Flapping around... Elmer's Kimble

[Foozer]

Getting fancy there, I best acquire another bag of BBQ chips, detect a video coming up shortly

Robert

 

[Blogwitch]

Arnold,

I think the Kimble is one of the most difficult engines that Elmer decided to show how to build.

He showed one way to make it, and I am sure, like you are doing, there are many ways to achieve the same result in the end.

That is what model making is all about, finding ways to achieve a final result. If it works at the end of it all, then you have done it correctly.

You are doing great on this one, and I can't wait for the next installment. :bow: :bow:


John

 

[arnoldb]

Thanks Robert - there's still quite a bit to do though, so the video won't be too soon.

John, thank you I have to agree; Kimble is not an easy engine - maybe that's the reason why there's not more examples of completed ones. I think it's a good example of an engine that first have to be understood before one start to build it...

Today's little bit, the eccentric. It's not a difficult part to make at all - in fact all the difficult bits of the engine are now done - but once again I made a slight change to it.
If made as per plans, the eccentric is bolted to the flywheel, and when the engine is assembled, the eccentric ring is retained between the flywheel and the bearing column.
I don't want the eccentric ring to touch the bearing column when the engine is done, simply because the column will be painted, and the ring will either rub off the paint, or the paint will add quite a bit of friction while running - or both.
So I decided to add a step to the eccentric and eccentric ring to prevent that. The ring will still run against the flywheel on one side, but that's OK, as the flywheel won't be painted.
I'm also going to make the eccentric ring a split assembly rather than one piece. This is mostly for ease of assembly; this engine will be finicky to assemble when done, so I'd rather do a bit of extra work up front. It will also add some visual appeal - I hope.

Started turning up the eccentric - a bit of 20mm silver steel turned down to 17.5mm, and a 1mm long step turned down to 16.5mm diameter:

Off to the mill and mounted on the rotary table - purely for the fact that it's easy to center the RT to the spindle, plonk the chuck on it and dial in the hole locations. The two holes needed drilled - the most important one is the 6mm hole on the right, as that determines the eccentric offset. The hole on the left is 2.5mm - that will be transferred to the flywheel and then drilled out to 3mm:

Back to the lathe with the chuck, and parting off at thickness:

It looks like the lathe is running hell-for-leather in that photo, but actually, it's only running at 110rpm - I can't do much faster than that on parting steel. The lathe's spindle bearings is a bit worn, and I have a load of backlash on the cross slide feed nut as well. To top that lot, the "parting" blade I'm using is actually a HSS wood plane cutter that I ground down, and anything faster than that on steel would just toast the cutting edge. Not to mention the fact that this was an interrupted parting cut because of the two holes in there :big:

Once parted off, I spent some time and energy to file away the tool marks on the parted face, thereafter a bit of rubbing on emery, and the parted side of the eccentric is all nice and shiny. Shoved a bit of 6mm silver steel through it and the flywheel, and clamped the lot together with a toolmaker's clamp, and then clamped the clamp in the mill vise and transferred the 2.5mm hole into the flywheel - taking care not to have the hole exit on the other side of the flywheel:

Off to the drill press, and with the same toolmaker's clamp trick, opened up the 2.5mm hole in the eccentric to 3mm, and countersunk it for a nice fit for some 3mm countersink screws I have:

Next I tapped the hole in the flywheel to M3, shortened one of the M3 countersink screws for a proper fit, and this is what it looks like assembled together:

Regards, Arnold

 

[arnoldb]

A bit more progress; this is turning into a weekends-only project it seems...

With all the hard-to-do parts done, I don't know how long the yet-to-be-made parts will take to do, but soon I'll have to start assembling bits and pieces to see if everything fits. The base and sub-base picked up a bit of rust earlier on, and there were a couple of dings in them as well. The dings were my own fault - I didn't follow the rules of scrupulously cleaning the mill vise each time a part was moved, and some swarf got trapped and made dents.

So first I cleaned up the dings - had to lightly mill away the sides of both the base and sub base to get rid of them:

Then I set to with a file and some scotch-brite to remove the last major machining marks and all the rust from the bits, and gave them a coat of primer:

In the previous post I mentioned I might make the eccentric ring a split one, so I grabbed a bit of 3mm brass plate and roughly laid it out:

After picturing the finished part in my mind on the completed engine, I decided against making the split eccentric ring; it would look a bit "chunky" against the rest of the engine. The smallest taps and screws I have are 10BA, and even If I used these to close the eccentric ring, I'd have to turn down their heads just to fit, and they'd still look overly large.
I do have 1.4mm taps, but no die nut, and if I want to single-point turn screws for these, I first have to make some tools, which have to wait for another day.

So, back to a simple ring for the eccentric ring, and a bit of phosphor bronze turned down to outside diameter - I nearly grabbed a bit of aluminium bronze I have for this part, but remembered in time that I had to silver solder on it!:

After a bit of drilling, and boring, things were to size, with the step turned in to match the one I made on the eccentric:

There was nearly a brown-pants moment while drilling the bronze... I'd forgotten I recently bought a new 10mm drill bit, and it's still very nice and sharp... It grabbed into the bronze, pulling the tailstock chuck right out of the tailstock taper. I grabbed the old chipped 10mm drill, and roughly stoned its cutting faces to a more suitable profile for bronze and finished the job.

The eccentric fits a treat - turning closely, but smoothly in the ring, with the eccentric face _just_ protruding a bit:

Next I parted the ring off:

It was about 0.05mm too thick after parting off, so I flat-lapped that off on some emery, and ended up with this:

Elmer's plans call for 1.6mm (1/16") plate for the valve rod and connecting rods. I thought I had 1.6mm brass plate - well I thought wrong :. I have 1.2mm and 2mm. For a while I sat debating with myself whether to maybe make the rods from round rod, but decided against that as well. So, I'll use the 2mm plate, and I cut some strips from it:

Then trimmed the valve rod to width - 4mm in this case, leaving it about 0.02mm over size for final finishing:

I love my digital camera to bits; it takes fairly good photos without even trying hard, and it'll take 500 to 800 photos on a single full charge, but one thing I don't like about it is the fact that it'll suddenly show the low-battery-of-doom indicator, and only take two photos before shutting down completely on low battery. The last time the batteries ran out was last year when I was finishing the second Coomber, and I didn't give the batteries a full charge... You have three guesses what happened today, and the first two don't count.

Without photos while the batteries were recharging a bit, I silver soldered the eccentric ring to the eccentric rod, and cleaned it up a bit:

I didn't notice it in the shop; but the photo shows some interesting things colour wise. Both the eccentric ring and flywheel rim are phosphor bronze, but of two different compositions - I say that because they behaved a bit differently while machining. The rim has a bit of patina on it already, but is more yellow than the eccentric ring which is more copper in colour, suggesting a higher copper content in the alloy of the ring. Next the yellow of the brass eccentric rod follows. There's also the different grays - ranging from the darker shade of the silver steel eccentric (maybe indicative of it's high carbon content) to the zinc colour of the galvanized screw, then the aluminium approaching "white" and finally the silver sliver of high-content silver in the joint between the bronze ring and brass "rod".

Regards, Arnold

 

[arnoldb]

Today's bit...

One thing I didn't do when I made the vane shaft was mill out flats on it for the vane arm setscrews - that was easily done:

Then I spent some time with the base - flattening the primer a bit with some 1200 emery, and gave everything the first coat of paint:

Next I marked out the vane arms on some brass flat bar:

And drilled and reamed the vane rod holes:

Then I sawed both bits off the parent stock, and with a bit of 6mm rod trough the holes clamped them together in a small vise, then removed the rod and clamped them up with a toolmaker's clamp that's narrower than the workpieces:

The clamp could then be clamped in the mill vise, with the bits lying flat on top, and I drilled a 2.5mm hole trough to tap M3 - this keeps the connecting rod offsets exactly the same for both vane arms:

Elmer's plans use 2mm pins here - cross drilled for using a piece of thin wire as a retainer, but I had enough fun with that method on my Grasshopper engine; I prefer screws and bolts.

I used a bit of rod and the 2.5mm drill to keep the pieces aligned, and clamped them up in the vise so that the center line is horizontal to the vise jaws:

Then drilled the top 2.5m mto thread M3 for set screws:

While I was about it, I just tapped the holes as well:

Next I used some bits 'n bobs to get things set up to mill away the sides:

And off to the big vise to file the rounds; it takes me longer to set up something to machine curves like these than it does to just file them to the line, and where it's a cosmetic feature like here, a file's plenty good enough:

After a quick rub on emery, things look presentable:

The arms needed a bit taken off on the one face of each; rather than set up the rotary table for this, I did it on the lathe:

Arms finished:

And where they fit on the vane; I'll have to shorten the set screws a bit:

Regards, Arnold

 

[bearcar1]

Looking real good Arnold, it won't be much longer until yet another work of art can be placed up on the mantle. (top shelf in the shop maybe? :big

BC1
Jim

 

[arnoldb]

Jim, thanks my friend This one's a bit slow - once it's done it'll join the others on the side-board in the lounge to trap unwary visitors :big::

There's some missing there; I've given away a couple, and others are paperweights in my office. The office ones might join this crowd at home soon though, as I'm at a bit of a turning point in my career and might not have a permanent office in a month or so... Guess I'll have to break out the woodworking tools soon - to build an add-on shelf :big:

Yesterday was a dead loss in the shop; "work" work all day interfered...

This morning I started off with the crank webs - digging through my stock I had a choice between aluminium and bronze in the approximate sizes needed. As the flywheel web is aluminium, I decided on the aluminium to match it; all the linkages will be brass anyway, and I like a bit of contrast. Cleaned off, and drilled and reamed to 6mm:

Next, turned the step on the first web:

And parted of with a bit of oiled 6mm rod in the tailstock chuck to both help support and catch the web:

The second one followed - using the same measurements. I'm slowly starting to get better finishes on parting cuts - it still looks horrible though - I wonder if it's possible to get a really smooth finish on a parting cut ? :

I'll just keep on trying harder :big:

Cleaned up the ugly parting marks:

The webs must be made as a left and right-hand version, and to prevent binding on the engine later on, their crank offsets must match exactly - so I shoved a bit of rod through them held back-to-back, and clamped them together and clamped them flat on the mill vise:

Then I used the edge finder to locate the center line in Y and also the X edge of the pin; then I just dialed in the hole position on the X handwheel - it takes a simple bit of work on a calculator to calculate crank throw - (half the pin thickness + half the center finder thickness) and dial that in . A quick spot with a center drill, and drilled a 2.5mm hole to thread M3 later:

While I was busy drilling holes, I drilled the 2.5mm holes to tap M3 for the grub screws (set screws) as well:

After sitting down and playing around with the set of M3 taps, I had the finished webs:

There's some scuff marks on them; those I'll remove at a later stage.

I did a bit more paint work on the columns, and COMPLETELY stuffed it up :hDe: :rant: :

Hopelessly over-sprayed, and there must still have been some contaminants on there to boot. As the bushes are slightly proud of the column faces, there was only one way to recover; I dunked the lot in acetone and got rid of every last vestige of paint on there, and started anew - right from primer.

While waiting for primer to dry, I started on the valve arm - pretty much the same method as the main crank arms:

Rounding over with facets before filing:

Thinning it down - I used a bit of 3mm rod chucked up in the ER11 collet chuck. Just filed a flat on it for the grub screw to hold onto, and turned it down. You'll see that the grub screw was a bit long, and I'd turned a bit of that away in the process as well:

To get more use from that same grub screw , I just screwed it half-way into a 3mm nut, and with a 3mm cap screw turned in from the other end of the nut to lock up against it, I had enough to hold on to to go to the bench grinder and grind off the excess:

The grub screw was still a bit long, so I plonked it on the end of an Allen key and carefully ground down the other end as well to shorten it further making a slight point on the end:

A bit of work with a fine file and emery, and the valve arm is done:

The bits left to make are getting less now, but some things depend on getting the engine assembled partly to take some measurements. I did start to clean up the two bits of brass plate cut in an earlier post - that's the start of the connecting rods:

: I guess I'd better start putting drill bits back in the index - before they slip into the fourth dimension.

Before I left shop for the day, I gave the offending column another coat of paint; it still does not look great, but I'll let it dry for a couple of days and give it a rub-down with some 1200 emery before a final coat of paint:

Kind regards, Arnold

 

[steamer]

Arnold,

Read through the whole thread...it's clear your a "Faceplate" guy! :bow:


Fabulous workmanship friend!

Dave

 

[bearcar1]

Progressing well A', and it is always nice to see Fred and company once again.

Jim B.

 

[zeeprogrammer]

Howdy Arnold! Very happy to find another thread from you. Always a good read.

By the looks of your mantle you've been a busy guy. And that 'new' mill shows a lot of use.

Looking forward to seeing more and knowing you...that won't be long.

 

[arnoldb]

Thanks Dave - I tend to do some things a bit "old fashioned" :big: ; my face plate is a good bit of kit to use!

Thank you Jim ; the "paperweights" I have in my office will also have to come home now, as I accepted that new job that will leave me office-less :big:

Carl, Thanks - I'm getting to grips with the mill - though it still needs some sorting out; a power feed is definitely in the pipeline, but I must first get my small lathe installed properly as well. LOTS of tooling work to do once this engine is done ;D.

This afternoon I made some small bits. As I mentioned earlier, I'm not going to use Elmer's "pin with hole and soft wire" method for retaining the connecting rods and valve rod. So it was time to start making screws.

First up, a small screw for linking the valve rod with the valve arm. I started with some 4mm silver steel and turned a 2.5mm step on it to match the hole in the crank arm, and then a 2mm step to thread M2:

If you look carefully at the photo, the first section of the smallest step is undersize; I'd overshot and turned it down to 1.8mm - which wouldn't do as that is too small for an adequate M2 thread. It's great for getting an easy and straight start to the thread though

After threading with the tailstock die holder, I turned off the excess 1.8mm bit, and parted of the screw. It just needs a slot:

Next, some 5mm silver steel - turned with a 4mm and 3mm step, and threaded M3:

That was parted off, and repeated another 3 times.

If you look carefully at the previous photo, you'll notice that the 3mm thread does not run to the shoulder. Normally, one would make an undercut there for a crank screw like this, but I'm a lazy rotter and didn't want to grind up a narrow enough cutting bit for the undercut. Anyway, the crank rods need some slight spacing off the webs and crank arms, so I rather set about making some 0.5mm thick brass washers - ID 3mm and OD 6mm.
If one first drill the brass rod and then part off the washers, each is left with a burr on the side that must be filed down; a real pain. So I used a method that leaves much less burrs in a case like this.
I first made all the parting cuts - leaving the core at just under 3mm. The first section was a bit thick ::

Then I center drilled the end, and drilled a 1.5mm pilot hole through - the pilot hole is needed to prevent the 3mm drill from wandering around for the next step. Then I just drilled down the lot with the 3mm drill, and all the washers are left on it with a minimum of burring:

This is what the bunch of washers look like without any clean-up whatsoever:

Next I slotted all the screws - not the ideal setup to do it with, but it worked:

For today's shop session, I ended up with this lot:

Not as much as I'd hoped to get done, but I spent about 1 1/2 hours at one point searching for my ER11 collet closer nut after dropping it, the collet that was in it and the screw that was in that :wall: :wall: I never knew these things were made from rubber; everything bounced all over the show, and not having chameleon-like eyes it's impossible to follow the flight paths of three madly bouncing bits at the same time :
I eventually found the nut - there's an old V6 engine standing between my lathe and mill at this point, and the nut had lodged between the water pump and its pulley:

:big: I've found another entrance to the fourth dimension!

Kind regards, Arnold

 

[AussieJimG]

Thank you Arnold, you have just solved yesterday's problem: how to make a thin washer without that annoying burr on it. This forum is great stuff. :bow: :bow:

Jim

 

[zeeprogrammer]

Nice tip making the washers. They look great.

My favorite 'where did it go hide-y holes' are the cuffs of my pants.

 

[lazylathe]

As usual full of good info!!!!

Maybe for your next project you can build a frame for the V6?
At least that way it will be out of the way!!! :big:

Andrew

 

[arnoldb]

Thanks Jim - that's exactly what HMEM is all about

Carl, thank you - ??? why do you wear pants with cuffs in the shop ? - that's a sure-fire place for swarf to collect and get you in trouble with the better half :big:

Thanks Andrew - That's an old Ford Essex engine... No frame needed; just a long chain to make a boat anchor out of it; I just need the boat as well :big:

Today's bit; more fiddly stuff and making screws.

First a teaser - I had to assemble things well enough to judge how to bend the front connecting rod, as the perspex engine cover is quite a bit thicker than the cover from the plans:

I then bent the connecting rod to match:

The back one was bent to plans, as I didn't change any measurements there.

Then I drilled the big end holes in both rods:

:Sorry - out of focus photo!

Next I located the hole against the vise stop and set the mill x handwheel to zero on location:

Then I dialed in the con rod length on the x axis and prepared to center drill:

After center drilling and drilling through at 4mm on the one rod, I flipped them and drilled the other. This made sure they had exactly the same length hole-to-hole in each even though the are bent. It's crucial to get this measurement the same for this engine.

Next I rounded over the ends with a file, and cleaned the lot up with some scotch-brite:

I turned up the main shaft, and loctited the flywheel to it before taking a bit of a lunch break - that gave enough time for the loctite to cure, as it was a nice and warm day today:

One more part required was the vane seal - I prepared some 2mm brass plate for it, and drilled a 0.8mm hole to retain the spring in it:

I need to buy some smaller drills at some point :

The vane seal was then sawn off from the parent stock, and filed and lapped to size. Elmer specifies some very thin stainless wire to make a spring from. I don't have that, and I was thinking of using a bit of thin high "E" guitar string for that, but I couldn't find the bit I stole off the guitar - till I remembered I used it to repair the cheese slicer. Then my eyes fell on the big wire brush, and I clipped one of it's bristles off and bent that to the spring shape - that's the thin black part in the photo:

The valve rod still needed a hole drilled and tapped M2 for connecting to the valve arm - that followed:

I'd originally intended to use some 2mm all-thread "studs" and nuts to mount the engine top to the body as I didn't have long enough M2 screws for the job, but as everything else on the engine now use slotted screws, that would look a bit out of place. So I chucked some 4mm silver steel in the ER11 chuck, and turned it down to 1.95mm diameter 13mm long, and filed a good cone on the end to allow the M2 tailstock die to start easily Then I turned a short section down to 3mm - that will make the screw head:

When turning down thin long sections like this, it's imperative to hone the toolbit to a very sharp edge on all cutting edges - then lathe max RPM (~640 for my Myford) and a smooth and steady hand feed to keep a consistent thin chip coming off. Works a treat, but seems to take a bit of practice. I need to build myself a box tool like Tel showed.

Thread, part off & repeat 3 more times, and I had this lot - just needs slotting:

: The one on the right's head is a bit big... I forgot to turn it down to 3mm :big:

Easily fixed:

I'm really starting to enjoy the ER11 collet chuck working along with my ER25 chuck like this for small jobs!

I slotted them the same way as yesterday's screws. Next I turned up the steam connector from some 5mm hex brass:

Then I laid out all the bits and started giving them a once-over to remove the last tooling marks and to make sure everything was there:


Regards, Arnold

 

[zeeprogrammer]

Carl, thank you - ??? why do you wear pants with cuffs in the shop ? - that's a sure-fire place for swarf to collect and get you in trouble with the better half :big:

True enough. When I do wear pants in the shop...they don't have cuffs. ;D
But I'm getting shorter and occasionally have to fold the ends up.

That's a fine looking engine Arnold. I'm very much looking forward to the run.
Got your celebratory drink ready? I'm thinking that bottle you showed me some time ago must be gone now. :'(

 

[vascon2196]

Your work is amazing....the engine is looking sweeeeet.....

Chris

 

[arnoldb]

Thanks Carl - Your wish is my command :big:. :-X That bottle is LONG gone - Doctor's prescriptions: Start the course and finish it :big:.

Chris, thank you I hope today's photos are OK!

;D ;D ;D Well, the Kimble is a runner, but it didn't come without a fight. Actually I had it running yesterday evening, but I was too dog tired to get a video and shoot a couple of photos.

After I assembled the engine, I had some troubles with binding.

The way the engine gets assembled is awkward to say the least, with a major fiddly bit being trying to hold the columns with the flywheel, main shaft and valve rod all in place and getting the column mounting screws in place from the bottom - all the while trying not to scratch things and damage the paint. This played havoc with trying to get the bearing columns aligned for the least amount of friction.
If I can provide some advise in this respect for anyone contemplating a build of this engine: Make split bearing blocks! - You'll save yourself a lot of hassle.

I found another source of binding eventually; I couldn't figure out where it was coming from initially; the vane would "stick" on one side - even though I'd taken great care in keeping tolerances close but not tight. I finally traced the source to the one crank arm on the vane shaft; it had a high spot on the rounding that I didn't file down far enough, and that was touching the base at one end of the throw : - a quick lick with a file and some emery cleared that up.

Once I'd gotten all the binding sorted out, I connected it to air, and it would try to run, but only go through three or so revolutions and stop. I tried upping the pressure a bit, and when I got to 30psi I stopped - I didn't want to blow off the perspex cylinder cover. I traced the problem to the timing - and this part was definitely my own fault for messing with some dimensions on the rotary valve. Earlier in the build I'd made a slot in the bottom of the valve to compensate for the holes that had wandered into the engine top - but I made that slot wider than the diameter of the original port hole. As it turned out, the slot would very nearly connect both steam ports at the same time, but once I really fine-tuned the valve on it's drive arm, the engine started running.

OK, enough blubbering - some photos and a video ;D

[ame]http://www.youtube.com/watch?v=WXH6AFwspUw[/ame]

I must say, this was a really fun build - even though it took me a lot longer than any of my other engines before to complete, and to see the engine running is a real treat!

 

[mklotz]

Ausgezeichnet. A truly curious engine and you've done a superb job modeling it. My congratulations.

 

[Blogwitch]

I've never seen one running before Arnold, and always wanted to make one, but never go around to doing it.

Your model is absolutely wonderful and is truly an extraordinary engine.

Very nicely shown and made, a real credit to you.


John