HB2 Construction

These are four helical beam shaft couplings I purchased. The "stock" couplings recommended are just straight with no flex. These are flexable, yet have zero backlash. They are about 1 inch long and 1 inch in diameter.

This is the spacer/heat sink I drew up in Rhino 3D and created the G-code in RhinoCAD. The needed spacing is the depth of the center hole and all the rest is heat sink. Slots and fins are both 1/8 inch. Overall size is 4" x 4" x 1"

I purchased a 24" x 4" x 1" extruded slab (um... billet) of 6061-T6 aluminum. The suppliers cut was a little off. An extrusion like this is not very even in thickness but for how I was going to use it, that doesn't matter

I milled off the crooked cut and was pleased to discover that my cuts were close enough to not require this extra work. The CNC program I produced does a clean up series of passes around the entire part at the end and that takes care of irregularities.

This is the very first trial run, my "learner's permit" I decided. The clamps were inadequate but I did get this far. I discovered I needed to make a true fixture to hold the part and I needed to rough out the major areas with a bigger end mill. This would of course required a tool change. I actually split the run into two programs and did all the 1/4 inch milling first, requiring fewer tool changes.

This is the low profile clamping system I developed that worked like a charm. No more hold down worries. I shoulda-oughta done this first. Ha! It is what I built the surface plate to do. I was just in too big a hurry to run the CNC program, guilty. Still running the trial piece here and was able to finish it into a very useable part with only cosmetic flaws. The red nozzle is mist cooling in all the photos.

This is the roughing program using a 1/4 inch end mill. I am making the "real" parts at this point. There is quite a bit of aluminum removed by the time I get to the finished part.

The four heat sinks after rough milling. The bottoms are actually finish surfaces. The square side is the motor insert depth and the round side is the inset for the tube spacer.

This is the set up on the Taig. The black hose is the air line with 35 PSI pressure. The blue green bottle is the mist solution. Only a very fine mist is required. The amount missing here is enough to finish one side. There are no puddles in the pan!

The computer side of the process. The screen shows MACH3 running. The tall computer box is the new computer I assembled for the HB2 and I used it (burn in) to run the CNC for the heat sinks. The box with the big red button is the power supply/ CNC controller. The little computer against the wall will be put back into service for the Taig mill.

A close up of the mill in action on the final side of the fifth and final heat sink. There is a mist coming out of the red nozzle and the mill is spinning at 10,600 rpm but the flash stopped the action.

Finished at last, finished at last. Thank goodness we are finished at last. It took 40 hours of run time not including probably double that time for design, setup, testing adjusting, clean up and everything else it takes to see a CNC milling project like this to the end.

This is the backside of the left Y axis motor mount. The four holes were precision drilled using a template when the part drilling was laid out.

All the bolts I use with aluminum are stainless steel. These are 3/4 inch 10-24 socket head. I used 1 1/4 inch on the motor end.

I have added a bit of blue "Locktite" to the end of the bolts instead of lock nuts. Blue Locktite allows for disassembly when required.

I made these mounting shafts using the Proxxon lathe seen in the background in some of the pics. I used 1/2 inch 6061- T6 aluminum. 16 pieces were faced, turned to length (1.7"). drilled, tapped (32 times), counter reamed.

The mounting shafts are bolted to the back plate. Note the slight squeeze out of the Locktite. Every shaft was precision cut to exact length.

This is the check of the coupling. I had to loosen the bearing retainer on this end and tighten the retainer on the other end, shifting the shaft to the left. The left edge of the coupling needs to be just flush with the ends of the rods.

The original split tube is inset into the heat sink. I faced the split to the bottom but it could be placed anywhere and covered with a bit of masking tape to keep debris out. That heat sink looks good!

This was the last motor mount and I got a little generous with the Locktite. It was easier to put it in this end than apply to the bolt ends.

All bolted up. The socket heads are the only way to go. The original kit called for pan head bolts that had to have the heads turned (filed) down to fit. The 1 1/4 inch bolts are used here.

The back view. Note the over generous use of Locktite. That's Texas December 31st weather you see outside the shop. Like I said up top, it took to the end of the year to get to this point!

Motors and their heat sink spacers fully assembled and ready for wiring. I positioned the wiring to the bottom of the motors. Just seemed like a good idea.