Edwards Radial 5 Build

[Swifty]

Hi Brian, I've seen those Hercus lathes with the tiny dials, makes it very hard to be accurate. I'm a toolmaker by trade, most of my work was specialising in complicated follow on press tools for electrical and automotive components. The last 10 years of my working life also included the manufacture of tooling for transfer presses, assembly stations for companies like Bosch etc. I've only worked at one place all my working life, however I did end up owning it for 10 years before I retired, due to me having to eventually go on dialysis. I employed 10 tradesmen and I was also very hands on. I sure could use the equipment that I had now, it would make it a lot easier.

Paul.

 

[Brian-in-Oz]

Hi again Paul,

thanks for the info and I hope your health is under control to allow you plenty of shop time. Maybe a future project would to make some larger dials for the Hercus with more space between the graduations - I wonder if any members have done this to their Hercus or Southbend lathes?

Cheers - take care and stay tuned - Brian Thm:

 

[xjs]

Aloha Brian and all Radiaphiles --

Just a note to assure that Radial production here in the Islands hasn't ground entirely to a halt, but it did suffer a bit of a setback when it was discovered that the set of finished cylinder heads, so lovingly machined, photographed, and celebrated, were just pretty pieces of junk.

Somehow or another I'd managed to get the valve seats out of whack with the centerline of the valve guides. This became horribly apparent once I acquired a valve seat cutter and began to chamfer the seats. All of you who have gone through the arduous process of producing these heads know how much time gets invested in those babies. So, for the last couple of months, another seven heads (two spares) have been very slowly brought into being. So v-e-e-r-y slowly, partly because of the extreme caution, and partly because of a taxing travel schedule, keeping me out of the shop for weeks at a time.

So they're not quite done yet, but they're well on the way, and mistakes have been learned from. So far, they seem perfect in every respect (he says, reaching to touch the largest piece of wood available).

As I've been creeping along with this re-make I've been meticulously keeping notes along the step-by-step way, and this really seems to help. For all I know this is common practice for everyone here, but I'm very much in the business of picking up good work habits as I go along by trying (and then discarding) all the bad ones first. Anyway, taking notes seem to help keep my flaky mind organized.

In between bouts of despair I've been keeping up with the thread, and continue to be astounded by the quality of workmanship and the abundance of ingenuity.

So, all's well out here, just a bit slower than we'd like.

All best everyone.

 

[Brian-in-Oz]

Hi Michael and All,

that's really bad news about the heads and I wonder if I may even be at least partly responsible for suggesting the screw in method for securing the valve guides.
I also had some misalignment with the inlet ports to the valve seats but it was only very small and could be corrected by reaming the ports a little before cutting the valve seats. Despite this I think if I was making the heads over again I would
make a guide and seat cage as one and insert into the head maybe even before machining the combustion chamber and drilling the side entry inlet and exhaust ports. Are you doing the guides differently this time?
On my home front I am continuing the quest for the perfect piston ring. I have made two new complete sets of oversize rings that are slipped onto a jig to
hold the gap open at 080 thou. while being heat treated (see photo).
They are off to a temperature controlled oven in the morning to sweat it out at
600deg.C for about twenty minutes after being raised to this temperature from ambient room temperature and then allowed to air cool.
If all goes well they should have then taken a new "set" to provide tension when closed. They will then be compressed and placed into the alignment tube of the grinding jig (see earlier post) and gapped to .004 thou. and tightened in position and ground to exact cylinder size. This is about the last thing I am going to be able to do on the Edwards for about three months.
I will post the outcome results.

Cheers Brian :toilet: *bang* *club* *beer*

 

[Brian-in-Oz]

Hi Michael and radial fans one and all,

Today I heat treated my batch of piston and oil rings in a temperature controlled oven thanks to the generosity of a friend with a machine shop. The rings on the gap spacing mandrel were placed in the cold oven then switched on with the thermostat set at 600deg.C. Once this temperature was reached it was maintained for 30 minutes before switching off and opening and the rings left to air cool.
It would be an understatement to say I am happy with the results. The rings have taken the gap "set" beautifully and are nice and "springy" and show not the slightest sign to bend and loose the gap set when closing them. Now "fingers crossed" and just one step to go - fit the rings to the grinding mandrel and carefully grind to bore size. I will try and achieve this with the tool post grinder but if accuracy is a chore my machine shop pal has offered me the use of his commercial cylinder grinder graduated in microns. ( oh! I would kill for one of those).
Just out of interest I tried the grinding jig I made on the old Model A 9" Hercus lathe on this high precision cylinder grinder and checked it for any "run out" and was delighted that it ran dead true even by the high standard set by this machine. Not bad for a 65 year old lathe.
God bless your soul Fred W Hercus.

Cheers all - stay tuned for the grinding

Brian Thm:

 

[xjs]

Brian, I'm learning so much from your experiments and experience with those rings. As you know I made a quantity of rings using the Edwards' recipe, and I was well pleased with them at the time -- but then I hadn't planned to install them until the final assembly stage, and they've just been snoozing in their Altoids tin, waiting. Now at least I'm prepared for a nasty surprise if they aren't as perfect as I've imagined (the way I thought my heads were at one time), and I'll know how to detect their faults, and I've got a good idea of how to make better ones. So, thanks for your research and industry, and for passing along the results.

And, please don't worry about suggesting the screw-in valve guides. I'm using the same guides in the new heads, and expect them to perform beautifully. The mis-match of axes of valves and guides in my first set of heads was gross human error, pure and simple. I'm making the second set with a caution and technique that could only have been born of experience. Screwing up every now and again is how we learn not to. And, unlike life outside the shop, all it costs is a chunk of metal.

 

[Brian-in-Oz]

Hi Michael and all,

Here are the rings (two compression with oil in center) all clamped up in the mandrel ready for grinding to bore size.
Runout around ring circumference is only 1 1/2 thou. and I have 5 thou. to play with so the only stuff up now would be to grind undersize. Be careful Brian.

Cheers Brian *knuppel2*

 

[Brian-in-Oz]

Hi Michael and all,

Today was the day of reckoning as I very carefully ground the rings to exactly bore dimensions. I managed to do it with the tool post grinder on the lathe so have had the satisfaction of doing it with my own equipment.
Am I happy with the result? You bet! The rings now have no option but to fit the bore precisely when compressed and none of my previous concerns are evident.
A lot of rings have gone down the drain to get to this point but certainly in my own mind I feel this the only way to get a truly precise ring. Not rocket science when you think about it - correct temperature control for heat treating - make rings slightly oversize - compress tensioned rings in a true running jig and grind to size. I think it would probably be OK to turn the rings to final size but more care would be needed in regards to getting a nice finish.
The rings have been fitted to the piston and piston to the cylinder and tomorrow I will re-assemble the cylinder and head to the Edwards crankcase and report on the compression results compared to previously.

Cheers from the Happy Edwardian Brian ;D

 

[petertha]

That's really neat, Brian & they look great. I was waiting for your pic before my follow-up questions.

So now you have a (single) set of perfect OD rings. Was that a proof of concept operation & you can re-use the exact same jig holding elements (blue bar & red bar) chunks for subsequent ring set grinding operations? Or are these clamping chunks kind of sacrificial elements to each pair/set? ie, the fact that the jig stubs are now = finished ring diameter, doesn't matter, they will continue to do their job & clamp oversize rings for subsequent grinding.

Could you stack up more rings in the same jig, or you are concerned about a slight taper yielding slightly different OD's?

 

[Brian-in-Oz]

Hi Petertha,

Thank's for your continuing interest in the radial engine project.
I could stack a few more rings in the jig and any taper grinding would not be an issue as I am fortunate in that my old Hercus lathe does turn nice and parallel.
The reason I am only doing three at a time is (two compression - one oil ring) is that I am fitting each of the five cylinders individually. I gave each cylinder a light lapping with a brake cylinder hone which gave a nice finish but a tiny difference in bore diameter. Only a few tenths of a thou. across the five cylinders but I want the rings for each cylinder to be as precise a fit as I am capable of making them.
You are correct in your assessment that the jig can be used for subsequent grinding of the other four sets of rings. The alignment tube for centring the rings prior to clamping them up tight fits along the entire length of the jig so that the small over grind past the rings is of no consequence.
This whole exercise has been a huge learning curve for me but I guess that's what this hobby is about. At least I will know how to make piston rings for the next engine.

Cheers Brian :idea:

 

[Brian-in-Oz]

Hi all - after three months touring the World I am now back in the workshop and keen to put the finishing touches to the Edwards Radial. Today I ground another set of piston rings and now have two cylinders with nice bouncy compression.
A highlight of my trip and as a direct involvement with HMEM was personally meeting with Michael in Honolulu and spending a few hours in his very nice workshop discussing our mutual Edwards Radial projects over a few beers. Thank you Michael, that was a great evening.
My engine is now virtually finished apart from three sets of rings so most future stuff will (hopefully) revolve around things like glo drivers, oil and fuel tanks and trying to get the engine to run.

Cheers all and stay tuned - no more big trips planned.

Brian th_wav

 

[petertha]

I am continuing the quest for the perfect piston ring. I have made two new complete sets of oversize rings that are slipped onto a jig to hold the gap open at 080 thou. while being heat treated (see photo). They are off to a temperature controlled oven in the morning to sweat it out at 600deg.C for about twenty minutes after being raised to this temperature from ambient room temperature and then allowed to air cool.

Hi Brian. I'm just completing an Excel spreadsheet that replicates the Trimble method. I think the math is working & I'll post once its all ironed out. I've also been inserting dimensions of a few existing engines just to see how the parameters compare, interestingly including a commercial RC (OS-56-4S) piston/ring assembly of identical 0.945" bore.

Anyway, the Edwards rings have me baffled. I was hoping you could elaborate. Attaching plans excerpts, assume this is the latest version. The way I read their machining sequence is:
- rough OD & ID turning
- slot a ring gap = 0.080"
- close the ring gap (in chuck)
- turn to finish OD = 0.944" & ID = 0.875"

... so no heat setting AFAIK. The radial tension is presumably achieved 'cold' by radially closing the slot & machining to final size?

Now onto your procedure. Did you snap the ring (meaning break as opposed to slot) & then heat set to the same 0.080" gap? Reason I ask is the Trimble calculation suggests 0.142" dowel pin diameter (=recommended heat set opening). That's 0.062" wider than 0.080" & prior to post-heat-set gapping. The article goes into substantial detail as to what is trying to be simultaneously achieved: 30 psi wall pressure + max installation & operating stress etc.

Turns out the OS-56 ring has a smaller gap too, but not to this same proportionate degree. Which leads one to wonder if the commercial RC engines are happy with what must equate to less than 30 psi.

Anyway, I wont further divert your build thread, but if you could elaborate on your method so I can hopefully compare apples & apples, I'll do my best to show the results in a dedicated post on this subject along with some plots that re-create the original article graphs.

 

[xjs]

Welcome back Brian!! It sounds as though you had a perfectly wonderful trip, and it was a great honor to have you come visit my little chip-shop. It was a special pleasure to have you explain your ring-making ideas & practice, which finally began to make sense to me. Seeing all the pics you took of your process helped a great deal, and I'm sure there would be others who would appreciate seeing them posted.

Now that you're through racking up the miles though I'll bet you're happy to be re-united with your Edwards, especially since it's so close to coming to life. As you've seen my motor isn't quite as well-developed, but I have great hopes for the New Year. Let's continue to compare notes, and maybe we'll have that R/C radial race yet!

All best from the Sandwich Isles,

m

 

[Brian-in-Oz]

Hi Petertha - your interpretation of the machining sequence as described in the Forest Edwards plans is correct. No heat treating is involved nor is any necessary because as you stated tension is achieved by closing the slot. I have no issue with the theory of making rings by this method but rather not being able to get the precision I desired with the equipment I have at hand. My chuck is a little worn and the jaws tended to splay a little at their extremities and I could not get the slot to close perfectly along its entire length. It was a little open at the end and I was also concerned at the possibility of movement in the chuck while machining resulting in less than perfect rings. I also don't much like the idea of parting off when there is a slot in the workpiece that could catch the parting tool and let all hell loose. If I had a new high precision chuck I may be telling a different story.
After turning the rings 5 thou. over bore size I snapped the rings in a splitting tool (see photo) I made and placed them on jig to hold the gap open by 80 thou. and then heat treated them as in previous post - photo. The heat treating process simply relaxes the molecular structure of the cast iron to its "normal" state so that there is now tension when the gap is closed as opposed to having to apply force to open them to put them on the heat treating mandrel.
After being heat treated (I was fortunate to have access to a temperature controlled oven) the rings were held in a closed state in in the 5 thou. oversize tube of the grinding jig and the precisely fitting tube slid onto the jig and a clamping cap tightened up to hold them concentric and compressed ready for grinding to exact bore size as shown in an earlier post. After grinding they are placed in the cylinder and carefully gapped with a feeler gauge to a clearance of 4 thou. As far as wall pressure etc. is concerned I would not have a clue as I have no engineering training and tend to look at things in practical sense and apply what I think will work (rightly or wrongly) to the problem at hand.
There is no denying that of all the components of the Edwards it is the rings that I have spent the most time on but I have now finished grinding all the rings and have assembled the engine and have excellent compression on all five cylinders.
The compression is so bouncy I think it is going to need a fairly gutsy electric starter to spin the engine over. I am confident that if the engine won't start it won't be from lack of compression but because of screwing up something else.
I know plenty of people seem to get their engines running with rings made by the Trimble method but to my purely practical way of thinking it has two major drawbacks being imprecise temperature control for heat treating and machining rings to size then opening the gap and heating which has the potential for creating slightly out of round rings.
Anyhow! I guess the method that works for the individual is the best.

I hope you can understand the ramblings - cheers Brian

 

[Brian-in-Oz]

*beer*Hi Michael - that was a fun and informative evening in your work shop. I still owe you a couple of beers and hope I can repay you with a visit to my shop at some future time. Thank you so much for your hospitality.
I have now finished all the rings and assembled the engine and it suddenly hit me, it is finished, the Edwards Radial is actually finished so what on earth am I going to do now! Well actually there is still a bit of tinkering - make a test bed - organise oil and fuel tanks - source a glo plug starter and find a nice gutsy electric starter. I don't fancy trying to start it by hand because even just flicking it over the prop will bounce back on compression and crack the knuckles so I don't dare think what a backfire might do to the digits. And of course who knows what lies ahead when the crunch comes to seeing if it really will run.
It doesn't seem much to do but with family commitments at Christmas and some grand kid minding in January time will slip by again. Retirement has been so busy I don't know how I ever found time to work!
I know this has nothing specific to do with the engine but my daughter gave me a radio control transmitter and receiver for my 70th Birthday and I bought Aerofly RC7 flying simulator software and loaded it on my computer and have mated it to the actual control transmitter and it is amazing how it is actually like flying a RC plane. It will be great for honing flying skills if I eventually get around to having the intestinal fortitude to put the Edwards in a plane. In any case it is great fun and I will probably get a slow cheap plane to practice actual flying on.

Cheers from Downunder - Brian Thm:

 

[petertha]

Hi Petertha - your interpretation of the machining sequence as described in the Forest Edwards plans is correct...cheers Brian

Thanks for taking the time to explain & all the best on your successful start-up. Let me digest this info into my comparison. Look for a separate post on the Trimble calc I'm still messing with. As mentioned, I suspect your HT opening distance is proportionately quite similar to a commercial (OS) 4S engine I had access to, so hopefully your 'bouncy compression' feel will yield equally good results.

Last question - did you replicate the ring axial thicknesses that the plans called for? (example 0.030" thickness for compression rings). And ditto question for thickness & V-recess profile of oil rings?

 

[Brian-in-Oz]

Hi Petertha, I made the rings as per plan dimensions. The only slight adjustment was to cut the circumference groove around the oil ring 2.5 thou. deeper to adjust for the amount of cast iron removed during grinding.

Cheers Brian

 

[Brian-in-Oz]

Hi all - just a quick note about the Edwards progress.
Getting to attempted startup has been delayed by being side tracked with assorted family commitments and the usual overload of all sorts of social and important trivia that retirees seem to be subjected to.
Non the less start up should not be to far away. My involvement in building a test running bench seemed to get way out of hand and has finished up almost as involved as the engine itself. What could have been a simple plank of wood has turned out to be hours of milling and drilling and tapping some 8mm aluminium plate. I have purchase a glow plug driver and have 5L of methanal just waiting to be ignited.
I will post some photo's of the finished setup in the near future.

Cheers Brian - :wall:

 

[Brian-in-Oz]

Hi all radial engine fans - well after a little over four years of on and off turning, milling,tapping, grinding, tube bending and jig and tool making my first ever engine is complete and hopefully ready to run. Behind the aluminium cover on the mount are two 4.8v NiMH batteries and a glow plug driver. One battery is for the driver electronics and the other (a higher capacity one) lights the glow plugs.
The socket on the panel is for pugging in another 4.8v battery to provide extra capacity during starting (it is then unplugged) and the red led indicates when the glow plug driver is on. Behind the round hole is the switch on the glow plug driver to switch it on and off. It should only need to be on during starting and low RPM running. The mount itself will be bolted to a piece of wood that can be clamped or bolted to bench. The lever at the rear is the throttle so that I don't have to get to close to the propellor to adjust RPM. The large tank is for fuel and the small one for oil.
All that remains before attempting starting is a trip to Adelaide to purchase some nitro methane and suitable synthetic oil and an electric starter. I have already sourced some methanol. Recommended percentage of nitro methane in methanol is 3% to 5%.
If startup is successful I will try and post a video if I can figure out how to do that.

Cheers all - :big: see attached pics.

 

[xjs]

Brian, that is a fine, FINE looking engine. It looks as though it's doing 5000 rpm when it's just sitting there and imagining the way it's going to sound is a pleasant way to spend time. That's a terrific and sturdy-looking test rig, too. just as soon as I know it's fired up I'll be raising a glass or two in your direction. Four years and a lot of patience well spent!

My own Edwards has some catching up to do -- life, and it's partner, has been a bit distracting since last we met. But I'll be back to the bench very soon, and that Anglo/Aussie air race is still in the cards.

Meanwhile, thanks for setting such a great example.

Cheers,