Demon V8 (multiplied 1.5)

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Hi Foketry!
Thank you for the Photos. That is the same process I'm using on my PeeWee V4 but the hole is getting about 0,02mm tapered. I remember someone here saying that this type of lapping causes the hole tapered.

Thanks,
Edi
 
Both the Demon and the Peewee are designed so they can be lapped or honed as a through hole. The block can be honed from the top and flipped to be honed from the bottom. By flipping the block back and fourth the taper can be taken out.
 
e.picler said:
Hi Foketry!
Thank you for the Photos. That is the same process I'm using on my PeeWee V4 but the hole is getting about 0,02mm tapered. I remember someone here saying that this type of lapping causes the hole tapered.

Thanks,
Edi
Click to expand...
I used this lap for Holt 75, Howell V4 and Demon V8 and the max tapered shape was 0.005 mm
I use 2 laps , one for roughing, one for finishing
In this case I have turning, grinding and lapped the cylinder liners before assembly, but once pressed inside the engine block, they have become deformed 0,01-0,03 mm in the 2 contact areas of the engine block. ( bottom and top )
It was necessary to lap again.
This is a lesson learned, next time I will insert the cylinder liners without interference fit , but with little backslash
 
Hi Foketry.
- how did you go about grinding the liner bores? You mean like a tool post grinder in the lathe?
- on the lapping side, did you take much material off or just t correct the max 0.03mm eccentric shape?
- what kind of lapping grit on the roughing tool & finishing tool?
 
petertha said:
Hi Foketry.
- how did you go about grinding the liner bores? You mean like a tool post grinder in the lathe?
- on the lapping side, did you take much material off or just t correct the max 0.03mm eccentric shape?
- what kind of lapping grit on the roughing tool & finishing tool?
Click to expand...

yes, I built a post grinder tool with 2 electric motors 24 volts for model aircraft , for internal holes and external shaft ( photo is with a grinding wheel for shaft , I can also mount a small grinding wheel for holes)


IMG_7793 (2).JPG
IMG_7795 (3).JPG


I normally leave 0.02 mm before lapping , max 0.03
I use silicon carbide, grit 400 for roughing, grit 600 for finishing , I don't use diamond paste because I read on this forum that a diamond is forever .....

IMG_8960.JPG
 
I see that you have used a grinder on the crank - makes perfect sense to me. Earlier this year I started a small V8 using my own plans but had to put it aside to get on with more pressing jobs, once I return to it your comments on the cylinder bore lapping will come in handy.
 
First stage processing of the rods by flat endmill 4 mm

IMG_8211.JPG


I glued 3 + 1 aluminum plate with epoxy glue on a wooden surface , these were faced and milled , unglued by heat, glued on another wood plane already leveled and faced on the opposite side.
After they were reamed in the 2 holes.
 
Crank and camshaft tunnel
To make these 2 holes I modified 2 reamers extending them with an extension so that the reamer was guided through each hole on the next one.
This is to ensure alignment
Initially I drilled with a long drill , then enlarged the hole with a long end mill to make the hole straight, then enlarged with a drill and finally bored with a long special reamer.


IMG_8873.JPG
 
That is coming along nicely. There is another fellow that started a 1.5 build but it never was finished. I met another fellow at the Zanesville show that has a 2X in running condition. These over scale builds are cool as heck!
 
stevehuckss396 said:
That is coming along nicely. There is another fellow that started a 1.5 build but it never was finished. I met another fellow at the Zanesville show that has a 2X in running condition. These over scale builds are cool as heck!
Click to expand...

I ask myself how it is possible to start this project and not complete it, the first pops give a great satisfaction, they make you happy, I work on this project at least 10 hours a day to reach the goal as soon as possible.
I saw this engine roaring on YouTube , your model and that of Doc, mine too must rumble ......
 
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