Rockcliff CNC Large Flying Gantry Model

[ger21]

Originally Posted by tjskcnc I have run rapids in excess of 100 inches per minute, but, seriously, can you safely cut wood at that speed?

Big commercial routers can cut over 2000 ipm, so yes, you can.

Originally Posted by tjskcnc I have run rapids in excess of 100 inches per minute, but, seriously, can you safely cut wood at that speed? How many inches per minute are you routing by hand?

With my router table, or with bearing guided bits, probably between 150 and 300ipm. Say you want to use a bearing guided 1/8" roundover bit to put a round edge on an 8 ft board. Using a laminate trimmer, I'd do this by hand in about 15 seconds. That's almost 400ipm.

Originally Posted by tjskcnc It's not a matter of how fast the machine can run, but, rather, how fast should you be cutting the wood.

For optimum toool life, you really want to cut as fast as possible, as long as the quality of the cut doesn't deteriorate.

[BVKT]

Originally Posted by dart19 I am currently building the D model, modified slightly, to handle 24 x 44 inch sheets. I am using inverted steel angles and skate bearings for slides. Seems to be solid with no binding or sloop. I am also using the rockcliff contoller and power supply. My question is with dual x axis lead screw motors will wiring in parallel (sp) pull to many amps thru the x axis contoller?

Hi Dart 19,

I am going to be building the D model very soon and I was wondering the same thing. Rockcliff actually helped me out on this so I can't take credit for it. I have already ordered and received my 4 axis driver and motor kit from Rockcliff and have tested the electrical parts. There is actually an option in Mach 3 called slaving which basically send the same step commands to 2 axis outputs at the same time so you end up with 2 motors that move perfectly synchronized to each other. For my dual X axis motors I am planning on using the X axis and A axis from the driver board to drive the 2 motors. If you search for slaving in the Mach3 manual you will see how to set it up. It is really simple. Hopefully you get this before you connect 2 motors to the same output from the driver board.

[skyburt]

Originally Posted by BVKT Hi Dart 19, I am going to be building the D model very soon and I was wondering the same thing. Rockcliff actually helped me out on this so I can't take credit for it. I have already ordered and received my 4 axis driver and motor kit from Rockcliff and have tested the electrical parts. There is actually an option in Mach 3 called slaving which basically send the same step commands to 2 axis outputs at the same time so you end up with 2 motors that move perfectly synchronized to each other. For my dual X axis motors I am planning on using the X axis and A axis from the driver board to drive the 2 motors. If you search for slaving in the Mach3 manual you will see how to set it up. It is really simple. Hopefully you get this before you connect 2 motors to the same output from the driver board.

I have built the "D" model and slaved the "A' axis off the "Y" and it woks fine. The support I have had from Rockcliff has been 1ST class. This is the first machine I have built and completely new to CNC. So the help I got from Nick at Rockcliff is very much appreciated

[tjskcnc]

Hi ger!
Not to argue with you (I'm sure you are much more experienced in this field than I am,) but I beg to differ about cutting speeds.
Cutting a simple bevel or corner round on a piece of pine, which you can run at very high speeds, is not the same as cutting 5/8" individual letters in a 1/8" veneer (in this case, made from alder.) I am currently cutting small individual letters for a customer and the blow-out rate on a small serif letter is extremely high (using a 0.04" end mill.) The bit just catches the serif part of the letter and breaks the stem (I will be posting in another area of this forum about the technique I am using and see if anyone can improve on it or has a better process.)

I am building a larger table with a 4'x8' cutting area, and the X axis is belt driven. According to Mach3, I am running rapids in excess of 500" per minute. The 495 oz/inch Keling stepper motor is not even being pushed hard, so I am sure I can achieve faster speeds, but see no need to (I was running rapids over 300" per minute with a 240 oZ/inch motor!) Will I be cutting at this speed? I doubt it. I will be very happy cutting at 100" per minute.

Your feedback (as well as all the other people on this forum) is greatly appreciated. Please chime in and tell me where I'm wrong. I've got a very thick skin, so go ahead and beat me up - I want to learn.

P.S.~ I ran more speed tests on my machine after your earlier response about cutting speeds. I ran rapids up to 100" per minute without coming close to pushing my motors to their max, but, due to manufacture's defects (okay, beat me with a rubber hose, I'm the manufacturer,) my gantry racked at a specific spot in my X travel at 60" per minute, so I set Mach3 to 40" per minute to avoid any motor stalling.