Homebrew boxer twin prototype

[gmac]

Jeff
Ron Colonna uses 0.010" pure silver sheet (not sterling silver) for his Offy engine which is a pressurized oiling system with dry sump. He also superglues the ears of the shells to the cap/rod halves.
Cheers
Garry

 

[Lakc]

Ron Colonna uses 0.010" pure silver sheet (not sterling silver) for his Offy engine which is a pressurized oiling system with dry sump. He also superglues the ears of the shells to the cap/rod halves.
Cheers
Garry

Thanks Gary, I didnt know Ron used that too. I included allowances for the single tang overlap when I spec'd out the reamer, we will see how long it lasts.

Sidetrip to Hades!​

When we last left off I was anticipating the arrival of an ebay purchase to throw together a cheap (and quick) heat treat oven. The results were a FAIL, but somewhat encouraging.

What you see here is the ebay $12 special surplus temp controller, an old toaster oven (~$15 at wallmart 8 years ago), a brand new 120v relay and socket ($13 mcmaster), hi temp fiberglass rope seal ($6 mcmaster) a K type thermocouple (gift), and a few scraps of wood and wire. The controller was an "H" variant, which means it simply turns off at the desired temp. Not what I had in mind, but it would work if babysat and continually reset. Despite the approximately 1300 degree heating elements, the max temp achieved was 755 F. So, for the price of a day and a half work, I failed. I now have some high temp insulation to help with the heat loss, and a single 750 watt cartrige heater, so the second iteration of this is coming shortly.

Of valves and cages​

Earlier I mentioned I had never tried to make a caged valve system, and that hasnt changed. The forums have been pretty active with valve discussions lately, and I have weighed all the advice I have seen. I still dont have anything against the cage system, except my own inexperiance. While I have a lot of experiance with full size practice, I went that route for a test head. Cocentricity and accuracy in the setup will be challenging, so here is my take on it.

Start with a head! I always feel like a sculptor at this point, chop off a block of 1.5" square 6061 1.1" and true it up to 1" height. Then, get so darn excited you forget to take pictures of the 1 3/8 counterbore and 15 degree cut for the combustion chamber Once off the lathe its back to the mill where I "lop the ears off" for another 15 degree cut.

Now life gets interesting. Back to the lathe with a 3/8 stick of W1. Drill a bore with a 19/32 drill. In my case I ruined the part with a dull cobalt 19/32 drill :'( Out to production tool and 8 dollars later we have a replacement cobalt drill that actually cuts. Follow up with a delicate touch of a 90 degree countersink. Then we turn a whole length down to .350. Carbide inserts and plenty of lube keeps the surface finish up to snuff. Trying to part a .200 length off for a valve seat just dulled my A1 fin tool. Switching to my commercial (hard) parting tool I find the piece wont part off, the tube just deflects away from the cutter. Trying to make lemonade out of lemons, this appearant work hardening is not a bad quality to have for a valve seat, but required an old nearly abandoned practice of a dremel mounted with an abrasive cutoff wheel to part off. This was the very first tool I made when I bought that lathe 13 years ago, and I havent used it since, but it sure saved my bacon this time.

Sorry, so excited I forget the pics of the seats by themselves.
Now that leaves me with all this stock sticking out, already turned to the same size as the seats. I turned a .1870 pilot on the end and proceeded to make a counterbore/reamer tool to ream the seat cavity in the head. Press fits are new to me as well, and a lot of creeping up on dimensions with abrasive cloth was indispensible. I also made an installer tool (also not pictured), similar except for a looser tolerance pilot, no cutting teeth, sized 19/32 for the inside dia of the seat, and made from cheap 10something cold rolled steel. I spent a hour reading machinery's handbook on making cutters, and found it (26th ed.) pretty lacking in the counterbore section. I did pick up a few interesting bits such as cutting the flutes .010 below center to give the sides some rake angle, (and a smidgeon smaller for the press fit), and to offset the teeth +- 1-2 degrees. Eventually I came up with this.

On to the drilling​

Keeping everything concentric is the major challenge here, and I took it to heart. I realized early on my drill chuck seems ever so slightly eccentric, mounted only with a 33 jacobs taper to a 1/2' straight shank for holding in a collet. To avoid using the chuck I ran out at the last minute back to production tool and bought a quality 3/16 R8 collet for the guide hole reamer, then I could use the 3/8 collet for the seat hole reamer. This worked marvelous, with the exception of forgetting to relieve the cutting teeth on the seat reamer I made, hence the first guide is slightly higher then the flush surface I was shooting for. A bit of quick work with the dremel fixxed the tool and the second seat came out exactly as planned. The press fit for the seats came out perfect as well, just a few stiff taps with a hammer drove them all the way home, with some red loctite for good measure.

Now were all up to date again. You might be able to see in these pictures what I considered a problem with the origional Edwards radial plans, that when you bisect a cone off-center with a cylinder, the resultant surface is shaped just like a wave washer. Making the valves seal against that is one thing I saw omitted from the plans, which led me to cad model it, which in turn led me to this point.

Coming up next, we have plenty of chips still to make. Bronze (yep, I splurged and bought the good stuff) will be turned into valve guides, and you will experiance the absolute horror as I mix in a metric dimension into an otherwise all english unit design. We have counterboring, and drilling through aluminum to bisect the tool steel valve seats for the ports. It may be coming up on Christmas, but the next installment looks like a better fit for halloween. :-\

 

[Royal Viking]

I was wondering about your oven. At 755 deg F that thing must be pretty hot. Can you throw some additional insulation over the glass and sides to reduce heat loss ? I am wondering if the glass is only working as a barrier to preventing a draft.

 

[Lakc]

Its entirely possible your correct about the glass RV. The most economical solution I could find was some 3"x1/2" rolls of foil backed hi temp insulation. I have 10' of the stuff to try out when I next get a chance.

 

[stevehuckss396]

Head looks cool.

Sorry the oven didn't work out.

 

[Lakc]

Thanks Steve.
All is not lost. I have enough firebrick laying around to do it correctly I assume. Even still, the small time and monetary investment to get this far has purchased an invaluable education in what doesnt work.
Whether it works or not, I still owe you and/or your club a visit. I think you guys meet where I used to go to the Mopar swap meets years ago.

 

[Lakc]

Success​

With a little high temp insulation help from Mcmaster, it works fine.

Ran right up to 950 without a problem. ;D

 

[Royal Viking]

Nice, glad to see the insulation worked.

That may work as a floor tile remover too...

 

[Lakc]

Nice, glad to see the insulation worked.

That may work as a floor tile remover too...

Well, the floor tile is perhaps the least flammable item in the room..... 8)
As its mounted on wood which has yet to show any heat distress, it appears there is little heat radiating downward. Still, I have a long cord attached to make it easy to yank out of the wall and a bucket of water off camera.

Warts is Warts​

I had this wonderful stretch of time off over the holidays, and big dreams of staying warm indoors finishing this project. I hope everyone had a merry Christmas and a happy new year. Alas, fate has conspired against me, with every vehicle in my family requiring my utmost attention. I spent almost my entire vacation working 14 hour days out in the cold Michigan winter doing collision repair, chasing parts, welding exhaust back together, etc. I am still not done, with one vehicle down with a blown coolant bypass hose and a charging system problem, but I could not arrange picking it up tonight, so that left me with some now quite rare lathe time.

Now that I had an opportunity to work for fun, I tried to tackle a valve. I had a new secret weapon, a McMaster 3244A546 insert, price almost $6. I had wanted to try a "high performance bit" and this one is a grade 3503. Generously rounded for a fine finish, it is shaped similar to a banna boat with sides that gently slope away from the cutting point, turning its negative rake characteristics into somewhat of a positive rake cutter with 6 usuable sides. The valve material is just a 3' stick of O1 tool steel, and with plenty of lubrication the cutter did a fine job leaving a pretty good finish. The length was turned down between centers to .350 diameter and the 1" of stem to .1360 +- .0002 with very little final finish work needed with my standard 180-320-400 grit emory cloth stock.

Now is where the trouble begins. I quickly learn my thin parting tool is too short to groove and then part to length with a live or dead center in position. so I part the valve off at the face and mark it up with my height guage.

Now the next big problem, the valve is too short to flip around in the lathe chuck and finish to length much less cut the e-clip groove. I thought of making a custom collet to hold in the three jaw, but I would first have to remove the bulge at the tip left by my cutting around the center. I am sure I will figgure something out but any suggestions in the meantime will be most welcome. I still have cars to fix, so it will be a few days before I can get back on this job. If I only had that 5C chuck and a 3.5mm collet I would be back in business. No, sorry, spending my way out of this corner I have machined myself into is not an option this soon after Christmas.

 

[NickG]

Nice work. As soon as I saw that i thought just make a split collet. If it's an issue removing the bulge, you could make the collet split completely maybe with dowel pins to pin the 2 halves back together in the correct place? Otherwise just cut the bulge off and don't completely split the collet - I would have thought that would work as well as anything.

I know how you feel with cars to repair, both of our cars packed in in a big way recently, luckily I've managed to spend my way out of it and pay other people to do the work this time, although I haven't got the cars back yet!

Nick

 

[Lakc]

Nice work. As soon as I saw that i thought just make a split collet. If it's an issue removing the bulge, you could make the collet split completely maybe with dowel pins to pin the 2 halves back together in the correct place? Otherwise just cut the bulge off and don't completely split the collet - I would have thought that would work as well as anything.

For lack of a surface grinder or commercial collet system, its looking like a home made split collet and hand grind the bulge.

I know how you feel with cars to repair, both of our cars packed in in a big way recently, luckily I've managed to spend my way out of it and pay other people to do the work this time, although I haven't got the cars back yet!

Nick

Sorry to hear about that. My problem is more professional then monetary here. I spent the first decade of my working life in a car dealership, mostly repairing other technicians screw ups. For more then the last decade I have been phone support for those same technicians. With my luck, I just dont trust anyone else to work on my vehicles. :-[

 

[NickG]

You're spot on there, that's why I started to live by the motto, 'if you want something doing properly, do it yourself' but these days I just can't find the time / motivation sometimes to do it myself!

Nick

 

[Lakc]

Well, hopefully those things that should not be mentioned will stop breaking and allow me some time in the shop.

Just a quickie update, tried the next valve backwards as compared to the first attempt. Both methods have drawbacks but this one provided a serviceable valve. Center drill 3/8 rod of tool steel and leave the tulip part towards the tailstock center with the stem pointing back at the chuck. This allows the chuck to support the grooving and final parting operation with the tailstock cleared out of the way of the toolpost. I will have to invest in one of those half centers one of these days. The .020" Grooving/parting tool is made from A2 tool steel, torch heated for the hardening and annealed in the homemade heat treat oven, which is coming in quite handy. The pictures tell the story pretty well so here they are.

Hopefully, this weekend, we can put the valves behind us, and maybe even the first cylinder head itself.
Sunday is a swap meet, (ham radio) but I will be picking up my loaned out oscilloscope because once we get the cylinder heads done we can change tack a little bit and begin work on an ignition system.

 

[Lakc]

The cars have not stopped breaking but most of the failures have been non-critical so we have a litte bit of work done.

Valves themselves were too simple to get very hung up on. A few jigs and more careful machining could reduce the waste material a bit but for the sake of progress I moved along leaving the head oversizedx enough to allow my crossslide and toolholder to clear the tailstock and center.

In this image you can see the "banna boat" sides of the cutting bit which sorta allow the negative rake bit to act like a positive rake one.

Here are the valves with grooves and e-clips as keepers, awaiting final head machining.

This was a bit of a pain as light cuts were necessary and I could not tighten the chuck as much as I wanted, but all the valves survived the experiance.


Next up, maybe tonight, Ill post the pics from the valve guides (done), rockers and rocker stands (under construction).

 

[Lakc]

queue Ethel Merman

There's no progress like slow progress......​

Well, its certainly better then no progress at all. :'( When last we left our intrepid hero, he was singing to a pile of metal the words to Pink Floyd's "one of these days", and thus was the result, soon to become rocker arms and rocker stands.

For this epsiode, the point of interest will be the four 1.5" long x.25" square pieces of W1 tool steel, chosen especially for the properties of being on hand and the correct size.
The pieces were chucked up in the vise and 1/8" hole was drilled 1/4" in from one side and .64" from the first hole. My favorite 1/8" spade drill was held in an R8 collet in an attempt to drill and ream in one operation. It met its unfortunate demise on the third rocker due to my failure to clear the parallel completely from the hole before it broke through. Then the rockers were held lengthwise while a cut was taken out of the middle. Two right and two left handed rockers were designated.

Then it comes down to the business of making a jig. A piece of 3/8x1 scrap aluminum of gummy hardware store variety was placed in the vise and milled to approx 3/16 thick, leaving a small square island at one end. The center of "eyeball island" was found and the table locked down, where it was center drilled, drilled, and tapped 4-40. Another 4-40 hole was tapped .640 away in the milled off section. My personal favorite method of tapping is chucking up an archery target point in the chuck and using the point and ogive to center the tap handle with a little light pressure on the ram to maintain contact.

Next my boring head is used to round off the island to exactly 7/16" to match the center reamed hole on my Sherline rotary table.

Now comes the fun part. I was being tricky and actually doing all the machining on the backside of the jig. Now I flip it over and bolt the rockers on one at a time. The nose is given a 1/8" radius for approx 270 degrees, and the pivot point approximately 90 degrees.

Now we create another jig. It doesnt come through well in the picture but this is the leaning tower of rocker arms. There is an 8 degree bevel on the bottom side. Here we take the square left opposite of the pivot and turn it into a trapezoid, and drill and tap a 6-32 hole near the end for an adjustable pushrod cup. Along the way, we re-learn the lesson that really tight is not always tight enough as the jig moves in the vise and my favorite cobalt roughing mill explodes throwing a large chunk against the wall with considerable force. :'(

They are still a little rough looking, but will do the job. Along the way I thought of several improvements to the design, but pretty much forged ahead anyway. Besides patience, I am trying to teach myself that Version 2.0 parts will never get built until you learn 1.0's lessons. That is why I called this a prototype, and I still have a lot to learn.

Its slow progress, but still moving along. I am beginning to get confidence that this one will be finished soon.

 

[Lakc]

Rocker arms and stands are done. Few misc pics to put up later. I am waffling on what to do about a spark plug still, but pretty much finished the drawing of the head, so here is a teaser until next update. ;D

 

[krv3000]

HI that will be a brill engine when finished

 

[stevehuckss396]

Rocker arms and stands are done. Few misc pics to put up later. I am waffling on what to do about a spark plug still, but pretty much finished the drawing of the head, so here is a teaser until next update. ;D

What size plugs would you be needing? Dale Detrich has 1/4-32's for 12 bucks

 

[Lakc]

HI that will be a brill engine when finished

Thanks KRV, I am hoping its finished sooner then later.

What size plugs would you be needing? Dale Detrich has 1/4-32's for 12 bucks

Thats a possibility, if Dale is the man I will have to look him up. I have 1/4-32 thread drawn there now, but could go a little bigger if I had to. I currently have a full half inch of thread engagement, and thats longer then any 1/4-32 plug I have seen drawings for, but easily adjusted.

I have large quantities of Hydrostone, which would be interesting to try an mould an insulator out of. I also have had ideas of making moulds and using slip to make my own ceramic insulators. Machinable ceramics look like just the ticket but are way too expensive. Corian pen blanks are a possibility as well. Still, thats a whole nother discipline I probably shouldnt sidetrack myself with now.

 

[stevehuckss396]

http://www.daledetrich.com/

Give him a shout!

He is also a very good engine builder.