ET Westbury Side Paddle Engine

[kvom]

An aweful lot of wasted material making that part Kvom..... Couldn't the hornblock be made as a seperate item and bolted to the main frame?

Regards
Eddy

That's the way ET made it using steel, with rivets and solder to hold the blocks.  However, this method seems to offer better accuracy in lining up the crank bearings later on.  This is one of four frames with the same configuration. 

I should also add that I got the material for all the frames for free.   

[kvom]

Latest progress was the staybolts and weigh shaft to connect the 4 frame plates together.



The next pieces I have in mind are the mounting brackets for the feet and the crank bearings.

[kvom]

Finished the mounting plates for the rear of the inner frames.  These took quite a bit longer than I expected.



For the front I need 4 longer ones.

[Eddy Matthews]

Once you see the frames assembled it starts to give an idea of just how BIG this engine is!!

Regards
Eddy

[kvom]

Made another pair of feet this evening.  Still surprising how much time these simple parts take.

[kvom]

Some small progress on the engine the past few days.

Made the front feet for the inner frames; no pics for these, but similar to the others.

The next goal is to make the bearings for the crankshaft.  I decided to make these as 1 piece and fit the crank to them before mounting to the frames.  This is possible as there are separate crankshafts for each cylinder.  These will be milled from some 1" round brass bar.  I tried the first via CNC milling yielding a .6"x.8"x1" blank.  Afterwards I thought up a better/quicker way that I'll document in a later post.  The first step is facing the end of the bar on the lathe via a 1" collet, then mounting the bar and collet in a square collet block.



The CNC mill then carves out a .8x.6 profile 1" deep.



I then "whittled" out slots on the side and bottom to fit one of the frame hornblocks using the Bridgeport.  I screwed up and made the side slots too wide, so this will be scrapped.  Once the block will slide fully onto the hornblock, I measure the amound the top extends beyond the hornblock and then mill it flat.



The bearings are held in place by a strap across the top of the hornblock.  It's necessary to drill and tap two holes for the screwing the strap to the hornblock.  Here's the setup in the milling vise:



I managed to get a second bearing block fitted before leaving the shop, as well as drilling and tapping all 4 hornblocks.



Next time out I'll try to fit three more bearing blocks and make the retaining straps.  Then it's back to the CNC to bore  and ream the holes for the crankshafts.

[kvom]

A bit of progress today.  I finished sizing the remaining three bearing blocks to their respective hornblocks, and made one of the retaining straps.



The center of the straps need to be drilled for an oil cup, but until I know how I'll make those I just center drilled a spot for a marker.

To make the rough bearing blocks from 1" round bar, here's the setup I used:



With that 1.25" endmill I could easily take .100" DOC, so it took only 6 passes to get the oblong.  Then it was off to the bandsaw to cut it off.  A smaller mill could still use this approach with smaller endmills and cuts.

I also spent some time tapping the base mounting holes on one of the cylinders.  I found that the cast iron tapped quite easily with light finger pressure on the tapping stand, which was a relief.

Before milling and boring the bearings, I need to do an assembly of the frames on each side to see how much room is there initially to fit the crank and conrod, and adjust accordingly.  I start out with the length of the outer staybar, and from that subtract the thickness of the hornblocks and the amount the bearings extend.  The distance  from the inner frame to the center of the crank needs to be pretty close in order for the drive components (piston/rod/crosshead/conrod) to line up.  It's not clear how close the tolerances need to be.

[PeeWee]

Some nice progress there. 

what mill are you using?  is it one of the chinease imports?

[kvom]

Some nice progress there. 

what mill are you using?  is it one of the chinease imports?

CNC mill is Novakon 200, a Chinese import.  Manual mill is a Bridgeport.

[kvom]

Got in 6 hours or so in the shop doing "little stuff", so not much to show photographically.  Also found one big "boo-boo".  Might be fixable.

The first job was to drill the cover mounting holes on one side of both cylinders.  The other side was done via CNC when milling the profile.  For this side I just centered the bore under the Bridgeport quill and used the DRO to locate the holes.  Still took a long time to be sure of everything.  After tapping all the remaining cylinder holes, I got the rear covers and one front cover to fit after some filing.  Any opinions on using those 5-40 set screws as studs?  Seems to look OK.



Notice anything wrong?  The front cover needs to go on at a 90-degree angle from what's shown, meaning I'm missing one mounting hole and have an extra.  I think I can put a dummy bolt in the extra hole and use the part.

In any case I drilled and tapped the holes in the front cover for mounting the crosshead guides.  There was no dimension for locating the holes;  I did a finger assembly and discovered that the end of the guides bars need to be flush to the front of the cover, so 5/32" out.  With two bars attached, one crosshead slides very smoothly, but the other is a fraction tight at the near end.

[derekwarner_decoy]

Hi PD's........kvom...I think it would be a pity to...... shall we say spoil the   build by showing the internal hex of your 5-40 hollow pointed grub screws......but  ...there would be no challange in reversing them & driving them in with a double 5-40 lock nut , then remove the double nuts & your cylinder studs would be depicted as original solid studs...... .....Derek

[kvom]

Good idea derek.  Thy will be done! 

[kvom]

My "plan" now is to use the grub screws as short studs but reverse them so that the hex hole in the end is not seen.  By using two nuts as locks I can tighten them into the cylinder and other short blind 5-40 holes.  Thanks to Derek for the idea.  I have ordered some hex-head bolts from American Model Engineering that will be used to connect the cylinder to steam chest to cover.  I also have some 5-40 threaded rod to use in other places as needed.  Those model-scale nuts and bolts cost $0.30 each, so the model will have a lot of expense just in nuts and bolts.

This weekend I bit the bullet and redid the inner cylinder covers to orient the mounting holes correctly.  I also decided I could use the CNC mill to get accurate centering of the holes for the piston rod.  The first order of business was a skim cut on some 1.5" diameter brass rod, yielding a diameter of 1.491".  Without removing the rod, face, then turn the inner spigot of the cover to a close fit with the cylinder bore.  Then drill a pilot hole and part off.  Repeat for the second piece.



Next use the CNC mill to create a soft jaw pocket to match the diameter.  Afterwards the Z-axis of the mill is centered on the pocket and thus the workpiece that's mounted in it.  Now I can face the parted end, mill the profile, drill the mounting holes and the hole for the gland screw, and tap the hole for the screw using the 1/2-28 forming tap.  Then screw in the gland screw and drill through it.  Hopefully everything ends up concentric.  I didn't have my .251" reamer handy, so that will be done later. 



The last operation is manually drilling and tapping the holes for the crosshead guides, as shown in an earlier post.  With everything assembled for a trial fit:



Of course, everything didn't go as smoothly as the above sequence would suggest.  Biggest issue was that the gland scews would not go into cover more than 1/2 turn.  The screws do go into the aluminum nut I made with the same tap, and the tap turns easily in the covers' threads.  I tried to set up the lathe to potentially recut the threads a smidge deeper, but couldn't get the screws perfectly straight in the collet chuck.  I finally decided to run a small triangular file into the threads while the lathe was turning slowly, and in addition put a slight bevel on the ends.  Now I can get about 2 turns of the screw, so I'll just have to put enough packing into the glands.

My list of parts to finish is getting smaller:

Mill and bore crank bearings
One piston rod and piston
Crankshafts and the connector
Conrod pins
Lifting links
Remake one weigh link, plus some lever mechanism to move the weigh shaft
Eccentric discs
Remake one staybar
Some sort of base
Air plumbing to steam chest inlets

Got an order into Enco for materials plus some roll pins.

Then lots of filing, adjusting, cussing, and remaking anything that proved inadequate.  One month to go before my 2-month trip, so it will be close.

[kvom]

Today's mini-project was making the conrod pins that connect the rod end to the crosshead.  I chucked some 3/8" drill rod in the collet chuck, faced it, and turned to 1.4" diameter for a length of 1/2".  The conrod ends have been reamed to .251, so I took off a couple of thou at a time until I had a nice sliding fit on the rod end:



Next, center drilled, drilled and tapped the end 5-40 for to  depth of 3/8".



Next parted off leaving a "head" 1/16" thick.  After making two, I reversed the pins in a 1/4" collet to smooth off the partoff tit. 

Not having done so previously, I needed to drill and ream the center hole in the outside crosshead cheaks.  With a 5-40 grubscrew stud screwed into the end of the pin, the crosshead and conrod assembly looks like this:



Eventually the SHCSs will be replaced with studs & nuts too.

[kvom]

Today I started on the cranks, and did not have a good day.  Here's the photo evidence:



The shafts are all 3/8" drill rod.  The webs are 3/16" thick and need to be separated by 1/2".  After drilling and reaming the webs .001" oversize, my process was to hold the webs  and the crank pin together in a vise with a .500" gauge block clamped between the webs for spacing.  I would then fix the crank pin to the webs with 1/16" roll pins.

I had two errors with this plan.  First, I had made the crank pin slightly too long, so that when I clamped the vise the webs and the gauge block were a bit loose.  I ended up with the webs about .04" too close together.  The second error was where I drilled for the roll pins, which need to be in the ends of the web rather than the side.  With the pins where they are the webs can move slightly side to side around the roll pins.

I also discovered that the crankshaft pieces I had cut will be hard to get straight, as the oversize hole and thin web make it possible to move slightly.

So my rework plan is as follows:

1) Make the crank pin slightly less wide than the width of the crank, allowing use of the gauge block to set the web separation.

2) Make the crankshaft one piece and use for aligning the webs.

3) Secure both the crank pin and crank shaft with loctite and let set

4) Drill and insert roll pins and the ends of the webs after the loctite dries.

5) Machine out the center section of the crankshaft.