Drive System
For this particular table we’re using a drive system that consists of an eccentric cam For this particular table we’re using a drive system that consists of an eccentric cam mounted to the drive shaft that ‘bumps’ against an off the shelf caster wheel. At first mounted to the drive shaft that ‘bumps’ against an off the shelf caster wheel. At first glance it’s a fairly rude and crude drive arrangement but in application it is extremely glance it’s a fairly rude and crude drive arrangement but in application it is extremely efficient, effective and very easy to build on a tight budget.
efficient, effective and very easy to build on a tight budget.
So far I’ve had the table running 24 hours a day using this arrangement and we’re now So far I’ve had the table running 24 hours a day using this arrangement and we’re now just
just under under 500 500 hours hours of of continuous continuous operation operation and and none none of of the the components components are are showingshowing any wear or stress so I’m confident that the system works even when using less than any wear or stress so I’m confident that the system works even when using less than optimum parts.
optimum parts.
Eventually I want to change out the cheap plastic caster wheel to a better quality hard Eventually I want to change out the cheap plastic caster wheel to a better quality hard rubber wheel primarily to cut down the noise level more than anything else. The plastic rubber wheel primarily to cut down the noise level more than anything else. The plastic wheel actually works very well but it creates a lot of noise since it doesn’t have any wheel actually works very well but it creates a lot of noise since it doesn’t have any bearings on its very loose axle shaft and the wheel surface is extremely hard.
bearings on its very loose axle shaft and the wheel surface is extremely hard.
Drive Components Drive Components
The drive components consists of what I call the ‘drive-bar’ which is secured to the The drive components consists of what I call the ‘drive-bar’ which is secured to the suspension frame, the roller ‘brackets’, the eccentric cam mounted to the drive shaft and suspension frame, the roller ‘brackets’, the eccentric cam mounted to the drive shaft and the tension/compression springs.
the tension/compression springs.
The drive-bar is simply a piece of 1x2 laid on the flat that is secured underneath the The drive-bar is simply a piece of 1x2 laid on the flat that is secured underneath the suspension frame as seen in Figure 27 highlighted with the arrow.
suspension frame as seen in Figure 27 highlighted with the arrow.
Figure 27 Figure 27
The ‘roller brackets’ that hold the caster wheels are attached to this bar. For a large table The ‘roller brackets’ that hold the caster wheels are attached to this bar. For a large table it is a good idea to add a strong-back on the topside of the bar to act as a stiffener to it is a good idea to add a strong-back on the topside of the bar to act as a stiffener to prevent deflection under load.
prevent deflection under load.
The roller bracket I made for this table was pretty simple and most fabricators can The roller bracket I made for this table was pretty simple and most fabricators can probably
probably come come up up with with a a more more elegant elegant design design but but this this one one works works but but it’s it’s something something II want to improve on down the road.
want to improve on down the road.
Figure 28 is a snapshot of the roller bracket we ended up using to mount the cheap 2”
Figure 28 is a snapshot of the roller bracket we ended up using to mount the cheap 2”
plastic caster wheel assembly.
plastic caster wheel assembly.
Figure 28 Figure 28
Figure 29 is a shot of the bracket attached to the drive-bar.
Figure 29 is a shot of the bracket attached to the drive-bar.
Figure 29 Figure 29
In hindsight I should have made the reinforcing wedge extend past the lower caster In hindsight I should have made the reinforcing wedge extend past the lower caster mount screw holes but even this unit has held up just fine so far in the project.
mount screw holes but even this unit has held up just fine so far in the project.
Figure 30 is a picture looking up from below the table frame towards the drive-bar and Figure 30 is a picture looking up from below the table frame towards the drive-bar and the roller bracket.
the roller bracket.
Figure 30 Figure 30
This snapshot also shows the relationship between the drive eccentric and the roller This snapshot also shows the relationship between the drive eccentric and the roller wheel when the table is in what I call the ‘neutral mode’.
wheel when the table is in what I call the ‘neutral mode’.
It’s not to clear in this snapshot but there is 3/8-inch of clearance between the eccentric It’s not to clear in this snapshot but there is 3/8-inch of clearance between the eccentric and the roller wheel when the machine is in the ‘neutral mode’.
and the roller wheel when the machine is in the ‘neutral mode’.