Public Service Announcement - Make More in Less Time via Tuning

Quote:

---

Originally Posted by barrowj

I will give this a try, was cutting a Chip/Dip bowl this weekend and the corner cuts was so slow that the bit looks black at the tip, guess that is the issue (hope so anyway).

---

Probably. The best thing would be to reset your VR to default via the fill-in sheet to make sure other settings didn't get messed up. I don't know why, but some people's settings get jacked up for one reason or another, through no apparent fault of their own. It's always good to take a peek and check your settings.

Unless it is a very specific/exotic job, I only mess with the Slow Corner Speed, Min Distance to Check and 3D Ramp Threshold. It is rare, and usually unnecessary to mess with the other settings, but there are times where you need to.

Oh...VERY IMPORTANT: Be sure that your MS is set to something reasonable when machining. So if you are hogging out a 4x4" pocket for a bowl, it is not possible to run this job at 6" per second. Maybe 2" per second is more reasonable because of the accel/decel ramp. It will only be at 2 IPS for a very short distance before it needs to slow down to move in stepover & raster back again the other way.

If you set your speeds too high (MS), then the tool can get choppy and erratic as it tries to compensate for poor choices in MS. You cannot go by speed values in ANY CAM software - they are just defaults with NO logic behind them. I cannot tell you how many times I have trained someone only to find they were running v-carve toolpaths at the default MS,6,6 - because they thought those were recommended speeds. This is not so!

You can observe the effects of improper MS values for yourself as an experiment to get greater understanding. Put an obscene MS value in for XY to cover a small area (say a pocket in a 4" square space @ MS,6,1) and leave your VR @ default settings) An 'air cut' above the table is fine for this. No need to actually cut. Observe the movement of the tool & maybe even place your hand on one of the gantry end plates and feel what is going on. Then pull your MS back to like 1.5 or 2 IPS for XY and hear/feel the difference. There will be some variation in effectiveness from one model to another, but you should be able to pick up on "do's & don'ts" with this.

-B

Brady,

I had the speed set at ms 2,.5 and was using a 1/2" bit to do the rough pocket and as it would do the 1"-2" half circle it would seem to crawl at (just as an example) .1 or .2 then jerk up to 2ips. I cut this same item before upgrading my communications card and SB3 3.6.46 and it was fine. I was also using the Shopbot arc file you sent me a few weeks back but even changing that didn't seem to matter. My slow corner speed in VR is 65 .

The tool can't go 2 IPS within an area of 2" (assuming 1/2 circle with dimensions of 2x1") with a 1/2" bit. This means that the largest straight line distance would be only 1.5" using a 1/2" bit. 2.00" minus 0.5" = 1.50"

-B

Brady,

It really is a bigger project than that, I've attached a copy of my crv file so you can see what I am working with. If 1/2" is too big to rough this, please let me know.

Thanks,

Joe Barrow
joe@joebarrow.com

http://www.joebarrow.com/download/xmas-bells.crv

Joe,
I don't see any problem with that shape aside from the 1" circles where it may slow down a bit. Where are you getting the burn marks specifically?

-B

Thanks for the info Brady, thats what makes this forum great, I spend more time on the mechanicals and my designs, I forget about tweeking the controls.

Brady,

It's occurring in the arc/ 1/2 circle's and really slows to a crawl and just starts smoking then pulls out of the arc and cuts normal. I appreciate the help, really appreciated.

Joe

Thanks Brian.

Joe,
Post a screenshot of your VR settings.

-B

Brady,

As requested, I have not made any changes, still learning this but hope to learn lot's more at the Aspire camp in SC.


http://www.talkshopbot.com/forum/att...id=24408&stc=1

Sorry for jumpin' on Brady's thread here, but you need to reset your ramp values to default settings. The reason it's slowing down so much in the corners is due to the xy ramp speed of 0.1. Default is 0.4. A slow corner setting of 65 will also contribute to it. Try dropping that down in increments of 5 to see the results.

On a side note here, depending on what version of SB3 you are using (older versions had this problem), clicking on the 'reset' in the corner of the fill-in page may or may not set the actual defaults for your machine. I have seen it set values that are completely off, which may be the case here. You are better off to use UR and choose the default config file for your machine.

For anyone that takes the time to tune your ramp settings, take the time to also save out those settings so you can easily return to them at any time. You can do this with US to save the file. Open that file and edit it so that all there is in the file is the VR line and save as a .sbp or .sbc. You can then set up a custom cut that loads this file any time you want to use those settings. As an example, I have custom cuts to load various 3D ramp settings, various v-carve ramp settings, and my preferred default ramp settings all from the 'Cuts' menu.