I ran some Lithophanes this evening. I realized I had my iPhone in my pocket so I grabed a short segment of the HB2 in operation.
What you need to note is the quiet operation with the Taig spindle running at 10.600 RPM and the bit cutting at 50 IPM (Inches Per Minute). Most of the noise is the cutter in the Corian solid surface material making the 0.10 to 0.20 depth cut. If you listen carefully you can also hear the higher pitch “chirping” of the z axis stepper motor. I am “eighth stepping” the motors so it takes 1600 steps to make one shaft rotation. You are hearing those steps.
Most folks are running very loud (screaming actually) routers or high speed rotary tools to do this work. It’s hard to even think over the noise level. I have to wear ear protection with those spindles, but not with the Taig spindle. It’s nice…
I ran an 8×10 Lithophane yesterday which required a few minutes over 3 hours of continuous running on the HB2. Not a single glitch. It sounded and ran so good I was able to do a lot of regular work around the shop, like cleaning up.
The sound level is extremely low with the Taig spindle and the new tune up with the finer microstepping. Now the loudest sound is the cutting of the router bit through the material. No problem with normal level conversation right next to the operating machine
Most owners of these machines are using small wood routers. They do a great job (I have one) but the sound level is extremely high. It requires ear plugs or ear cans (headset) to protect hearing. Not so with the Taig spindle.
Now I can spend more time on project design and equipment refinements like material mounting methods. Breaking couplings looks like a problem solved.
I put a little spray of my very special grease behind the thrust bearings on the HB2. Not hard to do as it goes in as a thin spray foam and quickly congeals into grease. A double shot behind every thrust bearing was perfect.
HB2 runs like a new machine! Wow, it is really more effective than I imagined. I just ordered a mini grease gun with this brand of lube to use on the linear bearings. Good stuff!
Still a Drag?
I had a great weekend. I had to mow the grass but that is expected and still makes for a great weekend. For this Blog it was great because I got to put a lot of run time on the HB2. About six hours in total.
I even ran the Mayan calendar in a 7.75″ diameter on some Corian. I’ll post some pictures soon. The detail was excellent.
I think I may still have a little drag on the axis screws. It didn’t bother the CNC work this weekend. I have some spray bearing grease I will inject behind the Thrust bearings and see if the intermittent slight rubbing noise goes away.
If the grease doesn’t help, I already have a plan to put a “step” at each end of the screws and just remove the thrust bearings. That way the only thing the screw end can contact is the center race of the bearings.
That’s what I should have done in the first place. I did find out how easy it is (when you have a lathe) to modify the ends of the axis screws.
How I noticed what may be the rub is I changed my micro-stepping from quarter to eighth. I now run 8,000 steps per inch rather than 4000. That’s 0.000125 inches per step, way too fine than really useful . This was done not to increase accuracy but make the steppers run a lot more quite (but also a lot hotter).
Quarter stepping was still more accuracy (0.00025″) than I needed and it is supposed to provide more torque. The motors run cool. The noise however is more than 3 db higher and the twin Y’s were driving me crazy with their loud sound. Now I hear a sweet soft… Continue reading
HB2 Bearing Replacement (X – Axis)
Here is how I trimmed the Axis screws for the added thickness of the thrust washers (bearings). They are really being used as washers to keep the screws from impinging on the bearing seals.
I thought I might have to protect the screws when in the lathe chuck but I discovered clamping firm but lightly did no damage. Also the screw nut never gets that far down to each end of the screw. I generally use aluminum cut from a soda can for protection when needed.
I was surprised to see the “juices” leaking from the far end bearing The grease didn’t show while assembled.
The thrust washers turn with the screw shaft. The close up picture shows the washers do not ride against the bearing seals. They actually contact the flange on the inner ball bearing race. So in my opinion they are working perfectly as intended. Note the high quality of the thrust washer finished edge.
All axis screws are barely end loaded. Just barely on the loaded side of touching with zero end play.
After doing all the investigation and testing and more reading, I remembered a drive screw specification I studied long ago that affects how fast a drive screw can or should go in RPM. It all has to do with the end bearings support, screw diameter, unsuported length and preventing vibration. The best set ups are double bearings at both ends for rigidity. The lessons I learned here on the HB2 are the bearings ARE the most important factor for a good running machine. However, I doubt I need double bearings on each end. HB2’s screws theoretically could run over 3K RPM as they are. I’m not going there!
I have settled in… Continue reading