Arnold building the "Little Blazer"

[arnoldb]

With a couple of compressed air/steam engines under my belt, I feel like a foray into the world of flame lickers...
I have quite a couple of plans available, but for most I would require items (mostly small ball bearings) that are unobtainable locally, and hence require running the gauntlet of E-Bay and poor and unpredictable postal services to Namibia.

I nearly glossed over Phil Duclos's Little Blazer because of some of the small screws needed, but then I realised I could make them myself, so I started sourcing raw materials:

Bits of the above will go into the build. The big round piece of aluminium is to make the base from; I can't find a rectangular piece of suitable size, and the feeler gauge will have its one blade sacrificed for the valve spring.

The build was actually started last Sunday; I milled the big round bit of aluminium down to form the rectangular block from which the engine base is to be built First roughed it out to a rectangular block:

Measured and marked up final dimensions:

Finally down to size and as square as I have ever gotten anything...:

Then I calculated and marked out the bit that has to be faced off at a 20 degree angle. Nothing fancy; just some trigonometry to calculate offsets, and draw a line. I used the height gauge on the mill vise to check that I clamped up the block at the required angle:

And faced off with the flycutter:

I used a small file to de-burr the cut edges while still clamped up, and then used an obsolete needle valve chucked up in the dremel chuck adapter to locate the one corner as accurately as possible by eye; Mr Duclos used a wiggler's needle for this step:

The mill's x and y dials were zeroed at this point for the next steps.

I dialled in the 12.7mm offsets needed on both X and Y and spotted the location with a center drill, then drilled about 13mm deep with a 6mm drill:

This was followed by a 16mm drill:

And finally the boring head to get the hole to 17.4mm - I used the 12-19mm telescopic gauge to measure; at the larger end of it's range, it's not entirely necessary to get its handle in alignment with the bore of a hole, as long as it's head is kept square to the bore central axis:

The boring was followed by offsetting the Y axis further to locate the position for the valve rod guide, and spotting and drilling a 2mm hole for the valve rod:

I hope this does not bite me in the back; Mr Duclos specified a #49 drill which is between 1.8 and 1.9mm - and I decided to go for a 2mm valve rod... It will be a bugger to turn up a bushing if needed :big:

Next followed some more markout; a lot of it was just to help me visualize the base and to double-check that things were still going to plan...:

More milling followed; pretty much following Mr Duclos's instructions:

The next photo was originally only intended to show how I use a square in the vise to set up a part a distance from the bottom of the vise when I don't have suitable parallels around, and accuracy is not of the greatest importance. When viewing the photo on-screen however, I noticed some additional details with some valuable personal lessons behind it. Original intent: I have a small flat square with a wide edge on the short end. By putting the wide edge on the vise bed, and pressing it down with my middle and ring fingers, it is held fairly secure to the vise bed. Then I use my thumb and forefinger to squeeze the part to the vertical edge, and tighten up the vise (The milling cutter is quite a way away from my hand and not dangerous here):

Now the anecdotes; there's three here.
1. Just to the right, and slightly above the bottom of the milling cutter is a scar on my hand. That has been there for about 15 years, and the damage was done by my "small" 115mm (4.5") angle grinder. I was making a security gate for a friend and was grinding away my (bad!) welding marks; using the hand in picture to hold the gate, and my right hand to run the grinder. I was getting tired, and it only took a minute lapse in concentration and the cut was done; it could easily have been much worse, but fortunately not. I have never since worked my "small" grinder with one hand only; the work gets clamped down, and both hands works the grinder. If I feel I'm getting tired, I stop - a grinder tires one out quickly.
2. If you follow the very top of the square from left to right, about a quarter of the way just above the edge there is a small scar on my hand. That was done by a thin Dremel cutting disc breaking; my hand happened to be in line of the disintegrating disc. Personal lesson learned; keep as much as possible of body and soul out of the spinning line of stones and discs - even a small Dremel needs to be treated with respect.
3. To the left of, and below the top of the square, there's a scratch on my finger. Shrek the African Gray parrot did that this morning; he was in a bit of a bad mood. Lesson - animals (and people!) have bad moods; these I just have to accept in the spirit of love

Enough digressing and back to the build.
Once again the impromptu center finder I mentioned earlier comes into play to locate the center for the rounded bottom "inside curve" of the base:

Though it looks like I'm only working to one line, there is a tiny prick mark left by the compasses when I did the last layout. If you don't believe me, click here for a bigger photo.

A 6.5mm hole was drilled, followed by a 19mm (my biggest!) drill:

I was concerned about the big drill doing an interrupted cut, but as quite a lot of its tip had to follow the pilot hole, things went well. The drill was still under size, so if it strayed a bit, there was not too much of a concern.

The 19mm hole was then opened up to 22.2mm with the boring head:

Up to this point, I've been fairly brutal with the workpiece - taking fairly big cuts at good rates of feed. For the next phase I slowed down a bit, as workholding was becoming less secure. After de-burring, I started by using a square to set the workpiece vertical to the angled face in the vise; once again using the method with the square - and - fingers mentioned earlier, with the centerline of the bore from the previous step above the vise jaws, and some old business cards between vise jaws and the workpiece to get things as tight as possible. Then I milled down the back to meet the bored hole - as the face end is getting thin and high above the vise, I took just 1.5mm down-cuts at a time staying away from the final thickness:

The other side followed:

Milling down the "step" in the base proved problematic for workholding. As the workpiece was getting whittled away, there were less - and more irregular - features to clamp down. I _COULD_ have mounted my mill vise's swiveling base, but getting everything in tram would have required a lot of fussing about. So I gambled on a "back-to-basics" method. I clamped the workpiece directly to the mill table with thick bits of paper between it and the mill table, as well as between its top and the clamp. Once again I used the small square with the offset base to align the face:

The single clamp point is far from ideal - but I didn't want to clamp through the bored hole in the face, as clamping there could distort it...

Then started milling away - lightly. Several passes in Y to get to depth, offset X and repeat the Y Part-way through:

Before I hit final dimensions, I checked with the square again - just to make sure nothing moved. It didn't

Before removing more metal from the base, I decided to drill and tap the mounting holes, as well as the mounting hole and screw-down for the retainer clip for the burner:

And tapped that lot - all M3 instead of 1-72 and 2-56; I deviated from the plans a bit for "comfort" :big::

At this point, and about eight straight hours from starting the day's machining, my cellphone rang. I tried to answer the workshop electronic calculator... - That seriously meant time to pack up; I don't want any more scars. So, no more machines, but I still wanted to do a bit more...

The base needed rounding over around the cylinder mount. Mr Duclos does that using a rotary table on the mill. Filing buttons would do as well, but machining was out for me at this stage, so I deeply scribed the curve using a conveniently sized bit of rod as a guide and trimmed the excess off with a junior hacksaw. Then filed roughly to the scribed line with a big coarse file:

Followed by my favourite "smallish" file - down to the line by eye and judging "squareness" by eye as well:

Took all of 5 minutes to saw, coarse file, and fine file down; would have taken longer to turn up filing buttons!

A quick "lick" around the filed edge with some emery wrapped in the self-same rule in the next photo, and that's where I packed it in for the day:

I've actually had a very active day in the workshop; it feels like I've been to the gym from just contorting to check angles for holes and so on. And of course, cranking the mill wheels - lots of exercise there! - :big:

This was a bit of a marathon post; I value all questions, input and criticism!

Regards, Arnold

 

[doc1955]

You're off to a really good start looking nice!
This is where I get my micro bearings they have a good selection and prices are pretty good.
VXG.com Bearings

 

[ozzie46]

Looks good Arnold. I know what you mean about getting tired. Thats when I make my major mistakes. :wall: :wall: Know when to quit. Theres always tomorrow.

Ron

 

[arnoldb]

Thanks Doc - I appreciate the link :bow:; they have some really nice bearings in metric sizes!

Ron, thanks We all learn the hard way!

Kind regards, Arnold

 

[cfellows]

Lookin' good, Arnold. Since I have one of these underway, I'll be watching. I've got the frame and cylinder done. The piston is mostly done, but I still have to make and fit the innards. Getting a good sliding fit between the piston and cylinder was a bugger, especially since the cylinder is closed on one end.

Chuck

 

[arnoldb]

Thanks Chuck - Yes; I also foresee a couple of problems with the cylinder fit... The most important bit of the cylinder is toward the crank side, and it's going to be too easy to have that section too big. I'm expecting to have to do quite a bit of lapping as I did not get a great finish on the bore today :-[

On to today's bits.

Phil specifies the clamping screw on the collar as a 1-72 cap screw; I don't have anything that small, so I settled on an M2 machine screw. Head clearance for this screw is 4mm - and the collar is 4.7mm wide; that leaves 0.35mm either side; loads of space :big: - as long as I could pull it off accurately.
I used the sharp pin to locate the edge of the vise jaw on Y, zeroed it and dialled in 2.35mm offset. Then I located to the center scribed line for the X and locked that:

Then with a 4mm center-cutting slot mill, very gently bored down to 1.5mm above the depth mark:

Next followed a small center drill - just a shallow hole with its tip:

That was a guide for the 1.6mm drill that followed - about 10mm deep for tapping M2:

A 2mm clearance drill followed; just 2.5mm deep, and then I tapped the holes - still in position, but with the collet holding the small drill arbor loosened to allow the arbor to rotate and slide in it. I just chucked the tap in the drill arbor and twirled the shaft with my fingers to tap the hole; it does not take a lot of torque to thread M2!:

As a final step, I slit the collar with a 0.5mm slitting saw:

Some more layout followed:

I used a 10mm mill to clear the big bit of excess away - just by eye to the lines, making sure that the bottom met the curved section in the base nicely:

To mill out the section between the two bearing columns, I had to revert to a 6mm mill. The 10mm is too big here, and I thought I had an 8mm long series. Well, so much for "thought" : :

:wall: Notice the ding on the top of the collar ? - :-[ - I forgot to check clearance for the collet chuck and left too short a bit of the cutter sticking out, so I ran the collet chuck into the collar... Fortunately not to bad; the chuck lost some black off it's closing nut, and the ding was very shallow and easy to file away. I just hate that sudden extra "grrrr" noise!

Then I milled the back end to 10 degrees as per plans:

For laying out the center line for the crankshaft, I needed a plug turned up to fit closely in the collar. This calls for a "scrap" bit of "something - but I couldn't find any, so I used a good bit of aluminium. It was really nice to get back to the lathe for a change ;D :

That piece was then just parted off and clamped up in the base collar. Phil recommends clamping the base to an angle plate for the next step; I don't have one, so bodged it by holding the piece against a square with the base edge firmly lying on the glass plate. Then get the height at the top of the plug, subtract its radius, set the height gauge to that, and scribe the center line on the one column:

It looks as if the base is not sitting with it's one edge flat on the glass plate in the photo; that's an optical illusion.

The other "crossing" center line is easily marked from dimensions, and this is the result:

The piece was then set up squarely in the mill again, and the axle bearing holes drilled at 2.9mm for reaming out to 3mm later. At this point it was 14:00 and my elderly neighbours like to take a Sunday afternoon nap. Their bedroom is very close to my shop, so I shut up with the machines for a while, and brought out the small needle and riffler files to clean up the base a bit - after I used a larger file to round off the one sharp edge and the tops of the bearing columns:

A while later, and after some 320 emery followed to get a brushed finish, I ended up with this:

Well, while posting up I noticed it's not quite good enough yet; the one bottom mounting hole came through the base between the pillars :-[ - so that needs to be fixed. And as always, one sees some more places that requires finishing off - the camera is pretty good at showing those up!

Once I heard the neighbours were awake, I started off on the cylinder. A bit of 30mm cast iron - faced off and center drilled:

Then turned down to 1", and cleaned up a bit with emery:

The neck turned down and a trial fit to the base; it had a bit of a step at the back that needed further relieving, so it appears a bit short:

Turning the fins on the cylinder was a no-brainer; much to my surprise ;D I thought I'd have to make a turning bit, but found one among my assortment. BONUS - it was already sharp and suitably profiled for cast iron And its tip was 1.6mm thick! - Well I needed 1/16" - 1.59mm. That half a thou won't make much of a difference And another bonus; my lathe's leadscrew is 8 TPI, so one turn per fin; no messing with numbers! Fins started:

And done - 15 minutes later:

It took longer to get in there with some emery to get a bit of shine showing up in the bottom of the grooves than it did to groove them :

Then I bored the cylinder... I'm not entirely happy with the finish inside, so I suspect a lot of lapping will be required later. Not sure though, as cast iron is deceptive. Brass and aluminium will machine to a mirror finish indicating that it is smooth, while cast iron can be very smooth and still look dull...:

I parted off the cylinder .5mm over length for clean-up - then chucked it with some paper to protect the finish on the fins, and cleaned off the back side:

The cylinder to this point; I quit while I was ahead today :

And assembled thus far:

I don't think there will be any progress during the week; so most likely next weekend only.

Thanks for checking in!

Regards, Arnold

 

[swilliams]

Fantastic progress Arnold. Looking very nice

Steve

 

[metalmad]

hi Arnold
very very neat

 

[arnoldb]

Steve & Mike - Thank you !

Kind regards, Arnold

 

[kustomkb]

Looking good Arnold.

Some very nice parts you have made.

 

[cfellows]

I had to work on the bore quite a bit on mine to get it smooth. I'm not experienced with lapping so I tried using my 3/8" boring bars with soldered carbide tips but couldn't get a smooth finish. So, I bought a new, 3/8" boring bar with a TCMT insert with a small radius on the points. Taking off about .002" per pass, I got a smooth finish, but the finished bore is about .030" oversize. As a result, I didn't mill the flat on the outside of the cylinder quite as deep as Phil had put in his design. However, I think the result will be OK. I made a piston from steel and it is an easy sliding fit all the way down the bore but bounces back pretty well when seal off the hole with my finger. I've never had very good luck with flame lickers. Don't know why I keep subjecting myself to this kind of torture!

Chuck

 

[doc1955]

Arnold you are really moving along and it is looking excellent!






May I ask where you acquired the drawings for this model?
I seem to remember seeing this one somewhere but can't remember where. I know eventually this is another I would like to build. Was it featured in the Home Shop Mag back a few issues? I have all the issues going way back. That magazine is what really got me started in model engine building.

 

[arnoldb]

Thanks Kevin - nowhere near the looks of your engines though :bow:

Chuck , thanks! - This is new territory for me, so a new kind of torture :big: If I made the cylinder from ali or brass I would have had a mirror finish in the bore... I left mine at 10 thou under size, so theres a bit of room to work. I don't think you'll have problems with your outside flat, unless you also did what I did and have a thicker valve rod - then clearance can get to be an issue. As it is, I may have to make my cylinder flat a bit deeper than planned just to compensate for the thicker rod I'm using. I'm really out on a limb on this build; it makes the steam engines I've done so far seem extremely tolerant of dimensioning changes - except for the Elbow engine that is!

Thanks Doc I don't know about HSM for the plans; These are from the book "Two Shop Masters" by Frank McLean and Philip Duclos. I don't have access to any HSM's; don't get them here in Windhoek :'(

Regards, Arnold

 

[doc1955]

Thanks Arnold!
I've been debating on purchasing that book now I know I will be putting it on my Christmas list.

 

[arnoldb]

Pleasure Doc - Lots of nice goodies in that book!

Some more progress for today

I clamped the cylinder lightly (to prevent distorting it) in the mill vise on top of one of my crude parallels. Some cardboard serves to both protect and to ensure a better grip. Then I used the height gauge to find the top, made a note of the reading, and marked out a line to depth for milling away the port face:

Of course, I first cleaned the mill table well of any swarf in the area where the base was located before doing this!

Then I milled away the port face. As the cylinder was clamped lightly, I milled away the face in small increments; 0.5mm max depth of cut a t a time:

All the passes were done in line with the cylinder bore to prevent it trying to rotate in the vise. When I got close to the scribed line, I checked again with the height gauge, and fed in the last required amount using the Z handwheel scale. As this pass was very light, I opted to do the last cuts perpendicular to the cylinder bore, as it would make it easier to remove the tooling marks later. As a final step, I also milled the clearance flat for the valve pushrod.

I very lightly marked out the location and size for the valve port with the cylinder still clamped:

Very lightly, as I didn't want deep scratches to have to remove later on!

I went to my engineering suppliers this morning, and returned with a couple of new bandsaw blades and some milling bits, and while there something kept tugging at my mind and wouldn't quite surface. At this point it did : - I needed a 3mm milling cutter for the valve port, and I didn't buy it... 4, 6, and 8 mm, but no 3mm oh: By then the shop was closed as well - So I settled on using the 2mm cutter I have, and milled the port - widening it to 3.2mm with a couple of edge passes:

While milling the port another thing raised its head... I'm a pretty easy going person, but one thing I HATE is squeaks. And the mill's y-travel handle had started to squeak - deep in the inside :rant:. I removed it, and tried getting some oil in there, but it just wouldn't go down and stop the squeak, so, on to the lathe, and drilled a hole into it from the other end:

A drop of oil in there, and squeak sorted ;D It's a pretty crappy plastic handle, so I just might make a nicer metal one in future.

Back to the build... I have the princely sum-total of 2 slitting saw blades; one 1mm thick, the other 0.5mm thick, and fortunately both of the same diameter.
Ganged together on the slitting saw arbor, I could slit the head fins with a 1.5mm gap instead of the 1.6mm called for in the plans. Phil's plans actually calls for slightly thinner fins on the head than on the body, so this is fine; except that I made a slight miscalculation, and instead of keeping the original spacing called for and making the fins slightly thicker, I decreased the spacing to keep the fins to dimensions... Silly me; that left the bottom fin a bit on the thickish side :-[:

Next I removed the cylinder from the mill, and flat-lapped the port face using different grades of emery on my glass "surface plate" to get rid of the tooling marks, making very sure that I kept it very flat. It wasn't a lot of work; just a few strokes each on 320, 600, 800 and finally 1200 emery, and ended up with this:

This is one of the nicest surface finishes I've ever gotten on cast iron; and now I know it is possible to get CI to a near-mirror finish!

On to the piston, and for this, I brought out the best in my minimalist arsenal of tools; my prized Moore & Wright micrometer and Mitutoyo telescopic gauges. My one sister gave me the M&W many years ago as a gift, and I have never used it much. The set of telescopic gauges I bought last year in a "Cash Converters" shop for the then equivalent of US$10. And they are not fakes... Once in a while one gets VERY lucky ;D. I'm digressing :-X
I set the telescopic gauge to the cylinder bore, and used the micrometer to check the reading; three times over to make sure I had no errors, and then another couple of times just to be 100% sure. I did pick up a slight tightness mid-way along the cylinder bore using the gauge; that's a problem to sort out later:

On to making the piston; I turned the piece of phosphor bronze I have for it down to just over size on the OD, and then drilled and bored the ID to the required size:

Then I finished off the OD of the piston to 0.005 mm (that's a quarter 'thou give-or-take) smaller than the bore of the cylinder as measured earlier - using the micrometer to check. I have gotten into the habit of working accurate to 0.01mm on my lathe; this was really pushing the envelope for me, so I used my HSS cutting bit as sharp as I have ever been able to hone it, and I was careful to keep a consistent feed while doing the cutting. I used the compound slide set over to 30 degrees to dial in the final cuts; there's quite a bit of reading material on using this method available. Then I parted off the piston; the threaded rod in the tailstock chuck is just to keep it from ending up in the swarf heap:

:wall: :wall: I'd done well up to now, but forgot one of the most important things I'd learned while making and then parting off pistons oh: - The parting off raises the metal next to the parting area :-[ - and I didn't pause to clean that up while parting, or even better, do a partial parting before turning the piston to size.

Fortunately I did leave the piston slightly over-size, and would need a mandrel to finish it off together with the cylinder bore. I left the "left-over" phosphor bronze I used for the piston in the 3-jaw chuck and removed the chuck from the lathe; if needed be I could make another piston from that. Then I mounted the collet chuck, shoved a bit of 12mm aluminium in it, and turned it down to a light slip-fit for the bore of the piston. I then used a center drill on the end of it, to allow clearance for the revolving center, and slided the piston over the aluminium, and used the center to nip it up in place. Then I used a rule with emery to get rid of the high spot on the parted-off side of the piston:

Next I removed the piston, drilled for and tapped an M2 thread into the aluminium arbor, and screwed down the piston on it:

I mixed a couple of drops of thin oil (3-in-one) and some metal polish ("Brasso"), covered the lathe ways with absorbent paper, and coated both the piston and cylinder bore with this mixture.

PLEASE DO USE GOOD SENSE IF YOU TRY TO DO WHAT I DESCRIBE IN THE FOLLOWING SEQUENCES - note I say "good sense" and not "common sense" - last of which is unfortunately worthless nowadays IMHO. With the lathe running at a low speed (on my Myford I chose back-gear medium speed), I started lapping the cylinder onto the piston using the oil-and-polish mixture - with the cylinder lightly gripped in my right hand and moving it up and down the piston, and my left hand on the lathe clutch to stop the lathe if something went wrong. Don't try to use just metal polish; it dries out and will tighten up; the oil added to the mixture helps to lubricate it. And if things tighten up, release your grip on the cylinder first, and then stop the lathe.

There was not a lot of lapping required, but the tight spot I mentioned earlier in the post while measuring the cylinder was still there (easily felt by a tightness requiring a bit more holding torque when moving the cylinder over that point), so I chose a quick-and-dirty fix for that.
A proper lap would be the best way to go, but I sawed a slot on the mandrel to hold some folded up 800 grit emery trimmed to size to lightly fit the bore of the cylinder when wrapped around the arbor.:

I shoved the cylinder over that, moved it over to where I'd judged the tight spot to be, and started the lathe, once again holding on to the cylinder with my right hand and moving it side-to-side a little bit. Just a couple of rotations of the lathe to run that tight section in a bit, and I was done with the more dangerous stuff. A video to break the monotony, and show how the piston fits the cylinder:
[ame]http://www.youtube.com/watch?v=cYymhGpVKfk[/ame]
OK - End of risky sequences

Next I started on the wrist-pin bracket. This one called for aluminium as well - I'd originally set out brass for it, but with the weight of moving parts on this engine playing a major role, I changed my mind and used aluminium. I have some 5mm aluminium rod scavenged from old UHF TV antennas, but that is horrible stuff to machine, as it is extruded soft ali. As I have been extravagant on wasting aluminium on this build thus far, some more wouldn't matter anyway, so I flipped the bit of 12mm I already had in the collet chuck from doing the piston to get at the un-machined end, and turned it down:

I just used the step-turning to prevent flexing; though the whole lot could have been done in one go. The tip is down to the correct size, with some room for machining left on the thicker bit.

The front bit needed to be slit for the connecting rod - and with some more machining in the lathe to come after that, I took the plunge, and unscrewed the lot - chuck-and-all from the lathe, and lightly clamped the collet chuck in the mill vise. When I built the collet chuck, I left it chunky, so I don't think it will distort from getting used in this rather unconventional way:

Then I slit the ali for accepting the connecting rod - specs show 1.6mm, but I did it at 1.5mm:

And cross-drilled for the wrist (gudgeon) pin:

Back on the lathe again, and I just used the rear parting tool to trim the lot down to length, and with a 2mm diameter back end - to get threaded later:

After final parting off, mounting in the collet chuck to thread the shaft M2 with the tailstock die-holder and a bit of clean-up, the wrist pin bracket was done:

;D I was surprised; this is a fairly small part and it came out OK without any hassles!

The valve pushrod followed; nothing difficult; just a bit of 2mm bronze brazing rod - threaded M2 at one end:

And with a flat filed free-hand on the other end for a grub screw (set screw):

One valve push rod done:

With a bit of time left in the shop, I started on the connecting rod - marked out some ali:

Drilled for the big- and small ends:

And milled to size on the accessible sides:

I used a slitting saw to trim it off the parent stock:

When it started to wiggle around - JUST before it was fully parted off, I stopped the mill, and broke it off by hand. Saves one from having to search for a part tossed across the workshop on final cut-through :big:

Some filing was required; I could have done more to it on the mill, but setting up sometimes takes more time and energy than a bit of judicious filing:

Connecting rod done; I'm not entirely happy with it as I over-filed some spots (So much for "judicious" filing :) - but it should do for now:

For anybody that reached reading this point in the post, - :bow: Darn, I admire your persistence, as I was starting to bore myself!

In a nutshell, the results of today's efforts:

I hope to get a bit more done tomorrow

Regards, Arnold

 

[winklmj]

Looking great! That is one shiny cyl.

 

[arnoldb]

Thanks Mike

I didn't get as much done today; which makes for a shorter post for a change :big:

Following Mr Duclos's instructions I turned a piece of aluminium stock down to the outer and core diameters for the combined crank web/cam:

This was followed by drilling the center 2.9mm and reaming it out to 3mm for a fit on the crankshaft.

Reading through the steps required to machine the cam on the mill and rotary table, it seemed (and was!) a good idea to make up something that I could clamp in the mill chuck for centering purposes. Seeing as the crank shaft would be ideal, I cut that off from some 3mm music wire I have. The Dremel and a cutting disc works great for this; the music wire instantly blunts the junior hacksaw blades I have : :

I then centered the rotary table to the mill spindle, clamped up the workpiece in the small Myford milling vise, and used the shaft chucked up in the small drill adapter to center the workpiece-with-vise combination on the RT - with the RT set to 0 degrees. When I built the RT I took great pains to make sure that the T-slots were exactly on 90 degrees apart and the one on 0 degrees was just that. So I used the edged square shown in a previous post with the edge located in a T slot to set the vise square, and clamped a bit of flat iron down against the top of the vise to keep the reference Phil mentions in his write-up:

Then I just followed Phil's instructions and dialled in the offset needed on the Y axis, moved the vise against the clamped down reference bar, and used the shaft-in-chuck to locate the final spot to clamp down the vise. Then milling the cam profile was easy - though I did get the milling depth slightly too deep and ended up scarring the lower workpiece face :-[:

Fortunately the scar is not as bad as it looks; it's mostly a burr... That 6mm milling bit is getting a bit blunt!

It was easy to set everything back to "0" after milling the cam, and then to dial in the 43 degrees counter clockwise on the RT needed, and then dial in Y to depth to locate, drill and tap the connecting rod screw-hole:

The workpiece was then removed from the RT, and parted off from the parent stock on the lathe. I wish I'd read the instructions trough to the end again before doing this, as I could have saved myself a lot of work later oh:. Phil mentions at this stage of his instructions that you have to leave "sufficient" extra stock on the back of the workpiece to later clean up... So I left 1mm extra and parted off...

A bit of a diversion followed; the parted off workpiece had to be clamped to the RT again to mill out the webs. I do not yet have a good selection of bits 'n bobs for clamping to the RT; my mill's clamping kit is waaay too big. The RT's T slots are the same size as my lathe's, and I always just used 6mm cap screws of appropriate length and home-made T nuts to clamp things on the lathe's vertical slide. I couldn't find a suitable length cap screw today, so I had to use a bit of high-tensile threaded rod. One thing I did not do in my more inexperienced making of said home-made T nuts, was to prevent anything screwing right through them - as an arbitrary length of threaded rod would do, so a quick-fix was called for. A chisel, a hammer, a T-nut clamped upside-down in the big bench vise, four quick blows, and the result:

Now a rod or bolt won't screw through past the end ;D

I laid out the back of the workpiece, and an odds 'n ends clamping session on the RT followed, using the shaft-in-chuck to make sure the shaft-hole was on center:

No super-accuracy was needed for this step, but parts do look better if accurately made, so I took a bit of time getting it just right.

Then I milled out the web; 6 degrees offset On the RT for each side, and to the lines:

To drill and tap the web for an M2 set screw, I clamped it in the mill vise, and used a bit of 2mm brazing rod chucked in the small chuck to locate the hole:

There was not enough clearance for a center drill to get in there, so I used the 1.6mm tapping drill to make a little dent to act as starting point. With the mill stopped, lightly press it down on the workpiece, lift of, turn the chuck 180 degrees by hand, press down slightly harder, lift off, turn the chuck 90 degrees, lightly press down again, turn another 180 and press down slightly harder again. Lift off and start the mill, and drill the hole; the small drill bit will hit the correct spot using this method most of the time without wandering, as the light dent in the workpiece serves as a center mark.
I drilled the 1.6mm threading hole using this method, and then tapped it M2 for a set screw.

Phil notes at this point to chuck up a suitable rod (or turn one down) to 1/8" (3mm in my case) and make a flat on it, and then mount the workpiece on it, locking it down with a set screw through the threaded hole made in the previous step, and to face off the the back of the workpiece to get it to an overall thickness of 1/4" (6.35mm). I tried that and it was no fun at all... This is on an interrupted cut with a puny screw trying to hold on... And remember I left 1mm extra to face off oh:. When the workpiece came loose from the shaft the second time, I went to plan B - which was to wrap a bit of paper around the cam, chuck it up in the 4-jaw chuck by the cam; just roughly on center, and face it off to thickness:

.
Had I read the instructions up to this point, I would have parted off to just 0.01mm over size initially, and just removed the toolmarks on a bit of emery; that would have left the workpiece perfectly on size without a lot of additional faffing around.

After a bit of filing to round corners and some work with emery to clean up, I ended up with this:

The crank/cam took quite a while to make, as I expected, so shop time was running out for today. I did manage to get some additional small bits made though.

The crank pin bushing - 2mm ID, 2.48mm OD and 4.35mm long:

Followed by a 2mm bolt from some 1/8" brazing rod, and a little retaining washer:

I will most likely re-make the bolt from silver steel; it just occurred to me that it will experience quite big forces on it when the engine is running!

At least, things are starting to resemble an engine now ;D:

Regards, Arnold

 

[arnoldb]

We had a public holiday here in Namibia today, so I had some shop time.

First order of the day was the cam fork - a straight forward milling job to get to size:

And after sawing off from the parent stock, drilling and tapping and a quick rub over emery:

Then I made the cam roller:

This is the second one I made; the first one went on a flying trip while I was trying to clean up burrs - I just heard it hit a wall and something metallic; didn't even see where it went... At least the shop monster got a bit to eat :big:

A little M2 bolt followed to act as roller pin - just some brass threaded rod turned down, threaded, and the head section filed to a hex while on the lathe:

Then I had to re-make the cam roller again : - I made the original one 3/16" and when I started putting things together, it looked way too small. Misread the print; it was supposed to be 5/16"! Parting off on the lathe no longer intimidates me like it used to, but on these smallish bits I always end up with quite a big burr that have to be removed from the parted face afterward. I tried something different for this one: before drilling the center hole, I parted it to just under the drill size, then center drilled and drilled the hole to size. Works a treat; I ended up with the roller sitting on the drill and only a very light burr:

The finished fork with the roller installed on it:

While posting, I happened to notice this photo was the 2000th one taken with my current digital camera - and I've only had it for about a year. A quick calculation, and it has paid for exactly half of it's purchase price in saving on having 35mm film developed!

The valve plate needs a 0.28mm slot cut in it, and Phil very kindly describes making a small slitting saw for the job. I deviated slightly from his design, but used the same principle. First some 12mm silver steel turned down on the lathe; the section closest to the chuck I just cut using successive parting cuts with the rear toolpost, and then slowly and lightly faced the front section down to obtain the correct width. A very sharp HSS toolbit made this a no-brainer though I was a bit apprehensive of machining to such a thin width initially:

Then some delicate-but-rough-looking milling on the rotary table followed. The first person to spot the boo-boo I made has a choice of one of two prizes:

The prizes to choose from are a) an under-water hair dryer or b) a steam loco catching kit consisting of a bag of charcoal and a bear trap :
Fortunately, my mill can run in reverse....

I very gently filed cutting clearance behind the teeth, and then hardened the cutting teeth by heating red hot with a blowtorch and dunking vertically in oil.
For this cutter, I didn't bother to temper afterwards; it did not come out quite as well as I would have liked, so will most likely be a single-use one for brass only.
I then started work on the valve plate. Some brass, carefully milled down to size:

And then used the cutter made earlier to slit the top - worked a treat ;D:

After using a bigger slitting saw to separate the valve plate from it's parent stock, it was just clamped by the protrusion in the middle, and milled down to the correct thickness of 0.3mm:

A bit of clean-up, and careful flat-lapping of the face (to remove toolmarks and get it really flat and smooth) followed - and that's the valve plate done:

I noticed something interesting while doing the flat-lapping. Normally I can see the lapping starting to take effect very slightly on the outside edges first, but on this one, it started in the middle and took quite a bit of lapping to reach the outside edges... I think while milling the bottom flat, the milling cutter bent the thin outside edges slightly down. Just a tiny detail to consider in future....

At this point my woes really started... I had the bit of 0.1mm feeler gauge to make the valve spring plate from. Mark-out went easy and a pair of tin-snips made short work of trimming it down. Then I had to consider drilling a 2mm hole in it to fit on the valve pushrod. Thin plate and drills don't go well, so I sandwiched it between some aluminium scraps clamped with a toolmaker's vise:

Drilling went well, but I could feel that this feeler gauge plate was something different; it was tough to get through with the drill...

When I tried bending it, this happened:

:wall: - this steel plate does not like bending...

That was the only bit of 0.1mm plate I had... The off-cuts are too small to use, but I used the busted bit to do an experiment; I tried bending it around some 1mm rod, and that went OK:

Except, when I tried the minutest adjustment after the original bend, it promptly snapped again.

I tried bending it while heated red-hot with the pencil torch; same result. I had a closer look at the feeler gauge set this came from, and it's made by Gedore in South Africa - pretty good quality kit - hence good quality, but frustrating, steel in this case. I thought it was a cheapy set of imports; what a waste of good tooling. At that point I decided to call it a day and have a good sleep over what to do next for the valve plate spring. Besides, it had started raining and rain is best appreciated sitting on the stoep (porch) with a very cold beer in hand.

Regards, Arnold

 

[arnoldb]

;D It helps to sleep over problems...

This morning when I woke up I knew where to find some plate that should work; amongst the scrap from the old dot matrix printers that I'm stripping for parts. I found a bit that was 0.12mm thick - and appears to be stainless steel:

The third time round making a bit goes quick; a couple of minutes later, I had the valve plate spring:

All set up for silver brazing; I squashed a tiny bit of flux into the groove before fitting the two pieces together:

Poking at this lot with a thick silver brazing rod was hairy, but I got the job done - sort of. After some cleanup:

Next I raided my acoustic guitar for its high E string - Its been years since I played it as I tend to hurt my ears - and started making springs; something I've never attempted:

I made a booboo on this one; I need a compression spring, not a tension spring; but it was good practice. The spring's internal diameter must be just over 2mm in my case, so I used a 1.5mm drill bit chucked in reverse in the pin vise. The start of the wire was just squeezed between the jaws of the pin vise with a sharp bend to get started, and I turned the chuck manually by left hand - while just keeping tension on the wire and guiding it with my right hand.

After making a compression spring, I had this:

Not the most beautiful - but functional. It would have benefited from a proper guiding setup instead of just trying to wind the spacing by eye...

Next call of the day was the flywheel. Roughly trimmed down to size on one side:

The boss in the center is called for in the plans; I nearly missed it - and would have had to make a spacer later on if it was not there.

When I built the Grasshopper engine, I made up this double-sided tool for doing undercuts in flywheels :

Flipped around, and the other side done. For now, I left the excess on the outside, and only after I took this photo realized I had not completed the hub:

On to the RT on the mill; some 8mm holes drilled:

And then milled further with a 10mm end mill:

Back to the lathe, and this time with some suitable short stock chucked in the 3-jaw, then press the flywheel against the jaw faces with the revolving center - and with a bit of cardboard in between the wheel and jaws to provide friction. Turning the rim to final size was then a breeze:

Then back to the mill to spot face, center drill, tap drill and thread the hub for a grubscrew:

I needed some M2 grub screws... Some bits of M2 threaded stainless steel were slotted 0.5mm for a flat screwdriver:

I just used a junior hacksaw to saw them off after slotting while still held in the vise.

Hmmm, let's see now.... Going back through the plans, there's little check marks next to all the engine parts, and I made the additional ones I needed... Al that's outstanding is the base and burner. Some assembly followed, with some careful adjustments to work out a couple of tight spots, and a test with a recalcitrant pencil torch that does not want to stay lit with a smaller flame:
[ame]http://www.youtube.com/watch?v=e5IBDqiNznU[/ame]
woohoo1 - it's alive; not very well yet, but a good sign ;D
I'll try and finish the base and burner tomorrow and get it running properly

Regards, Arnold

 

[mklotz]

Well done, indeed, Arnold. You just keep racking them up.

Isn't it amazing how fast these little devils can run? When you consider the heating/cooling cycle that is occurring with each revolution, it just doesn't seem possible. I see that yours has the same banshee whine that mine has - almost like a turbine spooling up.

The start of the wire was just squeezed between the jaws of the pin vise with a sharp bend to get started, and I turned the chuck manually by left hand - while just keeping tension on the wire and guiding it with my right hand.

Do me a big favor and build yourself a winding guide before you make any more springs. Spring winding is one of the more dangerous things one can do on a lathe and I don't want to read about any new scars or injuries you've acquired.

All that's really needed is two thickish brass washers on a bolt. The wire is trapped beneath them and a Nylock nut is used to squeeze the washers together to provide tensioning.