The wether has been below freezing for a week and a half. The garage windows has remained frosted over for most of that time. Looking at the window it struck me as an example of “Math in the real world”. The metal window sills leaked heat out of the glass forming a differential curve. Looked to me like a k(1/X +m) curve – or maybe a tangent function. Weird but it made me happy.
So really I should Ban Ian from my shop entirely – but that is hard to do when he shows up for things like moving the mill. The middle picture there shows my justifications to ban him – the ridiculous poses he strikes around my tools whenever a camera comes out – the other pictures show why I am unlikely to ban him – the mill he showed up to move.
The move was part of optimizing my shop layout. I moved the mill over to where I had space to build a coolant cage around it, and added vibration dampening feet to it. The feet really help with vibrations caused by “high speed” CNC moves. Without the feet my mill would walk whenever I drove it faster than about 30IPM.
So Vegemite is basically yeast poop left over from making beer. It is spread over toast in Australia. I went 3 years living in australia before a girlfriend insisted I had to try it. I hated it, but she had it on her toast in the morning and after the 3rd or 4th time trying it I got used to it and grew to like it. Now when I miss Australia I get a hankering for Vegemite.
So Ian came over again Sunday – he brought the bottle of Johnny walking black and the second half of his Christmas gift project. A man who knows how to get invited back.
So this plaque was for his dad, and was the word DAD with the A replaced with a stylized sail boat.
We cut the part from some 1/8in 6061 Aluminum stock I had in the scrap pile. After the part was fixtured we tried something new. Normally I do an air cut of a pencil outline of the part to be cut, checking the clearance and placement of the part relative to the stock. This time I held a sharpie against the endmill. The result provides a pretty useful way to visualize where the pattern to be cut will sit on the stock. I am definitely going to use this trick more often.
After that we just cut out the part. My spindle was going 1280rpm, and we used a 12.8ipm federate with an 1/8in diameter end mill. Seemed to like cuts just shy of 1/16th of an inch. Once we had the part cut out Ian filed the edges and polished it with 150/320/400 grid sand paper on my surface block. Wetting fluid with Isopropanol and not water, but other than that pretty straight forward. I unfortunately forgot to tell him I had a scotch wheel – so he de-burred the edges with small files.
So a while back I tried and online dating site. As part of the process they ask you a bunch of questions. One of which was – “on a typical Saturday night you are…” with a bunch of options. None of which seemed a good fit. So last Saturday night I was looking at the bench next to my mill where I was working and it struck me – yeah this is a pretty good pictographic representation of my typical Saturday night.
So Ian came over Sunday with a project and a bottle of Johnny Walker black. An excellent combination.
The project was milling two plaques – one for his mother and the other for his father. His mom is a pilot – so her plaque were the letters MOM with an airplane at as the hole in the O. For his father’s plaque the A in DAD was replaced by a boat.
We spent a while messing with software and screwing around getting things set up – so we only cut the MOM plaque. Cut it from a 1/8 inch thick strip of wild cherry I had in the shop.
For fixturing we clamped a board to the mill – then screwed the cherry into that board. This way we could machine through the cherry into the wood below with a sacrificial cut. Doing this helps get a clean edge on the cut.
So the series was pretty obvious in retrospect – the summation of integer values from 1 to N has a known series that is so close I should have seen I could start there and work backwards. Ugh.
Yeah, I know I could Google this stuff – but where’s the fun in that?
I am working on a problem from project Euler solving for Pythagorean triplets. I think it is supposed to be a simple coding problem solved brute force with two for loops. Something about the problem has my gut telling to try to solve the problem a little more elegantly. To that end I was looking at trying to calculate N^2 as a series so I could break up the triplets into over common and different components to manipulate.
This is the first thing that jumped out at me – obvious pattern when I thought about N^2 having 2N as the first derivative and 2 as the second – but I did not see it right away. Might be useful.
So Ross suggested a CAM lock that was better than what I was originally thinking. If the ABS flexing is not problematic I think it will work. I am less happy with the spring loaded spool. I wanted it to help provide tension in the system – but I think it looks like overkill.
Hmmm, I think I am going to add the mount points and start building. Just build the carriage last after I have thought about it some more.
Project Euler Problem #1:
Problem: “If we list all the natural numbers below 10 that are multiples of 3 or 5 we get 3,5,6,9. The sum of these multiples is 23. Find the sum of all the multiples of 3 or 5 below 1000.”
Solution:
