Gallery, Projects and General > Project Logs

Valve Base

<< < (6/16) > >>

Darren:
TBH honest John the trepanning came out neater than either the hole saw or simple drilling. I guess it was too low a speed for the drill bit and I gave it very little support.

But the hole saw, though quick was a bit messy on the paintwork. Dragged the swaf around a bit I guess.

Not to worry, it will all be hidden in the end and I'm pleased with the result. Great when I was considering buying a new tool and made do with what I had.

As ever, thanks guys you lot are a real bonus....  :dremel:

Bernd:
Looks good Darren.

I guess I'm going to have to find those pics of me doing a 1/4" thick aluminum plate. I put a 14.25" dia hole in it with a home made tree panning tool. I'll have to put up a thread in the tool area about it. Don't want to hijack this thread.

Bernd

Rog02:
A couple of suggestions on using a hole saw.  For a neat clean hole without destroying the painted surface start the hole saw from the painted side but stop just after the teeth of the saw mark a full circle.  Withdraw the saw and re-insert the pilot bit from the reverse side and proceed to cut the hole.  The result will be a clean hole on both sides without the normal "tear out" and the swarf will not be harming the surface.  This tip is especially useful when hole sawing wood.

When cutting a hole in a thick piece of material again pierce the material with the pilot drill and cut just enough to mark the perimeter of the saws kerf.  Once the kerf is clearly defined stop the saw and withdraw it from the work.  Drill a "chip relief hole" just inside the outer kerf mark.  Make the relief hole so that its circumference is tangent to the outer edge of the kerf mark.  The idea is to give the swarf an exit when sawing through rather than filling the tooth gullets and plugging the saw.

Also be sure to use plenty of lube/coolant that is appropriate for the type of metal being cut.

I hope the sketch makes sense.  Using the drawing function in a word processor is rather limited.

Darren:
Nice tips there Roger, I have another to do yet, and prob more after and will take note of what you said, ta.... :thumbup:

Onward we march....

Now we have the holes cut in the chassis it's time to mount the valve bases/holders. I need to make some fixtures and incorporate a method of electrical isolation from the valve pins and the chassis itself. These two pins carry the voltage for the valve heater. In this case 10V @ 10A. Nothing too scary here even if it is a tad power hungry at 100VA.

1VA = 1V @ 1A = 1W, so these valves (ok, tubes for you guys over there) consume 100W each just for their heaters and there are two of them to make stereo reproduction.
Quite and expensive amp to run this one, but oh the sound... :)

Anyways, I took a 30mm SS 303 bar and drilled a 6mm hole through the center



Parted them off and made four pieces, note outer dia not turned to size as yet. That comes later.
You may also note in the picture a collet stop ready to be fitted to the collet also shown. I wanted to make these four pieces identical in length and a collet stop is perfect for this. It allows each piece to be fitted into the collet at identical depths. But,it also serves another purpose.
Because each piece is so short it would be very difficult to clamp them in the collect squarely. In fact it would be almost impossible. Having the stop to push them up against solves this problem.



Here you can see the stop fitted. The depth is set by the thread on the bar and a locknut.



First piece faced off. By zeroing the topslide on the lathe and with the use of the collet stop we can make all four the exact same length.





Now they were turned around, again against the stop and chamfered



All four done



Now I needed to make the electrical isolators. For this I chose to use a bar of Teflon. I got part way through and realised that white teflon picked up dirt like a magnet picks up steel swarf  :bugeye:
Not good, in the final application appearance is everything and dirty white bits just won't do.....



So, I junked that idea, thinking I've learnt something new tonight at least. Save the Teflon for another use later.
Swapped the Teflon out for a bar of Acetal, or Delrin if you prefer.



A bit of jigery pokery and a little while later we have these, some top hat isolators and some washers.



Now I needed to true them all up to the same diameter. Slipped them onto a 6mm allthread and clamped with a nut.



Well that didn't work did it. I suspected it wouldn't, not enough support and too much vibration=chatter = a rough finish.
Well, I was turning 30mm held in a 6mm threaded bar after all.
So I shortened them down and did half at a time. But I still needed to steady the end with a tailstock center. But alas I don't have one for this lathe. I do for the mini lathe but it's not here.
I came up with this. Centered the allthread and used an old center punch held in the tailstock chuck. Crude, but it worked quite well. Scuse the rust, it got left outside at some time.



Well that worked just fine, here is a pic of the washers underneath. The electrical connections will also fix here with a lug.



And the top, all neat and tidy





All in all it's going quite well so far and progressed another stage.

Darren

Brass_Machine:
Watching this one.

So Darren... when you are done, can you help those of us who want to build a valve amp do so? I would like to tackle one perhaps next fall. I am sure with smaller valves though. Would need help in selecting the right stuff and the electric schematics.

Eric

 :mmr:

Navigation

[0] Message Index

[#] Next page

[*] Previous page