Another Paddleducks build log

[ozzie46]

  You might consider drilling the holes before milling the slots. No worries about bending the sides that way.
   
   Just my 2 cents worth.   

   Nice build. Keep on truckin.

  Ron

[spuddevans]

 You might consider drilling the holes before milling the slots. No worries about bending the sides that way.

That's a good point.  I did consider doing it that way, but by being as gentle as possible, I was able to drill without bending the sides. The reason I did it that way was because the cross-drilled holes are 2mm thru one edge of the fork, and 3mm thru the other fork-edge, and I didnt want to accidently drill too deep with the 3mm and spoil the part. This wouldn't be a problem at all if I had DRO's fitted, but I only have the rather vague markings that the factory deemed fit to inscribe, and as this is a small part ( well, small to me in my short experience ) I thought that milling out 1st, and then just very gently drilling would be safer for me.

I was very watchful for any bending of the sides when I drilled them, but I think because they were sitting completely in the vice, the edges were fairly well supported and, if needs be I would've put a sacrificial 4mm shim ( at what thickness does one stop calling it a shim?   ) in to prevent bending.

Tim

[Bernd]

Lazy I know, but I try to kid myself that I will have a better idea of what I want from a proper vice stop by making up these temporary forms. (well that's my excuse and I'm sticking to it  )


Tim

That excuse usally works for me too! 

Hey, you never know you may just come up with a very unique stop that.


Bernd

[CrewCab]

at what thickness does one stop calling it a shim?   )

Good point  ........... how long is a piece of string scenario 

Nice work Tim 

CC

[spuddevans]

how long is a piece of string scenario 

Ah!! This one I know. The piece of string is exactly twice the length of the middle to one end. 

Tim

[bogstandard]

A piece of string is also one of the best weather detectors known to man.

If it feels warm to the touch, and when held by one end hanging down, it stays motionless, then it is a fine day.

If it swings side to side, it is windy.

If water is dripping from the end, it is raining, and if you can turn it up by 180 degrees and it still stays straight, it is freezing.

But getting back to topic, it is coming along well now Tim, just that final little push and you can introduce it to a bit of air.


Bogs

[spuddevans]

Well, a little update on this one. I have not been able to spend much time in the workshop over the last few weeks due to family health issues, but this afternoon I was able to steal a little time to have a play work seriously on the project. I still havent got some fire-brick-bits to make a hearth yet, so I decided to get on with making the packing glands for the piston valves.

I started off by taking a bar of 20mm brass rod and chucked it up in my ER32 collet chuck on the lathe. Fortunately the bore of the headstock allowed me to chuck the whole length ( about a foot, give or take a few mm depending on the size of your shoes  ) and only have a little sticking out each end.



Then after turning down a section to the required 16mm, I then turned down a 6mm length to 8mm diameter, centre drilled it and then proceeded to drill a 5mm hole about 6mm deep.



Then I tapped the hole M6 for the packing nut ( or should that be packing screw  as it screws into the packing gland )

Much earlier in the build when I was making the packing glands for the cylinders, Kvom very kindly mentioned that the gland screws for the cylinders are identical to the gland screws for the valves, and suggested that when making for the cylinder glands it would be an easy thing to turn out a few extra for later on. I took this advice and made 3 extra ( 1 to break or lose and 2 to actually use).

All that meant that rather than having to make the gland screws today, they were already made. So now I took one of the 3 previously made gland screws and screwed it into the newly tapped hole, then centre drilled it and followed up with a 4mm drill and bored all the way through to full depth, thus ( hopefully ) resulting in the hole being concentric to the bore that it would fit.

I used a little depth collar on the 4mm drill so that I would not go too far into the parent material.



Then it was just a case of parting off from the main brass rod and repeating the above.

Or so I thought. All was going well until I got to the point of drilling the 4mm hole in both the packing screw and gland. I drilled thru the screw ok, but as soon as the bit started to drill into the actual gland, the head of the gland-screw sheared off. ( I reckon that I made the undercut at the end of the threaded portion just a little too deep, and so with the 4mm hole up the centre there was just not enough holding it together, and so with the vibration of drilling along with the friction of the drillbit, it just let go )

Thankfully the threaded portion was not jammed in the gland, so I was able to gently unscrew it using a little dental-pick-type-tool. Then with some trepidation I screwed in the last of the gland-screws that I had made, and again drilled it. It went ok this time, drilled thru, parted off, and then reversed the gland in a 8mm ER32 collet to clean up the face that would sit against the bottom of the valve block, and also custom fit the little 1mm flange that locates the gland into the valve bore.

And this is the result. ( also shown is the broken gland screw )



So one more step done, next I will be drilling the glands for the mounting screws, and then drilling and tapping the valve blocks for the same mounting screws.

One thing I would say to anyone who is also building one of these, dont just make one extra gland screw, make 2-3 extra. It wont take very long to make an extra one or two, but it could save a lot of time later ( and a lot of sphincter tightening when you are working on your last "spare"  )


So that's all I got done today,


Tim

[chuck foster]

looking good tim 

sorry to hear about the health issues, hope all is well real soon.

chuck 

[NickG]

Nice work Tim. Delicate little things that we make aren't they! Luckily there is negligible force on the gland nut when it's in service though! I can see why you've done it that way to ensure they are concentric, but I guess they should be anyway if you're using the same lathe and tail stock etc, still, nice knowing they are DEFINITELY in line.

Nick

[bogstandard]

Just a little tip here for when you make any more stuffing glands like this.

Stuffing glands don't usually get screwed in all the way to the end of the thread, because you need a certain amount of adjustment to keep the gland steam tight.

So just by turning your die over in the holder and using the non tapered side will usually give you enough thread length under the head for the job. If you are single point cutting, ensure your end relief isn't any deeper than the thread core, otherwise you are weakening the part to a stage where it will fail, as you have found out.

Coming on real nice now.


John

BTW I checked this evening just how many downloads of the plans there have been since I made them available on Rapidshare.

Well over 500.

So it looks like there might be a few more being built out there.

[spuddevans]

Thanks Nick, Chuck and John 

If you are single point cutting, ensure your end relief isn't any deeper than the thread core, otherwise you are weakening the part to a stage where it will fail, as you have found out.

I see, when I was making them I had in mind a 3mm hole going through them ( for the piston rod ), but I must have undercut a little too much on the failed packing gland screw.

BTW I checked this evening just how many downloads of the plans there have been since I made them available on Rapidshare.

Well over 500.

So it looks like there might be a few more being built out there.

Just show's how easy to follow and straightforward they are 

It sure would be nice to see some more build logs of it.


Tim

[shred]

Thanks Nick, Chuck and John  

BTW I checked this evening just how many downloads of the plans there have been since I made them available on Rapidshare.

Well over 500.

So it looks like there might be a few more being built out there.

Just show's how easy to follow and straightforward they are  

It sure would be nice to see some more build logs of it.


Tim

My build log is over here: http://www.homemodelenginemachinist.com/index.php?topic=4294.0

The engine gets oohs and ahhs even from non-technical types.  

I can't thank John enough for the plans and write up.

[spuddevans]

My build log is over here: http://www.homemodelenginemachinist.com/index.php?topic=4294.0

The engine gets oohs and ahhs even from non-technical types.  

I remember following your build, thanks for reminding me of that

I especially like the bent tubing into the piston block, I think I may well be copying that on my build. Where did you get the plans for the tubing bender? It looks pretty handy to have.

I can't thank John enough for the plans and write up.

My sentiments too, I have learned so much on this build, both from the plans and from the helpful comments and advice from Bogs and the rest of the crowd on here 


Tim

[shred]

My build log is over here: http://www.homemodelenginemachinist.com/index.php?topic=4294.0

The engine gets oohs and ahhs even from non-technical types.  

I remember following your build, thanks for reminding me of that

I especially like the bent tubing into the piston block, I think I may well be copying that on my build. Where did you get the plans for the tubing bender? It looks pretty handy to have.

I can't thank John enough for the plans and write up.

My sentiments too, I have learned so much on this build, both from the plans and from the helpful comments and advice from Bogs and the rest of the crowd on here 

Tim

I'm happy I went with the bent tubing; It made my engine look a lot better and is one of those things non-ME types notice right away.  I got the bender info from Bogs too; there are also other benders posted here and there that would work as well.  The hardest part is making the rollers.  No problem with a vertical RT, but requires some slightly off-book jigging otherwise.
 

[spuddevans]

Well I managed to steal a bit of an afternoon in the 'shop and got a little more done. I started out by taking the jig I made earlier to drill the mounting holes in the piston glands and adapting it to drill the mounting holes for the piston valve glands. ( basically turned the jig upside down and drilled a 6mm hole a few mm deep to locate the gland into, then drilled the glands)
No pics of this as it is virtually identical to drilling the piston glands ( and I got carried away and totally forgot about taking pics until just before I came back in the house  )

Then I used John's tip of alligning and then fixing the glands to the valve blocks with a drop of superglue, letting it set and then spotting thru to mark the holes. Then after a blast with the fire-producing-monster, a quick wipe over with a rag while still hot, and the parts were seperated and cleaned up. Then I drilled and tapped M2 the valve blocks.



While I was waiting for the glue to set I turned the little connecting pins that attach the whole eccentric strap assembly to the actual piston valve. I turned down some 4mm stainless to 3mm, and then turned down a 4mm section of that to 2mm ( actually just under 2mm ) and then threaded it. Then I parted it off leaving about 8mm of the 3mm diameter section, and repeated the whole process again.

Then I chucked each pin with the M2 threaded end facing in, and faced each pin to length.

Then I had another little job to get done for a friend and so that is as far as I got today.

One thing I did come across was this little parts organizer that I got months ago. It is just the thing to keep all the tiny parts and screws in for a project like this, I think I'll order some more of the larger sized one ( this pic shows 1 set of small and 1 set of larger compartments, they are all interlockable or can be all seperated if you like) They are great as they have individual lids that latch closed  or open.



I got them from dealextreme, Here and Here

Tim

[Bernd]

Tim,

I like that parts box idea. Reason being I never seem to finish one project before I start another. Then I have parts laying all over and can't remember which one goes were.

Bernd

[spuddevans]

Well I got a few moments in the workshop this afternoon, so I got a little more done on this.

I have to admit that I had been kinda putting off the silver soldering as that is something new and unknown to me, but this afternoon I decided to have a go. So getting out the citric acid I made up some pickle, then I mixed up some flux (tenacity 5 if my memory serves me right) and got out the SS and blowtorch.

Rather than try my first joint on a real part I took some scraps of brass, drilled some holes and used some 4mm brass rod. It wasnt as bad as I thought it was going to be. It took a couple of attempts but I got there in the end.

Feeling elated from this I made a start on soldering up the eccentric straps to the con-rod to the little con-block. I had read about how it is good to have a slightly slack fit when soldering, I now know from experience the value of this. I had decided to try and solder the whole assembly in one go, and so had cleaned and fluxed both holes ( one in the eccentric strap and one in the con-block ) and both ends of the little rod, and put them together. Applying the heat to this, first of all gently to evaporate the water in the flux, then with a bit more heat. It was while this second phase of heating that there was a sharp "crack" sound and the con-block decided that it would violently leap at the wall and bounced off, landing quite neatly on the floor directly underneath the rest of the assembly.

I guess that there must have been a bit of water/steam/gas that had got trapped until it heated up enough to propel the block off the rod. Taking this as a sign, I decided to solder one end at a time, and it worked out much better, if a little longer to do.

Then I attempted to do the 2nd eccentric assembly. I gave soldering both ends at once another try, but this time drilled out the holes to a slightly larger diameter. This seemed to work much better except that just when the solder started to flow, the con-block (I'm not sure that is the right term for it, but I've used it enough for it to stick ) started to move a little off the rod.

This is them after being quenched.


Those of you who are not completely blind will see that there is approx 2.3mm height difference between the 2 assemblies. I dont know if there would be enough adjustment to compensate for this, or whether it would be better to re-flux and then reflow the solder and just push the 2 pieces back together? (any and all thoughts would be welcome)

Anyway, I have learnt that silver soldering is not all that hard, but that I do need to practice a bit more. Also learnt that you need to get the workpiece much hotter than I originally thought would be needed.

I did notice that when heating up the joint, the flux 1st of all will evaporate the water in it, going white, then it darkens to the point of looking a bit black (perhaps I am burning the flux? ) then it goes clear and you can see it cleaning the metal, then the solder flows. Does all that sound about right to you guys who are experienced with SS?


Tim

[NickG]

That's how I remember it Tim,

Looks like you have good joints there. I haven't done it for a long time but remember getting a nice thin tidy ring flash around then thinking, ... I better put a bit more on, and a bit more for good measure and it ends up a messy joint! I know some of the guys use thin wire and wrap a bit around the joint to keep it a neat fillet, never tried that myself but it sounds logical as that must be about the right amount of solder.

Nick

[spuddevans]

I know some of the guys use thin wire and wrap a bit around the joint to keep it a neat fillet

That's how I did it, seems easier for a beginner like me

Tim

[bogstandard]

Tim,

When I do joints as you have just done, I invariable put a 'stopper' at each end, a bit of metal or firebrick resting against them. That usually stops the 'blow apart' that is caused by the water in the flux turning to steam, and the joint acting like a piston in a cylinder. The correct gap for all silver soldered joints should be about 0.002" (0.05mm) clearance. Tenacity 5 is the latest flux and is designed for stainless, and you will be very hard pushed to make it lose it's properties. I think the brass would melt before you need to worry about it. I have recently changed over to that for all my silver soldering work.

For your already soldered bit, stand upright, and gently warm up the centre rod until the solder melts, then just push the bit down until in the correct position, then let the assembly fall over, while still heating, press the two parts down onto whatever it is standing on to get the both plates level with each other. Use a bit of metal, not your fingers.

If you do it right, and don't overheat it, you will find it will be just fine without any further flux.

Another string to your bow, nicely done.

John

[spuddevans]

I'll give it a try as soon as I can get back into the workshop, thanks Bogs

Use a bit of metal, not your fingers.

Ahh!! so thats where I was going wrong  HHMS, Hot, Heavy Metal Syndrome 


Tim

[spuddevans]

Well, I have not forgotten this build. I have managed to fix the SS joints that went a little wonky by doing as Bogs suggested and heating the piece up and then compressing the joints together, then laying it flat and pressing the whole assembly flat.

That was about 3-4 weeks ago. Since then I have only been able to get into the workshop for fairly short periods of time, about an hour at a time.

I have temporarily halted the paddleducks build as I have pretty much got to the point of making up the pipework and flanges, and I want to go with bent pipes instead of the extended flanges that the plans call for. So that meant that I needed a pipe bender. John ( Bogs ) was kind enough to send me some plans for a pipe bender, and I have made a start on constructing it.

Yea, yea, I know  but because of only being able to get short times in the 'shop I have been forgetting to take the camera out with me 

Anyway, I will try and take the camera out the next time to show you what I've got done so far ( which isnt that much  )

Tim

[NickG]

Ha, I do that quite a lot Tim, esp when things are going wrong and am under the cosh! Looking forward to seeing it.

Nick

[spuddevans]

Well, having managed to finish my pipe bender ( well, I got it to the point that it can bend pipes, it isn't finished in the "by the plans" sense of the word, but it works good enough for me) I have got back to this build ( finally  )

Today I got started on making some pipe flanges, the plans call for making the "stand-off" type pipe flanges to withstand the pressures of machining. But because I am using bent pipes I decided to make them out of brass.

I used some 12mm brass rod and parted off 4 thinner ( about 2.5mm ) pieces and 2 slightly thicker pieces (about 3.5mm ).



I then made up a split collet to hold the "flanges" while facing both sides to thickness and smooth, and drilling the 4mm holes. I was pleased to see that using the split collet in an ER32 collet worked well.



Then it was over to the mill, where I used the split collet again to hold the sized flange blanks to drill the mounting holes. I clamped the split collet in the vice with a very expensive vice stop  and put one of the flange blanks in it, and centred it by putting a 4mm drill in the mill (switched off) and then adjusted the x and y until the drill would drop in and out without friction. Then I swapped over to a 2mm drill, moved the table over by 4mm, drilled and then moved the table back by 8mm to drill the other hole, and then repeated for the next 5.



And here's the result along with the split collet.



Here's a mock-up with a bit of bent 4mm pipe.






Next I have to mill the sides of the flanges and then silver soldering the pipes to the flanges and also bending the pipes.


Tim

[Darren]

Very cleaver Tim, gave me a "lightbulb" moment with that split bush  ....