Gallery, Projects and General > Project Logs
Valve Base
Darren:
The Pillar.........
In the background is a prototype that I'm making more of in the lathe. I'm making them back to back as this makes holding them easier and there is little waste this way.
Here you can see I'm marking the bars with the cutoff tool. In the collet is a collet depth stop. This enables me to mark the bar, change the workpiece and mark another bar in exactly the same place. Makes my life easier as I had four to do and two marks on each end making eight marks altogether.
Here you can see a length of 20mm SS bar in the milling machine. I'm using a center finder that arived in the post only yesterday, so first time out with this one.
It's so simple yet it works very well.
Darren:
Now I need to put some flats on the ends of those two bars. I could do this in the mill, but, my mill is not so clever and I can't hold the cutters that I have left in it !!
No matter we can use the lathe instead.
Here you can see several things going on, the 1" cutter is being centered in the 4 jaw chuck with a dial gauge, the workpiece is being held in a tool holder that just happened to be the right size. To the right of the tool holder you should just be able to make out a square...
Having marked the bars previously with the parting off too gave me a clear indication of where to mill to.
And now for the other side, squaring it up with, well urm a square....
Almost done
There, that's that job done
Darren
Divided he ad:
Hi Darren,
Well I like what your doing even if I haven't a clue about these valve thingys ???
I've heard of valves and even seen old footage of them in various things.... Well pre-birth date! So I'll see if I can't pick up a little knowledge along the way ;D
I'm going to have to e blag some stuff in order to get the together to purchase an E36 collet set for my mill and a 5c collet set and chuck for my lathe.... It's no good I just really think these items will make my machining more interesting and occasionally less frustrating! (Tool variants do my nut in... I have some metric and some imperial and can't hold all with the MT3 collets that I have!)
I do like that centre finder do-dad I've seen them advertised etc but never knew that was their use.... Never really investigated though either!
To finish my little blathering... I'll just say this. I'm glad your posting and look forward to seeing what you make and learning a little on the way :thumbup:
Ralph.
Darren:
Ralph, blather away by all means. It can be a lonely hobby otherwise...
TBH it's nice to be able to share, I've done very little of this sort of stuff but do enjoy it. No idea if I'm doing it right or wrong ??? Like I said before I'm learning as I'm going along.
If you have any tips please fire away.
I used the 4 Jaw cos I didn't have a 1" collet, milled at approx 460RPM and I've been turning the bars at 1800 RPM. That seems to be the sweat spot.
For the life of me I can't get a good finish on steel, Stainless is great. Turn it and it's done, OK maybe a quick run over with a Scotchpad and it looks really nice.
Brass of course is easy, I tend to turn that at 3000RPM with high feed speeds too.
Plastic is cheap and nice to use, esp for prototypes.....
If you can afford it you should seriously consider a collet set-up. They are a dream to use compared to a chuck for smaller items. The runout is almost non existent, even if you take the work out, rotate it and put it back
Darren
Darren:
OK for those interested a little tutorial for you.... ;D
The valve I'm making the bases for is what's known as a triode (as in three elements) Simply it's an amplifying device that amplifies the flow of voltage/current which is the flow of electrons. (electricity, voltage=pressure/current=flow)
We have a heater which we typically connect to a low voltage of around 6.3V, though this can vary from valve to valve. This heats the cathode which is sitting at a negative DC voltage potential. The anode is sitting at the positive DC potential. (voltage potential typically 250-500V DC)
Point to note, electrons move from negative to positive and not the other way around as most people believe. This is important.
Our heater heats up the cathode, this makes the electrons become a little excited and thus easier to leave the cathode. Some will hover around and just off the cathode, this is called the "space charge"
Now, opposites attract, and equals repel, remember that girl from school?
Electrons are no different, they want to flow across the vacuum inside the glass envelope and hurtle towards the positive anode, bit like us young men on our first date ;D
We need to control these electrons into some sort of order, Slow them down a bit if you like.
We do this by applying a negative low voltage on the grid, typically 60-100 volts, but can be as low as 1 or 2 volts. If we increase the negative voltage (more negative) the flow of electrons will slow from the cathode to the anode (equals repel), if we make the grid more positive more electrons will flow.
So there we have it, we have a low voltage controlling a much larger voltage,
Now imagine that the low voltage is coming from your CD player output.......music modulates, so we have a negative voltage modulating the grid of the valve which in turn modulates the higher voltage flow and thus amplifies a low signal into a much larger one.
I hope you can follow that? It sounds complicated, but it's really very simple :thumbup:
Darren
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