Help - Ramp Speed Crisis

[Matt Barinholtz (Unregistered Guest)]

Howdy, all! Well, the Covenant House Artisans are back cutting some awards, and after goofing with Ramp Values, we are really having a tough time keeping the 'bot from jerking instead of making smooth cuts. We are running the DOS software (that's how we learned, and built our curriculum - I know, just too lazy to switch...) and are running a .75" 90 degree v-cutter, milling letters that are only 3/16" high in some places. We are running the machine at mxy .2, mz .2, jxy .5, jz .5 to keep is slow and smooth. Our VR is currently set at mxy .13, mz .13, no MA, jxy .35, jz .4, no JA - but I think i screwed up because we chanced the MS distance, JS distance, threshold percentage and minimum distance.

Does anybody vcarve little letters, and have preferences for the ramp values?

Are there default values? Now the machine is just cutting jagged lines - ruined a couple pieces of stock - you should have seen my student come running across the shop yelling and pointing....that's what the s key is for!

Please help - our project is due soon!

Matt Barinholtz
Covenant House Washington, DC

[pacoisa@cooptel.qc.ca]

Default could be; XY ramp=.85,Z ramp=.45,Acc ramp=.4
XY jog ramp=.95,Z jog ramp=.75,Acc jog ramp=.45

Hope this help!! Look you're in rush!!!

[billp]

Matt,
I'm just guessing here, but if you were to reinstall the software wouldn't that bring you back to the defaults?

[srwtlc]

You could delete the shopbot.ini file and when you restart the software it will create a new one from the PRT96.dfl file (default values). If you have/had some custom settings that were written to the shopbot.ini they will be lost though. Or you can use the UR command. Be sure you have your unit values written down somewhere in case you need them.

I've found that the windows version does a better job of ramping with v-carved files. Trying to find that sweet spot with the dos version has always been a challenge.

[Matt Barinholtz, Covenant House Washington, D.C. (Unregistered Guest)]

Thanks for the suggestions - drilling down a little further, any recommendations for ramp values to complement our very slow move and jog speeds? The challenge is with the combination of move/jog speed distances and threshold percentages, and minimum distances. I don't know what to sent them at if we are using the following:

mxy .2, mz .2, jxy .5, jz .5, no accessory axis settings


Just having the MXYZ and JXYZ ramps set to 60% doesn't take into account the MS distance, JS distance, threshold percentage and minimum distance (which we have accidentally changed, and cannot seem to reverse.)

Help!

Matt Barinholtz

[sheldon@dingwallguitars.com]

Matt, I'm away from my manual, but there are other values you can adjust after you close the MS fill in box. After you hit enter once, the box closes and there is a string of values on screen. These can be manually edited. I haven't messed with the threshold percentage or minimum distance, but I have adjusted the ramp length.

[Jeffrey Guinn (Unregistered Guest)]

Matt,
As previously suggested,why don't you delete & reload shopbot DOS software.Imput your unit values & set your ramps to 60 percent of your move & jog speeds.You shouldn't need to change any other ramp parameters.I often use .2 move speed with a .13 ramp with excellent results. Hope this helps.
Jeff Guinn

[kerrazy]

What is the hieght of the letter you are cutting? I think you could pick up the speed somewhat.
Dale

[srwtlc]

Matt, I think what your trying to change is the move and jog ramp distance. Try experimenting with those settings. Look at the command line after entering the VR command. MrpDist (default 100) and JrpDist (default 150) are the parameters you want to play with. Try raising the number(s) by 25 and try your file each time to see what works better. It's possible you may have set these way off inadvertantly (been there done that). You also may have changed the Thrsh% from its default of 100.

Again, give the windows version a try. I've had good results setting the move ramp value to 0.35 (windows version has different values for ramping than the dos version).

Scott

[Matt Barinholtz, Covenant House Washington, D.C. (Unregistered Guest)]

Thanks for all of your postings! ShopBotters are wonderful folk!

To answer your questions and ask some more:
Sheldon - how have you messed with the ramp length? The moves for these letters are very short (they are 1/4" high or less), and I wouldn't know how long or short to make the lengths (in inches, pulses, ??)

Jeffrey - took your and several previous suggestions and reloaded the shopbot.ini file, reset the values for our heavy duty z axis motor, and still had jerky moves. We looked deeper into the ramp values (Sheldon's suggestion) and changed the Mrp Dist and Jrp Dist to 125 and 150, and the thrsh is set to 100%. Still a little jerky.

Dale, the letters are between 1/4 and 1/2" in height, with serifs. We used ArtCam to create the .sbp file. I would like to move the speed up to .5 or greater, but the machine vibrates and jerks too much trying to turn thise LITTLE corners....Good to hear from you! I've been watching you're message on th eforum - congrats of really making your program shine!

From Bill Young, he mentioned that it may be a function of the timig speed between the control box and the computer. Ours is running between 455 and 470 units.

I tried to install the windows software (our machine is a win98) and our version of Windows does not support the newer version of the SB Control program. And it's not connected to the internet, with no NIC or modem. Don't know if Microsoft still offers patches or upgrades for Win98. Anybody with similar problems - Error 430'S?

Thanks!

Matt Barinholtz
Covenant House Washington, D.C.

[kerrazy]

Matt,
Silly question but are you running the latest DOS version for your tool, I know there was issues in a couple of previous version.

I will check my numbers and get right back to you for ramp speeds. Or better yet give me a ring and we can get it done quicker.
613.880.8292
Dale

[srwtlc]

On the windows version and Win98 problem, yes, you need to go through the windows update senario before it works.

[Brady Watson]

Matt,
I recently had to modify my ramp speeds for the plasma setup. My understanding is that the ramp value is actually a multiplier. SB support recommended a value between .75 and .85.

-Brady

[sheldon@dingwallguitars.com]

Matt, I believe the ramp distances are measured in steps. What I did was increased and decreased the values, then manually moved the tool around to see the effect.

[Mayo]

My ShopBot manual has the ramping information starting on page 78. On page 80 it states that the THRESHOLD ANGLE (the 4th parameter of the VT command) is set at a default 115. This controls when ramping occurs or not, based on the angle of the next segment.

Also the default .20 setting for ramping small circles is set at the 8th parameter of the VU command. This means circles or arcs with diameters less than .20" will be cut at ramp speed.

You can set the ramp DISTANCE using the VR command. If you are cutting very small lettering you may want to decrease your ramp distance.

[matt_barinholtz]

Many thanks to all who posted and called to help. We truly appreciate your assistance. The awards our students created were for a program in Denver, CO that offers golf lessons and tournaments to inner city youth, called Open Fairways - a great cause. We were hitting a deadline to get those awards to them, and your help really hit the spot. We also were able to complete some incentive gifts for a couple of Covenant House Washington donors. The machine is really a godsend, and we are so grateful that it comes with a huge community of caring, wise, and friendly users.

Here's some photos of our work!

Thanks!

Matt Barinholtz
Covenant House Washington, D.C.

5147
5148
5149

[gerald_d]

Hey, you "stretched" this thread off the screen!

You should rather have typed:
\image{Golf Awards}
\image{Box Awards}
\image{details}
to make the pics one below the other.

Good work!

What are the approx. overall dimensions?

[kerrazy]

Matt,
That is some really great looking work. Your participants should be very proud of their efforts. And you should also be very Proud with your guidance to them.
Keep it up!
Dale

[kaaboom_99]

Matt,
I am jealous of what I see. Almost makes me want to run from my wife and kids, move to DC, live on the streets and have you invite me in so I can learn to do the same quality of work on the Shopbot.
Looks Great!! and Great Cause!!!
Keep it up