Another Edwards built.

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Glorfindel

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Hi guys. It's my first built. I'm mostly doing it by the plan, but i adapted some parts to my machining capacity.

Im using a DMG DMU50 (5 axis mill), DMG 1250CTX (mill/turn) and a 4 axis wire EDM and a 3d printer ( mockup purpose)

Here are the parts i made so far:



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Glorfindel

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Did those parts today

Everything went good. Still not sure why the carbs is offset center tho.

I tought that it was about "centering" the carbs vs the 2 longer intakes tubes, but if that was the goal, it can be better than that.
20190117_162745.jpeg
 

petertha

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Nice parts.
I'd like to see some details of your cylinder liner one day. Is the one in the picture 'prototype' (as I like to call my first knock offs :) ). Are you grinding bores or lapping or...?
Did you decide you will proceed with the original design lubrication pump?
 

Glorfindel

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Nice parts.
I'd like to see some details of your cylinder liner one day. Is the one in the picture 'prototype' (as I like to call my first knock offs :) ). Are you grinding bores or lapping or...?
Did you decide you will proceed with the original design lubrication pump?
Yes, i usually do a couples of "prototypes" before the final ones ;-)

I did the liners on the 1250ctx. So i did the outside diameters in lathe mode, and i did the bore with a Udrill and the finishing with a boring bar.

I left some little material for manual honing with cross pattern.
 

Glorfindel

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Did the rocker brackets today. It take exactly 4:00 min to do one, about 1.5 hours of programation.
20190118_160111.jpeg
 

Glorfindel

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Did the pistons today. I changed the ring groove to 1mm( 0.039") instead of 0.0325" because i already had the 1mm grooving tool, so i adjusted the pattern.

I will make the ring 0.008" thicker.
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tornitore45

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If I understand the post and pictures you did a stress analysis of the part as designed and of a new design and concluded your much simpler new design is sufficiently strong. Right?
 

Glorfindel

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If I understand the post and pictures you did a stress analysis of the part as designed and of a new design and concluded your much simpler new design is sufficiently strong. Right?
Yes sir. Same weight, same strengh, just a different design adapted to my tooling/cnc.
 

petertha

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Neat! Just curious, is the program showing stress of the threads for the screwed in rocker button & valve adjustment screw or that is just omitted for simplicity?

Most all of the (commercial RC) 4-strokes I've seen have hardened steel rockers, but I guess one big reason is one end is acting directly on the valve. Whereas the Edwards uses 7075 and has steel thread-ins for both contact parts.
 

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Glorfindel

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Neat! Just curious, is the program showing stress of the threads for the screwed in rocker button & valve adjustment screw or that is just omitted for simplicity?

Most all of the (commercial RC) 4-strokes I've seen have hardened steel rockers, but I guess one big reason is one end is acting directly on the valve. Whereas the Edwards uses 7075 and has steel thread-ins for both contact parts.

Yes, it's a simplified analysys. I guessed that the threads are not the weak point.

There is place for "optimizing" some of the parts and crush some numbers. Lots of fun ahead of me.

I want to also make a small dyno to record everything and compare designs.
 

editor123

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Did the pistons today. I changed the ring groove to 1mm( 0.039") instead of 0.0325" because i already had the 1mm grooving tool, so i adjusted the pattern.

I will make the ring 0.008" thicker.View attachment 106923View attachment 106924
One thing to be careful of is when you increase the height of the ring, you can significantly increase friction. Have you read the Trimble ring article in Strictly IC? StrictlyIC.com if you don't have the article. The only caveat in the article is that he uses too high a temperature to set the rings. 1100 degrees F for one hour is better.
 

tornitore45

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There is not a lot of room between the wrist pin and the piston top to pack 2 rings and one scraper.
 

editor123

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An oil control ring will work below the Wrist Pin.
 

Glorfindel

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One thing to be careful of is when you increase the height of the ring, you can significantly increase friction. Have you read the Trimble ring article in Strictly IC? StrictlyIC.com if you don't have the article. The only caveat in the article is that he uses too high a temperature to set the rings. 1100 degrees F for one hour is better.
Thx, i'll take a look at the article.
 

tornitore45

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An oil control ring will work below the Wrist Pin.
There is where I plan to put mine. But the bore on the piston bottom (no diameter dimension) 0.30 deep need to be stopped early, like to a 0.20 depth to leave enough metal.
 

Glorfindel

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First side done, but i'll make another one, the material was harder than expected, i will corect some speed and feed next time.
20190206_155748.jpeg
 
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