Custom 53 mm spreader jaws for the Record Power SC1 mini chuck

I made these 53 mm external jaws to fit bowls I made with the Nova chuck with standard jaws on the SC1 so I could finish or post-work the bottoms of bowls more easily. The SC1 is so small (51 mm diameter) it is not in the way when working, and this way I kept my Nova free for other use. 
Last but not least I feel more safe working close to these plastic jaws than to steel ones. If I accidentally touch the jaws with the chisel it is not such a drama. Also, the jaws have additional height to provide more space. 

I use them in connection with back-up by the live center of course, and for light work only.

The image above shows the access to the workpiece. (Yes, the bottom of that box needed some work, LOL!)

Because the jaws are printed and not turned, the aft wide of the jaws could be shaped for maximum support by the chuck front end. 

Keep in mind the jaws do not represent a quarter circle. The outside should be a circle when the jaws are expanded a few mm. 

Printing:

The model files give one jaw. Best start by printing with that and check the fit of your print on your chuck. I experimented and tuned the depth and width of the recess at for the slides such that there was a tight fit on the slide of the chuck and outside the slide, with the screws tightened, just enough space between the jaw and the face of the chuck to let a piece of thin (newspaper) paper slide freely. Then I cloned to print the other 3 jaws.   

I used the standard screws for mounting

I had no ASA or PCGT available. I used PETG, Structural, nozzle 0.4, with settings as in the 3MF with good effect. I would not recommend to use PLA here because of its brittleness. 

The print orientation was chosen as a compromise to make the best use of the material strength while minimizing the need for supports to the small area shown in blue. In hindsight could have avoided that little piece of support also. 

Printing in the orientation as shown ensures that the layers are as far as practicable oriented such that a chisel, on involuntary contact, will have the least ‘catch’ on it.  

Note: The model as it is may not fit on the SC2 chuck. The slides of the SC2 are a tad wider so groove for the slides may need to be adjusted.  I do not have an SC2 available so I cannot test it now.