The Low Down On Homemade Tops....

Here is another fun lathe project that I did and unlike the Multicenter Lathe Statue this one has some actual practical use! I decided after some suggestions by Otto Jr. and Matt Mylar that I should try my hand at making some tops on my Homemade Wood Lathe. The top was a pretty straightforward project with the only really tricky part being the metal point at the tip that the top spins on.

 

 

 

The above picture is how the top turned out on the lathe (pun intended). The wood that I used is one of my favorite types to use for turning practical stuff  - bamboo. These days you can go to the local discount store and get laminated bamboo cutting boards for cheap. There are also some expensive ones out there that you can get that have some advantages that I'll mention. These boards are made up of small pieces of bamboo that have been machined smooth into strips and then the strips glued into a board. I have found bamboo to be a relatively easy wood to work with that has basically no grain and is easy to sand. Although when sanding bamboo (or anything for that matter) make sure you have some dust management system and wear a face mask. The difference between the cheap boards at the discount store and the more expensive ones is the cheap ones tend to have voids and empty spaces inside them in random places. You can't see the voids until you cut into it but be aware that they might be there if you decide to chop up your bamboo chopping block.

So after getting the bamboo boards I got a hole saw and cut small discs out of the them . Then I glued all the discs together into stacks. I drew black lines on each disc to show where the grain direction was and made sure that when gluing the stacks together the black lines didn't line up. In this way the grain is at right angles in each layer. It's actually a bit more complicated because the cutting board alternates layers of bamboo and those are also at right angles... but simply put they are not lined up.

  

In order to mount the stacks on the lathe I had to glue each stack onto a piece of base wood that I could use to mount to the lathe spindle. In the above picture there are two stacks glued and dried with one on the lathe.

 

 

 

Turning the top down to the classic top shape was easy and a lot of the fine shaping I did with a wood rasp. The lathe gouge is handy for big cuts but finer detail is easier if you use a file or rasp and essentially power sand/file it into shape. A measured drawing of this project is available upon request if you want to know the shape!

 

 

 

Once the shape is right sanding and waxing the top is next. To get the top off the base plate I just law a saw blade against the place I want to cut and turn the lathe on. I don't recommend anyone using a saw blade like that or a wood file to shape stuff on a lathe. Be safe and don't do what I do!

The point of the top I made with a screw that I glued into a small hole that I drilled in the end of the top. Onto the screw I threaded a small aluminum shoulder nut and glued that too. Again I grabbed the file and filed the screw to a point.

Tops are fun if you can figure out how to wind the string onto them and throw them. Some people are good at it and others not so good. I am better at making tops than throwing them I think.

 

 

 

Tops when left alone like to conversate amongst themselves as shown in the above picture. Leave them alone while they are conversating or until the urge to throw one becomes too great and you must do it. If this is the case use caution when approaching the tops and it's wise to make a low whistling or humming sound as you approach so as not to surprise them. Stampeding tops can be dangerous as they have a sharp point on one end (the bottom).

 

 

 

The picture above shows a bit of the point that is made from a filed down screw and the aluminum shoulder nut. The shoulder is important to keep the string from falling off the top as you wind it. I did consider making that shoulder on the lathe from wood and just put a metal point in it but I didn't think that it would be strong enough. Repeated throws and impacts with cement or roadway and it would be chipped and broken off.

There you have it:

- The Low Down on the Homemade Top -

Electric Hub Motor Bicycle Prototype... not much to write about but pretty pictures included

A short time ago I had the opportunity to get a good deal on an electric wheel hub motor for a bicycle. These motors are built into the hub of a bicycle wheel where the spokes attach. At the time that I got it I didn't have a bicycle but I thought it would be something fun to have around the house. Well not really... right after I got the electric hub motor I went out to Target and bough a bicycle for $95.00. I don't know a whole lot about bicycles or what all the correct names are for the various parts in a bike, but I did build an electric bike and at the same time designed a rear dropout. Don't get upset if I don't know what I am talking about when it comes to bike stuff... just post something angry in the comments.  As I mentioned in the title of this post there isn't a whole lot to talk about but I do have some nice pictures!

 

 

The electric hub motor is made by a German electric motor company Heinzmann and is spoked into an Alexrims DM18 rim. I gather in talking to people that both the wheel and the rim are much better than the bike that I bought at Target. I don't feel too bad about this - having good expensive wheels on a crappy bike - because where I live almost everyone has a $900 piece of crap car with $3000 spinning chrome rims on it. At least I look super cool on the bike and they all look like idiots.

 

Anyway the aluminum box that I hose clamped into the frame holds the 12 volt SLA batteries (Sealed Lead Acid). There are three of them in there wired in series for a total of 36 volts. On the front of the aluminum box is a motor speed controller that is wired into the grip throttle on the handle bars. The grip throttle and the controller are both made by the same company and I got them with no documentation. I used a ohm meter to figure out which wire went where as far as the batteries and motor.

 

 

I got a small plastic box and added a couple of switches to switch a car battery charger to each SLA in succession. In other words I can charge each battery individually and then when the charger is disconnected they are all drained in series to run the bike. Mostly this project was just piecing together some parts. I had to get a single speed freewheeling sprocket for the Heinzmann Hub Motor to get it to fit into the bike. Other than some shimming and spacers the whole thing took less than a week to put together. With the rear single speed sprocket I just have the three front gears so the bike is a three speed + the motor.

  

Once fully charged I can make a round trip to the post office of the supermarket on one charge and just a little pedaling at an average speed of 20mph. I think if I got newer batteries instead of the used ones that I have it would get a bit more distance. As the price of gas has come back down a bit I'm not as eager to tinker with this but it is something that I will mess with. One thing I want to do is now that I know it works I'm going to make a cover for the aluminum box so it's sealed and I'm going to paint it blue like the bike.
  

  

During the construction of the bike I designed a rear dropout for another bike project that a friend of mine is doing. The CAD model of the dropout is in the picture above and he helped me get the parts for the electric bike. UPDATE: I made a post showing the bike this dropout is used in HERE Check it out!

  

Now I have told you everything that I know about bikes. When I get around to cleaning up the electric prototype pictured above I'll put up some more pictures...

Robot Base Mechanics

Finally after much filing, cutting and drilling the 4 legs are assembled to the robot base. As mentioned in other posts and to summarize here the base is made from an Epson printer cover and each leg is built from 3 Futaba S3004 (or in some cases S3003) servos. It took some time to get the whole mess to this point, mostly because of other life things getting in the way, but now that it is done (partially) I can take a break and focus on the electronics.

 

 

When positioned carefully the legs can support the weight of the assembly and be stable without falling over and without power. I am considering using this position as a generic starting position to power up from but having the base sit flat on the floor might be better. With the base sitting flat on the floor the challenge would be to get the legs under control and the entire thing to stand up. Once standing up of course getting it to walk without falling over would be next.

 

 

 

 

At this point there isn't a lot left to do mechanically other than routing the servo cables so the don't get tangled as the legs actuate. While I am doing that I'm going to be looking into servo controllers and the software needed to control them. Initially I'm planning on just having a "serial to servo" converter on the robot with an umbilical connecting it back to a computer and a power supply. I'll use that set up to debug most of the motion and work out walking. The eventual goal will be to have a processor board with batteries on the robot so it can move autonomously but until I can figure out how to make it move a remote PC to control it will be easier. Why do anything the hard way?

More Legs and Some Progress ( or More Futaba Servos Assembled...)

This evening I have a bit of an update on the construction of the robot.  It may seem like this is taking a long time to build but the project itself isn't taking too much time (all things considered) I'm just not finding a lot of time to work on it. I did manage to get all four legs built up. As mentioned these are using mostly Futaba S3004 and a couple Futaba S3003 Servos that are inexpensive and so far easy to use.  The only difference between the Futaba S3003 and the S3004 is the 3004 have bearing and not bushings. Each leg consists of three servos in total giving each leg what I call Turn, Rotate and Extend motions. It's pretty irrelevant what I call each axis of motion but for now I'm sticking with those names. In the last update that I posted I had a picture showing the plastic base that I cut from the top cover of a desktop Epson printer.

 

 

 

This shows more or less how I intend to have the legs sit but there are only three legs in the picture. I am happy to say now that I have the fourth leg built up using the Futaba's and I also have all the turn brackets fabricated for all three legs that I mentioned in the Aye Robot post. Also I figured out a couple of issues in building up two of the legs as 'mirror images' of the initial prototype leg. Anyway here are all four if full color for your enjoyment:

 

 

As mentioned these are all using Futaba S3004 servos (mostly a couple of Futaba S3003's as well). The orange colored parts on the end are cut pieces of K'Nex that I used as bushings. There is a 4-40 screw holding a nylon spacer that runs in the center hole of the K'Nex acting as a bearing (bushing technically). On the bottom of each Turn bracket I mounted the round disc Futaba Servo Horn that comes with the Futaba in the box when you buy it. That servo horn will allow each one of the above legs to mount directly on top of yet another servo that is mounted in each corner of the 'hacked' Epson printer top. I took a picture to help explain a bit better what I mean.

 

 

In the picture you can see one of the Futaba S3003's sitting in the corner of the printer top that I'm now going to start calling something like 'robotic base chassis' instead of Epson printer top. Maybe 'Base Chassis' is better and shorter. Anyway on the bottom of the leg assembly you cab see the round Futaba Servo Horn screwed to the Turn Bracket with a couple of 4-40 screws. Immediately remaining at this point is cutting 3 more holes on the Base Chassis to mount the Futaba's in and figuring out a way to secure them in those holes. Right now I am thinking of cutting up the remaining pieces of the printer cover and gluing them onto the Base Chassis to provide screw points for the Futaba's.

I need to give it a bit more thought but maybe metal brackets would be better than glued plastic.