Another Paddleducks build log

[spuddevans]

Presume the crank journals set 90 degrees apart on this engine? Do you have a method of achieving this or just by eye?

Nick

Hi Nick, yes, as I understand it ( and that is quite a statement  ) the cranks are set at 90degrees. I think that it is set by trial and error ( in my case, probably more error than trial ) I could be in error in saying that, I have read through the plans a few times but I have the memory of a fish.

I got a bit more done today, worked on the flywheel recess.

I started off by re mounting the flywheel in the 3jaw, I wasnt too worried about it being precisely concentric. I ground up a new Hss blank to do the job and then had at it.


I then changed tools to a 6mm round profile and put a little radius to take the sharp edges off.


Then I had to tackle putting the 3 holes in the flywheel. This meant breaking out the rotary table. I now have yet another item on my "To Make" list, as I need a means to attach my 3jaw self-centering chuck to the rotary table. But until then I have to make do with a slightly more convoluted means of attaching items to it.

So then, how does one secure a round item, ie my flywheel, to the Ro-Tab and get it centred up?

Well this is how I did it, there's probably many other ways, and maybe easier ones too 


I eyeballed the flywheel into the center and attached with 2 clamps, but only tightened them thumb tight. Then mount a Dti on a mag base mounted on the table, with the finger set against the inside of the 5mm mounting hole. Then just rotate the table and "bump" the flywheel ( or whatever you are centering ) until the Dti reads the same all the way round the flywheel, or within reason ( I haven't finished the outer edge of the flywheel yet, so it still has some marks which bounced the Dti needle a bit, but I just got the reading at an average all the way round it )

Then drilled the three 4mm holes at 120degrees spacing.

Then I drilled and tapped m3 for the securing screw.


And this is the resulting flywheel,



That's all I got done today.

Tim

[bogstandard]

Tim,

I don't think there is anything in the writeup about how to get the cranks at 90 degs to each other.

But it is easy enough to do by setting one vertical and lining up the other by eyeball against say the edge of the baseplate. As long as it is near enough, the engine will run perfectly. They could be up to about 5 degs out either way, and it would still run OK.

The secret is to tighten up all the crankwebs and pins except for one at the centre bearing position, then once that is in position, tweak it up and everything should be in line. The critical bit is the 90 degree lead on the eccentrics for the timing, and if you took my advice and marked a line on the eccentric, that makes it much easier. Each end is timed individually, to the crank nearest the steam chest, that is why the crank position isn't so critical. That is ok for a piston valve engine, but not for a slide valve twin.

Hope that hasn't confused too much.

John

[spuddevans]

I don't think there is anything in the writeup about how to get the cranks at 90 degs to each other.

Well that would be why I cant remember reading it then 

But it is easy enough to do by setting one vertical and lining up the other by eyeball against say the edge of the baseplate. As long as it is near enough, the engine will run perfectly. They could be up to about 5 degs out either way, and it would still run OK.

The secret is to tighten up all the crankwebs and pins except for one at the centre bearing position, then once that is in position, tweak it up and everything should be in line.

That sounds like a good plan to follow, thanks 

The critical bit is the 90 degree lead on the eccentrics for the timing, and if you took my advice and marked a line on the eccentric, that makes it much easier. Each end is timed individually, to the crank nearest the steam chest, that is why the crank position isn't so critical. That is ok for a piston valve engine, but not for a slide valve twin.

I havent made the eccentrics yet, but when I do I will make sure to mark a line as the plans call for 

Hope that hasn't confused too much.

No, that has cleared things up quite nicely.

I just have to say that I really appreciate your advice and helping me out, it is good enough of you to have taken the time to write the plans in such a clear and easily-followable format and make it freely available to all, but you go beyond the call and carry on giving advice and tips to help others out. I really really appreciate that   


Thanks again,
Tim

[spuddevans]

Got a bit more done, started work on the crankshaft rods, I only had 5mm stainless ( got some 4mm stainless rod on the way ) so I just cut the 3 lengths of the 5mm, sized them on the lathe and then polished them while still on the lathe with some wet-n-dry.

Then I set up the spin indexer on the mill and milled the 2 flats on the longer 5mm rod, and then the flat on the other one.



Then I moved on to the eccentrics, I grabbed some steel and chucked it on the lathe. Turned it down to 18mm and installed the 4mm groove's on each eccentric.


The next step will be drilling the offset hole and then drilling and tapping for the fixing screw.


Tim


edit: If anyone wants to see larger versions of the pictures click Here

[spuddevans]

Got a bit more done today, got some 4mm stainless rod so I cut off 2 pieces for the big end pins.

Then I turned to the eccentrics, and the slight problem as how to hold them in order to drill the offset hole in both of them. It occured to me to try clamping my little 3 jaw self-centering chuck directly onto the mill table, and what do you know, it worked!!


Then after drilling both, it was back over to the lathe to re-mount them using a 5mm rod that was tapped M3 and a M3 screw.



After a little turning



One lesson I have learned is to keep your mouth in the closed condition when turning steel (or other metals too), if you think the little chips are a bit hot on your bare arms, wait til you get one shoot into your mouth 

Anyway, after that I drilled and tapped the fixing holes, then I discovered that I dont have any M3 grub screws left, so at the moment the eccentrics are fixed by faith. Being the excitable type I quickly assembled the bottom plate, bearing blocks with ball races, crank assembly (in my hurry I mounted one of the crank webs the opposite way round to the others, it doesnt make a real differance I think, but it looks a bit odd) and flywheel and eccentrics.


Whoo hoo!! It's starting to look more like an engine and less like a collection of parts 

Next will be the support posts I think 

Tim

[kvom]

don't forget the oil holes on the tops of the bearings.  

[spuddevans]

don't forget the oil holes on the tops of the bearings.  

Do I still need these as I'm using ball races? 

If necessary I can add them when I bling up the bearing blocks.

Tim

[bogstandard]

Tim,

Very nice indeed.

I thought I showed how to drill the offset holes using the vice on the mill and a backstop. I do all my offset drilling by that method, it is much more accurate than playing about with a four jaw. Such a long time ago now, I just can't remember all the details I wrote.

If you had bearings at either end of the blocks, ie 2 per block, then yes you would put an oil hole in between them, as it would lubricate both, but as you only have one in each, then the oil will drain away without going thru the bearing, so there is no point in putting oiling holes in.


John

[spuddevans]

I thought I showed how to drill the offset holes using the vice on the mill and a backstop. I do all my offset drilling by that method, it is much more accurate than playing about with a four jaw. Such a long time ago now, I just can't remember all the details I wrote.

I think you did show that, but my issue was holding the eccentrics firm and square, I wasn't confident about just holding them in the vice as my Vee blocks are too large to use in my vice ( or rather my vice is a bit too small and the vee blocks are a little too big)

Anyway, it only took 2mins to clamp the 3jaw self-centering chuck to the mill, and that held them secure and square.

If you had bearings at either end of the blocks, ie 2 per block, then yes you would put an oil hole in between them, as it would lubricate both, but as you only have one in each, then the oil will drain away without going thru the bearing, so there is no point in putting oiling holes in.

I have 2 races on each of the two central bearing blocks, so I could put in the oil holes in those. I have got some more of these bearings coming from the ebay supplier you gave the link to, so I could install the extra bearings on the outer bearing blocks as well if needed. That would challenge me to accurately bore out for the ballraces to match and keep concentricity with the existing bore.

Tim

[chuck foster]

looking good tim 

i have been looking at the plans/book that i downloaded and i like what i see...............if i just had more spare time 

keep up the good work 

chuck 

[kvom]

I'm curious to know how the bearings are working out.  Is the crank pretty "free spinning", or is there still a bit of friction?

[spuddevans]

I'm curious to know how the bearings are working out.  Is the crank pretty "free spinning", or is there still a bit of friction?

They are pretty free at the moment, and I have done absolutely nothing to the bearing blocks apart from boring the holes. No lapping or anything. I have a bit of friction with one bearing block when it is clamped down tight. I cant lap the bearing blocks as when boring out for the ball races the bore's do not go all the way through  ( if you know what I mean ). I might get all the bearing blocks clamped together with ball races installed and a 5mm rod through them, and then gently polish the bottom with some wet-n-dry on my granite surface plate to see if that will reduce that friction.

Having said that, it is only when that particular block is tightened up well that the friction appears, so I reckon that whatever differences that exists between the blocks can only be very slight. With that block's mounting screws just slightly loosened up the crank is quite free spinning. I have some edges of the bottom plate that need filing to give a better clearance for the crank-webs, and without the eccentrics having a grub screw to fix them, they tend to rub and cause a bit of friction too.


Tim


EDIT

Since this post I have bored the bearing blocks completely thru @8mm, and then Lapped them as per the plans, but using a length of 8mm ground stock and some T-Cut. This has made the whole bearing/crankshaft assembly exceedingly free and smooth, even with the bearing blocks completely tightened down.

If I was to do it again I would just bore the bearing blocks all the way thru at the required diameter for the ball races, if needed you can always make up a little packing bush to seperate the 2 ball races in each block.


Tim

[arnoldb]

Tim, you're doing well  and 

I'm scared - very, very scared... - I think you are infecting me with       

  , Arnold

[spuddevans]

Thanks Arnold 

I'm scared - very, very scared... - I think you are infecting me with   

Dont be scared,  is nothing to be afraid of, just keep a healthy stock of barstock and keep making chips   

Tim

[bogstandard]

Tim,

For the low block, just shim it up with layers of bacofoil, it might only need one or two. But get it before you have done the Sunday roast in it, less crinkles.

If you start to try bringing the others down to match the low one, you just might make it even worse.

John

[spuddevans]

Tim,

For the low block, just shim it up with layers of bacofoil, it might only need one or two. But get it before you have done the Sunday roast in it, less crinkles.

If you start to try bringing the others down to match the low one, you just might make it even worse.

John

That's a good point, I'll try the tinfoil shims 


I got a little more done today, I got some temporary ( unless I can't come up with a fancy blingy design ) columns. Nothing fancy here, just some plain stainless rod cut to length and then tapped m3 at each end.
Then I cut up a couple of pieces of 4mm stainless for the Little end pins and single pointed one end of each piece m3, then cut a small slot for a screwdriver in the other end.



Then I got excited again and assembled the top and bottom





It's looking more like an engine now 

Next will be the con-rods and then on to the steam chests.

Tim

[arnoldb]

It's looking more like an engine now

Very true Tim  - looking good!

  Arnold

[NickG]

Wow Tim, it's looking great. To be honest, I'd probably leave the columns too - but that's just boring old me!

[chuck foster]

thanks for the film canister in the picture, it really shows just how small the engine is 

the columns look fine just the way there are................but it's your engine build so the sky is the limit 

chuck 

[spuddevans]

Thanks for the encouragement guys 

Got a couple of hours in the workshop today, started on the con-rods. I decided to try a little something different and used some brass Hex rod. I then marked up for drilling the 2 holes. I set up and drilled the 1st hole in both con-rods before repositioning the y-axis using the dial to make sure the spacing would be exact.

While I was worrying about getting the holes precisely at the right distance I neglected to make sure the hole's were exactly on centre on the flat of the Hex  But it should be ok, I cant notice it with my eyes closed 

Here's a pic of the setup for drilling, I dont have a hex collet so this was the best way of holding the hex bar to drill perpendicular to the flat of the hex. I squared up the hex rod with a small square and then tightened the vice up.



I then made up a little filing button ( my first forray into the world of filing buttons  ) and then used it to round over one end of each con-rod.



After that I only had a few mins left before I was called to do "more important things", so I cut down some 19mm square brass bar for the 2 steam chests and milled them to length. Next time I'll be breaking out the little flycutter to bring them down to the final dimensions, and then the fun starts when I start boring it out.


Tim

EDIT

Since getting this engine to run I have found a number of places that can cause friction, one of which is my design of Con-rod would tend to catch on the crank-webs. But the fix was very simple. I just put a m4 threaded rod in the chuck and placed the crankshaft end of the conrod over it and tightened a nut to hold it on. Then I just shaved about 0.5mm off the side of the conrod to leave a little boss. Then flip the conrod over and do the same.

This really helped ease the friction and catching issues with the conrods.

[sbwhart]

Nice work Tim
 

Good to see you getting into the mystery of buttons, no mystery really just a nice simple way to get a neat rad.

Good thread well explained and great pics

Keep up the good work

Stew

[spuddevans]

Well I left you all on the edge of your seats ( you were all on the edge of your seats, right?  ) The small delay in the build was caused by some "Man-Flu".

Anyway, I started off today by flycutting the steam-chests down to size, then I marked up the Datum end and drilled the hole for the spool valve using progressively larger drills until I got to 5.9mm.



Then after marking up one side for the steam inlet flanges I set up a stop on the vice and drilled the 1st hole on each block, using a vice stop ment that it was easy to find the 1st hole, drill it and then swop over the steam-chests to drill the same hole in both without having to measure and re-check. Then it was just a case of winding on the x-axis the right amount for each hole.



Both chests


I was about to start on drilling the other side, but I was feeling a little tired and didnt want to muck it up so I called it a day.


Tim

[NickG]

Great progress Tim! Hope you made a good recovery from the Man-Flu, awful thing that!

Slightly  Your photos are always so good. Did you say you were using a DSLR? Sure there was another thread on it? The wife is hankoring after a better camera so I immediately said DSLR then realised I know nothing about photography! There are these bridging cameras that fill the gap now, are they any good? If I went halves with her, sure I could put it to good use in the workshop!

I need to get used to flycutting, I'm sceptical now whether it'll be rigid enough in my ER collet chuck as it protrues quite a bit from the spindle. I might have to get a 1/2" finger collet just for that job.

Well done, coming along nicely.

Nick

[spuddevans]

Slightly  Your photos are always so good. Did you say you were using a DSLR? Sure there was another thread on it? The wife is hankoring after a better camera so I immediately said DSLR then realised I know nothing about photography! There are these bridging cameras that fill the gap now, are they any good? If I went halves with her, sure I could put it to good use in the workshop!

Yea there's a thread in the "How to" section on taking photos in the workshop. I do use a Dslr, a canon 400D, but, as I said in the how-to thread, the key to a good photo is good light, unfortunately something that isnt always found in a workshop. Hence I use a powerful flash mounted on my camera, but I "bounce" the flash by pointing the flash up to the (slightly dirty white) ceiling thereby creating a nice flat even light for the picture.

Those bridge cameras are very good too, my advice would be to read up as much as you can on them before buying, find one that suits your needs, then go into a jessops or some such and try it out.

I need to get used to flycutting, I'm sceptical now whether it'll be rigid enough in my ER collet chuck as it protrues quite a bit from the spindle. I might have to get a 1/2" finger collet just for that job.

I flycut using my ER32 collet, I have a set of 3 flycutters but I've only sharpened up 1 of them for use, the smallest one (it has a tip swing diameter of about 2" ) and have found no problem with rigididididididity. It leaves a lovely silky smooth finish.


Tim

[NickG]

Cheers Tim,

Will have a look at the thread. Will do that (reading up), I do that for everything I buy, but the wife isn't so patient! I did say we'd go into jessops, went into comet but a shop that specialises in cameras will be able to give better advice and being able to try them is a must.

Great, will definitely be using flycutter for facing cuts in future then. I think I've only tried the small one too. My mill seems to be trammed in pretty well so should be fine, couldn't notice any ridge or step when using the big end mill.

Nick