Re: [CAD_CAM_EDM_DRO] Novice Timing Belt question

Hi Robert,
I used a moving belt on my plasma to keep the weight of the gantry as
low as possible. However you need a longer belt which is more expensive
and difficult to obtain. Also I have had some belt resonance problems. I
have occasionally had the belt flapping quite a lot due to resonance. It
does not seem to affect the cut noticebly but it isn't ideal.

If I was building a new machine I would use a stationary belt.

Les

>I have pretty much given up on trying to economically source a ball
>screw for the long axis and am looking at timing belts.
>
>>From the CNC machines on the web it appears that the most popular
>configuration to use is the fixed belt method ie "....the driving
>axis, idle rollers, and platform proceed as a unit along a length of
>belt that's held fast at both ends. Belt and drive sprocket impel the
>load while linear bearings support it"
>
>My question is why isnt the method where the belt is stretched around
>a driving and idler sprocket used more often? ie "....The driving
>pulley pulley and idler pulley of equal diameter are offset. The
>load is linked to the belt and moved parallel to the span between the
>pulleys. This system contains a platform or slider that moves on
>linear bearings"
>
>For diagrams of both systems see:
>http://apps.mectrol.com/applications/doc/linear_day2.pdf
>
>The reason I ask this question is that with the fixed belt method the
>weight associated with the motor, idler rollers etc must all make the
>trip around the table meaning bigger motors may be required, more
>inertia etc and also the fixed belt method appears to require more
>parts. I'm assuming that there are advantages of the fixed belt
>system over the closed belt which more than offset these
>disadvantages.
>
>Thanks for any responses, in advance.
>
>Robert
>
>