Author Topic: A "Different" Different Opposed Piston Engine  (Read 51371 times)

Offline smfr

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Re: A "Different" Different Opposed Piston Engine
« Reply #15 on: January 16, 2014, 06:28:55 AM »
My, Gail, you're not messing around! Looks like you got your rocker arms done before Brian received his CNCed ones  :Lol:

Simon

Online Jo

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Re: A "Different" Different Opposed Piston Engine
« Reply #16 on: January 16, 2014, 07:57:33 AM »


Jo
Enjoyment is more important than achievement.

Offline steamer

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Re: A "Different" Different Opposed Piston Engine
« Reply #17 on: January 16, 2014, 10:09:42 AM »
Thanks for that Jo!

Dave
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Offline sbwhart

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Re: A "Different" Different Opposed Piston Engine
« Reply #18 on: January 16, 2014, 10:54:36 AM »
I'm watching this one  :ThumbsUp:

Stew
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Offline cfellows

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Re: A "Different" Different Opposed Piston Engine
« Reply #19 on: January 16, 2014, 04:34:19 PM »
Guess I'm going to have to  break down and try a hall effect ignition.  Where do you source your hall effect sensors from?

Thx...
Chuck
So many projects, so little time...

Offline gbritnell

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Re: A "Different" Different Opposed Piston Engine
« Reply #20 on: January 16, 2014, 06:37:37 PM »
Great progress Gail.
You like me enjoy making things a little smaller than the norm. I'll be following along. Lord knows I don't need another project.
gbritnell
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Offline GailinNM

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Re: A "Different" Different Opposed Piston Engine
« Reply #21 on: January 18, 2014, 04:41:45 AM »
Thanks for the interest and comments everyone.

Chuck: For the hall effect device I am using a SS441R in the flat TO92 package by Honeywell for my pickup.
http://www.alldatasheet.com/datasheet-pdf/pdf/345668/HONEYWELL/SS441R.html
This not what the CDI module distributor supplies but is equivalent. It has good magnetic sensitivity so magnet spacing and strength requirements are not very critical. They are a little more robust than some of the other manufacturers products. They are available from many distributors but I get mine from Mouser as they are generally a little cheaper there. Besides they are in your and my neck of the woods.  Price is about US$ 1.70 each but they drop to just under a dollar each if you buy ten.

George: You are right that both of us like small toys.  Really no harder to build once you get used to it.

Now what good is a cylinder mount with out cylinders?
A few changes were made to Brians's design (of course you say) to suit my style.  Same basic geometry.

First off I increased the thickness of the outboard spigot so I could fit an oil cup.  Briqan mixes oil with his fuel and I don't so I have to lubricate the cylinder. Typically on engines this size one drop of oil in an oil cup is good for about an hour of running. A little more for the first couple of hours when breaking in.  This extra thickness then needed to be cut away with a counterbore spotface for the cylinder mounting bolts.

Second I shortened the spigot that goes into the cylinder mount to clear the valve rather than cut a relief into it. I will lengthen the piston by about 0.014 inch to bring the compression ratio back up.  This means that the piston will go beyond the end of the cylinder into the combustion chamber. This won't hurt anything.

A little more care was necessary in finishing the bore because of the smaller size and I will be using a lapped piston cylinder with no ring.

Started by turning one end of a bar of Class 40 cast iron to the outside shape with one spigot on the end and finishing the fins. After cutting off I machined the spigot on the second end and bored it to about 0.3745 to finish to 0.375 by lapping. Boring was done with a solid carbide boring bar.


To remove the high spots from boring I ran a fine grit Flexhone into the cylinder about 6 strokes with the Flexhone in a hand electric drill motor.   This brought the bore diameter up about 0.0003 inch. Finishing was done with a adjustable brass Acro lap charged with 10 micron diamond compound.  A very good cleaning followed, first with solvent and then with hot water and detergent.  A spray of WD40 followed as the iron would start to rust within the hour with no oil protection.
Gail in NM



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Offline cfellows

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Re: A "Different" Different Opposed Piston Engine
« Reply #22 on: January 18, 2014, 05:13:42 AM »
Thanks for the interest and comments everyone.

Chuck: For the hall effect device I am using a SS441R in the flat TO92 package by Honeywell for my pickup.
http://www.alldatasheet.com/datasheet-pdf/pdf/345668/HONEYWELL/SS441R.html
This not what the CDI module distributor supplies but is equivalent. It has good magnetic sensitivity so magnet spacing and strength requirements are not very critical. They are a little more robust than some of the other manufacturers products. They are available from many distributors but I get mine from Mouser as they are generally a little cheaper there. Besides they are in your and my neck of the woods.  Price is about US$ 1.70 each but they drop to just under a dollar each if you buy ten.

[Deleted]

I got lucky, I think.  I ordered 6 of these from Element14.  Cost me a total of $11.75 which included shipping and some tax.  The unit price was $0.78.  By the way, what are you planning to use for a carburetor?

Chuck
So many projects, so little time...

Offline steamer

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Re: A "Different" Different Opposed Piston Engine
« Reply #23 on: January 18, 2014, 09:00:13 AM »
Outstanding Gail!...are the laps a stock item?....gotta picture?   Additionally, who's carbide boring bar is that?...Microbore?

Dave
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Damned ijjit!

Offline Roger B

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Re: A "Different" Different Opposed Piston Engine
« Reply #24 on: January 18, 2014, 09:23:12 AM »
http://acrolaps.com/index.htm

Very helpful people. They sent me some 15 and 25 mm laps to Switzerland for $28 P&P
Best regards

Roger

Offline GailinNM

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Re: A "Different" Different Opposed Piston Engine
« Reply #25 on: January 18, 2014, 02:53:57 PM »
Thanks for following along.  Nothing like interest to speed things along.

I should have provided more details about my bore finishing operations so will do so now.

For boring I used a solid carbide micrograin boring bar. Several people make them and since I have been using the same one for 15 years or so I am not sure whose I am using.  But the specs are 0.320 inch minimum bore with 1.25 maximum depth and a 0.375 inch shank.  It is the equivalent of this one but a lot less money back when I bought it.

http://www.mscdirect.com/browse/Turning-Boring/Boring-Bars-Grooving-Tools/Boring-Bars?navid=12105888+4288237782+4288232280+4288237789+4288232279+4288215366

The Flexhone is this one.  They can generally be had on Ebay for about 1/2 as much money.

http://www.mscdirect.com/browse/?navid=12100209+4288246421+4288168592+4288225324

The URL that Roger gave for ACRO laps is a good one, but note that their price list is 7 years old and prices have about doubled since then. They also make metric sizes which are not generally cataloged by USA suppliers but they do sell direct. If you are going to be using more than one grit of abrasive for lapping buy an extra barrel for each grit.  After using itl, put it in a plastic bag with a label and always use it with that grit.  Never mix grits on the same barrel and you can not tell by looking at it which grit it was used with. Here is a link to the one I used on the MSC website.

http://www.mscdirect.com/browse/Abrasives/Laps-Hones/Through-Hole-Laps?navid=12100079+4288090273

For abrasives I use diamond compound. Don't be put off by the seeming small amount in a 6 gram tube.  I have used about 2 grams over the last 10-15 years.  It does not take much. Since I bought mine Shars has started carrying it at about 1/4 the price of other suppliers.  I have not tried the material from Shars, but it should work OK.  Here are links to both Shars and Enco for suitable compounds.

http://www.shars.com/products/view/5291/USBS_9_Diamond_Polishing_Compound

http://www.use-enco.com/CGI/INSRIT?PMAKA=619-0158&PMPXNO=16717886&PARTPG=INLMK32

Very important is cleaning the bore after lapping.  It does not make any difference if you are using aluminum oxide , silicon carbide or diamond compounds you must SCRUB the bore before ever inserting any hard into the bore. No pistons, plug gages or anything hard.  If you do residual abrasive can be forced into the bore and will never come out with cleaning.  I use test tube brushes, dish washing detergent and hot water.  Nylon tube brushes are available at many stores but Amazon has them as well as Harbour Freight. The Harbour Freight assortment only has one or two useful ones for me, but if lyou are visiting their store they are cheap enough to pick up a package.  Amazon's has a variety and if you are ordering other things and qualify for free freight they are cheap enough.

http://www.harborfreight.com/9-piece-tube-pipe-nylon-brush-set-90631.html

http://www.amazon.com/Test-Tube-Brush-Pack-10/dp/B003LRVR4W/ref=sr_1_8?ie=UTF8&qid=1390050562&sr=8-8&keywords=tube+brush

Some general information on what I am trying to accomplish which is plateau honing.  The Flexhone leaves a relatively rough finish with grooves on the order of .0005 deep.  When lapping this only the tops (plateau) is removed leaving these grooves with very smooth tops.  These grooves act as oil retaining areas and reduces the sliding area reducing friction while still maintaining a very good seal.  For more information do a search on "Plateau honing".  It is being used quite a bit on high performance automotive engines. I don't know if l am accomplishing this or now but it makes a good story. I do know that this procedure works for me.

Any questions -- just ask. I may not have the answers but you can ask and others may chime in with the answers.

Gail in NM
« Last Edit: January 20, 2014, 01:22:20 PM by GailinNM »
I would like to be the kind of person my dog thinks I am.

Offline GailinNM

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Re: A "Different" Different Opposed Piston Engine
« Reply #26 on: January 18, 2014, 03:04:17 PM »
Chuck:  I forgot to answer your carb question.  I will probably just use a simple fuel mixer with a spray bar.  I might build up an adjustable speed carb later as I have several engines that coud benefit from it.  I have been following your thread on carbs with interest.
Gail in NM
I would like to be the kind of person my dog thinks I am.

Offline Doc

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Re: A "Different" Different Opposed Piston Engine
« Reply #27 on: January 18, 2014, 03:17:01 PM »
  Things are looking really good NICE WORK. I am thinking of building an Atkinson Differential but this has gotten my attention. I'm in the middle of an end mill sharpening setup build right now. So I'll just follow along with your build right now and I must say it is looking nice.  :ThumbsUp: :ThumbsUp: keep up the good work I'm following along.

Offline smfr

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Re: A "Different" Different Opposed Piston Engine
« Reply #28 on: January 18, 2014, 04:57:19 PM »
Thanks for the great info on bore honing, Gail. It's these kinds of posts that make MEM such a valuable source of information.  :ThumbsUp: :ThumbsUp:

Simon

Offline philjoe5

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Re: A "Different" Different Opposed Piston Engine
« Reply #29 on: January 18, 2014, 05:59:48 PM »
Nice work Gail.  Thanks for the info on the carbide boring bar.  I've been tempted to buy a small one for boring holes under 5/8" but since they are pricey I was waiting for someone to comment on them.

I'm enjoying the thread.  You've put in lots of useful information and photos.

 :cheers:
Phil

If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.  - Mark Twain

 

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