Grz Software View Topic

1. Grz Software View Viewtopic

O.k., it looks like I'm going to have to e-mail Rob directly on this one because I can't upload any images because 'the board attachment quota has been reached'. Nevertheless, I will try to explain what is happening in the hope that someone recognises the problem, or user error if that's what it is. I am trying to calculate toolpaths to mill the two 3/4' (19 mm) half sections of a guitar body. The upper section has some full depth cut outs and some areas where I am cutting to a depth of 15.5 mm and leaving 3.5 mm.

The lower section has no full depth cut outs, only pockets. MeshCAM 6 crashes every time except on simple toolpaths so is basically useless to me. I first highlighted this to Rob back in October IIRC and the advice I got was to select 'by layer' instead of 'depth first'. Even that is not making any difference now.

GRZ Software ‏ @grzsoftware 1. Follow more accounts to get instant updates about topics you care about. Find what's happening See the latest conversations about any topic instantly. Never miss a Moment Catch up instantly on the best stories happening as they unfold. Okay so here is a little more complex one. Meshcam will not cut the circle geometry but will do the slot. I have tried both rough pass and waterline and both.

I previously only experienced crashes on the long neck toolpath calculation; I did not experience any problems with the guitar body toolpaths which are almost exclusively 2.5D in nature. MeshCAM V7 Beta Build 4 calculates a toolpath in a reasonable timescale but I get suspiciously short estimated toolpath times (e.g. 33 mins waterline, 7 mins parallel path & 2 mins pencil cleanup). For the full depth cut outs, it only uses waterline which seems logical enough. However, something appears to be wrong with the parallel path on the visualisation.

It appears to assume that all the depth above it has magically disappeared and only does a parallel path at the bottom of the pocket instead of doing a parallel path at every depth increment (in this case 1.00 mm) as I assumed. This happens on both sections where there are full cut outs or only pockets. I haven't noticed this problem before with previous beta versions.

A summary of my parameters: 4 mm four flute carbide FLAT end mill, 25 mm flute length. Overall length 75 mm.

No roughing passes, tolerance: 0.05 mm, machining margin: 4.00 mm, 2,000 mm/min feed rate. 120 mm/min plunge rate, stepover 2.00 mm, stepdown 1.00 mm. Depth per pass 1.00 mm, cut along Y. Don't machine top of stock selected.

46/44 Surface angle limit/min surface angle. Needless to say I'm getting pretty frustrated with this software. Doug wrote:However, something appears to be wrong with the parallel path on the visualisation.

It appears to assume that all the depth above it has magically disappeared and only does a parallel path at the bottom of the pocket instead of doing a parallel path at every depth increment (in this case 1.00 mm) as I assumed. Doug, that is how finishing works. It does assume that you have done a roughing cut first. Finishing passes by their nature and design follow the surface exactly. With waterline, of course, you set a stepdown increment, but that only applies to the waterline.

For the parallel finishing, you specify a stepover, which is analagous to the waterline stepdown. If you have a pocket that is deeper than your comfortable finish cutting depth, you must rough first. Randy wrote:Doug, that is how finishing works. It does assume that you have done a roughing cut first.

Finishing passes by their nature and design follow the surface exactly. That's perfectly logical but. I have never used a roughing toolpath on any of my toolpath calculations because it generated preposterously long toolpaths at the outset. I have done all my previous successful calculations with finishing options (parallel, waterline and pencil cleanup only!

This is the first time that I have encountered this issue. I thought use of a roughing toolpath was optional? Well, in any case I presume therefore that something has changed in MeshCAM 7 beta build 4 that means a finishing toolpath is now mandatory?

Where can I find the release notes for each new beta or build of MeshCAM to check what changes have been made? If you've gotten by without roughing then you have been fortunate. Part outlines and holes all the way through the stock (which are themselves outlines) are of course done just with waterline and pencil finishing. Part-depth pockets that are less than twice the cutter diameter are also cleaned fully with the waterline+pencil.

But part-depth pockets wider than twice the cutter diameter will leave 'islands' in their interior that must be removed by parallel finishing. If they are not too deep to do in a single pass (i.e. Without snapping the cutter ) then you don't need roughing.

But in general a roughing process will be needed for large, deep (by the criteria above) pockets. That has always been so. I don't know about release 7 at all-I'm without a MeshCAM PC entirely for the time being. The only place I know release notes exist are in the Help menu after you have already installed the new release.

Grz Software View Viewtopic

Many thanks for that insight. I have made progress with MeshCAM 7 and some sensible roughing parameters since my original post. I realised that stepover for a flat end mill in the roughing toolpath can simply be equal to the end mill diameter (i.e. I am going to do some simple back and forth test milling on some offcuts using a 2.0 mm depth per pass with the 4.0 mm end mill to see if this can be tolerated by my system. The automatic toolpath wizard suggested 1.0 mm depth per pass but 2.0 mm will bring the longest roughing toolpath duration on the guitar body sections down from 101 minutes to 54 minutes which is more tolerable. I will need to revisit the neck toolpath given this new insight (or dumbass original assumption on my part). In this case I was using a 4 mm ball end mill so I will need to think it through very carefully particularly with respect to whether I change from a flat end mill to a ball end mill for the finishing toolpaths.