Zeroing bits C2 command

[bob buttons (Unregistered Guest)]

Quick question. the z jog speed determines the first dropping speed of the bit til it hits the zeroing plate then the second time down it goes slower i assume at the z move speed. is there a way to get it come down slowly on the first and possibly the second time without adjusting my jog/move speeds when i change bits. if i use a small bit and let it rip it will slam down too quickly if i forget to change the settings. Thanks in advance.

[gerald_d]

Bob, we have a 1/8" cushion of foam rubber under our 1/8" thick aluminium plate and we have no problems with small bits. (The foam rubber is actually thick double-sided tape with only one side peeled off).

Hope that someone else can answer your speed questions - I haven't fiddled with that file in the last couple of years.

[superior]

Gerald: Does the thickness of the foam change your depth of cut reading? I am still having a difficult getting consistent readings. I have micro'ed the plate I have, and it reads .113. Using this as a depth reference, I still get inconsistent depths, some too deep, most of the time a lot shallower than I need. Seems to be very eratic, though. Do you need to compensate for the thickness of the tape, I guess is my question. I have pulled a "Bill Young" and zeroed off the table top, and the same thing seems to be happening. Hope my stupidity is not showing....
not too much anyway.
Thanks for the help..
Doug

[gerald_d]

Of course the thickness of the tape must be allowed for, meaning that we have a "plate" of around 1/4" thick. We never bother to measure our plate thickness (because it is spongy) - we measure the thickness of a resultant job and then tweak the thickness value in the file to calibrate everything. Even a bit of dust between the table and the job can throw the readings off.

[beacon14]

Bob,

The answer to your question is yes, you can modify the file that is called by your C2 command. One way is to insert a line to set the move and jog speeds to whatever you want, i.e.:

SS,,.25,,.125

(the second comma tells the software that you are setting the Z speed, not the X & Y speed). The drawback to this approach is that unless you reset the speed at the end of the file, it will remain at this slower setting after the routine has completed.

Another option is to change the first plunge move from a JZ to a MZ, so it will use move speed for both plunges. The problem here is that you aren't setting a speed, you are using whatever speed the machine was set for previously.

I know that most users report no problems with the fast plunge, but I can't bring myself to do that to a nice, new, sharp bit - it may not snap, but the likelyhood of microscopic dulling is too high for me. I always used a modifed version of the program with a single plunge, at a fairly slow speed, and just made sure the bit was within an inch or so of the plate (using the keyboard commands) before calling the routine.
For my plate, I used a piece of 1/8" x 3/4" aluminum bar about a foot long, with one end bent into short "L", so I could attach the wire to it.
I made sure to hold the bar down firmly to the workpiece as the bit plunged. My results were very consistent.

By the way, your family didn't by any chance have a souvenir shop in Newport, Rhode Island, about 30 years ago? I met a kid there while on vacation with my family - his father had changed his name to Mr. Buttons, which was the name of his shop, and the son's name was Bobby Buttons. It's a long shot, but I had to ask.

David B.