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View Full Version : driving from one side and the 'racking' phenomenomenom



nobby
07-07-2017, 02:45 PM
so, IF its a plasma table and only pulling round a torch.
do you get racking?

want to use an oem linear stage thing as x
http://i.ebayimg.com/images/g/tzEAAOSw9uFW-fgt/s-l1600.jpg

driven from one side, rail on the other

stupid idea?

or do I simply lay down two and drive both motors on the same drive

Clive S
07-07-2017, 03:13 PM
I think you need to state the size of the machine, driving anything is not going to be good from one side. you could use a long belt between them or two motors and two drives

nobby
07-07-2017, 04:09 PM
hello, the picture gantry/axis
about 40 inches
will buy three 40 inches long...
two for x one about the same size for y
a tiddler for z

do I link them with a belt or drive both x axissss

nobby
07-07-2017, 04:11 PM
I have to use modular bits and bobs so it becomes portable

routercnc
07-07-2017, 04:21 PM
I wouldn't drive anything from one side personally no matter what the machine is. Out of interest have you seen it done somewhere?

For plasma cutting forces are not there and as long as bearings under gantry have a fair spacing I don't see that it would rack in that sense (bind up)

But inertia forces are there. So rapid changes of direction on the gantry would start to give a bit of lag on the non driven side which means slight out of position cut. Question is whether this error would be large compared to kerf - someone who has used plasma more recently than me may be able to answer that one.

I would slave both sides or drive both sides direct.

Clive S
07-07-2017, 08:01 PM
hello, the picture gantry/axis
about 40 inches
will buy three 40 inches long...
two for x one about the same size for y
a tiddler for z

do I link them with a belt or drive both x axissss

Personal I wold use slaved motors as already been said. simples:onthego:

Boyan Silyavski
07-07-2017, 09:15 PM
I think he is talking about the portable plasma machines like on video. But as a portable machine, this is not a do all one. It just serves specific purpose . Anyway, plasmas have to be fast, so as other said, No, make a proper 2 side driven one


https://www.youtube.com/watch?v=F92wZYP1CA4

Web Goblin
09-07-2017, 05:07 PM
There have been many single sided drive plasma machines in the past but these were industrial machines and very well built with servo drives via gearboxes to rack and pinion drive on rail tracks. I think the widest machine I worked on would have been between 3 and 4 metres wide. Some had single heads and some with two. Twin drive machines are better and can move faster but then again cost more.

Ger21
09-07-2017, 05:55 PM
Yes, it really just depends on how rigid the machine is.
We have a Morbidelli router with a cantilevered gantry, that's only attached at 1 side. It has no trouble cutting through 30mm particle board in one pass at 25m/min

Web Goblin
09-07-2017, 08:20 PM
Nice addition Gerry. I forgot about the routers. We also have a scm router at work. Single side drive cantilever machine. Nice piece of engineering.