Machinist's test indicator holder for Petsfang

thingiverse

This is a test indicator holder that attaches to Dave Petsel's PetsFang-v2 fan shroud. I'm a hobby machinist, and wanted a bracket to hang a test indicator (DTI) from my printer. I wanted to use a DTI to assist with tramming and mechanical adjustment along different axes, as well as a poor man's CMM (!). Note that this is for a dial **test** indicator (DTI) and not for a simple dial indicator (a test indicator uses a lever arm as opposed to a plunger). The advantage of a DTI over a dial indicator is that you can get the point into confined spaces (like directly under the hot end close to the nozzle) This is just the support bracket. It's intended to be used with an articulating arm like the [Interrapid holder](https://www.mscdirect.com/product/details/00369348?fromRR=Y). I'm also attempting to create a printed (poor man's) version of that holder, but I'm not yet satisfied with the rigidity. The photo shows an early prototype (I'll post it separately when I'm satisfied with the design). A decent DTI, holder, and precision reference square will likely cost considerably more than most printers, but I can't be the only one with access to machinist's tools. If you don't have the tools, but are interested in acquiring them, I've seen DTI's as cheap as $30 USD, but you definitely get what you pay for. Decent quality indicators are $150 to $1000 new. I'd recommend 0.01 mm resolution indicators for this application (0.001" or 0.0005" resolution if you use Imperial tooling). Anything finer is far too sensitive for 3d printing. SPI makes a cheaper version of the Interrapid holder (about $40) but again, you get what you pay for. I think I'll get the printed part to work well enough eventually (though it will likely be bulkier and far, far more ornery to use). I tram ("level") my bed perpendicular to Z using the indicator directly on my glass bed, and used a 1" thick precision granite square laying flat on the bed to verify that X and Y truly moved orthogonally (within about +/- 0.0015" over 9" — not stellar, but sufficient for printed parts). Precision granite is extremely expensive, but a normal [machinist's square](https://www.mscdirect.com/browse/tn/Measuring-Inspecting/Dimensional-Measuring-Tools/Squares-Combination-Squares-Protractors/Squares-Square-Sets/Squares?navid=12108136) should be sufficient (though it will be difficult to sweep the narrow blade). As printed, this holder bracket is an intentionally tight fit into the touch probe bracket on the Petsfang. I've added some stiffening along the edge which obscures the screws on the left side of the shroud, so you'll have to fully assemble and adjust the Petsfang before adding this bracket.