X AXIS BELT REPLACEMENT UNIVERSAL X600, X660.
The following information is provided for educational reference ONLY. All repairs should be undertaken by a qualified engineer. The use of the following information is done so entirely at your own risk! Kent Lasers is an INDEPENDENT service provider and not affiliated with any machine brand or manufacturer.
Most of the mechanical set up on Universal machines has not changed since the launch of the X600 series, which are now nearing 20 years on the oldest models. The drive system for both X and Y axis, on these systems are belt and stepper driven, utilising small 0.9 degree NEMA 17 motors. Similar mechanical set up can be seen on all legacy machines as well as the more advanced VLS systems and PLS (Professional) machines.
The belting utilised is MXL pitch, which is a standard size of 2.03mm pitch and 6.35mm width. Belting utilises glass-fibre tension chords, is light-weight and highly flexible. This results in good positional accuracy (low deviation from micro stepping rotor tolerance) however, due to the small size, belting can loose tension (and stretch) over time. This is usually noticed when the machine is cutting angles, or circles, with failure for start/stop segments to join correctly, or wavy lines in circles and other complex geometry (resonance).
The X axis suffers most from this, as it is the faster moving of all axis. The belt replacement procedure is quite simple, and can be undertaken by loosening the small belt clamping plate, which is affixed to the cutting (tool) head. (image opposite).
Please note that being American machinery, all fixings are Imperial sizes. Removing the two visible hex-head bolts from the cutting head will separate the head from the belt, but will not result in remaining belt tension being lost; the belt will still be in tact.
**PLEASE ENSURE EQUIPMENT IS POWERED DOWN**
The belt is now separated from the cutting head.
The two additional hex-head bolts can now be removed. This will result in the belt tension being lost, and the two halves of the clamp plate being further separated. The belt tension chords can clearly be seen in the opposite image(s).
Keep all fixings, and components in a safe place, a clean, unused paint-mixing cup is ideal for temporary storage of screws, fixings and removed components.
IT IS IMPORTANT NOT TO PULL OR REMOVE THE OLD BELT FROM ITS HOUSING; THE OLD BELT WILL BE USED TO THREAD THE REPLACEMENT THROUGH THE GANTRY EXTRUSION.
Please ensure your working environment is clean, and no dirt, oils or debris is allowed to stick to the belting, and is NOT drawn through the machine when threading the new parts (belt).
The replacement belting (available here) should now be offered up to the old belt with the teeth profile facing each other. This is to ensure the tooth profile is an exact match. (The profiles should mesh perfectly). The required belt length will be the length of you X axis travel +150mm for tolerance and fitting purposes.
The end of the original belt, should then be taped (here we used high-tack masking tape) to the replacement piece ENSURING THAT THE TEETH ARE FACING THE SAME DIRECTION.
The original piece can now be used to pull the replacement through the various mechanical parts, gantry extrusion and pulley. Please be cautious not to allow the belting to snag on any mechanical components, and make sure it is free to be pulled through.
If the temporary joint fails, further strip-down will be required, which is beyond the scope of this tutorial.
The replacement belt can now be gently pulled through the hollow section in the gantry.
The opposite images show the idler/tensioner on the left-hand-side of the gantry. the belt should be carefully, and completely pulled through ensuring it has not become snagged, or twisted.
The replacement belting can now be fed through the idler wheel, and back towards the cutting head, where it can be joined to the other (starting) end.
The masking tape joining the two pieces of belt can now be removed, and the original belt discarded.
The belting can now be joined. This is achieved by prepping the clamping plate:
The two clamping plate halves should be fixed together with the original bolts, ensuring enough room is left to feed the belt through them. Take note of the orientation of these two parts; the semi-circular portions face the rear of the machine, with the bolts facing the cutting head.
a pair of long-nosed pliers can be used to gently pull the two pieces through the clamp plate, in order to apply a small amount of tension to the new belt.
The bolts can now be tightened, and the excess belt trimmed.
Please ensure the tensioning mechanism (at the left-hand-side of the gantry is set as to apply the lowest amount of tension (grub screw released) this will allow additional slack to be taken-up, as explained in the next step...
The clamping plate can now be attached back to the tool head.
Imperial size ball-end Allen keys are useful for this job, as the installation space is rather tight.
Tension plate and idler can now be set:
This is achieved by gently tightening the grub (set) screw on the bracket (as show opposite) until the slack in the new belt is taken up.
Extreme care should be taken not to touch the optical surface of the reflection mirror.
A belt tension meter can be used to accurately set the tension within the system. For users without access to this equipment, the belt should feel tight to the touch and not allow excessive "pulling" or play.
The protective cover can now be replaced, and the system is ready to use.