Radial progress

[makila]

I have put off posting this engine on the forum as there has been several recent good threads detailing the same engine. As I was inspired by this site to build an engine, I thought it would be ok to share with you all my progress to date.

The progress so far is illustrated in the pictures. I had built a substantial amount of bits and decided to make the stand, this meant assembling the cases and some of the internals to get a good idea of the appearance and dimensions of the stand. I never liked the hockey stick stand as per the drawings as they did not look authentic enough and a tubular truss would have meant a fire wall design so I went with some 6061 t6 sheet/plate and 'rolled my own'. The cylinders are held in with some ptfe tape wrapped around the skirts so they don't drop out, just for effect.

It all has to come apart again to fit the crank etc. But I had to see what it would look like with the prop, held in with a pencil! The cam follower guides have not been pressed in yet, but look cool sticking out.

Jobs completed are... Cases, main bearings, cams, oil pump, sealing plate, impeller, air-guide, cylinders and distributor. The crank, rods, pistons and compression rings have been done but require matching and fitting. The drilling of four taper pins in the crankshaft will hold the assemblies together, one of which will have to riveted in-situ with less than ideal access. Once all the internals are done, I will start the heads, still some way off yet.

As far as the build is concerned, I think the heads might be this engine's nemesis. They look quite complex and having 9 to build (plus 1 to practice on) seems daunting enough, not to mention 18 valves and seats etc.

My tool set up is all manual and, just as many have here on the forum, not the best equipped shop, but I enjoy the time spent in the workshop even though it's not as frequent as I would like.

Progress on the engine will be quite slow as I work away frequently in the summer months, so will not be able to post progress too often. Here are some pictures of the present status.

Steve

 

[Swifty]

Great job so far Steve, you have done very well with manual machines.

Paul.

 

[mayhugh1]

Makila,
Really nice job. I especially appreciate the extra effort you took to clean the unneeded features off the rear cover casting and then to polish it. First rate. The head milling fixture for the heads is well thought out, and it will be your best friend during the head fabrication. Take care to make it as accurately as you possibly can; and the head machining, although tedious, will follow. No one tires of seeing radial builds. Don't be bashful about showing your progress. - Terry

 

[makila]

Thanks for the comments Paul and Terry. Yes, I did polish off the two bosses and would have polished the rear case casting further but there are a number of deeper pits that might have caused a material thickness/strength issue so it was prudent to stop at a tidy finish rather than go for a mirror all over.

The heads will of course be last parts fabricated. I will need to make a back plate for the angled tool so it attaches across the base much better than hanging on a 3/8 thread.

I have posted a couple of pictures from some of the stages of fabrication. It all started with the major crankcase assembly and here is a picture of it just about fitting in the lathe's chuck on day one. My largest drill was 5/8 inch which only reached half way across the material and just large enough for the boring bar to enter. The internal diameter had to be done in two stages, the first so that the drill chuck would fit into the first bored hole so as to continue the boring to depth of the internal diameter.

I thought I would assemble the crank assembly for fun, looks quite an artistic arrangement. But I must stop playing about and get the crank tapers drilled and fitted so that I can test the final crank alignment and move on to the heads.

Steve

 

[makila]

Here is an update on the radial build.

18 valves have been almost completed with just the retaining holes to drill. These were made from 303 stainless steel and the valve stems were polished down on the last .002" to give .186" each. The valve angles are cut at 45 degrees to give a working seal against the seats which will be cut to 46 degrees.

I made a start on the heads this week. I had to square bar stock of 2.050" x 2.050" down to 12 pieces at 1.8" x 1.8" x 2.50" each which took a whole day! That's 9 required plus 3 to practice on or if I am lucky, some spares.
These were drilled and a Q hole cut for a 3/8 - 24 TPI thread. I decided to deviate slightly from the drawing here by machining the .625" on the rotating table, it seemed better to do it this way rather than the octagon called for. I will be able to cut the 25 degree angle using the minimum diameter of the valve towers as shown in the drawing.
The heads themselves do not look easy hence leaving them to last and I am concerned that the seats and other stages to complete them might be the nemesis on this build.

My next engine will be a twin, or even a single, this 9 x repetition is a bind!

Steve

 

[hussien95]

it look very Impressive engine,excellent work.

 

[makila]

Further update on the heads;
I have completed operation #1 on the heads in the lathe and returned to the mill. I am using a tool that is designed to provide a 25 degree working angle on the valve towers and act as a holding tool for the heads. I have cut the rear of the heads on the mill that will hold the intake and exhaust flanges, this requires cutting into the fins at the rear circumference of the head.
The next stage will require cuts at 25 degrees from the front of the head that will eventually allow the spark plug attachment cut to be accessed. So far there has been 17 individual tasks on 12 heads that sum up to 204 tool changes and their associated indicating tasks. There are many more to follow on this component but at least there have been no failures that would require abandoning an individual head assembly.
Unfortunately, duty calls and I shall be away again travelling overseas for the next 4 weeks so progress will be on hold till then.
Steve.

 

[makila]

The heads are complete!

I have just completed the heads, starting from 12 blocks, 2 practice blocks + 10 completed makes one spare!

The plans call for a .002" interference fit for the valve seats. I tested the fit of one seat in a piece of scrap and thought the seat would not be tight enough for an in service fit as it was quite easy to extract. Therefore I made a .003" interference fit which was a good tight fit. Perhaps it was the soft nature of 6061 material that made the seats quite easy to fit? I chamfered the seat slightly on the leading edge so that it would not "broach" it's way into the the seat recess and and all valves survived later machining to prove they were tight. I also discovered that my Mitutoyo caliper jaws read a bit different between the ID and OD measurements, something to watch for later. I need a calibrated internal and external measuring block/ring to see what the exact difference is.

The seats were cut to 45 degrees to set against the valves cut at 46 degrees for a better gas seal, however I noticed that two of the seats suffered a bit of chatter, no matter what I did, perhaps due to the use of a three edge tool, I left more material on these seats and will come back to them when I get a two edge cutter. Also, I noted that the inlet and exhaust tracts could interfere with the back of the valve seats if the seats were too recessed, luckily none of mine were but something to watch for as the depth of seat recess was not easy to judge during machining.

That's it for now, the main parts are all done, just a bunch of small parts to make which will keep me out of trouble for the next couple of months. I am not sure what the next parts will be yet, will keep you posted. Once again, I am off for a few weeks, West Papua to be precise.

Steve

 

[makila]

I have not posted for a while on the progress of the H9 radial so here is an update.

I have started the assembly and all crankcase components are complete apart from the final cam timing. This will be done when I fit #1 cylinder. The only components left to make are the push rods, manifold gaskets, drill the cylinder attachment flange and the rest is mostly spanner work. The valve seats will require a quick lap as a couple of seats have slight chatter marks but should clear up without too much stress, but achieving a good compression is essential.

The crankshaft had some machine work to do as the forward bearing flange had to be adjusted so the bearing aligned with the front case and all the pin holes were drilled to fit the last few gears. All of the crankcase components are complete and the crank turns, complete with master rod assembly, oil pump, impeller and distributor assembly via the bevel gears with no binding... that made me very happy!

The inlet/exhaust tubes were a complete hassle, I had to make a tube bender that could cope with neat bends in thin brass tube, see bending brass tube thread within Q's and A's. On the bright side, I now own two very good tube benders!

I have made all the rockers and tappets, completed the cylinder honing, the bores look good and the pistons fit well, they will (hopefully) give a good gas seal once the rings are fitted.

I have not worked out how the engine externals will be placed, I presume I need to put the fuel tank level or above the carb if no pump fitted, perhaps someone could advise. The fuel/oil tanks would look best low on the engine stand but perhaps they need to be high to prevent starvation of fuel and oil cavitation on the inlet side?

I have not hardened the cylinders, primarily due to not knowing what to do, I do not have an oven that can reach those temps. Can these be hardened without distortion and if I do not harden them, the engine will only be run occasionally so the wear will not be an issue, they are made from 12L14 so not much carbon content anyway. I think they look ok without bluing. The cam ring, made from 4041, has not been hardened either, this will most likely need this treatment, I have a propane gas torch but again, I am concerned about distortion or cracks if I harden this. Any advice on hardening will be considered, but I am reluctant to try based on how long it takes to remake these components. Perhaps a practice shot on a similarily sized part should be attempted?

Will update again before Christmas, I don't expect to see this engine run before next year and that is after fault finding and adjustments here and there.

 

[mayhugh1]

Hi Makila,
I don't think I would attempt any hardening of the cylinders as they don't need it, the 12L14 really won't respond to heat treatment, and you'll likely distort them and screw up the fit to your rings.
I'm not sure what 4041 is - maybe you meant 4140. I'm not sure what to tell you because the shape of the cam ring makes it susceptible to distortion and rapid unequal heating by a torch might ruin a part in which you have a lot of hours invested. If you can't get it locally heat treated you might consider using it as is. If so, I would grind the ends of the tappets slightly for a bit more contact area with the cam ring so you reduce the pressure between the two, and then I would harden them instead. If you made the tappets from drill rod they will harden easily, but be sure to use anti-scaling compound on them to keep their contact surfaces smooth. Nice job. I know how much dedication is required to build one of these. - Terry

 

[makila]

Thanks Terry, I will not heat treat the cylinders, that's a relief. Yes, 4140, I keep getting this number muddled. I will find a local engineering works to get the cam ring case hardened as I can see wear occurring on this during even short runs. The tappets are made from drill rod and I will look at the profiles so they spread the contact area to reduce wear.
Steve.

 

[makila]

The engine has finally been assembled.

I have just to fit the spark plugs, I need another 8 as I had one for measuring, then fit the HT leads and the engine will be just about complete.

I made a start on the engine externals - the oil and fuel tanks. I had some 2" diameter thin walled brass tube that polished up well and decided to use these. I made the end caps and that is as far as have managed to get. The tanks are both 4" long so the capacity will be sufficient for the oil reservoir and I estimate about 5 minutes running time on the fuel tank.

I primed the oil system by hand cranking the prop with clean oil being introduced to the pressure port and was pleased to see oil being pumped out of the scavenge side after a few minutes of cranking. The scavenged oil was not recirculated as it was fairly black and had small amounts of build debris flowing with it, after about 50ccs of oil it cleared up to a cloudy consistency and will probably be black again when (if?) the engine runs.

There was a small oil leak coming from the lower cylinder skirts but that was expected as I did not use any gasket sealant on these joints. The cam timing went well and all valves appear to be operating as designed.

I am thinking of raising the tanks at the rear of the engine to about center height, so as to maintain some gravity prime to both the carb and oil pressure feed, although once the fuel drops to carb level and below the mixture might change, I might need to use a pump. Should I need to use a pump, I will need to make a float chamber to maintain constant fuel flow, and so it goes on. But will wait and see after running to see if that will be necessary.

So far I have spent about 15 months making this engine, but could have spent less time if I did'nt have to work away as much, I am in Houston for two weeks in January so at least I will be able to raid the tool shops again!

Will update once I have figured out how the externals and engine control will be placed.

I wish all HMEM folk a happy Christmas and a prosperous new year. I hope Santa manages to fit all that heavy machine shop stuff in his sack, I sent him a list!

Steve

 

[10K Pete]

It's a beautiful engine and I can hardly wait to see, and hear, it run. I love
the sound of round engines!

Pete

 

[gus]

You are my hero. Manual machining so many parts. Wish I have all the patience.

Waiting for the great day when engine goes Vroom Vroom.

 

[bazmak]

When i see posts like this i feel like i would be better off taking up knitting
Absolute magic.Keep it up

 

[makila]

It's been a considerable time since I last updated the progress of the radial, mainly due to work commitments keeping me out of the workshop, but I must not complain about that too much.

I have been making some external parts such as controls, tanks, mounts etc, in order to get closer to the day it runs. Some say, it must be soon or the materials will go brittle and turn to dust!

Some items of note that required some thought was the heavy brass throttle lever, which required a friction device to prevent it's weight closing the throttle. There is a adjuster on the ignition system to allow fine adjustments during engine running, and of course, will be useful to get that slow running - as well as max RPM - just right.

The control box has a LED RPM and battery voltage indicator (and a on and off switch-the mind boggles). The RPM indicator has a problem regarding the input signal provided by the CDI unit. The CDI unit is designed for a single cylinder engine thereby indicating 4.5 x the actual RPM (being a 4 stroke or it would be x 9) and the work around is programming a PIC to divide the leading edges of the input RPM square waves to the correct value. I did look at changing the crystal ocsillator on the tiny circuit board but it has an internal arrangement and surface mounted in a impossible position, hence the creation of a input board that will provide the right square wave frequency. The spark plug caps were made from delrin rod, drilled and cut at 45 degrees to try and make them look more scale in appearance, but I am not sold on them however, I might just pull them off and go for a clamp as their connection reliability is not 100%.

The remaining tasks are to test the tanks for leaks using compressed air before filling with fuel and oil, complete the electrics and try and tidy up the mess of HT wires. I will video the results on start up day, and post it here. I will be hand cranking the engine to start it, and if that is not turning the engine quick enough to get that first cough, I will have to make a center prop spinner that will not undo it-self when the starter motor engages.

So nearly there, but unfortunately tomorrow, I am away overseas working for the next month so it will be a month or more before the next installment.

Till then, stay well and keep the machines spinning.

Steve.

 

[makila]

And of course, the front of the engine. The whole reason for building a radial is the front!

 

[Parksy]

Just amazing! Absolutely amazing! Nice work.

 

[michael-au]

What a great looking engine, nice workman ship

 

[Davewild]

Truly beautiful, one day maybe i will have acquired the skills to attempt a radial, again absolutely lovely.

Dave