bornity blogs

Fixed! 5 iterations and it feels better than the original part.

The cracked Lift Gear raised the foot. A stress point in the original design combined with the plastic becoming brittle with age, led to the failure. 

This thing has a metal frame! It's really well built. Just let down by 30y.o. plastic formulations which didn't age well.

This is the backside.

This is the front side, which you see looking into the machine.

Working on the correct Center Distances. Off by ~.5mm. I also had 17 teeth instead of 16 like the original. When I fix this later but do something stupid...

Nailed the Center Distances. Hole was to save time on the print.

Checking the feel of the up-down motion. Feels good. Next I need to add the mounting points for the lifter bar.

The Lifter Bar fits but the torsion spring behind, is forcing the gear off the flat head shaft. (See next photo.) The side facing the camera looks like crap b/c of the support interface.

You can see the lift gear working its way out from the motion. There is supposed to be a split ring to retain the lift gear, no idea where it went and I didn't have one lying around.

You can see the torsion spring which wraps around the lift gear standoff on the right of the shaft.

This time, printed upside down to improve the finish on the side visible when mounted on the machine. Added a collar on the shaft to retain the spring and a flange to retain the gear.

I also redesigned the gear to the correct 16teeth, fixing the incorrect 17 I orignally modeled.

Good fit. Everything seems good. Notice my mistake?

Yeah it's backwards. D'oh. When I changed the Gear from 17 teeth to 16 teeth I remodeled it from scratch. In the process I aligned the lifter bar slot to the wrong side of the arc. Woops.

Yeah it's backwards. Welp. Modify and print one more.

Here we go. Back view of the finished part. No incorrect geometry, ready to install.

Here's the front view. Printing the part face up gave a much better surface finish, which you see when you open the machine.

Installed and looking good. Notice the all the beige internal frame you see is metal. It's a solid cast piece which is really impressive and give the entire machine a very solid feel.

Installed with flash. Slightly blown out but wanted to capture some of the finer details.

Cool photo to take at the end of the process. 

In addition to the gear, I modeled and printed a Arm Lifter to attach to the end of the Lifter Bar.

Good view of the torsion spring wrapping the standoff shaft.

Good view of the torsion spring wrapping the standoff shaft, now with Flash.

Version 5. Inventor 3D Model Screencap.

Version 5. I started with a fullsize gear and trimmed it to the teeth I needed. Gives a good idea on how to achieve the shape.

Here's another photo of the process of reverse engineering of the part. Left is the 25 tooth existing gear that I needed to model to design the teeth on the wedge-shaped Lift Gear. I miscounted teeth, so the yellow large gear has 89 teeth total with 17 teeth on the Lift Gear. Redesigned part on the right has 86 teeth and 16 teeth on the Lift Gear, correctly replicating the original, broken Lift Gear.

Sketches, notes and dimensions to work from. I used a Digital caliper to determine sizes. Some dimension were hard to measure accurately working with a broken part and curved surfaces.

Also printed a new Lifter Arm (in white) which attaches to the Lifter Bar.

Also printed a new Lifter Arm (in white) which attaches to the Lifter Bar.

I spent 6hrs on the Gear and 45mins on the Lifter Arm. Of course which one do you see when you close up the machine...

The finished look is very nice. The blue painter's tape holds it closed for the moment b/c I need a #6-40 screw. Couldn't find one in any of my small screw bins.

Close up on the Lifter Arm in the down position.

Lifter Arm 3D model render. Seriously, took 30mins to design and 15mins to print.

Lifter Arm 3D model screencap.

My heavily modified Delta

My heavily modified Delta

(Not the same print as the above photo, that's Version 5)

His name is Apollo.