Home Brew 2
Fixing the Broken Axe
I received the new couplings today for the HB2 from PDJ, Inc.. The new one is the bright and shiny one in the picture. The black one is the original style that has been giving me problems with breakage. (6208K6 @ McMaster-Carr)
The new one is rated for 495.6 oz-in. The old one is rated for 42 in-pounds (peak). That is 672 oz-in! So the old one should be the strongest, right? The new one LOOKS stronger and is a different style. They are both considered Helical Beam Couplings. If you want to see what a broken one looks like check HERE.
So what gives? Well, the old couplings certainly do. Maybe the key word is the “peak” rating rather than a continuous rating. I can’t tell. The Mark One eyeball says the new one is stronger. That’s old Navy jargon for eyeball engineering.
I think I will soften the acceleration on the steppers a bit more to lessen the start stop shock loads.PDJ has been using these shiny couplings without failure so I hope my problems are over, at least with the couplings.
Broke My Axe
The HB2 broke a coupling on the Y axis again. The couplings have been fine for 6 months. Must be more loads on it than I thought, but it is the axis with the dual steppers. It should have ½ the loads. The X and Z axis have never been a problem.
I thought it was most likely an alignment problem causing the couplings to flex too much. I was very particular in checking the alignment in the last replacement.
This time I am ordering extra heavy couplings from PDJ. They are the same style and exact size as I have been using but are built much stronger. They are a bit less expensive too, probably because Phil buys them in greater volume.
The failure spoiled a project I was cutting. Always happens near the end don’t you just know… I am glad it was a concept part and not some valuable slab of rare wood.
Listen, You have to see this.
Here is a video of the Taig ER spindle running on the HB2. If it will not run in IE7 or IE8 browsers, turn off the protected mode. Microsoft has gone psyco on protection!
In the close up pictures the camera microphone was about 6 inches away from the motor. Note that the Stepper “tunes” are not drounded out by spindle noise. The farther away shots give a clearer understanding how quiet the Taig spindle operates. The cutting in this video was at 10,600 rpm and the travel was 50 IPM.
I love this operation and have a complete new spindle setup on order. Actually several. I also did some V-carving as a test. Works as expected as I have been running this setup on the Taig mill for several years.
Here is a picture of the finished carving. Two passes in 45 minutes. Nothing fancy, just some pocketing to give the HB2 a bit of a workout. This is not a keeper, but looks great.
Name and Callsign
Taig ER16 Spindle Added to HB2
Here is the first look at making the mount and installing the Taig ER16 Spindle and continuous duty motor on the HB2. This is the same spindle and head that I use on the Taig CNC mill. In fact it IS the head FROM the Taig CNC mill.
I’ll be running a project tomorrow to test out the set up. If all goes well I already have the TAIG order made out for a new set-up exactly like this for full time use on the HB2. This is lower power than other spindles used on the HB2 but much quieter. From my experience using it for wood carving on the Taig mill, I think it will be just perfect for most work I do. I can fit up through a 3/8 inch cutting tool.
The ER spindle is far superior to the one in the little hand router. The big difference is sound level and the fact that the Taig spindle is 1/3 slower and 1/3 the power.
One thing to note though is there is the opportunity to select 6 different speeds. With the belt drive I always get full motor power as the motor is always running full speed.
The change over from one head to the other is about 30 minutes. It could be less but the one bolt in the center of the back-plate mount is a bugger to get started. It is between two linear bearings and behind the lead nut. I taped the nut to the wrench to get it started. 🙂
I will also post these pictures over in the THMS web site. That probably won’t be for a week or so. I am also considering doing a sound video so you all can see AND hear how she runs.
Just Getting Better
The parts breaking seem to be behind me for now. I have run several very long 3D projects with no qualms from the HB2. It has just been rolling along doing it thing at fairly high speed (at least to me).
I have increased the MACH3 frequency to 60,000 Hz and now been able to run the steppers as high as 200 fpm (1000 rpm on the steppers) but not reliably. My rapids are now set at 150 IPM and that is as good as I’ll probably need. I was running the roughing at 100 IPM and the 2 hour finish passes were running at 70 IPM. Working just fine.
Ahhh… Life is good!