My modified build of "Chucks Single"

[cfellows]

Apologies, MB, the bottom crankshaft drawing isn't particularly accurate. Here is an accurate view of the crank. The total width and thickness of the webs and the length of the connecting rod journal will all need to be adjusted a bit to suit your connecting rod thickness and the distance between your crankshaft bearings.

Chuck

 

[radfordc]

Having just done a crank for Chuck's John Deere engine (and ruined the first one) I can appreciate your concern. Here are a couple of links to some good info on making cranks:
http://modelenginenews.org/techniques/crankshafts.html
http://modelenginenews.org/cirrus/crankshaft.html

The scary part is having a tool sticking out over an inch from the tool post and fitting it into the slot for the rod journal.

Charlie

 

[Metal Butcher]

Apologies, MB, the bottom crankshaft drawing isn't particularly accurate. Here is an accurate view of the crank. The total width and thickness of the webs and the length of the connecting rod journal will all need to be adjusted a bit to suit your connecting rod thickness and the distance between your crankshaft bearings.

Chuck

Chuck, no need to apologize. Others before me used your drawings and didn't have a problem building. Its just self inflicted confusion caused by a habit of over analyzing. The upper drawing on page 6 of the original download is what confused me. It shows the crank and piston rod journals at opposite ends of the web, and the lower drawing shows the crank journal central to the webs.

Wow, that's a long throw compared to what I normally build. If I made the webs as discs they would be approaching a fly wheel size!

The throw indicates that there will be about .050" head clearance for the piston. Is that correct, and is this the usual amount to aim for when drawing up a design?

Thanks.

-MB

 

[bearcar1]

I agree with you Rad', that sticking cutter about a mile long ;D into a slot in a piece of metal spinning at some un-godly speed isn't exactly a calm and soothing experience. The thought terrifies me, but I am working up to attempting to overcome those fears. th_confused0052 in the future. Those site addresses go to some very interesting and thorough steps to machine up a crank from solid. The section marked con rods for the second listing is an interesting method using a ball turning attachment. cool. 8)

 

[tel]

You've been busy, MB!



Tel, I like your spring ring retainer. What size spring wire do you reckon would be good for a 3/32 retainer?


Chuck

I have a small coil of fineish stainless that I use for little one like that - not sure of the size, I'll mike it up next time I go down there.

 

[cfellows]

Here are a couple of drawings of how I proceed in making a crankshaft from solid, flat bar. Hope I haven't forgotten anything or gotten them out of sequence! :-[

 

[Metal Butcher]

The valve stem project ended with success! I tested it with air pressure and there was a small amount of leakage. Then I remember that the seat needed to be set on a thin layer of gasket silicone. After I added the silicone step another series of tests showed the valve to be airtight.
I snapped a series of step-by-step photos that show the unusual way I made the valve stem. The idea was to use a simple and precise approach to make a functional part and it worked!

1) Rather than machining the outside diameter of the valve stem I used precision ground drill rod. After cutting to length the e-clip groove was added.

2) The valve stem head was cut from 3/16" scrap brass rod at 45 degrees to match the valve body seat. I drilled and reamed it undersized (.1865".) After adding a little Locktite to both parts, the tail stock chuck was used to press the stem into the valve stem head. Then the finished valve stem was cut off using a parting tool.

3) Below is the valve stem installed part way into the lower half of the valve body.

4) Below is the completed valve and a supply of spare parts. If you focus on one of the brass seats you can see tool chatter, something I didn't notice before. The camera does not lie.
Chuck was correct when he indicated the difficulty in handling one of these small e-clips. Trying to pick one up with my fingers drove me to the edge of insanity! After I walked away to take a break a solution came to mind. I used a piece of Scotch tape held between my thumb and forefinger to pick it up at the open end. Then with the help of my bench magnifier I grabbed it on the opposite end with a pair of precision needle nose pliers and installed the clip in it's groove.

-MB

 

[Metal Butcher]

Here are a couple of drawings of how I proceed in making a crankshaft from solid, flat bar. Hope I haven't forgotten anything or gotten them out of sequence!

Thank you Chuck! :bow:

That just what's needed before I embark on the seemingly impossible crank shaft voyage! :big:

-MB

 

[cfellows]

That's a good idea of using loctite to put the valve together. Which variety of loctite did you use?

Chuck

 

[Metal Butcher]

That's a good idea of using loctite to put the valve together. Which variety of loctite did you use?

Chuck

Hi Chuck. I used green 609 to assemble the built up valve stem. I'm really relying more on the press fit due to using a .1865" reamer (under size).

I forgot to add that another good choice (besides Acetal) for the separate valve seat would be hard urethane. I have some rod stock that I was going to use, but forgot all about it. :

The use of a material like urethane is based on a previous experience when I used it to seal valves subjected to 900 lbs of pressure. It was not my idea , I was just replacing very old existing seats used on a valve stem system nearly identical to your engine valve.

-MB

 

[radfordc]

In Chuck's drawing, note how the tools are angled. The drawing is a little exaggerated, but the idea is correct. The angle keeps the shank of the tool clear of the side of the slot. The first crank I screwed up I didn't do this and the tool caught on the work and jerked it out of the chuck...and bent the crap out of it.

Charlie

 

[cfellows]

Good point, Charlie, thanks for emphasizing that. The angle in my drawing is 5 degrees, but it doesn't need to be that severe. If you don't angle the tool, the side of the crank web will taper inward or, worst case, grab the web and create mayhem!

Also, you probably could get by with a 1/8" thick cutoff blade if you don't have 3/16".

Chuck

 

[Metal Butcher]

I followed Chuck's informative drawings and text to machine the crankshaft from a solid piece of cold rolled steel. After the layout I drilled the required hole and sawed the relief cuts. To my surprise the steel sprung quite a bit and this was verified with micrometer measurements. The picture below shows the blank drilled and the relief cut. Look at the measurements written-in on the upper drawing!

I ground the profiles and clearance angles on three 3/16" round carbide tool bits to make the required cutters. My DRO (0-1.000" Dial Read Out) had to be removed to clear the large face plate that came with my lathe. This left me to rely on the hand wheel dials. This and the vanishing view of the work piece when it was spinning was a little nerve racking. I spent a good amount of time taking very light cuts and lots of breaks to relax my nerves. This also allowed a cool down period for the work piece. Below is a picture of the set up used and one of the cutters I made in it’s simple tool holder.

I adjusted the dimensions on the crank to suite my idea and way of doing these things. The altered drawing below shows that the crank will be spaced away from the bearing blocks with two .040" spacers. I may just use longer length bushings and press them in standing proud by .040".

I think that I could have made at least four crank shafts using a build-up brazed together in the time it took to machine this one from solid. But then I would still be fearfully avoiding this preferred method used by most builders with more experience.
Would I recommend machining a crank from solid to a beginner? Definitely not!
Will I do it again? Probably so.
Will I enjoy doing it again? Probably not.

Below is the finished crank. I parkerized it (a chemical surface treatment) as a precaution against rust and I also prefer it’s look compared to raw or painted steel.

-MB

 

[cfellows]

MB, you did a darned fine job on that Crank. And it does get easier and more intuitive as you do more of them.

I acctually prefer the cut-from-solid approach. I'm fearful that the soldered / brazed approach just won't come out straight and square!

Different strokes...

Chuck

 

[Metal Butcher]

MB, you did a darned fine job on that Crank. And it does get easier and more intuitive as you do more of them.

I acctually prefer the cut-from-solid approach. I'm fearful that the soldered / brazed approach just won't come out straight and square!

Different strokes...

Chuck

I use a precision bored jig to hold everything together while brazing. I found that most if not all cases the "warping" was really just a set up misalignment. Using dissimilar metals is another culprit. Getting impatient and throwing water at a hot crank or a quick cool water dip is a great way to produce a first class "Pretzel Crank."!

Of course I never did anything stupid like that, I just heard a few stories. :

-MB

 

[cfellows]

I use a precision bored jig to hold everything together while brazing. I found that most if not all cases the "warping" was really just a set up misalignment. Using dissimilar metals is another culprit. Getting impatient and throwing water at a hot crank or a quick cool water dip is a great way to produce a first class "Pretzel Crank."!

Of course I never did anything stupid like that, I just heard a few stories. :

-MB

Wouldn't mind seeing a picture of that jig. Sounds useful.

Chuck

 

[Metal Butcher]

Wouldn't mind seeing a picture of that jig. Sounds useful.

Chuck

No problem, I'll post a picture of the crank building jig. I will build a jig for the John Deere crank along with posting its photos and exact dimensions.

To build the jig I searched looking for dimensional drawings and finally gave up. Where are the John Deere plans that others have-used or are-using? All I found was one picture in the file repository. Are they building a similar look and making up there own dimensions?

Its was on my mind to use a built up crank on this build, but I really needed to break away and machine one from solid.

Thanks. -MB

 

[radfordc]

MB, I drew up a set of plans in TurboCad for the John Deere. I started with the pictures and dimensions that Chuck posted in his thread and just drew everything to fit from those. I can send you a file of the drawing if you want. I will be leaving for the NAMES show at noon today and be back home on Sunday evening.

Charlie

 

[Metal Butcher]

MB, I drew up a set of plans in TurboCad for the John Deere. I started with the pictures and dimensions that Chuck posted in his thread and just drew everything to fit from those. I can send you a file of the drawing if you want. I will be leaving for the NAMES show at noon today and be back home on Sunday evening.

Charlie

THANKS! That file would be a great! I don't really have the ability to build without drawings. Learning how to machine and become a successful engine builder is my goal. Learning computer skills and mechanical design/ engineering is not what I had in mind for my remaining years. Being left behind and not being able to built some of the interesting designs presented on this forum is very frustrating. I would imagine that most members with my handicaps and disabilities wouldn't even bother to post or become involved with certain projects.

I don't want this to sound like I'm complaining. There is a great deal of helpfull and willing members on this forum. And I'm thankful to all of them for their patients. However, It could be that my motivation is causing a little frustration and impatients on my part.

I look forward to getting your TurboCad drawings. Thanks again!

=MB

 

[ozzie46]

MB
I am very interested in those plans as well. I have Turbocad deluxe V-12.
If you are willing to share them I would be very grateful.


Ron