Yes, I'm here... been busy...

[harryball]

Got an email from someone wondering if I was still around... I haven't been gone that long!

Good news... I've been busy! Could be busier but I'll take it. I feel like a baby sitter at times... gotta keep an eye on the batbot so I can't go too far.

I've been optimizing my files, running them faster, better tool pathing etc... One of my files was taking a total of 38 minutes to run, I've now shaved that down to 25 minutes. Most of the improvements have been by tweaking the toolpath. For me, using a grid cut vs. a profile cut has saved a tremendous amount of time. This keeps the bit from having to pass between two parts twice. However, working with start nodes and reducing jogging has given me a big advantage as well.

The other gains have been made by increasing the jog rate to 20 ips and tweaking the turning and ramping speeds. I don't know what I'm doing with them completely yet... but the bot runs smooth and keeps picking up speed.

I also changed my cutting tool. I'm using a 1/4" mortise style onsrud cutter. It is similar to a compression bit but it only has a slight upcut on the bottom and the rest is downcut. It saves time when the cutting is finished. My parts are clean top and bottom and I need to do little more than pick them up.

My twin fein setup is working well though more airflow would be nice. When my table is sealed off with a full sheet I'm pulling 6" of Hg. I find with as little as 2" Hg my larger parts stay put with no trouble. I will probably add more feins in the future as my work volume increases.

Til later,
Robert

[pete]

Robert - can you provide more info on the "Grid" cut vs "Profile" cut - I am not familiar with those terms - how did you make the change - when you have time pls. Thanks, Pete

[harryball]

It's basically arranging vectors in different ways to get the same results. This method would not be a good choice for quick one time projects as it requires more design time. It would also not be the best choice if you need a high degree of accuracy since you are relying on the bit width and each side of the bit is producing a finish cut.

Here is an example...

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On the left are 10 roof panels 2.5" wide by 20" tall spaced at .250" apart. On the right are the rectangle and vectors I created to toolpath. I start by creating the parts that I want then I create a 20" tall poly line and center one between every 2 panels. I finally create a 20" tall x 24.75" wide box and center it around the entire group. I will leave them all together and only toolpath the polylines and rectangle. I moved them off each other above so you could see them clearly.

When creating the polylines you need to place the start points for cutting on opposite ends. So the bit starts at the bottom left, cuts up, moves to the right, cuts down and so on. Add your tabs to keep the parts in place to the rectangle where needed.

Here is the result of tool pathing each one.

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On the left I let the tool path profile each panel. On the right I ran them using the grid method. Can't tell the difference.

In actual application I've found it really helps keeping the smaller parts in place during cutting as well. I cut the internal lines first which leaves the panels solid. Then as the outside is cut and the tabs left behind I'm never doing any significant cutting on a parts while tabbed.

The time savings adds up, the machining time for the conventional approach is 4 minutes, while on the grid cut it is 3 minutes. One of my projects runs a full sheet of 150 small parts and the machine time was 2hr 2m. After taking the time to change to the grid method the machine time has been reduced to 1hr 9m. The more "double cut runs" you eliminate the more time you save. For my bat house fronts panel which cuts 10 panels from a single sheet my run time dropped from 19 minutes to 10 minutes. No internal cut runs twice.

For these production run projects I'm converting all my bat house files to use as much of this method as possible. It takes time on the front end but it pays off in the shop.

If you're not clear on something let me know

Robert

[harryball]

I thought you might get a kick out of seeing this...


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This is my latest version of my kit parts sheet. I'm sure with some time I can eliminate some of the waste. :-)

Robert

[pete]

Robert - well done on the nesting of all those parts - you are certainly getting your money's worth on those panels.

I'm still a bit confused on your grid method - do you create a polyline 20" long and then block copy it, say, 10 times at 2.5" apart? I tried that and then put a rectangle around the lot. And then alternated the starting nodes for each line top-to-bottom and then the rectangle. Is that what you do? I did not account for the bit width - so my panels will be too short and too narrow - correct?
Pete

[harryball]

Sounds about right. When running your outside box you profile outside the rectangle thus your part size is accurate. When you machine on the 20" vectors in the centers you must account for the bit width, .125 on each side of the line.

Block copy works... but I used VCarve Pro as I've begun to avoid PartWizard. Besides a few quirks I can work around I just find its inability to export intolerable. I did a small project for a customer and needed to give them the vector art as part of the deal. I did the work in PW then had to use the sbp to dxf converter to get at the work. I spent an hour cleaning it up and still made a mistake. The next work I did for him was in VCPro, File - Export - done. When I open PW I feel like I'm in a room with no windows or doors.

Robert