My First Cut File, Easy Profiles, Couple of Speed Questions

[mjindustry]

Well, finally after like 3 weeks of preparation I think we are finally ready to try our first cut! It's simple enough, baby steps here.

I have attached a screen shot of my first job I want to do with my PRT 48x96. It's a few shelves and canvas frames. It will be particle board and is 5/8" thick and a brand new 1/4" end mill bit.

Question: What would be a good speed for the machine to cut this file? IT seems like it always goes to a default of like 1.7 ips and I can't change it. I can but it always goes back to that 1.7.

Then, as for how many passes it will take and the depth of each pass, in the partwizard default seemed to be .1 inch. Does that seem ok with the 1.7 ips for this job? It seems kind of slow, but I dunno what to be expecting of this thing.

At this rate the entire job will take just under two hours...

Thanks in advance for any assistance!

[bill1]

You must have forgot to upload your screen shot.

[mjindustry]

Here is what it looks like...(thats pretty much a whole 4x8 sheet btw)


4970

[mjindustry]

Ok, figured this out on my own here. I need to be selecting my speeds, stepdowns, etc, while I am selecting my tool for any particular toolpath. Got it!


Now, I went ahead and made the change to 3.5 inches per second, and .25 stepdown. I just want to get a hint of whether or not these settings are near appropriate before actually executing. I will probably give this a go if I don't have a response here within an hour or two.

[butch]

Jason
I would cut at 2.5IPS speed, and .5 stepdown, and .5in plunge. Depends on the partical board. If you get a good cut, then increase the speed on the future cuts. Sometimes, I get deflection in partical board, and have hit metal so I cut it slower than something like MDF or hardwood.
But you are right on.

[blackhawk]

Jason - Are you using a router or spindle?

[mjindustry]

Butch, thanks for the tip! I'll go ahead and try those settings.

Brad, I'm using a Router.

[blackhawk]

Since your material is 5/8" thick, I would use a .32" stepdown instead of a .50" stepdown. You are going to have to make 2 passes anyway, might as well split it evenly and reduce the load on the first pass.

Here is a tip that I just learned the other week. While your cut file is running, you can hit 'shift' + '>' to increase your X and Y feedrate. 'Shift' + '<' will decrease it. The shopbot window will show the new feedrate value on the display. This allows you to change things on the fly. Your .sbp file will not be changed.

[richards]

Jason,

It's good practice to make a series of test cuts at various speeds and various depths to see what works best for you.

On my PRT-Alpha, I can cut at 12-ips, but the best quality for cabinet type work is closer to 5-ips. I use the chip-load calculator to get a 0.015 to 0.025 chip. That gives the best results for MDF and particle board on my machine.

Also, whenever possible, I normally cut the first pass at 75% to 85% full depth using a climb cut. The last pass is made full depth (or leaving a 0.020 skin to keep pieces in place) using a conventional cut. The climb cut tends to cut just a little oversize and the conventional cut, being very light, cleans up the edge nicely. That's a trick that Gabe Pari taught me when I dropped in on him a while back.

Since I have a Colombo 3hp spindle, I watch the Amp meter. As long as the Amp reading is less than 7A, I feel safe with the heavy cut. Technically, (3hp X 746) / 240 = 9.325A, but the spindle bearings tend to heat up more than I like when I really push things to the limit.

[bleeth]

A note regarding changing speed on the fly: Unless there has been a change in latest SB software when you change speed this way the ramping stays the same. Therefore if you raise the speed too much you may end up slamming into your corners.