Renimeter

During my own FFF experiments I faced problems with fits. I couldn’t know how precisely the Makerbot that I use at my university does follow my 3D models. So I came up with the idea to create some kind of “meter” to find out what kind of clearances would be appropriate for my machine, material and CAM parameters (layer height, speed…)

My solution for this problem is a block, which side shape is triangle and it has several holes, whose sizes increase in certain steps. The triangle shape allows to study that are there any differences between horizontal, vertical and 45-degree-from-normal shapes. The pins (or axles) have just one size, but they are also created in these orientations. These pins may also have chamfers or rounds. I named this system as “Renimeter” after my nickname ^^

This meter with its pins tells you what kind of clearance (according to your CAD model) is suitable for tight or sliding fit with your machine, your materials and these CAM parameters without extra grinding or machining. Of course, if you measure the dimensions of holes and pins you may see how much gap there is between the cad model and the printed model. In my point of view this meter is suitable for other AM methods too.




Renimeter Basic 10 mm:

The prime dimension of Renimeter basic is 10 mm and the clearance (or offset) increases 0.1 mm by each step. For instance, the 0.5 mm clearance of the hole’s dimension is 1 mm bigger than prime dimension (10 –> 11mm).

Hole is basically considered as circle shape but my solution includes also square shapes, because in my opinion the current FFF machines create rectangle shapes more precisely than circle shapes. Why ? Because these machines operate in Cartesian coordinate system.

According to my own experiments 0.5 mm clearance in horizontal direction is good value for sliding fit. It seems also that 45 degree pin has lover friction in these horizontal holes. (Machine: Makerbot Replicator, material: ABS, layer height: 0.2 mm, Fill: full solid).



Renimeter Optimized 10 mm:

The holes of this meter have same dimensions as basic one but they are optimized for FFF machines according to my point of view. There is no support needed in vertical or 45 degree shapes and horizontal shapes are good for Cartesian coordinated machine. It also seems like pins can be fitted in smaller holes than in basic meter.