CNC
New Article Posted in THMS
It’s been awhile I admit since I posted new material in the THMS website. This BLOG has served well for most small projects but the glass stamps have a lot of photos. Go check it out here:
http://thehobbyistmachineshop.com/cms/projects/brass-stamps-for-beadmaking
The new format permitted me to add a new feature. All the pictures in the article will zoom to a larger size when clicked.
Hardware Pulse Board for CNC
I am going to make (hopefully) an improvement to my CNC operations in a week or so. I have ordered and will install a USB SmoothStepper board made by Warp9 Tech Design. Inc. into one and maybe both of my homebuilt CNC controllers. Probably the first one will be installed and tested in my original chopper controller that I am now using on the Taig CNC mill.
I have used a serial pulse generator before in that controller. Years ago I obtained the pulse card from DeskCNC called their 2nd Generation Controller Board. It is actually still installed but not connected inside the controller case. This controller worked perfectly but is proprietary to DeskCNC software. It can be seen operating in the video viewable HERE running the HB1 mill. That was more than several years ago. A hardware pulse generator makes for a very smooth running machine.
Since I am now doing very small, almost micro-machining (1/32″-“1/64” ball end mills) I am becoming more concerned about accuracy. Several articles in the CNCCookbook blog by Bob Warfield got me to thinking. Read both parts written by Bob.
Tormach CNC has a White Paper about this very subject that I recommend for your reading pleasure. Click on the link in the previous sentence. They mention the Smoothstepper for use with MACH3.
I then remembered how well I like the DeskCNC controller I gave up to use MACH3. So I investigated the currently available motion control boards. By the way, the 2nd Generation DeskCNC Board is still being produced
The Warp9TD Smoothstepper seems best suited to my needs and especially budget. It is designed expressly for use with the MACH3. There is now a LAN version board as well as the USB version.
Some other brands of these… Continue reading
CNC 4th Axis Update
The Taig CNC mill is closer to having its 4th axis operational. All that is really needed is to get the wiring completed. The tail post is not mounted where seen in the pictures. I was making adjustments to the height. You can see it is easily adjustable.
I will bolt down the tail post once I have an application where I need to use it. I now have the shims I need so a couple of bolts in the base and I’m in business.
When I have it running I’ll post a SHORT video to prove it works, Ha! There is nothing more boring than watching 10 to 20 seconds of a CNC axis moving around doing nothing.
4th Axis on My Taig
The screw drive of the standard rotary table has a lot of benefits in this 4th axis application. There are a few limitations in the area of backlash (controllable) and rapid speed (not really necessary.)
With small mills like the Taig and the Sherline, weight (mass) is a required parameter to consider. Most rotary tables are designed to have a lot of weight as part of their design. It adds stability for normal machining. However for miniature CNC machining, it is undesirable to abuse your drive system with a lot inertial mass to start, stop and reverse perhaps up to a hundred times a minute.
The winner in my selection is the Sherline 3700-CNC rotary table with motor mount. At $320 it is not the least expensive of my 4th axis schemes but I think it is the best in this case.
First point is the weight. At 8 pounds it is heavy enough and when you look at it, you see it carries no extra weight in a heavy case or mounting system flanges.
Second point is it is specifically designed for CNC operation internally (Sherline says in the worm housing) as well as the included #23 motor mount and coupling.
Third big point with me is the drive is 72/1 turns. Some rotary tables are 40/1 (yuk!). At 72 turns and 1/4 stepping, each step is 0.00625 degree. (Sherline uses 1/2 stepping.) A 90/1 would have… Continue reading
Thinking Small for 2012
I am investigating very intently the world of very small CNC machining. I am looking at small items such as mold machining for model parts and jewelry sized items using very small milling bits and high speed spindles. Actually I should call it CAD/CAM/CNC. It is far more than running the CNC mill.
I also looked at micro machining but that is a very high tech world that is still outside the needs and abilities (and machinery) of the personal machinist. It is truly amazing what can be done in the very tiny micro machining. I am not going there.
What I can do using my Taig CNC Micro Mill and a +10,000 rpm spindle is overwhelming. My recent Christmas ornament project is what has driven me into this investigation. The fantastic finish in wax that I was able to obtain actually surprised me. The Taig is a truly capable machine in this precise machining task.
I have now found web information of other, higher speed spindles added to the basic XYZ Taig movement. The Taig non-linear bearings and ways actually are up to the task for precision machining. I have many hundreds of hours of operation on my machine and it is still holding the performance line.
For now I consider myself “good” as far as machinery needs. I also have the appropriate software for CAD/CAM. That may change but not for quite some time. I will be adding a forth axis very soon, but other than that, I am comfortable.
I have the HB2 for larger projects and I will use the Taig for my miniature machining. I hesitate to use the word “micro-machining” but I am thinking it within my own definition.
I will also continue in my mold making and casting of components. I will definitely… Continue reading