Bogstandards "Paddleducks" engine

[shred]

It's kinda late for me, so I'm just going to throw some pictures and a little text up and add commentary later as needed.

This post is about making the support columns. I experimented with blinging them up from the plan stock rods and made square fluted columns. I figured there wasn't a lot of metric on them to occupy my few free brain cells so I could play a little.

The first (well, second try, but first 'good' one) sample and raw stock for the next 3. Note they are extra long.

Here's why they're extra-long-- to give the vise something to hold onto at either end. The one in the vise has had one side cut, then flipped to the other to do the next two cuts with a 3/8" ball end mill. See the dark area in the middle bottom of the part where there's no material anymore. Were these cut to the 70mm final length, there wouldn't be much there to hang onto (see the next picture)

The final columns, drilled and tapped #4-40.

And test-assembled to get all of the parts made to date attached into one glob. I think they'd look better in brass, but I had no 3/8" brass square stock handy. I can always color them later at painting time.

(and one note-- I'm tending to illustrate items not illustrated in Bogstandards' book. So if something seems unclear, check there as well..)

 

[shred]

Made the con-rods and pins, did some tuning and running-in and put a couple sleepers on the bottom for now.

Alas the fluted con-rod test part I made was deemed ugly and/or out of place on this engine and straight turned ones were used, so I still await a chance to play with Marv's latest program. Due to my de-metrification of the crankshaft pins to 3/16", the 6.5mm square dimension on the plans only had a very small amount of material surrounding the pins; maybe 1/32" either side, so I thickened the rods up a little at the big end to 5/16"x1/4" (the small end is on a 1/8" pin and is 3/16" wide-- You'll note a slightly different pin style versus the plans). The only trick was turning the round section on the con-rods without fussing with a 4-jaw chuck. I did that by milling the 5/16"x1/4" out of 3/8" round in a collet block. With a holding/turning nub on the end, it's no problem to round the shaft in the lathe.

Here's my Lego guy showing what we have to date and trying to sort the eccentric timing. It turns over well on an electric drill with good compression but is still a little stiff turning by hand. I expect that will loosen up with time.

 

[Maryak]

Shred,

Looking very nice. :bow:

I like the lego engine driver. Now all you need is the Fat Controller ???

Oops - English joke. :

Best Regards
Bob

 

[steamer]

Nice Build Shred! Can't wait to see her running on her own!......with a little help from Lego guy of course


Dave

 

[shred]

Latest update-- got the valve blocks done. For the playing-along-at-home types, I went with #2-56 for the steam port threads, and #4-40 to hold the blocks on (aside: I don't know if drills, taps and screws are commonly available in 0.5mm steps in this size range, but if so, metric is the way to go for models this size-- several more options). The rest of the holes are whatever number drill was close to the right measurement in mm. The ports were cut with a 3/32" end mill and the spool valve bore is 1/4"

We're continuing the 'Alamo' bling style here with the rounding bit. At the moment they intentionally doesn't quite align with the top of the main block, on the theory I can always cut more off if I don't like it in the end. I'll be putting in nicer screws or studs later as well.

 

[RobWilson]

Real fine looking engine your building :bow: :bow:
Rob

 

[ozzie46]

Shred would a 1/8 end mill be to big for the ports?

Ron

 

[shred]

I don't think it would matter much if you used a 1/8". There's enough metal around the slot as-is and it's just a way to get steam from one place to another. I was about to use a 1/8" end mill when I discovered the 3/32 hiding out in my tiny endmills box.

You can see the slots in this picture and get an idea how much space there is.

Also in the picture is the valve spools I just got done with (they are somewhat less gnawed-out-looking than the pic). That took four tries to get two decent ones-- When reading the instructions, when he says "put the unthreaded end in the chuck", he means "Stuff that end far into the chuck and don't cut on it, dummy!" ;D). They also get very fragile when drilled out-- no heavy cuts allowed.

I tapped the end #4-40 (there doesn't seem to be any text about how the two female threaded ends get connected on the eccentric strap, but I suspect I can work that out based on the pictures) and cross-drilled with a 1/16" end-mill. I had no spotters or centers that were going to sneak down that far next to the collet block I used to drill them and 1/16" is only a little over 1.5mm anyway.

 

[steamer]

Looking good!

Mr. Lego appears to be deep in thought? ;D

Dave

 

[ozzie46]

Thanks Shred, Looking good.


I have 4 Blocks ready to be bored at this time. I expect to make a lot of mistakes. :big: :big: :big:


Ron

 

[Blogwitch]

Shred,

there doesn't seem to be any text about how the two female threaded ends get connected on the eccentric strap

Top of page 53 and bottom of page 54 shows it all.

A tiny bit of threaded rod.



Blogs

 

[shred]

Thanks Shred, Looking good.

I have 4 Blocks ready to be bored at this time. I expect to make a lot of mistakes. :big: :big: :big:
Ron

Those blocks have lots of places to mess up, but if you take it steady and recheck everything you should be good. Remember not to do the final valve spool bore until after the cross holes are all drilled. I reamed mine .249" (I have an O/U reamer set), then made a toolmakers reamer out of the drill rod I'd made the spools from to do the final hole sizing (as seen here but leaving a small flat on the end of the reamer-- no need to harden for one or two-time use in brass).

Shred,

Top of page 53 and bottom of page 54 shows it all.

A tiny bit of threaded rod.

Blogs

Thanks.. I finally noticed that this morning.. that makes two errors in the plans I thought I found and didn't!

 

[shred]

Making a quick run-by to check what I did on something earlier...

Here's the in-process eccentric straps to-date. I got a little more on them versus the plans. The first corner cut I did with the rounding bit to match the other flourishes, but that still looked too bulky, so I went for a little closer to the classic eccentric look and took some swoops out with a 3/8" ball end mill. I considered going a lot further and doing a nut-n-bolt style setup, but so far stopped here. Since I didn't pre-plan for this, I broke into the screw holes. No big deal for me, but if you care, you may want to be more careful when drilling them in the first place.

It took a while to bore the holes (I did that before the bling cuts when it was still easier to hang onto) since not only wasn't it a convenient drill size, but the eccentrics themselves weren't quite the same. Throw in a floppy boring head and it took a while of lapping with polish and hand work to get a good fit on both.

For the de-metricers, I used #2-56 for the strap bolts and 1/8" for the rod hole. A few more bits to crank out and we should be close to the first run.

Note on the plans the distance to the center of the eccentric strap is blurry and looks a little like 11.5. Obviously it's supposed to be 10.5 if the overall width is 21mm.

 

[bearcar1]

Looking good so far Shred, The suspense is killing us. I like the little bit of tasteful 'bling bling'. Rather Art Deco-ish. Nice touch.

BC1

 

[shred]

Got the rest of the valve string done. With a little plumbing (and reassembly) this thing would run, albeit without the control block. Maybe I can get on that after a mandatory yard-work break :-\

I also made the link pins according to the plans this time. It's the first time I've tried this method and it works well. I left some length on the off side to visually balance the nut, but it could go all the way flush if desired. If you don't have a copy of the plans handy, the pin is a short length of 1/8" rod with a #2-56 thread on one end. The joint sections are all reamed 1/8" except for one side of the outer joint, which is drilled to a #2 clearance. So, assemble the pieces, stick the threaded pin all the way through and bolt it on. No worries about the nut tightening and locking up the joint since all it does is hold the pin in place. The rest of the joint gets to run on a nice piece of smooth finished 1/8" rod.

De-metric notes: valve packing gland- 1/4-28 thread. Drilled to match spool valve stems. Attached to the block with, as usual, #2-56. A slightly loose fit on the gland attachment screw through-holes may help with fitting up later. Joint pins 1/8" with #2-56 thread on one end. The pack nut was made from 1/4" hex rod which will feel a tad small if your valve stems are large.

The eagle-eyed will notice I've loctited (using the uber-strong 'sleeve retainer') the top of the eccentric strap on versus silver soldering it for the time being until I decide if I want to bling it further.

 

[Blogwitch]

With a little plumbing (and reassembly) this thing would run, albeit without the control block

Go for it Shred, give yourself a Cheshire cat grin. It is just what you need at this stage to keep the momentum going after doing such great work.


[ame]http://www.youtube.com/watch?v=I8UCWr_BeqE[/ame]


Blogs

 

[ozzie46]

Is it just me or did shreds pics go away?

Ron

 

[ozzie46]

I can see the pics today, Why not yesterday??? scratch.gif scratch.gif scratch.gif scratch.gif scratch.gif scratch.gif

Ron

 

[shred]

The pics are hosted on my desktop server, which is on a poor-quality DSL link, so if the pictures go away, wait about 10 minutes for the link to reestablish itself and they should return.

I did get it all reassembled last night (about fifty #2-56 screws ), but it still won't turn over completely on air (it's close) so I need to go revisit the friction points and timing tonight.

 

[shred]

Not quite running, but here's where it is. The control block and plumbing up top is yet to be done.