"One Perfect Part at a Time"

Vectric

The Siren’s Song

I have to admit to myself that I have run amok and spun off into the rocks along the shore of the barren hobby/craft islands for a while. Of course, that is figurative. I think I am still pretty much sane.

I am referring of course to my workshop interests and making tangible and valuable art and crafts. It was the song of the mythological siren creature that lured me off course. Maybe put me asleep. Its name is “3D Printer”. Ha!

Yep, I fell victim under its spell. I love design and making things and doing that with a 3D printer is very enticing. Continue reading

No Mistakes – Making My Point

I seldom, almost never make mistakes… HA! But I found one in my tool definitions for Vectric Aspire. Um… maybe I do make a few mistakes.

I use a very fine pointed, down to 0.003 tip tapered ball-end milling bits. Tapered ball-end milling bits are defined by their one side taper angle and the tip radius in the Aspire tool table. That was what got me. The tapered bits are identified by the manufacturer with total (combined) taper angle and the tip diameter.

So, what the maker defines as a 10-degree 0.005 tapered ball-mill is defined in Aspire as 5-degree taper bit with a 0.0025 tip radius.

I got the side angle correct but I was entering the full tip diameter as the radius. I realized the problem when I would define stepover as a percentage rather than specified absolute distance. The percentage calculation was showing twice the correct distance.

Therefore, Aspire was also calculating the tool path to be twice as wide as it actually was. That’s because that is what I specified.

Hmm… wonder how long I have been doing that!*

I am trying to imagine how that would affect the milling operation. Probably some dimensional errors, the program calculating the bit to be twice as wide as it actually was. With the tiny bits, there error would not be noticeable or of any importance. Pocket sidewall distance would be a couple of thou’ too small.

I think the biggest issue would be the stepover. If I wanted 20% it would be cutting… Continue reading

Milling Wax Adventure

The year is running out fast. I will soon have to say good-bye to 2011. This is the year (last Saturday actually) that I became 65 years old. Time enough for pondering that event, now to keep moving. Ha!

I did some machining of wax on the Taig CNC mill Saturday. I love machining wax (the hard blue kind). The wax is not good for creating real finished useful items but it makes excellent models for making molds and doing casting.

I spent the morning doing the design work in VECTRIC Aspire software. I was creating a Christmas ornament as a negative. I learned how to mirror and reverse the lettering and other “thinking inside out” processes in 3D design.

The afternoon was spent machining the design into the wax, using the Taig CNC mill. That was an adventure.

I haven’t run that machine for some time. The milling started out OK, but I got a couple of stalls and lost steps in the Z axis. The mill has never done that before so it was a surprise. I wasn’t pushing rapid travel or cutting speeds that hard either. Lifting the spindle and motor is fairly hard work.

The rapids are only set at 65 IPM and I was running about a third of that. So I ran through the software set-up and MACH3 warned me I was pushing the limit on pulses for the pulse generation frequency for which I had MACH 3 set. The Taig has twenty TPI screws so it takes a lot of very short pulses with 1/8th stepping (32,000 per inch) to get any speed from the drives.

That’s 32,000 per inch so at 60 IPM travel (keeping the math simple) that’s 1 inch per second requiring 32,000 Hz (32 kHz)… Continue reading

“Proofs” of Concept

I was doing some product research today. This is something I made in about five to six hours. I had been thinking of how I was going to make these all week. I just needed a good Saturday to give it a shot.

As the title indicates this is a proof of concept not a real project. I didn’t want to slow myself down doing all the pictures of the process. The process is still experimental so  full disclosure can wait until a better time. I have my camera at the ready.

Long time readers know I have experimented with pewter casting before. Here is the LINK.

The “thumbs up” graphic is a 3-D rendering received free with the Vectric Aspire software. I used it to create the medallion. The finished result is seen in the first picture above. The picture was created within the software. I combined the thumbs up with some freelance drawing to form the disk. Actually in my opinion the disk is much thicker than it should be.

The edges of the disk did not come out well in the tool pathing. I need to find a better way to create the disk in the software. As this was a trial, I didn’t want to spend all day on the drawing so I accepted some imperfection in the edge rendering and moved on.

Next I had Aspire produce a roughing toolpath for a 1/8 inch ball nose mill bit. Then I had Aspire produce a spiral finish pass with a 5/32 inch ball nose. The disk is 1-1/2 inches in diameter. The aluminum (both pieces) is 1/4 x 3 x3 inches. The back plate is not machined in this test trial.

The machining was done on the CNC Taig mill. A… Continue reading

Thoughts on CAD/CAM/CNC

I am going to take a time out here from the product specific (BobCAD-CAM) examination I am making of a CAD/CAM software product.

I consider myself a competent self taught hobbyist CNC machinist. I didn’t get here without a lot of study and hands on practical experience. Let me say I have paid for my mistakes as well as my successes. The creative process of following through from an idea, to a sketch, Computer Aided Design (2D & 3D drafting), Computer Aided Manufacturing, (generation of Computer Numeric Control code), Controller (MACH3) set up and finally understanding the physical limitations of machine moves and feeds and speeds, and the huge variety of milling cutting tools… is a stupendous undertaking! I think I left out machine set-up for holding material and tool changing.

In my opinion CAD/CAM/CNC (the trinity) is a several orders of magnitude more difficult task than straight manual milling. However, I see thousands of examples of hobbyists running CNC so it is definitely a doable process for a single non professional to master, but not on day one.

CAD/CAM/CNC is not an easier way of machining simple parts. The actual machining stage of CAD/CAM/CNC is only a part of stage three (the CNC portion) of the trinity. There is a lot of “desk work” to master before making chips in the shop.

There exists a small number of hobbyist “Motor Spinners” out there. This is a slightly derogatory term for the folks that love the concept of CNC but build or buy a CNC machine just to watch the axis motors spin. They have no established need to make anything. I have no issue with that. This is what any hobby is all about. A hobby doesn’t need to do anything but make you happy.

I am guilty of… Continue reading

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