Author Archive

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. Read the rest of this entry »

Man Sitting In deep rut.

Gosh! Haven’t posted here in a while. Got derailed and off track by playing with the demon of three-dimensional printing. You know, push a button and out pops a three-dimensional PLASTIC component.

Pretty much a sit back and watch effort. Similar but different than CNC machining. No chips flying around, or mist cooling required. Additive rather than subtractive manufacturing. It has its place but IMHO not for durable goods. Great for prototyping and making plastic models.

It is not the printing that is the most value. The printer is just another tool. The most value for me is the amount of CAD drawing (and mastering) acquired in designing parts for printing. The same skills that instantly transfer to good old fashion CNC machining.

The point is Plastic 3D printing is here. I have learned how to use it at a hobbyist level. But for making real, functional items, subtractive machining is still holding its own.

Read the rest of this entry »

The fourth dimension is often mentioned in science fiction as a dimension beyond the human senses. Today, real scientists (if there are such people) claim the fourth dimension does exist. But there are IMHO plenty of pseudoscience, especially promoted as video “entertainment.”  Material for a future rant…

In machining there really IS a fourth dimension. Usually called the 4thaxis. The Hobbyist Machine Shop (THMS) has a fourth axis for use on the Taig micro mill. It’s been on both the mill used for metal machining as well as the wax milling machine. Currently it is on the Taig micro-mill used for wax carving

THMS has (owns) four software CAM software packages that can create g-code for the 4thaxis machining. I’ll list them but will not (here) get into the fine details of using them.

Two types of 4thaxis operations are most common.

First is indexing. The material to be machined is held in the 4thaxis rotational device. Standard X, Y, Z three axis machining is performed on the surface facing the Z axis. 3 axis machining is paused, and Z axis is raised to clear all dimensions of the material. The 4thaxis rotates (indexes) the material to another face. This can be 180, or 90, or 45, or any equal or non-equal rotation. Then 3 axis machining operation resumes on the new surface plain presented. Repeat as necessary.

The second process (A axis rotation) requires setting Z axis Y position perpendicular to the center rotational axis and A axis assumes the movements of the Y motion vectors by rotating. Where A axis was stationary in the first method, the actual Y axis is stationary in the second. I call it 3.5 axis machining as it is not full four axis movement. In CAD it’s called “unwrapping the A axis” and presenting it as a flat plain surface, output as either X or (usual) the Y axis.

It must be noted that this works for A substituting for either X or Y axis direction, dependent on how the A axis is configured on the milling machine. The post processor makes this adjustment in my system.

These two separate modes of operation are the most common, especially for the hobbyist. But certainly, both methods can be combined in a hybrid milling operation. Such as machining an irregular 3D shape with A axis rotation, then milling a non-radial pocket or through hole into the shaped surface, using X, Y, Z milling and A axis indexing.

The fourth axis operation is fun to use at THMS. Perhaps because it is unusual. I call it 3.5 axis machining at THMS because only 3 simultaneous moves are occurring. Certainly, there is an application for full 4 axis movement. I don’t possess the software that can produce that movement, but it is possible. The THMS CNC control hardware can move 4 axis at the same time. Industrial grade “pro” systems can use 4, 5 and even 6 axis movement. Far beyond the realm of this meager THMS workshop.

However, the only limitation is imagination and writing the proper code to make it happen. A big pile of spendable money helps too.

*At this writing, FUSION 360 can create 4th axis G-code. But it is not full 3D. It is 2.5D and/or X, Y, Z + indexing. 3D-4thaxis is under development.

 

It’s no secret one of my lusts is machining in metal and wax. Actually, machining any material is fine with me. Wax became my favored material because it machines so well, especially with very small tool bits. Primarily, jewelry CNC carving for lost wax casting (LWC).

But I have also machined wax for LWC casting in brass, and that also works very well. I am not involved with casting large objects. At least not yet. But I don’t have an interest in doing large scale sand mold type casting. That’s a whole ‘nother sideline.

My light weight Taig equipment is perfect for machining wax. Taig tools also do an admirable job on small metal cutting as well. I have milled everything from stainless steel to cast iron. I have had no problems with brass, at least the types I have machined. Like most metals, there are many alloys. I choose the easy to machine.

I recently viewed a railroading model project (a hand-car)* made by an old friend Ed Hume. It got me re-considering my old lust for live steam engines and locomotives. They are machined directly from metal. That fanned the embers again and created a bit of remorse that my metal shop hasn’t been productive as was intended, except for the LWC silver work.

*Don’t know how long this link will last.

I designed my shop and machine equipment size specifically to create model train and model engine components. Not (what I consider) full size, or real life-size components. The term often used is “Model-Engineering” workshop.  

I recently dusted off one of the machines, the Proxxon PD400 mini-lathe and turned down some leaded steel stock into a mandrel and cap for my wax carving. That effort really felt good, experiencing those perfect cuts and shavings (chips) coming off the steel. I didn’t even mind the stinging burns on my arms from the hot chips. Enjoying pain may be a bit deviant but goes with the work. Also reminds me that I should wear burn proof long sleeves in the shop. Hard to do when my garage shop is 90 degrees+ in the Texas summers.

So, I mentally struggle again for a direction for my future activities. I became very serious with my LWC silver casting. I believe I create very professional silver cast jewelry work. But I am realizing I am not going to move up to the level of a manufacturer. I dislike making multiples of the same thing on a large-scale production. I do love specialty designs and very limited runs of multiples when there is a reason. I don’t want to build stock just for inventory. I’d say I am always a Hobbyist at heart.

My problem is I get bored once I have something mastered. I want to move on to new challenges. That has me looking back at the one-off model maker. Every part is a new experience. Sometimes there are multiples, but they are a part of a single creation. Like wheel sets on a train car or locomotive.

Will I fan the coals, and re-stoke the fire? I’ve said that before. Just check back in the archives of this web site. All I need is a little push and I’ll be over the edge again.

I have the machines and the workshop. I have the time, that is if I manage my time wisely and don’t try doing too many things at once. It’s called maintaining focus. It’s one of my moto’s I really have to practice. “One perfect part at a time.”

At my age I remember the Ed Sullivan Show on TV and the act where the fella has about a dozen plates spinning in the air on long vertical sticks (The record is 108). The big job was keeping them spinning so none fall off. Probably a visual metaphor now lost on today’s young folks, about doing too many things at once.

My brother and I each had one plastic plate and a stick as manufactured toy. The only thing difficult was keeping a lot of them spinning.

For me it is too many hobby interests at once. When I turn one off, I want to add another plate.

 

Everything came together for the first real use of the forth axis mandrel for ring carving. It’s nice when the plan comes together and everything works as intended. There was of course far more than just making the mandrel. There is the CAD design stage and the CAM (Desk Proto) for generating the G-code for the 4th axis. Then running the G-code on the micro-mill. I use LinuxCNC and I had to write my own metric post processor for Desk Proto. Not all that hard, actually. I made a USC (inch) version too. One tiny code change.

The first picture is the carved ring blank on the mandrel. I can accommodate a wide range of wax sizes. There will be much more experimentation and determination of the correct wax width for a project. This example worked fine.

The second photo is after the wax master model was hand finished and at this point is ready for casting. Sprue’s were added the ring put into a flask and the investment added. This post is not about the lost wax process. However, I thought it was interesting to show the wax carving and the final result the mandrel helps create.

The last picture is the finished Sterling silver ring shown on my hand (size 11). It really looks great. I will be doing a lot more wax carving on the 4th axis of the Taig micro-mill.

Categories
NOTE: Log in is for admin and members only, not required to post comments.