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| Another Paddleducks build log |
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| NickG:
Don, Could be I guess, pockets of moisture flashing off inside. I don't know, I just put that brick to one side and didn't use it for that any more! Nick |
| spuddevans:
I found a couple of photos of the eccentric straps so I thought I'd share them. These are the straps before I started on the whole thinning and then boring the holes for the eccentrics. And this is them after much sweat, tears and tantrums, well, sweat and tantrums anyway. You can see the extra holes that I broke the drills in as mentioned before. I will be cutting those portions away when I shape the straps. Stay tuned for more updates, shouldnt be too long for more progress as I've got my bandsaw up and running now. Tim |
| spuddevans:
So I got a bit more progress made, Stefan (Spynapples) came over last night and we got some work done on the eccentric straps. We started by drilling the 3mm holes for the connecting rods, and with that under our belts we carried on to drill the little oil-cup-hole-thingys. It was at this point things started to go a little pear-shaped. 1st off we discovered that my 1.5mm drill bit is as sharp as a kleenex (mansize of course), so after burning a 1mm deep hole we switched to a 1.4mm bit. This went through the brass like, well a sharp drillbit through brass. We drilled thru with that then we followed up with a 2.5mm bit to a depth of about 5mm to make a little resovoir-cup-thingy. Now riding on a crest of a wave, congratulating ourselves on making such a fine job of the 1st strap, we ploughed on to the other one. The 3mm hole for the connecting rod was installed without a hiccup, and the 1st 6mm of the 1.4mm oil hole went swimmingly, and then :bang: :doh: :bang: :doh: The drill snapped. Cursing this unknown grade of brass sheet for being so tough we were forced to stop. ( We had been drilling using top speed (about 4800 rpm ) and also were "pecking" taking about 0.5-1mm per "peck" ) After a little thought we decided to try drilling thru from the other side, sounds simple except this meant drilling from the inside curved surface where the eccentric would sit. After carefully marking out where the hole should come out we started with a tiny centre drill at full rpm's and very gingerly started the hole. After about 1mm depth we switched to a 1.3mm bit ( crumbs, if I break any more on this the oil hole will be <1mm!! ) and again very carefully drilled thru to the broken bit ( if you are very gentle you can hear when the drill gets to the broken bit ) then withdrew. Then, using a thin awl we gently tapped the broken bit thru until it fell out. It's funny how things can go wrong on the final operations on a piece, but we figured we had little to lose by making this attempt at a save, and it turned out ok. Here's a pic looking down on the 2 halves of the straps as we left them last night. Then this afternoon I got a bit more done on the shaping of the straps. I milled away a little on each strap and ended up with something that looks a little art-deco ( completely by accident mind you ). Then I turned down some 4mm brass rod to 3mm and cut off 2 18mm lengths for the connecting rod for the straps. That's all I got done today. Next will be the forks, blocks and pins for connecting the eccentric to the piston valves. Tim |
| bogstandard:
Tim, Really I think you are taking things a little too literally. The oil hole is just that, a place to wack a bit of oil into. It could have been a lot larger, within reason. It was just a way of reminding people that it is a hole and it is there for a reason. When lubing up the engine, you see a hole, what is it for?, you remember that a spot of oil is needed down there occasionally, job done. It is only when you use a calibrated drip feed hole from a small reservoir that you need to worry about things like that. But coming along just fine now, you will soon be ready for the first air trials. Bogs |
| spuddevans:
--- Quote from: bogstandard on October 10, 2009, 01:15:00 PM ---Tim, Really I think you are taking things a little too literally. The oil hole is just that, a place to wack a bit of oil into. It could have been a lot larger, within reason. It was just a way of reminding people that it is a hole and it is there for a reason. When lubing up the engine, you see a hole, what is it for?, you remember that a spot of oil is needed down there occasionally, job done. It is only when you use a calibrated drip feed hole from a small reservoir that you need to worry about things like that. But coming along just fine now, you will soon be ready for the first air trials. Bogs --- End quote --- Ahhh!! I didnt know that it could've been made bigger. That'll be my inexperience with engineering-type-stuff showing thru again, oh well, everybody has to learn, I've learned from this, and hopefully others can read this and learn from this too. I do have to say, even though an awful lot of this is very new to me, and there have been some frustrating moments that make you want to chew your own foot off, all in all I am absolutely loving this!! And being able to share it all with the rest of the forum and benefit from the collective wisdom and advice is great too. Tim |
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