Those of you that have read my previous two builds will understand my machine naming convention so following on with that tradition Jabott has commenced gestation.
It will be a small desktop machine which can be used on site and I might even be able to convince “She Who Must Be Obeyed” (but rarely is) that I can use it on occasions indoors on a cold night. So for this to happen the machine needs to be constructed from aluminum and have low operating noise levels. Routers are out for this reason and after a lot of research I finally settled on a 12 volt DC brushless spindle. I got the spindle off ebay and mated up one of those motors from the car and helicopter model making sites.
The spindle has a brass body with two stainless bearings at the cutting end and a single bearing at the pulley end. The bearings are rated at 60,000 RPM which is more than adequate for my purposes. The collet chuck is 1/8 th inch and overall the spindle is made very well and the finish is good. I have matched a 12 volt DC variable speed Brushless Motor and the DC power is supplied through a modified 380 watt ATX computer power supply and a variable speed controller. The drive is an “O” ring which seems to be a limiting factor in the design. The “O” ring distorts above 25,000 RPM so they just don’t make them like they did when I was a lad – actually when I was a lad I don’t think they were invented but lets steer clear of that one. Measured at the collet the top speed is 35,000 RPM but I suspect some slippage in the “O” ring at this speed.
Although it looks like a toy this is one serious spindle capable of destroying most things in its path. I have done a couple of freehand cuts and drilled a few holes and it is going to perform well for its intended purpose.
I have attached photos of the spindle and the components for the three axis.
My machines evolve more than are planned so here are the details and ideas I have for the axis. It will be a moving gantry design with a cutting envelope of 300mm by 200mm by 70mm.
X axis is a THK KR30 actuator with a 6mm pitch ballscrew and I have 2 IKO LWLF42 linear slides to go with this.
Y axis is a THK KR33 actuator with a 10mm ballscrew and a pair of THK RSR 12W linear slides. The slides are a backup as initially I will fit the actuator and if this proves to be a weak I can add the slides later.
Z axis will be fabricated from the mini ballscrew and the linear slides. The ballscrew has 70mm travel.