Another Paddleducks build log

Gallery, Projects and General > Project Logs

<< < (38/70) > >>

spuddevans:

--- Quote from: bogstandard on September 13, 2009, 05:10:02 AM ---Get good measurements as I have shown how to do, and make accurate cuts. If you need to err on the side of caution, make the cutaway shorter. What you don't want to happen is have both ports uncovered at the same time. It is better to be 0.1mm shorter than 0.1mm longer on the central cutaway. Also, don't chamfer the edges of the cutaways, keep them as sharp as possible, but without burrs.

--- End quote ---

Thanks for those tips, I will attempt to follow them. I have now read and re-read the parts in the book about the spool valves, and I will read them again before I put tool to metal.

--- Quote ---Just trying to help a little.

--- End quote ---

and I appreciate you taking the time, I can surely tell you it is of great help to me :thumbup: :thumbup:

Thanks Bogs,

Tim

ozzie46:
Next to the upcoming control valve, these spool valves caused me the most concern. I took my time and they seem to be ok. I have no gaskets or sealing on the one I have test running and it runs with a little less than 10 psi with about 3 hrs running on it.

Ron

Stefan Pynappels:
Hey Tim,

I got a 50g bottle of thick superglue for you, was all I had left.

I also found my thread gauge from when I worked for Wurth, it has Whitworth 55deg and Metric 60deg gauges on it, I'm sure it will come in handy.

There are also 2 dead HDDs.

The missus can take them on Wednesday.

spuddevans:

--- Quote from: ozzie46 on September 13, 2009, 11:31:02 AM --- I have no gaskets or sealing on the one I have test running and it runs with a little less than 10 psi with about 3 hrs running on it.

--- End quote ---
That sounds great Ron, glad to hear it'll run on such a low psi even without gaskets or sealing.

--- Quote from: spynappels on September 13, 2009, 11:50:20 AM ---I got a 50g bottle of thick superglue for you, was all I had left.

--- End quote ---

That's great, thanks very much, that'll come in very handy :thumbup: :thumbup:

I got a little more done today and got the 2 piston valves made.

Started where me and Stefan left off, having just faced and drilled the 24mm deep hole. So I turned around the piece and faced off the opposite end to the required length, 46mm as I recall :scratch:. I then drilled it with a 2.1mm bit and then tapped it M2.5 ( I know the plan said to drill 2mm, but not having the same confidence with tapping stainless, I just went with a slightly bigger drill to ease the strain on the tap. According to the tapping chart I have, 2.1mm is still a strong fit )
Then with a bit more of the 6mm rod sticking out of the chuck, I turned it down to 4.05ish mm for a length of 26mm, then polished it down to 4mm with some emery. It actually has a very slight taper, I say slight as when measured with a mic it tapers from 4.013mm to 4.006mm, I figure that it wont make too much of a problem ( he says hopefully ::) )

Then I re-chucked it, gripping it by the 4mm end and faced the free end to leave me with 19mm of the 6mm diameter left. ( my measurements according to the plans were 18.97, but the plans said it's better to be slightly long so I went for 19mm) Then after marking 3.5mm from each end of the 6mm diameter bit I roughed out the centre bit, and then slowly brought the 2 ends to 3mm. Here's a shot of the 1st end brought to size.

Then I did it all again to make the 2nd one.

Then it was time to drill the little cross holes and so I used the spin indexer to hold the valves as I centre drilled and then drilled thru with a 1.5mm bit.

That's all I got done, next will be the eccentric straps, and that will plunge me into the world of silver soldering. ( that reminds me, I must pick up a couple of firebricks to make a hearth. )

Tim

EDIT 13/03/2010 (for those reading this thread and wanting the build this engine.)

I have been trying to get the engine to run and had nothing but escaping air to show for my efforts. I have traced the problem to these piston valves. I originally used 6mm stainless rods to make the piston valves out of, having just now measured the piece of 6mm rod used to make them I find that the rod is actually 5.9mm and that 0.1mm allows a lot of air around it.

So beware when using raw material to make sure that it is the size you need. I ended up turning down some 8mm steel to make the replacements.

EDIT 6/8/2010

Something I have found when trying to get this to run is a problem with the piston valves sticking, and I eventually chased down the problem. It seems that when you drill the cross-drilled holes there is an edge raised up around the edge of the hole. The solution was to just give the piston valves a Light wipe with a fine cutting file and then a wipe of some w&d while they rotate at a slowish speed in the lathe.

NickG:
Good stuff Tim, it's looking great.

Funny you mentioned about needing several hands to put end mills into the ER collets! I found the same myself the other day!

Sorry, bit :offtopic: here: We went to metro centre to look at new cameras on sun. Came back with one we didn't even consider. Will post some more info in a different thread as my waffling took up more space than I thought!

Keep up the good work.

Nick

Navigation

 Message Index

Go to full version