[Grandad]

Hi Guys, After the success of my first small machine I thought you might like to see the progress on mark2. It has a cutting area of 60" x 30", Twin leadscrew X axis drive (2 x 400oz steppers, that gantry is heavy). I'm about 60% into the build and making steady progress

[Weldtutor]

Nice looking steel construction!

Interesting bearing systems on both X & Y axis that should work well.

[Grandad]

Thanks Weldtutor....

[Grandad]

I am building router using twin acme leadscrews to drive the X axis coupled to twin stepper motors. The two motors are slaved together in Mach 3 and I will be using a Gecko G540 drive. I am having nightmares about the motors not running in sync and causing problems withe gantry. Can anybody out there give some input as to what problems I could possibly have...Thanks

[harryn]

There are some discussions about how to approach this in the stepper motor area of the forums. I have not done it yet, but I think that it is a matter of using some of the functions in mach III to pull it off.

I am just curious - how stiff are those Y rails ? That is where I see the risk of a "non stiff" machine. (not that my build is even close to your progess)

[Grandad]

Hi Harryn, Thanks for the info on stepper area, i'll check it out. This machine design is based on an earlier machine I built which was very succesful. The Y axis rails are 33mm heavy wall Stainless. The complete Y assy seems to be very rigid but only time will tell. How is your build, any pics?....regards Rod

[CarveOne]

Meanwhile, I am furiously building away on a machine that will use dual stepper drive motors on the X axis in the hopes that it is resolved soon. I don't have any plans to sync the lead screws with a timing belt or chain and hope that I don't have to.

CarveOne

[harryn]

Hi Harryn, Thanks for the info on stepper area, i'll check it out. This machine design is based on an earlier machine I built which was very succesful. The Y axis rails are 33mm heavy wall Stainless. The complete Y assy seems to be very rigid but only time will tell. How is your build, any pics?....regards Rod

Yes, that will certainly work as support rail.

My "build thread" so far is mostly a parts list collection. There are some pics in post 58 of my "plywood aided design" version. Basically, I decided to stop drawing pictures and build up a plywood prototype as a learning experience, them evolve it into something hopefully useful.

(edit - added link) http://cnczone.com/forums/showthread.php?t=38940


In terms of the "nightmare questions", I guess the thing to watch for is the make sure each stepper can provide the full torque required, as opposed to thinking the load is now divided by 2. As the router moves around on the table, the load will shift with it. I am guessing since you have already built one, you already knew this.

[Grandad]

Been busy on the lathe for a couple of days after long delay, but back on track again. Z axis is almost done as well. Will post more pictures when Z is mounted

[Grandad]

Finally got the Z-axis looking as though it might work, on to the dreaded twin drive X-axis. Still having nightmares about missing steps on X, gantries going sideways etc. The only way to find out is to try it, fortunately I have great faith in Mach 3 and the gantry rolls like a dream. I would love feedback from anybody running twin X's....Rod

[Grandad]

oop's posted wrong pictures

[BobF]

Grandad,
Look at Joes 4x4. There are dual motors on X. When frst built, he used a timing belt on pulleys on the back axel of the X motors. I think some of the current builders may have abandoned the belt as not needed, since the software sync seems to work well. Add the belt if you are nervous.