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Sunday, August 28, 2011

Homemade Wood Clock Test Run

This is going to be a short post... well maybe not. As I start to write this it's Sunday, it's late and I am tired! What I wanted to put up was the test video of the clock running. Anyone following my blog knows about the wood clock that I am making and if not you can check out the earlier posts in the Woodworking Label.  Without further adieu here it is - enjoy!
There are a couple of things that I would like to point out about what is going on in the video. The first thing is again this is a test. The clock motor is running a lot faster than it normally does to keep time. The second thing that I think I should point out it the hour hand. If you look really closely at it you might notice that it is a wood "q-tip" with a pointed cotton end! That is because I didn't have time today to make a hour hand so I stuck that on there in it's place. The more I look at it the more I think I will keep it actually.

Sunday, August 21, 2011

More Progress on the Homemade Clock

This was another busy week for me and I didn't get as much done on the clock as I would have liked to but... I did get some things done. In case you are not familiar with what I am doing you can read these posts HERE and HERE and HERE to get an idea. The short description is that I am making a clock that has a stationary hour hand pointing straight up. The face of the clock turns counterclockwise to line the correct and current time up with the hour hand and the minute hand rotates clockwise to indicate the minutes. HERE is a video that I made of the CAD model for this clock running and it shows pretty much how it's going to work. Seems simple enough!
What I got done this week is I made the small discs that the numbers will be attached to by cutting slices of 1-1/4" oak dowel. Obviously I made 12 good ones and a bunch of bad ones that were either too thick or too thin. You can see there in the blue tote bin in the picture below. You can also see in the picture that each disc has a Woodruff key glued to it. The idea is the the Woodruff key will add some weight and keep the numbers on the face of the clock upright because the discs will be allowed to spin relative to the clock face.
Clock Parts, Oak discs with Woodruff keys glued to them
Also in the above picture right below the blue tote is a gearbox and a motor. It's to the left of the wood gear on the back plate for the clock. That is another Tamiya gearbox that I got and used in another clock that I built some time ago. Check out THIS post for details of the gearbox. I picked up several of these gearboxes at a hobby shop that was going out of business so I got them at half price and figured that I would use them at some point. You can never have enough gearboxes I always say!

Sunday, August 14, 2011

Significant and/or Insignificant Part Number Systems?

Part Numbers can be funny and frustrating things when really they should be inconsequential. Over many years of working as an employee or a consultant to various companies in many different industries I have been amazed at the Part Number 'systems' that companies have tried to use. Part Numbers within a company are used to assign a unique 'identity' to different items tracked within the company. HERE is a Wikipedia talking about Part Numbers if you want to know more about what they are generally. The reason that I am bringing this up is because I have seen P/N's become a source of money wasting time and confusion and I want to put my opinion out there with some examples of what I have seen. I am only going to address the topic of Part Numbers in this post and not the Descriptions. Part Descriptions is an entire topic all by itself.
Significant vs. Insignificant Part Numbers
The first schism in the Part Number philosophy/religion debate is over how P/N's should be assigned to things. Some folks believe that a Part Number should have some unique significance built into it - or intelligence -  to describe what the thing is that has the Part Number. In other words by looking at the P/N one should be able to have an idea of what the item is. In this case the P/N really becomes the description of the particular part (or assembly) and usually each digit in the Part Number has a particular meaning. On the other side of the battle field is the army of people that say that a Part Number should just be a number, any number, that is just unique to an item and doesn't tell you anything about what the part is. These two approaches are usually referred to as Significant Part Numbers and Insignificant Part Numbers. Part Numbers are assigned to things as unique identifiers for tracking purposes and referencing records etc... The only stipulation when giving something a part number is that it be unique and never reused.

Insignificant Part Number Systems
Everything has a name and a number associated with it within a company, even the employees. Have you ever cared what the employee number is of a co-worker? Probably not, you are more likely to care about their name. The same logic follows when talking about part numbers in an Insignificant Part Numbering System. The number a particular part has isn't important in an Insignificant Part numbering system, but the description (or name) is.  That's the thinking with non significant part numbers.

Sunday, August 7, 2011

Gear Runout and my Wood Clock

I am still working on the clock movement (or gear train) for my wood clock that I wrote about a couple of weeks ago and the gear runout is a slight problem. This isn't turning out to be one of those projects that I can just "cut and glue" and be finished, it's requiring a lot of adjustments and finesse. Getting the hole in the center of the gear (or runout) has turned out to be a little more trouble than I thought... So I used a dial indicator and a couple of C-Clamps to check and adjust the runout by drilling an undersized hole for the shaft then filing it appropriately until the gears turned without much indicator movement. If you have not read the previous posts about the clock HERE and HERE are the first two. Check them out so you can see what I am trying to build.

Checking Gear Runout on a Clock Gear
In the above picture you can see what I am talking about. On the right hand side of the picture there is a dial indicator sitting on a base that is C-Clamped to the bench. To the left is a piece of scrap wood with a hole in it that the brass tube fits snugly in. So with this setup I can spin the gear and place the dial indicator tip on the gear tooth crests and valleys to see how centered the hole is relative to the gear teeth, that's runout.
In order to get the the point where I could check the gear with the 'real' brass tube shaft the I am going to use in the clock I had to get the hole made to the right size and in the right place. To do that I started out by drilling a small hole in what should be the center of the gear and I put a straight finishing nail in it. The scrap wood under the gear in the picture above has a hole in it that the finishing nail fits snugly into and with that I could initially check the runout by spinning the gear on the finishing nail. Out of all the gears I made all except one had the finishing nail hole a bit off center, by about 0.03". To remedy that I drilled another hole again, slightly undersized to the brass tube shaft, and compensated for the runout that I saw with the finishing nail hole. By compensated I mean that I moved the drill off the finishing nail hole just a bit. This hole is also undersized a bit from what the final hole will be and I have a shaft that will fit in this undersized hole just like the finishing nails did. Again I can check the runout of the gear with this slightly smaller hole and a slightly smaller shaft and if my "compensation" drilling isn't quite right I can make up for it by enlarging this hole to the final size with a small rat-tail file.