Simple Scissor Lift

In building my shop I spent some time thinking about how I was going to put the ceiling up. Metal pole building sheets were my choice for covering the ceiling. They are light weight, fireproof and already painted. The problem is the ceiling is almost 12 feet high and the panels are 3X10 feet. So how to get them up and hold them while attaching the panels.
I finally decided that a scissor lift would be a good idea. After looking at a number of commercial scissor lifts on the web I was coming up with all sorts of complicated designs. Then I remembered the saying KISS “Keep It Simple Stupid.
What I finally came up with consists of 8 8′ 2X4’s for the frames and some more bits of 2X4 for spacers. I used screws to attach the spacers making it strong and easy to take apart.

The center pivots are 3/8″ bolts, elastic stop nuts and washers. The end pivots are also used for the come-along to raise the lift so they need to be strong. I used 1 inch steel rod for this. There is also a safety chain to prevent the lift from collapsing completely if the come-along or its straps should fail. Your arms are inside the lift when working the come-along and a failure could easily break an arm or two.

To use it I drag it in place and slide a panel on top of the partially lowered lift. Operating the come-along raises the panel until it is in place. The position of the panel can be adjusted by dragging the lift or pushing the panel around. The panel is then attached to the rafters.

The only inconvenience with the lift is that the come-along is slow and fiddly to lower under tension. It takes twice as long to lower the lift than it does to raise it.  When I am done with the ceiling the lift will be taken apart and the pieces salvaged for future projects.

The lift has done its job and the ceiling is done.

I have posted a video on YouTube showing the lift in operation putting up ceiling panels. https://youtu.be/w5AClCLYUk0

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CNC Laser Cutter / Engraver Build

I see a number of articles on the WEB about using a blue laser around 2 watts for cutting and engraving. A lot of times the laser is attached to a 3D printer. Now I have a 3D printer but I wanted a cutter that was a bit larger and did not want to bother with swapping the laser for the print head. So I built a carriage for the laser based on  reprap Prusa technology.

The usable area of the bed is about 16″ by 16″ (400 by 400 mm). Unlike the 3D printer the laser is moved in both the X and Y directions rather than moving the bed in one direction and the laser in the other. A piece of 3/4″ plywood serves as the base and it sits on rubber feet so I can get my fingers under it to pick it up. The carriage and gantry move on 8 mm rods with dual linear bearings. I used two steppers to move the gantry in the Y direction to provide even force at each end of the gantry. There is no Z axis as the laser can be refocused for different height materials. There is a piece of sheet metal on the base that serves to protect the plywood from the laser.

Parts like the motor mounts and bearing supports are 3D printed and are based on the Prusa parts. For the electronics I used the Arduino mega with the ramps 1.4 interface. Since I have 2 steppers for the Y axis the Z axis driver on the ramps was used as it has two stepper connectors. To get this to work I modified the pins.h file in the Marlin software to swap the Y and Z axis.

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The laser is turned on by use of the fan circuit in the ramps board. This is really handy as the circuit provides the 12VDC needed by the laser and there is  Gcode functions to turn the fan on and off.

There is a bit more work to do on it. The cables need to be properly dressed. Then there is all the safety issues. It needs a lockout switch and an enclosure to prevent any stray laser beams and control the fumes.

Repetier-Host works well for testing and for sending the Gcode files to the cutter. The manual mode lets me move the carriage around and turn the laser on and off.  The first test I did was using handwritten Gcode to cut a 20 mm square. For generating more complex designs I have settled on using Inkscape for drawing and have tried both Gcodetools and J Tech Photonics Laser Tool extensions to generate the Gcode. So far I have had better luck with the J Tech tool.

Here is a short video showing cutting the fabric.

I did a number of tests to see what materials could be cut with this laser cutter and what cutting speeds to use. Regular paper cuts very easily. The cuts don’t even have a burnt looking edge like thicker material. Card stock cuts nicely with a slightly slower cutting speed. Cereal box cardboard would take a slow cutting speed and several passes to cut. Normal thickness cotton fabric cuts easily. I haven’t yet tried other types of fabric. Cricut vinyl cuts and you can adjust the cutting speed to cut just the vinyl and not the support material. It will mark wood with nice clean lines.

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Above is Cricut vinyl cut with the laser and below is after it has been weeded.

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Below is a piece of pine that has been engraved with the laser.

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I see many interesting uses for this laser cutter especially once I get better at using Inkscape.

Posted in 3D printing, CAD, CNC, Crafts, DIY, Electronics, Machine Shop, Software | Tagged , , | 2 Comments

DRO for my MIll

Like most of my blog posts this is not meant to be a “how to” but rather a “how did” in hopes that someone will find useful ideas for their projects.

It has gotten a bit frustrating using my milling machine recently and having to deal with the leadscrew backlash and counting turns to get the table positioned. A digital readout  would make using the mill much easier. A full 3 axis DRO for a mill costs almost as much as the mill. I did not want to spend that kind money for a full 3 axis readout so I found some individual scales and ordered them.

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The X axis scale was the easiest to mount to the mill. The front of the mill table has a T slot for adjustable stops. I had never used the stops so I figure I would not miss that function. With the readout is is easy enough to just stop at the correct position. The scale is mounted with some T nuts to the slot on the table and the sensor is mounted to the front of the mill using the mounting holes for the stop. An aluminum bracket and spacer connect the sensor to the mill.

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It was necessary to drill and tap some holes into the mill to mount the Y axis scale. In this case the sensor is attached to the moving part and the scale is attached to the base of the mill. It is tucked away under the table mostly out of harms way.

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The Z axis took me some time to decide how to mount. I did want to retain the depth limit function for the Z axis as I do use that frequently. The bottom of the scale is attached to the mill with two holes drilled and tapped into the mill. For the top of the scale I used a couple of disk magnets as drilling under the belt guard would have been difficult. The magnets make it easy to remove and adjust and they are up out of the way of any chips that the magnets might attract. I could have used a separate rod to mount the sensor but it looks better with the sensor attached to the depth limit screw. This made things more difficult because the screw still has to turn to adjust the depth limit. I added a wave washer where the screw attaches to the spindle and another wave washer where the sensor is mounted.  This eliminates any backlash that would cause error in the scale readings. The sensor is mounted to an extension of the screw to allow the depth adjust to still function over its whole range.

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The original plastic cover was replaced by some aluminum angle. Not really necessary given the digital readout but I added a pointer to the depth limit stop nut and a piece of stick on ruler left over from another project.  This is handy for quick and dirty drilling that does not need to be very accurate.

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I am still trying to decide how to mount the readouts for the DRO. Right now they are attached with their magnets to a steel plate sitting on the mill table. This is not a very good place for it as the chips fall on it. Many DRO displays are mounted near the top of the mill but I normally sit down to run the mill especially when doing careful work. Maybe not the safest thing to do but it is a lot easier for me to do careful work sitting down.

Recently I discovered information on the web about using an inexpensive android tablet for a DRO readout. This would let my setup have all the functionality of a 3 axis DRO for less cost. That might happen in the future but right now I want to get back to milling.

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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.

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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.

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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.

 

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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.

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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.

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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.

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Welding Bucket

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

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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.

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Painted Bucket

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

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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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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