Red version: creating the topside crank drive -the ‘pushmepullyou’!
(Previous post: ‘Red version: slinging the new crank underneath‘)
The new, ‘push-me-pull-you’ drive is shown in the image below, with one crank mechanism below and another on top, both working together to drive the head and neck biting mechanism. This post shows how this was achieved.
After making the new drive and mounting it on the top (see pic below) I decided that the easiest way to have a drive above and below would be to relocate it on the underside and then make another one for the top side.
New crank drive, topside:
The above crank slung underneath:
The next step was to make a new crank drive with the same design and to mount it above the first.
An housing was made using acrylic plastic sheet, 5mm thick and using 10mm thick low-density polyethylene spacers.
As previously, crank wheels with simple slip clutches were made and added to each side:
The drive was then attached.
A video of the two drives working together is shown below.
The con-rod used for the top crank drive was quickly made from a length of aluminium round bar which was been bent to shape and flattened at both ends.
Other versions were made using flat aluminium bar and also 5mm thick acrylic sheet.
The acrylic version was used as it helps keep the crank wheels aligned as shown below.
The next post deals with reshaping the neck.