3D CAD

Around about the time I got my 3D printer working I saw that the University of Iowa was offering a Senior College course “Designing and Manufacturing with Computer Modeling and 3D Printing”. That sounded useful so I signed up for it. The most important software tool for 3D printing is the 3D design program and I was looking around for a suitable program to use.  Just a week before the course started a friend turned me on to Autodesk Fusion 360. This looked like a nice program and it was targeted to 3D printing users. So I decided to learn it. Then along comes the Senior College course and it turns out to be primarily how to use Autodesk 3DS Max 2016 a much more complicated program. Since 3DS Max is not free like Fusion 360 I decided to concentrate on learning Fusion 360 and take whatever I could get from the course on the overall 3D design process.

The biggest hurdle to get over is figuring out the order things are done in 3D design. In 2D drafting if you wanted to draw a 1x2x0.5 bar with a 0.25 hole that is what you would draw. In the 3D system the general idea is to sketch out the basic form (bar with hole) then go back and add the dimensions and any other features for the design. When designing more complex shapes you really have to think through how best to go about getting the shape you want and the order of the operations. Several times I have gone down a path and had to back up or start over  to get where I wanted to go. I was hoping to get some of the how to go about it from the course but 3DS Max is so complex that about all that could be taught was the basic which button to push. It would have been nice if there were some student helpers there that could help with the basic questions about the program.

There is a difference in the process between creating an artistic pleasing shape and mechanical design where you need make a part that has precise dimensions that have to be followed. From what I know so far 3DS Max seems more suited to the artistic process and Fusion 360 to the mechanical design process. Of course this could be because I haven’t found the appropriate functions in 3DS Max. It kind of looks like you may be able to customize the 3DS Max workspace for different processes.

flywheel

Above is an image of half a flywheel that I am designing using Fusion 360. The goal here is to print this in plastic then use the plastic printed part as a pattern to cast the flywheel in metal. A plastic flywheel would not be too useful.

There are other approaches to 3D printing besides designing an object using a CAD program. Online there are several repositories of things already designed that one can download and print or order a print. I have used this a few times to get parts and accessories for my 3D printer.

ornament2

Above is a Christmas tree ornament that I downloaded the design and printed.

Yet another approach is making copies of existing objects either full size or miniature replicas.

I used the Autodesk product Memento to generate a 3D mesh of a broken gnomon. Hopefully I can digitally repair this, print a plastic pattern and using the pattern cast a new gnomon in brass.

gnomon2s

This process involves taking many pictures of the object from every possible angle then processing the photos using the Memento software. I have yet to figure out exactly how to go about doing the repairs. Memento provides some tools to manipulate the mesh and there are other tools to work with meshes.

Even if you don’t own a 3D printer a working knowledge of 3D design software can be useful. There are quite a number of companies that offer 3D printing services. You can submit your design files online and get quotes and order printed parts. These companies offer quite a number of different materials including metal.

 

Advertisements
Posted in 3D printing, Crafts, DIY, Software | Tagged , , , , | Leave a comment

Digger Bucket & Repair

Recently I needed a narrow trenching bucket for my digger that I built some years ago. In taking off the larger 18 inch bucket I discovered that the pivot pin for the bucket had become rusted into the bushing. So the new bucket project became both a build and repair project.

I built the digger with plans from CadPlans.com. Having built the digger repairs and modifications are not intimidating.

pin1

Pivot Pin Remains

The pivot pin was so badly rusted into the bushing that I had to cut out both the pin and bushing to remove the bucket.

diggerarm1

New Bushing

Here is the digger arm all cleaned up with a new bushing ready for welding. The hole in the top is for a grease fitting. I need to remember to keep it well greased this time.

bucketwelding

Welding Bucket

Here I have all the parts for the new trenching bucket cut out and I am welding it together.

bucketwelded

Welded Bucket

Here is the new bucket all welded and ready to paint and mount on the digger. The teeth are replacement teeth for an end loader and the cutting edges are part of a plow share blade.

bucketfinished

Painted Bucket

Here is the new bucket all painted and mounted on the digger.

trench1

Trenching

Here is the new bucket in action. I buried a power cable out to my weather instrument platform. Since then I have used it for another couple of projects.

You can also see in this picture another repair needed on the digger. The right axle support bracket broke and the wheel is bending up. I had to stop the trenching project at this point and repair the axle support.

Here is a short video of my digger in action. I am not actually digging here but using it to move brush around.

https://www.youtube.com/watch?v=eDUREWSWFGY

Posted in appliance repair, DIY, Metal Working | Tagged , , | Leave a comment

3D Printer

Like all of my blog posts this article is not intended to be a how to tutorial but rather just my experience and observations in building a 3D printer.

A few months ago I decided that I wanted to have a 3D printer. There are a number of things I have in mind to make with the printer. One thing is to make patterns for metal casting. Both sand casting patterns and lost wax (plastic) patterns. Also some of my other future project could make use of printed parts and I will probably make some artistic things.

The prices for off the shelf printers are a bit more than I am willing to pay so I looked around for what is going on in DIY for 3D printers. I like building things anyway. After a lot of digging around on the WEB I decided on building a Prusa I3 which is in the reprap family of printers. This printer seems to be quite popular and there are lots of vendors selling parts for them. To get just what I wanted I ended ordering parts from quite a number of different vendors mostly on Ebay.

One of the concepts explored with the reprap printers is the idea of a self replicating printer so many of the parts for the printer are printed parts. Of course when starting out you don’t have a printer to make the parts so you have to buy them. As long as the printer does not completely break down you can then make spare parts or upgrades.

Surprisingly I had very little problems with parts not fitting or being defective. The metal frame had two holes that were not tapped for screws. That was an easy fix as I have to proper metric tap. The finish on the metal rods used for the carriage motion was not the best and the linear bearings fit a little tight. I mounted the rods in the lathe and sanded and polished them and got them to fit properly. I should have ordered chrome plated rods. I spotted two solder shorts on the electronics boards before I assembled them. Again an easy fix with a soldering iron. Another problem showed up when putting the X axis carriage together. The X axis guide rods tended to come out of the printed supports when the carriage moves back and forth. I drilled a hole in the support part and inserted a brass rod to retain the guide rods.

The rest of the problems I had were my own fault. I plugged the two circuit boards together wrong and burned up a trace on one of the boards, easily fixed with a jumper. Later on while testing the printer the carriage snagged a cable to a stepper motor and unplugged it. Unplugging a stepper motor with the power on almost always burns up the driver IC. Luckily I had a spare driver board.

3dprinter1

The basic frame of the printer going together.

I drilled and tapped a few more holes in the frame to mount the power supply and the processor board. After assembly it is necessary to make sure everything is square so that it will print correctly.

3dprinter2

What a mess and that is not even all the wires.

When I get it working I will gradually dress up the wiring so it looks a little better. I did not like the way the Z axis limit switches were supposed to mount so I made some metal brackets to hold them. They can be adjusted up and down by loosening a set screw. A metal bracket at the top holds the LCD at an appropriate angle. With the printer working I can print up a plastic case for the display. designs for several versions of a case can be found on Thingiverse.

cube1

First successful print a test cube.

It did not take too much to get it to print. Mostly fiddling around learning how to use the software. The cube was printed with PLA which is supposed to be the easiest to use.

ornament1

Christmas tree ornament.

After some test prints this is my first successful print using ABS plastic. It requires different setting for the printer and a heated bed. The bed had difficulty getting up to the 100° C temperature suggested for ABS so I bought a cork tile and glued it to the bottom of the heat bed.  Since it was Christmas time some ornaments were appropriate to try out the printer. The default settings in the printer driver software are set up for printing PLA and I did not find any good suggested settings for ABS so it too some experimenting to get it right.

ornament2

Yet another Christmas tree ornament.

I decided this ornament would be a good “stress” test of the printer as it has a lot of “printing on thin air” going on. It is not prefect, there is still some tinkering to do. The first time I tried printing this the extruder jammed about half way through the 3 hour print.

There are all kinds of suggestions out there for what to use to get the object to stick to the printing bed while printing. I am using a borosilicate glass bed with Aqua Net hair spray. So far this seems to work well. The above ornament stayed stuck during printing even though it only has a small base and came right off after the bed cooled down.

Still to do is learning how to use the whole software tool chain to design and print a part. I did design a test disk and used it to try out printer setting. But for anything more complicated I will have to better learn the CAD tools. My collection of software consists of Repetier-Host, Meshmixer, slic3r, openscad, FreeCAD, 123D design, netfabb and InkScape.

Posted in Crafts, DIY, Electronics, Machine Shop, Metal Working | Tagged , , , , | 2 Comments

Fan Aspirated Temperature Sensor

The temperature sensor for my weather station is a commercial wireless temperature/humidity sensor that I have mounted in a commercial solar radiation shield. It has been in operation for a couple of years and seems to be reasonably accurate. The humidity sensor part did fail and the sensor had to be replaced. Despite being in the radiation shield the outdoor environment is hard on humidity sensors.

radshld1

Above is a picture of the commercial solar radiation shield with the wireless temperature/humidity sensor inside.

Another approach to protecting the sensor for solar radiation is to use a fan to provide a steady flow of external air. Essentially blowing away the hot air around the sensor. The processor that I am using to read the wireless weather sensors also has provisions for a wired temperature/humidity sensor which I have been using to monitor the conditions inside the instrument cabinet. I thought it would be interesting to compare the passive radiation shield with a fan aspirated shield.

I build a simple shield out of some 2″ PVC pipe and fittings.

fantemp1

The picture above shows the parts of the sensor. In the middle is the actual sensor mounted on a small PC board with a RJ11 connector. Above that is a 12VDC wall wart to power the fan. The 40 mm computer  fan to the left is mounted in a short section of 2″ PVC and glued in place. A length of telephone cable is used to connect the sensor to the processor. A PVC U fitting and a longer piece of PVC completes the sensor.

fantemp2

Above is a picture of the completed sensor mounted on my instrument platform. The fan draws air up the long tube and out the short tube. With both ends to the tube facing down it should help keep the rain and snow out.  The sensor is located near the middle of the U fitting.  It remains to be seen how long the fan and humidity sensor will last in this environment.

After it runs for a few days I will compare the performance of the two sensors.

6/22/2016 Comparison data between the two sensors shows that the fan aspirated sensor is affected by the sun more than the sensor in the shield. Next I will try a simple sun shade for the fan aspirated sensor.

Posted in Amateur Science, DIY, environmental monotoring | Tagged , , , , , | Leave a comment

Chainsaw Lumber Mill

A rather large silver maple tree trunk came down in a wind storm recently. I have cut most of it up for firewood but there was a nice 4 foot section that I decided to make into some boards. Maple has a tendency to rot in the center but this piece was solid.tree2

A few years ago I built an attachment for my chainsaw to let me use it to cut boards from logs. It is based on the Granberg small log chainsaw mill. The Granberg mill is made of aluminum and mine is made of steel so it is a bit heavier but it is used sitting on the log or guide board so it is not too much of a problem being heavier.

saw1

To guide the mill for the first cuts a 2X6 is screwed to the log.

log2

The log after the first cut.

log3

It makes cutting the boards a lot easier if the log is squared up first. My saw bar is not long enough to cut through the center without taking the sides off. It took some doing to get the log rolled up onto the 4X4s. A peavey would have made things much easier. log10

After the log was squared up I cut it into boards. Here I stopped the cut part way in to take a picture.

board1

The boards now get stacked in the shed for a year to dry.

Posted in DIY, Metal Working, woodworking | Tagged , , , , , | 1 Comment

Tankless Water Heater

Here is more than you ever wanted to know about fixing my tankless water heater.

A few years ago I bought and installed a Poloma model RMTG-53DVP tankless water heater in my home. This exact same model is also sold under the brand names of Rheem, Ruud and Richmond. After operating for about a year it shutdown and started flashing error codes C7, 13 on the remote control. If I unplugged it for a while it would work again but would only run for about 3 minutes before shutting down again. Some digging around on the WEB indicated this was a oxygen sensor fault. In other words the oxygen sensor was telling the controller there was low oxygen. Never having worked on a tankless water heater before I called a plumber that advertized fixing tankless water heaters. He came out and we had a nice conversation and basically recommended I fix it myself. For this I paid for a service call. Apparently he was not familiar with that brand of heater and did not want to figure it out.

Now a tankless is way more complicated than a conventional water heater with a microcontroller and lots of sensors and valves.

heater

Here is my heater opened up. At the top is the copper coil assembly where the water gets heated. The plastic with the black lines on that is an electric heater that keeps the water from freezing if the temperature gets too low. Below that is where the burner assembly goes. The burner assembly and manifold is removed in this picture. Below the burner assembly is the controller, valve and fan. There is a whole bunch of screws that have to be removed to get thing apart.

The oxygen sensor work by monitoring a flame burning in a special chamber. There is a precision orifice that controls the amount of gas burning and a thermocouple to monitor the flame temperature. The controller waits for 3 minutes after the heater starts to check the flame temperature so that everything is stabilized. If the temperature is too low the controller shuts down the heater and sends an error code to the remote control.

burner

This is the burner assembly. On the left is a round brass hole. That is where the sensor flame burns.

So what could cause the problem? Obviously there is plenty of oxygen and nothing blocking the air flow into the heater. The thermocouple could be bad but those thing are very reliable. The controller board could be bad (horrors). After a bit of poking around and inspection I discovered that there was some crud deposits around the precision orifice.

hole

It did not seem like the orifice was blocked that much but since I could not find any other problems I cleaned the orifice and reassembled the heater. That solved the problem.

Since then I have had to clean the orifice about once a year. Something in the propane  is forming the crud.  They also recommend cleaning the water lines by running vinegar through the heater with a pump for about an hour. I have done that once. It did not seem like there was very much lime build up though.

Posted in appliance repair, DIY | Tagged | Leave a comment

Soapstone Stove Restoration

Many years ago we bought a soapstone stove at a garage sale for $25. It was not in the best shape with numerous stones broken. I brought it home and dismantled it so I could move it. The complete stove weighs around 700 pounds. I stored the pieces in the barn. Now that I am retired, with a little more time on my hands I decided to fix it up and install it in the house. I have a lot of wood and it would be nice to have a backup for the propane heat we have.

The stove is a Hearthstone I made by the Hearthstone stove company of Vermont. I believe that the Hearthstone I is the first model made by the company and is no longer in production. I did learn from an online dealer that the Equinox 8000 stove replaced the H1. It looks similar but the innards have been modernized.

Replacing the stones

The first task was to see if it was even possible to replace the broken stones. A few years ago I visited the local Hearthstone dealer and asked about getting replacement stones. They said I should talk to the factory. I contacted the factory and they were kind enough to send me an owners manual for the stove but said I had to go through the dealer to get part. The old run around. The factory would probably have had to make the stones and that would be and expensive way to get the stones. I did find an online dealer that had some of the stones but they are quite expensive. One valuable thing I got from the online dealer was a chart showing the layout of the stones in the stove. That leaves me with getting some soapstone and making the stones myself. It turns out the stones are 30 mm thick which is the same thickness as the soapstone slabs used for kitchen counter tops and the like. There does not seem to be any soapstone counter top dealers nearby so I have been contacting soapstone suppliers. I got samples from three suppliers, Finnish soapstone, Brazilian soapstone and Virginia soap stone. I wanted  to match the look of the old stones. Shipping turned out to be quite expensive for the stone so I finally found a dealer a few hours drive away in Wisconsin. The slab I purchased there does not match the stones of the stove but arranging the new stones symmetrically it will look OK.

brokenstones

The picture above shows the broken stones. I used this to estimate the amount of new stone I needed to purchase. After I got the slab of new stone I realized that I actually needed more stone as I wanted to move the flue outlet from the back of the stove to the top. This requires a few different stones, which I have to make. To compensate for this I decided to glue the stones with simple breaks and no missing parts. This is a stove and the stones get quite hot so you can’t use just any glue. I have a gallon of sodium silicate which can be used as a glue. Sodium silicate when dry is essentially glass and can withstand high temperatures. This worked quite well and after refinishing the stones the breaks are hardly noticeable.

cuttingstone

The picture above shows the method I used to cut the new soapstone slab into the sizes for the stove. I put a diamond tile saw blade in my circular saw and cut the stone wet with a clamped on guide. This produced a nice smooth cut. I was careful not to get the electrical part of the saw wet and it is plugged into a GFI outlet.

I planned on cutting the grooves  and bevels for the stones on my table saw with just an ordinary carbide wood cutting blade. I tried cutting some of the broken stones to see if this would work and they cut quite nicely. When I went to cut the new stones they promptly ruined the carbide blade. The new stone was much harder than the original soap stone in the stove.  A 10″ diamond blade for the table saw solved that problem.

Each stone has a decorative beveled edge and grooves in the edges. Flat metal strips fit into the grooves to hold the stones in place.

Metal Parts

After sitting in the barn for years it was impossible to remember how all the pieces of the stove fit together. It was a jigsaw puzzle type of challenge to sort out the stones and metal parts. The metal parts had become quite rusted.

stovedoor

As can be seen in this picture of one of the stove doors. All the metal parts got sandblasted and the cast iron parts repainted with flat black high temperature stove paint. Some parts like the screen for the doors had to be replaced. I replaced the screen and all the nuts and bolts with stainless steel. I also had to replace some of the steel strips that hold the stones in place because I changed the vent from the back to the top of the stove. This requires some different length strips. The ugly bolts in the door handles were replace with some stainless steel rod and some nice brass acorn nuts.

Reassembly

Because the complete stove weighs somewhere around 700 pounds there was no way I was going to assemble it and then move it into place.

stovebase

In the picture above the base of the stove is placed along with some of the internal workings. There are cast iron plates and a channel around the bottom that supplies air around the base of the fire. The incoming air is regulated by a thermostatically controlled damper on the back of the stove. The 400 pound water filled cast iron radiator behind the stove provides and excellent radiation shield to protect the wall behind it from the stove heat. Not seen in this picture is another metal radiation shield on the right wall.

stoveinside

Above is another view of the stove being assembled. The three stones in the back with the fiberglass screen on them are some of the replacement stones. The original stones were shorter to allow for the vent in the back. You can also see the ends of the steel strips that hold the stones in place. Because of the way the temperature of the stove is regulated by controlling the incoming air it is important that the stove be airtight. The rope gaskets for the doors were replaced. New ceramic fiber paper gaskets between the door frames and the stone were installed. When assembling the stones into the stove each stone mortared with furnace cement to seal all the joints between the stones and between the stones and the cast iron frame.

Heating

stovefirst

Above is a picture of the completed stove with a nice fire going. Normally I use the side door for ash removal, loading wood and starting. This winter I have been using the stove daily. It will keep the downstairs part of the house warm without any additional input from the propane heat even on below zero days. When the temperature is in the 40’s it is easy to get the house a bit overheated. Because of the way the air is regulated I believe you are supposed to be able to load the stove up with wood and have it burn most of the day. I prefer to keep only a small amount of wood in the stove and add a piece every hour or so during the day. This way if it gets too warm I can just stop feeding it wood.

warmdinner

Since the stove is in the dining room it can be used to keep food warm. Here it is keeping thanksgiving dinner warm.

The dining room gets a bit warmer than the rest of the downstairs so I have a fan to help circulate the air to the other rooms.

References:

Hearthstone stove manufacturer http://www.hearthstonestoves.com/

Soapstone supplier http://www.elegantstoneproducts.com/

Posted in Alternate Energy, DIY | Tagged , , , | 13 Comments