"One Perfect Part at a Time"

prototype

Plastic Rut

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.

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Preview Taig CNC Lathe

Taig CNC Lathe

Taig CNC Lathe

Update! Article Published!

Click on text above…

Here is another one of my “Sneak Previews”. You can read the previous posts that hinted at this concept. The post before this showed where I was going.

You can see assembly is not complete but this reveals the complete design. The only part I had to make was the conversion mounting plate between the Taig lathe and the Taig mill table. The base plate of the mill is 3/8 thick and so is the adapter plate. A 3/4 inch 10-30 bolt works perfectly with the existing holes and doesn’t extend through the adapter plate. I am thinking of epoxy (and bolts) in the final assembly of the mill base to the adapter to prevent any possible shifting.

The adapter still has the Dykem from the very careful layout of the holes. The base plate was also squared very accurately (on my X3) and this precision is used for squaring the lathe on the mill table. I am aware the lathe bed must be accurately aligned with the mill table.

The pulleys and a chuck will be installed next. One cannot help but notice that honking motor hanging out there. That is the standard 1/5 hp PSC mill motor. 1750 rpm (only $30!) The power is a simple plug in to the existing switch.

In this view it can be seen that even with the full lathe mounted there is plenty of travel in the Z axis to  handle any width of material that will fit the chuck and bed clearance. I will experiment to determine if the stock Taig tool holder needs to be  mounted farther to the right. I think it does for wide facing cuts. A quick change or turret… Continue reading

Design Study

Hmm...

Hmm…

I have the design of my Taig CNC mill to CNC lathe conversion further along. I have the few scraps of the non-Taig material in hand and I placed an order for all new Taig components I will be using. I had an eight year old spindle and a 3,000 rpm Dayton motor but I decided to design with current parts and slower motor so there would be no surprises if I put together a kit. I also have a new idea for the tool mount that will be much easier and probably cheaper to implement.

The CNC lathe conversion is ultra easy and low cost if you own the CNC mill. I will dare call it a quick change process. It consists of mounting the Taig lathe bed on the Mill table, removing the mill spindle and motor assembly in one piece, and clamping on the lathe tool holder on the Z axis.  I will be using a standard lathe 3/4 -16 spindle with a 1/5 hp mill 1750rpm motor to power the spindle with standard mill belt drive. I like the fact that the standard Taig tailstock can be used if required. There is plenty of working room above the lathe with the mill head removed.

Lathes should not be spinning at 10,000 rpm so the smaller mill motor will be a good choice rather than using the faster CNC mill motor, at least for the prototype. Of course testing is needed to prove this point, but it only makes good safety sense not to spin too fast.

Future development could be with a geared drive for slower rotation and an rpm reader to allow for thread cutting.

I decided to design and build this conversion mostly because it seems so easy to do. I don’t… Continue reading

Machining Job for Roboboat

I just ordered a couple (2) 6-18 Volt Johnson 9167AK electric motors for the Roboboat project. I do not yet know if they are suitable. I’ll discover that once I receive them. This is part of the problem when buying something you can’t first touch and feel. Especially if it something you have never owned in the past.

The specifications seem to be OK and the cost was very low (about $7.00 each on eBay) so I figured it was worth the risk. That is all part of the cost when creating a prototype. If anything the motor’s physical size is what has me concerned. They just don’t seem to be big enough for the power they can handle. That is about 49 watts each. They weigh in at .45 pounds each so they seem to have some mass.

Johnson makes or sells a huge variety of small DC motors. These motors I picked are not the highest RPM but do have a lot of torque for their size. I also have to pay attention to the power they use as I don’t want to haul around large expensive batteries. I then also have to stay within the ratings for my speed controllers.

The reason I am posting this here is that part of my plan is to design and build (machine)suitable aluminium motor mounts for these (or any) electric motor I choose. High power also equals high heat so I need to design for the heat these motors are sure to produce. Of course I don’t expect to be running the motors at full power. (I could be wrong.) A lot will depend on prop size and pitch. Lots of variables.

The roboboat project is not intended to produce a high powered fast competition model boat. I am… Continue reading

…and a cast of thousands.


That’s a famous movie intro tag from when I was a kid. (Ben Hur, Moses and The Ten Commandments, etc.) In this case the “cast” is a bit different. No Charleston Heston. Yes, a pun.

The process here is casting pewter into a mold. Perhaps thousands could be made given enough time. What I find interesting is the use of a rubber mold. When I was much younger I remember toy soldiers cast in metal molds. (The metal ones are still available.)

The mold shown here looks like it was made with hot vulcanized rubber but hot metal casting process is also shown to work with RTV (Room Temperature Vulcanization) rubber. Of course metal and plaster molds can be used.

You will notice a few have short guns. The pour was a bit too cold and the flow didn’t get to the end of the rifle. Thin parts like that are tough to fill. I cast many more than shown here (just remelted them) before I got the process right.

All I did for the pictures was cut off the sprue while still hot and then file the flash from the bottom so each one would stand up. No clean up of the casting at this point.

My plan is not to make toy soldiers. This is just an inexpensive all-in-one kit I bought on sale to get the “hang” of casting pewter. I plan to make and cast my own mold designs and perhaps offer them for sale (the molds and what they make).

I choose pewter and this variety is lead free. There is so much concern about the “dangers” of lead, it is not a good idea to offer it to the public. Of course the other metals in pewter are not intended for… Continue reading

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