A few things

Discussions relating to MeshCAM development

A few things

Postby RichC » Thu Feb 25, 2016 2:44 pm

I have been using meshcam for a few years and am very pleased, however thee have been some developments in the latest versions which could just be a little better, plus I think that the waterline finishing could be a bit more efficient.

waterline OVERfinishing, I have been making some parts lately which have a different height across them and are undercut on the outside, imagine making a bowl, and using waterline finishing, on the inside it machines the inner surface but on the outside it cuts round the lip of the bowl all the way down, largely wasting time as i'm going to machine the outside when I flip it over. can we have an option to eliminate the excess toolpaths when the part has an undercut?

2-sided parts with different machining strategies, like I said I am making some parts which are hollow and 2-sided, I have been using meshcam in the 2-sided mode and have been having two issues.
issue 1, toolpath ordering, if I enable multiple toolpaths, i.e. roughing, finishing in y, waterline and pencil cleanup they are generated in that order, what I want to be able to do is generate a file with them in a different order. in the single sided mode I can generate the toolpaths one by one and "save them for later", which is great as I can put them in the right order then, but I can't do this in 2-sided mode.
issue 2, I am using different tools, depth of cuts and strategies for each side, but with large parts it takes time to generate the toolpaths and in 2-sided mode it generates them for both sides when I only want one.

I have started looking at just using single sided mode and reversing the setup, as this cures both issues but have already ruined one block of material with getting an offset wrong, can we have a "flip setup" button in single sided mode to machine the other side? that way my supports would also be in the right place :?

that's all,

thanks,

Rich.
RichC
 
Posts: 5
Joined: Thu Feb 25, 2016 2:22 pm

Re: A few things

Postby Randy » Fri Feb 26, 2016 6:34 am

Hi Rich, and welcome to the forum.

About the waterline "overfinishing", I have a favorite technique I often write about (search "almost fall off" and you'll find the posts):

There are neat things you can do on 3D contoured parts two sided, even if they have an unlevel "equator line". Use a ball-end mill, Machine Geometry Only with a Machining Margin of just less than the cutter radius (i.e. for a .250" cutter, choose margin of .123 or .124") and set the max depth to the bottom of the stock. The cutter will just barely not fall off the edge of the part, but machine as deeply as it needs to to get down to the "equator line" (parting line to be technical as in a molded part). You do need to use an extremely tight calculation tolerance for this to work properly--I always use .0001".


If you use a different diameter roughing and finishing cutter you'll need to set up your job and calculate and save just the roughing toolpath, then go back into the Generate Toolpath dialog, set the machining margin as above considering your finishing cutter, calculate and save just the finishing toolpaths. This works too for double-sided jobs, especially if you use a ball-end mill for roughing, something I like to do on contoured workpieces since it leaves less terracing for the finishing cutter to plow through.

On double-sided jobs, it is not totally unknown for me to set up the rawstock and supports and max depth, calculate the toolpaths for one side (MC will always calculate both the top and bottom toolpaths but look at the file save dialog header carefully and you'll see which side MC is prompting you to save at each step), then go back and change max depth and/or toolbit sizes etc. without touching the rawstock or supports and calculate some more toolpaths.

You may need to work some, but MeshCAM is an amazingly versatile program and there is not much you cannot do with it and some lateral thinking. :) Don't give up on the two-sided, but look at it as a "framework" that you can do neat stuff in.

Randy
All opinions in this post are mine alone. I am not a MeshCAM employee, I do not have a financial interest in MeshCAM, nor do I speak for MeshCAM. MeshCAM user since Beta 5 in 2003. viewtopic.php?f=11&t=15333 :ugeek:
Randy
 
Posts: 1812
Joined: Wed May 14, 2008 9:50 am
Location: North Texas, USA

Re: A few things

Postby RichC » Mon Feb 29, 2016 11:30 am

Hi Randy, thanks for the reply.
I have been doing as you have suggested for almost falling off, although with the machine geometry + set to zero as I will be machining from both sides and I have been using the cut-out toolpath for the final breakthrough, that works fine, I think perhaps a bowl was a bad example, I have a part with a complex shape which has a lip (bowl like most of the way round) but at one end has a vertical face, I want to do as you have described for most of the part, but use waterline for the vertical surface, I have been achieving this by using the machining regions to generate the waterline only where I want it, but this creates a number of files, not that that’s too big a problem.
As for the toolpath ordering, I really like the save for later function in single side mode, I’d just like to be able to use it in double sided mode, and generate one side at a time. I have been doing as you say and only saving whichever side I want, but some of the parts I am making are large and it takes a while to calculate the toolpaths, calculating both sides and throwing one away each time is a bit of a waste of time, that’s all.

Thanks again,

Rich.
RichC
 
Posts: 5
Joined: Thu Feb 25, 2016 2:22 pm


Return to Development