Access hole for belt puller and relocation of idler pulley on Y-axis

Access hole for belt puller and relocation of idler pulley on Y-axis

Halfway through making the y-axis drive, I realized that I had made a mistake in the placement of the belt idler bearings.

At that time my focus was on placing it in such a position that there would still be some clearance between the belt and the pulley of the drive motor when the belt was stretched tight horizontally at both ends.

Original mdf spacer weaken by cut

Original mdf spacer weaken by cut

Getting the belt idler bearings to be in the ideal position did pose a challenge because of the close proximity of all the components (motor, linear bearing, horizontal ball bearings, etc). Finally, I could only afford to place it so that there would be about 1 mm clearance between the belt stretched horizontally and the one wrapped around the idler bearings. The new hole position for the shaft of the idler bearings had to be drilled very carefully.

Spacers made of plywood not even

Spacers made of plywood not even

Then I found that I was not able to cut slots in the MDF motor spacer precisely to take in the timing belt. After cutting and filing the slot, the MDF spacer became too weak at certain spots and it just cracked at those locations. I did try to repair it with epoxy resin, but it did not look good. Furthermore, because the pulley attached to the motor need to be precisely in line with the timing belt, additional thin spacers had to be added. I made these out of plywood, but some of the wood veneers peeled off when the plywood was cut. This made the plywood spacers uneven.

Adopted motor spacer made from 2 wood strips

Adopted motor spacer made from 2 wood strips

Then, I decided to replace the MDF and plywood spacers altogether. I reckoned that the motor could be spaced just as well by using spacers at each bolt. I decided to use one spacer for two bolts for more stability. And instead of MDF, I used wood strips. That solved my spacer problem.

Checking spacers made from wood strips

Checking spacers made from wood strips

I also realized that in order to place the belt over the pulley which was installed on the Y-axis motor shaft, I would need some accessibility for my fingers. I created the finger room by cutting a round hole at the Y-axis assembly which was also housing the Z-axis.

Motor, pulley and idler fixed in place on Y-axis

Motor, pulley and idler fixed in place on Y-axis

Then I realized that the timing belt idler bearing was placed wrongly. In this position, the timing belt grooved side would be facing upwards instead of facing downwards. Although it would still work, I preferred the grooves to be facing downwards so that they would not collect dust.

Y-axis timing belt clamp

Y-axis timing belt clamp

Back to the drawing board! The idler bearings would have to be shifted. In addition, the ends of the timing belt would have to be shifted with the new design. This also meant that the securing clamp and tensioner for the belt would also have to be modified to suit the space available for them.

Y-axis timing belt tensioner

Y-axis timing belt tensioner

Finally, all the components were assembled and tested. This new design seemed to work.

Y-axis belt fixed over motor pulley and idler

Y-axis belt fixed over motor pulley and idler