fine” option.
SolidWorks also gives you the option to define your own quality level using the “Angle” and “Deviation” sliders. ”Angle” defines the maximum allowable angle between two triangles that originate from the same surface. If that threshold is exceeded, smaller triangles are used. The “Deviation” is the maximum allowable error allowable in the output. Put another way, “deviation” is the maximum distance that a triangle can be from the surface that it represents. For both settings, smaller values will give more accurate files at the expense of more triangles generate. MeshCAM can handle very large STL files so you can definately use settings that are beyond the predefined “Fine” values and still have no problems.
Here is my one complaint about SolidWorks- it will not save surfaces as STL files, it will only save watertight solids. To be fair, this is part of the STL standard and they follow that standard carefully. If you have a surface model you will not be able to save it as an STL without finding a way to make it into a solid.
For what it’s worth, most other CAD programs will generate STL files from surfaces and MeshCAM will happily machine them.
Hopefully this is enough to get new users over a few of the difficult starting points to get going with SolidWorks CAM. Be sure to post in the comments in there is anything else that should be added.
]]>
While there is a certain “elegance” if you’re an engineer, it’s a wall of grey numbers to normal people. Below is the new version which retains almost all of the functionality with far fewer buttons and numbers:
I think it’s better but I guess I’ll know for sure once new users begin playing with it. I didn’t delete the old code just in case…
]]>An undercut is an area of a model where one part overhangs another part, creating a void in the middle that cannot be reached by a traditional 3-axis mill or router. That probably sounds like gibberish so here’s a picture-
That “hook” creates an area between it and the back plate that cannot be machined. You’d have to leave a section unmachined or break it into multiple parts and bolt or glue it together.
It’s worth noting that an “undercut” is specific to a direction of machining. The part above only has an undercut if you machine it from the top or the back. You could flip it on it’s side to machine it but that’s not really a cure all- I could easily come up with a part where that is not possible. We’re using a simple part here to illustrate a point.
Special tools are sometimes used to machine simple undercuts. These are sometimes called “slot cutters” or “lollipop cutters” depending on their shape. Both tools feature a tip that is wider than the shaft. This gives the machinist some limited ability to reach into the undercut- but only by the difference between the tip and shaft diameter. For many uses this will be fine but it is certainly not a universal solution.
A big negative for these tools is that most CAM software does not support them directly. Because these special cutters are infrequently used, only the hig-end CAM programs include algorithms that can utilize them. For the rest of us, special cutters require manual gcode, tricking the CAM program, or moving the mill manually. I’ve never had a case where their use outweighed their negatives.
It’s easy to see that the cutter above may not have the reach to machine the whole undercut in our example part. Surely there’s another way…
I spent years as an electrical engineer working with factories in China, ignoring the plastic and mechanical parts of my projects. One day a friend of mine showed me how he modified a part to eliminate a small undercut that would cause excessive wear in one of our molds. It was a common practice for plastic injection molding but it was not something that ever occurred to me- cut a hole in the back of the part for a tool to get in. In retrospect it was obvious but it wasn’t something I ever spent much time thinking about.
This access hole in the back of the part allows you to flip the part over and machine the undercut from the back. MeshCAM has a built-in “two-side job” type that makes this really easy. Below is what the front and back toolpaths might look like:
The red arrow shows where the tool is now able to access the undercut and remove that material.
The same technique above can be applied to more complicated parts that would be much more difficult to machine in their “standard” configuration. Here’s one one of those, half a hinge:
The hinge is now easy to machine from two sides and would be easy to mold if necessary without slides or inserts. It’s not exactly going to work for a restoration job on an antique piece of furniture but it’s still a cool trick.
If you have kids then you’re probably going through toys at a rapid pace, try opening a few up and looking at how they are designed. You will likely be shocked at the number of shortcut and tricks used to make complicated mechanisms that can be produced in simple injection molds without undercuts. Most of these injection molding tricks are applicable to the milling process as well.
Cutting a hole in a part is not going to work every time but it does work more often than you think and it’s one of the easiest ways to machine a difficult part.
]]>
That’s a peak usage of 5 GB of memory without a crash. The model used in that test was a 12 foot diameter sphere machined with a 2mm stepover at a .001” tolerance.
When packed into the existing installer the 64 bit build only adds about 3MB to the file size. That’s pretty insignificant so I’m going to stay with a single installer for both 32 and 64 bit builds. 64 bit users will be able to pick which version to use while 32 bit users will automatically be given that version.
To get this build working I had to make hundreds of little changes so this build officially marks the start of MeshCAM V5 development. It won’t be done anytime soon but I will try to get some betas flowing over the next couple of months.
]]>The following post focuses mostly on 3D toolpaths so we’ll be assuming the use of a ball mill. Once you understand the basic concepts it’s easy to apply them to flat end mills and bull mills. We’ll try to build to some rules of thumb rather than derive equations that most users won’t be interested in.
Almost all CNC toolpaths are based on the concept of one toolpath being offset from another by some distance; this offset distance is generally called the stepover. Most CAM software, MeshCAM included, uses a couple toolpath styles in particular with these offsets- the raster toolpath (sometimes called a zig-zag toolpath) and a contour offset.
Adjacent sections of the toolpaths above are separated by the stepover value chosen by the user.
The pictures above show how a toolpath is arranged from above but a side view clearly shows the primary side effect of your stepover choice- scalloping.
The area in red is the part of the stock leftover on the part in between the toolpath offsets. It’s important to understand that these are not good; they are not in the CAD and may need to be removed after machining by sanding or polishing. CNC machinists are almost always trying to reduce the scalloping as much as possible and many man-years of effort have been spent trying to develop toolpath algorithms that minimize them.
A moment spent looking at the image above illustrates at connection between scallop height and the stepover value- increase one and the other increases as well. In the images below we’ll use a stepover equal to 1/10, 1/5, and 1/3 of the tool diameter to show this correlation. To put real numbers on this, that would be equavalent to a .012, .025, and .042” stepover for a .125” ball mill.
As you can see, the change in quality is so dramatic that you might be tempted to always use the smallest stepover possible.
It shouldn’t be surprising that you’ll have to give something up if you want to use a really small stepover. In this case you’ll trade time for quality- you give up machining speed to use a small stepover or give up quality if you want a quick machining time. This is easy to understand when you consider that the total length of a toolpath will approximately double if you cut the stepover in half. The question is, “Will cutting the stepover in half double the quality of my part?”
It turns out that there is a point of diminishing returns in the time/quality tradeoff. Below is a graph of scallop height vs stepover that illustrates the effect. The graph has been normalized to a tool diameter of 1.0 so it’s easy to scale it to any tool you happen to be using. (Click on it to see a bigger version)
The important thing to note is the shape of the graph- it tends to flatten out when the stepover goes below about one eighth of the diameter. This means that when you go below this point you’re going to take more time to machine without a proportional gain in finish quality. If you’re machining a steel injection mold then it may still be worth it but you really need to be sure before doing that.
Here’s the other thing we can glean from the math behind the chart above- for a given stepover, a larger tool will give you a smaller scallop. This means that you can get a better finish “for free” if you can use a larger tool. Obviously, this only works if a bigger tool will fit into all of the parts of your geometry but this is one of the few “win-win” things we can do get better results if it does work for your geometry.
Before you figure out what stepover you need to get a .0001” scallop, think about what you are going to machine- wood, tooling board, aluminum, steel, etc. I can tell you that in many cases you can do 10 minutes of sanding on a wood part to get a finish that would have taken you an extra hour or two to get straight from the mill. Likewise, tooling board like Renshape can be hand finished quickly enough that it may not be worth doubling the machining time to get a better finish. If you’re cutting steel or other hard materials then it’s probably worth letting the mill do more of the hard work.
The second characteristic of the material to consider is what kind of detail it can hold. MDF will not hold features in the .01” range but metal will. If your material cannot hold a detail that is smaller than your scallop height then you do not need to reduce the stepover; doing so will only waste your time without producing a better finish.
It may be a poor craftsman that blames his tools but we do have to be realistic about the nature of our equipment. In particular, how long do you trust your mill or router to run trouble-free? I started out with a small table-top mill that, while very good, could not be trusted to run for hours without missing a step or hiccuping in some way that gouged a part I had waited half a day to get. If you have a machine like this then it’s worth thinking about the picking the maximum stepover based more on machining time than finish.
That was a nice bunch of pictures but you may still be left with the question, “So what stepover do I use?” Here are a few suggestions:
Once you have a few projects complete you can adjust the guidelines above to suit you materials and machine.
]]>Here it is CNC Milling Feeds and Speeds Cookbook
]]>Below is a simple geometry that I’ve loaded into MeshCAM:
As you can see, it’s a very simple sphere but it has two very important characteristics that can be used to illustrate the benefits of the surface angle limit function, it has a relatively flat area on the top of the sphere and vertical walls at the edge when machined on a 3-axis mill. All toolpaths shown below will use a .25” ball mill with a .05” stepover and stepdown.
Below is what the toolpath looks like if we just use the parallel finish option:
This is probably a very familiar-looking toolpath if you’ve spent any time with MeshCAM. If we simulate it in Cutviewer we get the following:
Note that the vertical edges are really rough while the top is relatively smooth. This illustrates the most important characteristic of parallel finishing: you get good results for shallow areas and poor results for steep areas. We could get a better finish on the whole part by reducing the stepover but that has a direct impact on machine time and machine time is something that most people strive to reduce.
Waterline toolpaths are in many ways the exact opposite of parallel paths- you want them for the steep areas and want to avoid them for shallow areas. Here is the same part with a waterline toolpath:
Note that the simulation shows the opposite of the parallel finish- the shallow top of the sphere is really rough and the steeper parts look good. As in the parallel, we can reduce the stepdown to get a better overall finish at the expense of machining time but that is never something to consider if you have other options.
It’s also easy enough to enable both parallel and waterline toolpaths at the same time to get a better finish but that is like reducing the stepover/stepdown- you are just trading the finish for machining time since musch of the geometry would be machine twice. Surely we can do better.
This brings us to the point of this post, the “Surface angle limit” and “Min surface angle” settings:
The purpose of these setting is to tell MeshCAM where to apply the parallel and waterline toolpaths. If the “Surface Angle Limit” parameter is enabled, only areas that are flatter than the defined angle will be machined with the parallel path. Likewise, only areas that are steeper than the “Min Surface Angle” value will be cut with the waterline toolpath. Generally I like to make them overlap slightly so there is no hard edge between the two in the finished part. Using the values above the toolpath looks like this:
That get’s us close to an ideal condition- steep areas with waterline, shallow areas with parallel and most of the geometry is machine only once. That’s as close to win-win as you can get.
Here’s a quick recap of why surface angle limits are such an important feature:
For many users this should be something that is used on every job.
]]>My one caveat for this post is that it doesn’t apply equally to everyone; if you have a big machining center with an automatic tool changer and properly configured tool offset tables then this doesn’t apply to you as much.
It’s difficult to write clearly about sizes and edges when we talk about the location of the zero. MeshCAM uses the compass layout- north, south, east, and west, to describe the location. This can be seen more clearly in the image below:
At a basic level, the program zero tells the mill where to find the stock on it’s table. Since the mill table is generally much bigger than the stock you are cutting the mill must be “told” where you’ve put the stock. Without this registration process, there is very little chance that anything would line up.
The program zero also gives the CAM software a single reference point for the toolpath. On a mathematical level, the CAM program can accept any arbitrary zero point, it’s just an offset in space and one is as good as another. For you, the machinist, the program zero must be something you can locate with the mill; if the point cannot be located then you are probably going to have a lot of problems.
Imagine, for instance, a zero that was 10 inches to the left of the bottom corner of the stock. While this is a point that does exist, it’s in empty space so you have very little change of accurately finding it.
By contrast, if you were to pick a corner of the stock then you have three planes/sides that you can touch the tool off of, the top, side, and front.
While this zero may take a few minutes for a new machinist to locate, it’s not hard to do if you’re patient.
If I had to give you one default position to pick it would be the top of the stock, in the lower left-hand corner, the southwest corner in MeshCAM terminology. In general, this is what I use 90% of the time; it works well, it’s easy to locate and it keeps all of the X and Y toolpath coordinates as positive numbers. Z coordinates will be negative when you’re cutting into the stock and any positive Z number should be “in the air”. The only time the “Top Southwest” position may give you trouble is when you need to change tools…
All of the coordinates in the gcode file tell the mill where to move the tip of your tool. If you change tools in the middle of a machining job then you need to reset the Z value of the zero since the two tools are not likely to be exactly the same length. The point you pick for a zero must be available any time you need to do a tool change and reset the tool length. If the point initially used has been machined away by the roughing operation then you’ve lost the ability to set your tool length. Image that you’ve set the zero on the top, southwest corner as seen below:
Nor you’ve finishing roughing and you’d like to use a different tool for the finishing. You need to touch off that corner again except that it isn’t there:
In many machine controllers it is possible to preconfigure everything so that a tool change doesn’t require a rezero. This option requires very accurate tool holders that keep the length constant and a lot of effort on your part to measure and input all of the length data before machining begins. In my experience, very few people do this.
The one saving grace here is that you really only need to recover the Z value and you might be able to recover that from a different section of the stock or as an offset from the table, if you knew the original thickness of the stock with sufficient accuracy.
Well, there’s no single answer but none of them are very difficult. Here are a couple of things to keep in mind each time:
Those three criterion are good enough most of the time and most users will never have to go beyond that.
Two-side jobs are a special case in MeshCAM. It will do the bulk of the mental gymnastics to cut two sides of a part and give you two gcode files; one for the front and one for the back. The tradeoff is that you must provide MeshCAM with very accurate measurements of the stock so it can do the calculations on both sides. The whole process also requires you to remove the stock half way and flip it over to machine the back. While neither of these requirements is particularly daunting it does impose additional burdens on you as the machinist.
Below is what a cross section of the part might look like after a two-side machining job
If you do not accurately measure the stock or if you do not accurately put the stock back on the mill you are likely to end up with the following cross section:
This is completely avoidable if you spend the time to prepare the mill and the stock. First, align your vise or jig as perfectly as you can to the mill. Second, prepare the stock so that it is as square as you can make it and that you have the most accurate measurements possible. The your choice of program zeros can help reduce the error caused by doing either of these less-than-perfectly.
If possible, it is important to set the zero on the top of the stock, on middle of the left edge (“West” in the MeshCAM terminology). The helps mitigate the effects of error in the measurements you’ve given to MeshCAM as well as some alignment problems.
The only difficulty here is that desired zero point that cannot be directly located; you have to find the top and bottom edges and then set the zero to be at the middle point that you calculate between the two of them. It is important to zero the Y axis before the X axis; this lets you find the left edge at the same Y position for both sides of the job. If your stock is not completely square then this will help correct for erroneous offsets between the two sides of the job.
It takes another minute to locate the zero but I have found the results to be completely worth the effort. It may not be completely clear why this matters right now but it will become more obvious after you go through the whole process once or twice.
In my experience, 90% of machining is know how to hold the stock down and how to locate the features you need to get reference points (and taking the time to do both right). Once you get the “zero problem” figured out and you understand all of your options then you’re already well on your way.
]]>Once I do get it fully compiling I need to decide how I want to release it- as a V5 alpha or as V4. V5 is probably the route I’ll take because hundred of lines of code have been changed to make 64 bit builds work and I don’t want V4 to regress at all.
]]>Second, the parallel finish layout has been optimized to greatly speed it up. Most users will never notice unless they are using very small stepovers. If this is something you do then then I think you will see a difference.
The added feature in this build is integration with the G-Wizard Feedrate Caluclator. G-Wizard is a very cool piece of code that does some advanced calculations to determine an RPM and feedrate based on your material and tolerance specs. You can enable the output in G-Wizard in the “Settings” tab as seen below:
When you do a speed/feed calculation you’ll see a “Copy” button as seen here:
That button will copy the tool parameters to the clipboard in a format that Bob and I worked out. In the Edit Tool dialog in MeshCAM you will see a new “Paste” button if the clipboard contains data that is in the correct format.
I think this will be a big help for new users who aren’t quite sure what settings to use. It should also help more advanced users get the most out of their mill without sacrificing accuracy.
If you haven’t seen the CNC Cookbook site then be sure to check it out and try the 30 day demo of G-Wizard.
]]>A MeshCAM user, Eddie F, contributed that page to help the community and it finally convinced me to give it a try. I had always heard rumors that it worked well but I remember Wine being flakey many years ago and I never bother to try it. I found that MeshCAM worked perfectly under Linux for everything I tried. If you’re a Linux user then give it a shot, I think you’ll like it.
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