Archive for the 'Tools' Category

Alibre is Now Geomagic

3D Systems recently acquired Geomagic.  Several years ago they acquired Alibre.  Alibre is a parametric CAD program.  It appears that they are simply re-branding the existing version of Alibre as Geomagic, but will incorporate feature of the Geomagic product line over time.  Here is the basic product line.

  • Geomagic Design Expert $1999
  • Geomagic Design Pro $999
  • Geomagic Design Personal $199

I am also pretty sure that Cubify Invent @ $49 is a further simplified version of “Personal” that allows you to work at the part only level.  A comparison of the upper levels is here.

I have used Alibre and Cubify Invent and find them to be quite capable.  Some day I may loose my easy check out access to Pro/Engineer and these products are on the radar as possible solutions.  I found the even Cubify invent could do a few little tricks that are a pain in Pro/E.

 

DIY Jumper Wires

I love using these jumper wires for prototyping. They work great for breadboards and Arduino headers.

You can buy them all over the place including SparkFun.  They are available male/male, male/female and female/female in various lengths.

Sometimes you need to hook up something that already has wires attached. I got these pins and single pin housings from Pololu the other day.

I really like them.  The housing works for either male or female pins.  You can either manually crimp the pins with a needle nose pliers or use a real crimper.  The crimper works for both the male and female pins.

Here are the links to the parts.  If you know of other sources, please add them in the comments.

Male Pins

Female Pins

Single Pin Housing.

Crimpers

Proper use of a crimper is a learned skill.  You need to take the time to learn it.  I lend out my crimpers all the time.  Many people try to use their first attempt in project.  The pin falls off or does not have a connection.  They then give up and use pliers.  The bottom line is there is no better way to put the pin on than a proper set of crimpers.  This is how the professionals do it.  It only takes a few attempts to get it right.  Take the time.

One of the biggest mistakes newbies make is stripping too much insulation.  It is usually just a tiny amount and only the length of the wire barrel portion.  It is very important that the insulation barrel of the crimp grabs onto the insulation.  That is the thing that really holds the pin from being pulled off.

I always buy my crimpers from eBay where they are usually about 25% of retail.  Avoid generic or all purpose crimpers.  Try to get the manufacturers brand.

The crimpers I used are Ampmodu Mod 90418-1.  The can be found used on eBay for around $50.  Pololu suggests you can use this general purpose crimper.  I also have that crimper and it works better than anything you could do by hand, but is no where near as good as the real one.  The 90418-1 has a little “gate” thing that fits between the part the crimps on the insulation vs the part that crimps on the wire.  This allows it to crimp just right on each part and sets the depth of the inserted wire.  It also has two different wire size ranges.You can see this gate in the picture as the shiny bit with the square cuts.

 

 

Web Page G-code Viewer

Try this Web Page G-code Viewer

I met programmer and maker, Joe Walnes, through a few local Chicago maker groups.  He  showed me a really cool web based G-code viewer he wrote to preview his 3D printer G-code.   It used WebGL for super smooth motion of the model.  It also allowed you to drag and drop your own files right into the page.  It worked great, but really only worked with 3D printer G-code.  He posted the code on GitHub.

I have a couple programming projects in the works that need a G-code viewer, so I decided to update his program to handle more types of programs.  Joe had a really nice UI and design pattern for the code, so I left that  alone.  He also helped me out with a few issues as I worked.

G-code Parser

A parser is a bit of code that breaks down text into tokens, or the basic grammer of the G-code.  He was working with very well formatted G-code so his parser was pretty simple.

G1 X5 Y5 Z6 E0.124

I was dealing with really Fugly lines of G-Code like this, so I needed to totally rewrite the parser.

N100G17G91G1X5Y5Z6M03S1000(comment)G1X5;comment

Graphics Generation

Reprap 3D printers basically use G1 (straight moves) for everything.   I needed to add the code to handle G2 and G3 (arc moves).  This was a little tricky because there are no arcs in WebGL.  I had to break them into small line segments.   Joe also treated each Z level as a separate layer.  That is nice for printers, but not for general G-code.  I changed that and the way the color of the lines worked.

A Work in Progress.

It works on all my CAM generated 3D printer and CNC router G-code, but I want to add code to deal with more advanced features that are often hand coded like incremental moves, machine offsets, parameters, math functions and subroutines.

I will post the source code soon.

Usage

You need a WebGL capable browser like Chrome, Opera or Firefox.  I hard to turn on WebGL  in my Firefox.  I got it to run on my Android phone in Opera, but could not spin/zoom the model with the screen controls.

To view your own files, just drag and drop the G-code into the browser.  It will use the zoom settings for the previous model, so if you drop something that is a different size or offset to the side you may need to zoom around to find it.

 

Position Correcting Hand Tools

A post on the PS:One Hackerspace news group pointed me to this awesome digitally correcting hand tool.  It allows you to cut complex shapes by roughly following an outline.

The tool is attached to a hand held frame.  Actuators within the frame can move the tool to compensate for errors you would make when trying to cut a complex shape.

A high contrast pattern is placed on the work piece.  They are the horizontal bands of shapes in the image above.  The tool creates an internal map of the work piece using a camera.  It can then accurately determine it’s location anywhere on the work piece without the drift that might occur using incremental positioning sensors.  The outline of the cut to be made is shown on the screen.  The location of the tool center is also shown on the screen.  You only need to follow the line within the correction limits of the tool.  The tool digitally corrects to produce remarkably good results.

This same idea could be applied to a lot of different 2D fabrication tools.  There is a very comprehensive paper here showing all the details.

 


Thermal Friction Drilling

Thermal friction drilling very cool (hot actually) drilling technique that is especially useful for creating tapped holes in thin wall materials. The pressure and friction of a specially designed conical bit heats the material to a plastic state and forms it into a hole that has 3-4 times the depth of the wall thickness. It looks like it is best for hollow tubing because the back side of the hole is a little rough. The bit forms the top of the hole into a flat bushing which is perfect for fastening to round tube.

The bit is made from carbide and is held in a special holder/collet assembly that isolates the heat generated on the tool from getting to the machine. Lubrication is required to prevent the material from welding to the bit. Any machine that meet the speed and power requirments, including drill presses can use this technique. According to the web site a 6mm hole would require about 2500-31100 RPM at 1.2kW (1.6 hp).

Most of the thermal drilling companies recommend thread forming taps. These taps form the threads by displacing the metal rather than cutting it. The resulting threads are smoother and stronger than cut threads. I have used them on conventionally drilled holes. The pilot hole needs to be slightly larger than a standard pilot hole. The taps are a lot stronger because they do not have flutes. The can be run faster and don’t bind up with chips. It looks like the combination of thermal drilling and thread form taps creates a very clean operation.


MakerSlider – Fun With Bin Packing

I did not give a lot of in depth thought when choosing the MakerSlide extrusion length to purchase.  I did not want a lot of waste, so I just bought the largest piece I could handle.  I figured 6″-12″ average waste on each piece could be expected.  The longer the piece, the less percentage that would be.

The manufacturing size limit was set by the anodizer who could only handle about 20 foot lengths.  The limit on my end was about 15 feet.  This was due to what I could realistically cut.  My space is about 27 feet long, so if I put the saw in the middle I could cut most reasonable sizes with a 15 foot length.

When it came time to cut the material, the reward requests came in all over the map on length.  On past projects I had used some simple logic to fit the pieces into the stock, but that was yielding some serious waste now.  I dreaded the thought of 10-15% waste and little chunks lying all over the shop.  I had heard about cut optimization software and decided to look into it.

It turns out that there is pretty well established math behind this.  There is a good article on Wikipedia about it.  It is generally called the Bin Packing problem.  There are 1D (length, like my problem), 2D (area, like out of a sheet) and 3D (volume, like boxes in a container) problems that can be solved.

I tried a bunch of freeware, shareware and demo software.  I was really impressed with the results.  They did not always yield the same results, but generally agreed within about a percent.  The choice came down to a flexibility and a few key features.  I did not have the time to roll my own solution from free software libraries, but I knew I wanted to do some customizing.  I decided to go with an Excel add on from Optimalon.  The Excel format allowed a lot of quick macros and imports to be easily added.

The software allows you add in a number of stock lengths.  This allows me to put in the standard raw lengths, but also some scraps that might be able to be used.  You enter the cuts by length, quantity and ID.   The ID can be used to determine what customer the part belongs to.

One feature I wanted was a way to label all the parts.

 

I have several Dymo label printers that I use extensively.  I wanted to automatically print labels from the software.  I found that Dymo had an SDK.  The optimization software prints a cut table for each piece.  I feed this table to an macro that uses the label printer.

This string of labels is now my cut list for each piece of stock.  I print one string per piece of stock.  A single persons parts are usually scattered among several pieces of stock, so this helps sort it out later.

So far the software works great.  The more varied the lengths, the better it does.  My target is in the upper 90′s for yield.  So far I have found it does really well including some 100% utilizations where the last saw cut is less than the kerf of the blade.  Here is a typical final cut piece.

The only drawback is that the cuts are optimized for material usage and not cutting efficiency, so you are often moving the saw stop on every cut.  If I CNC the cutter, this will not be a problem and Excel can drive the cutter.

 

 

New Brushless DC Router Spindle

I have had a project going in the background to create a small, but strong and quiet spindle for small CNC routers. This is my second iteration of the design and I think it is close to what I want.

Frame

I started with an UHMW frame. This frame presses together then uses some hi-lo plastic screws to keep it together. UHMW is very stiff, but cuts well on a simple CNC router. I used a 1/8″ single flute end mill for all cuts. I try to ramp plunges wherever possible to limit the meterial that tries to climb the tool. It can all be cut from a sheet from one side with the exception of the pocket for the motor. This is needed to get enough shaft to come through. This pocket does not need close registration with the other so it is easy to flip it and run that side. The frame is rock solid. It feels like you could drive a car over it.

 

Spindle

The spindle shank was a key find off eBay. It has a ER11 collet which can handle a little larger then 1/4″ bits and there are plenty of cheap metric and inch collets available. The shank steps down to 8mm. This is great because the step can ride right on the lower bearing and cheap normal and angular contact 8mm bearings are available. I used an angular contact bearing on the bottom, and a normal bearing on the top. The top pulley installs with a spring washer to keep a 8-10 lb pre-load on the bearings to eliminate axial play. The bearings press fit into the end plates. The lower angular contact bearing takes the axial load from hard plunges. The axial bearing I found does not have a good seal on it, so I am a little worried about that. I am looking for a better bearing, but I might make my own seal that would seal to the spandle shaft. I might add a cover for the front and top.

 

 

Pulleys

I am currently using MXL belting which is rated for about 20k RPM, but at this diameter and length I think it can go a lot higher. I was planning to use multiple rubber o-rings, but that requires custom pulleys.

 

Size & Weight

The overall size is rather small at 90mm x 84mm x 82mm and total weight is 0.72 kgs. You mount it by tapping holes into back side. I will have a standard set of holes, but leave room for custom mounts.

Motors

It accepts a variety of motors. You can use univeral motors for small power tools. These will work on AC or DC and are good if you want to run it off 120/220VAC. You can also use RC hobby motors. These are available in brushed and brushless DC. A brushed 12VDC motor is cheap and the you can use a cheap PC power supply. I also test a water cooled brushless DC motor. This is the quietest option, but has the added cost of a speed controller. The motor shown will do over 30k RPM. I need to modify the top to give clearance for the water fittings. It can run for a few minutes before it gets hot, if you don’t load the motor too much. This motor can pull over 550 watts continuously. That is more than 2/3HP. I am hoping a simple PC cooling system will do the cooling.

 

 

Speed Control

The speed controller is controlled like a hobby servo. It uses pulses in the range of 1ms to 2ms to set the speed. You can program the controller though the servo interface to determine if you want reverse, etc. I decided to use an Arduino to control the speed. There is a servo library that makes it easy. I have the Arduino reading a pot them setting the speed accordingly. You program the controller by powering it up with the pulse input set to max speed. You then can set a few options like range and direction.

Next Steps

The next step is to find a way to do real world testing with it.  I need a water cooling system and something to mount it to.  The design will be released as open source.

Using a ShuttlePro as a Laser Pendant

I have been using a ShuttlePro as a pendant for years on my router.  A pendant is basically a hand held remote control for your CNC.  It allows you to control a set of functions right at the machine.  I typically use it to zero the machine on the part, tweak the feedrate, start/pause/restart the job and do an e-stop.

The router’s pendant is starting to die.  It has been through hell.  I have dropped it about 10 times on the concrete floor.  It has also seen a lot of oil and fine dust.  A couple buttons are getting intermittent.  I have the functions to working buttons, but I was getting worried it would stop working completely.  I could not live without it, so wanted to get a replacement on order.  I found a good deal on eBay ($54) and since they had several, I decided to get one for the laser as well.

The ShuttlePro was designed for video editing.  One thing you do a lot in video editing is jogging the video forward and backward.  Typically you want to race forward until you get close then slow down and even go frame by frame until you get to the desired spot.  Sounds like CNC doesn’t it?  It has three dedicated functions for this.  Full speed forward and back via buttons, variable speed via a spring loaded jog dial and a frame by frame little detented rotator wheel.  It also has a lot of redefinable buttons.  These buttons have clear snap on caps, so you can add labels to them.  I have a Corel and PDF template at the end of the post.  Someone at the Mach3 forum dicovered this product and within days there was a plugin for it.

Setting it up is easy.

Download the ShuttlePro plugin from the Mach3 downloads page.  Place the ShuttlePro.m3p file you download in a convenient place like your desktop.  Double click on it.  That will launch a program that registers it with Mach3.  Plug in the ShuttlePro into your computer.  It uses the built in Human Interface Driverss (HID) so you do not need to install a driver.  It comes with some software to test it, but you must uninstall it before using Mach3.  Start Mach3.

Use the config Plugins menu pick to open the

Make sure the plugin is enabled with a green check.  Now click on the word config to the right of the plugin name.

That will bring up the screen above.  Each button can be associated with any of many functions.  My config is shown above.  You probably want some keys across the top to select the current axis.  I like to have the two buttons to the outside of the central wheels be rapid movement buttons.  It is also handy to be able to lock the pendant so accidental button pushes do not screw up a run.   I used the second button from the lower right.  The rest are up to you and how you use your laser.

Below is a video demonstration on my laser.

Digital Caliper Tricks

I got into a discussion at work about digital vs. dial vs. vernier calipers the other day.  The discussion started because some of our aging eyes were having trouble reading some of the aging vernier calipers in the low light.  There were some pretty strong opinions about which is best.  We did manage to agree that the biggest contributors to accuracy were the quality of the caliper and the skill of the user.

I mentioned that, while I agreed with some of the arguments for mechanical calipers, I still liked the little tricks you could do with digital calipers.  Some of the die hard mechanical caliper people did not know what I was talking about.

The ability to zero the caliper anywhere on the scale lets you do some neat tricks.

Distance Between Hole Centers – If you have two equal diameter holes and you want to measure the center to center distance, you can measure the diameter of the hole, zero the caliper then measure the outside edges of the hole.  This will give you a good center to center dimension.

Shaft Clearance – Measure the shaft, zero the caliper and measure the hole.

You can easily figure out a few other clearance values you can do with the other modes of a caliper like the depth pin.  Some people said they even use it as a simple math calculator by moving it to a value zeroing it, moving again, zero it, etc then rolling back to true zero for your answer (ignore minus sign).

I found this nice little digital caliper instruction sheet here.  http://littlemachineshop.com/Instructions/UsingCalipers.pdf

3D model from 3D content Central

Laser Cutter Gas Containment Chamber

Fume Containment Box

I saw this post over at the Make Magazine Blog.  This is an interesting method of containing the exhaust gas on a particularly nasty material.  It basically puts the work in a box with an IR transparent window.  The box has a fitting to suck out the fumes.  It uses a polished silicon wafer as the laser window that was bought off eBay.

I probably would have put it in a Tupperware box, because the seal might be better and it is probably more resistant to the nasty fumes.  I could have used this when I tried my vinyl record cutting.