Author Topic: Farm Boy #876 - Mike's Build  (Read 3695 times)

Online Kim

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Re: Farm Boy #876 - Mike's Build
« Reply #15 on: September 24, 2022, 10:48:52 PM »
Very interesting operation to make that complex part!   :popcorn:

Sorry to hear about the broken tap.  We've all been there.  You made an excellent recovery from that though!  Well done!

Kim

Offline cnr6400

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Re: Farm Boy #876 - Mike's Build
« Reply #16 on: September 25, 2022, 12:57:05 AM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline Roger B

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Re: Farm Boy #876 - Mike's Build
« Reply #17 on: September 25, 2022, 08:16:06 AM »
Excellent progress and a good save on the broken tap  :praise2:  :ThumbsUp:

What insert lathe tooling are you using?
Best regards

Roger

Offline mikehinz

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Re: Farm Boy #876 - Mike's Build
« Reply #18 on: September 25, 2022, 03:35:31 PM »
Excellent progress and a good save on the broken tap  :praise2:  :ThumbsUp:

What insert lathe tooling are you using?

Roger, I'll answer in general terms with ANSI designations.  There are ANSI to ISO lookup tables if you prefer that designation.

I tend to mostly use the 'C' shape which is the 80 degree diamond shape.  The advantage is that they're very common and they can both turn and face without reorientation.  I also have mostly 5/8" tool holders so I tend to purchase the 3/8" inscribed circle inserts.

With that out of the way for Al I use CCGX-32.51 (sometimes indicated as CCGT) inserts.  That's a dead sharp, uncoated, highly polished, high positive rake chipbreaker insert.  It cuts Al like butter.  You can also use it for steel but it's not nearly as tough as a specific insert for use on steel or cast iron.

For steel, I use CCMT-32.52 inserts.  These are tougher than the Al specific inserts and I use them on cast iron, drill rod, and any other ferrous metal that I'm turning.  There are a wide variety of coatings and chipbreaker styles so you'll need to do a bit of research to find one that you'll like. 

For parting and grooving, I almost always use 2mm wide carbide insert designed as ZTBD02002-MM.  That's from ZZC-USA but that same insert is available from other vendors.  I also have the 3mm wide version and a 3mm round nose insert for creating small radii.  With the 2mm insert I can part off easily at almost any speed I choose and can also create wide grooves as the insert will cut when moved sideways, as long as you don't try to take too much off at once!

I also have a few inserts in the 21.51 size in both the 80 degree diamond shape and the triangle shape for use with small boring bars. 

There are of course, an almost infinite number of vendors for inserts.  But since I don't want to spend a fortune, I generally purchase either ZCC-USA and/or Korloy, both of which Shars sells.  Shars is reliable and you'll get what you ordered.  Cost is around $5/insert.  These days I tend to purchase from Shars as their price is barely higher than Ebay and you'll get exactly what you order. 

You can also try Ebay especially for Korloy where you can typically purchase a package of 10 inserts for about $40 with free shipping.  But on Ebay be cautious who you're buying from as there's almost no guarantee that you're getting what you think you're buying.  Inspect carefully upon receipt.

I do also use some HSS that I grind to whatever I need.  But I tend to use HSS rarely as the carbide inserts are so cheap these days and they work so well and last a very long time.  If I buy another couple of packs of qty 10 inserts, I doubt I'd use them all up before I'm dead and gone.

Hopefully the above is useful to you.

Mike

MIke
Wichita, KS, USA

Offline mikehinz

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Re: Farm Boy #876 - Mike's Build
« Reply #19 on: September 26, 2022, 02:55:26 AM »
Next up is the rear frame.  I thought that this was going to be the easiest of the 3 major frame components, but it turned out to be the hardest by far.  Read the following and weep  :'(

The first feature that I decided to do was the rear portion of the frame.  I started by blueing the stock up and doing a basic layout.  Then I drilled thru right at the center of the radius that forms the junction between the bottom of the part and the back angled part.  Since I modeled this I had the xy coordinates positioned the hole with the DRO.



Next the part was repositioned  as shown and i  chewed away at the material that needed to be removed from the back.  I first used a 1/2" roughing end mill.  You'll note that i stayed clear of the layout lines at this point.



Then I switched to a conventional 4 flute end mill and brought the bottom feature to dimension and tried to blend that portion to the radius as best i could.



Repositioned the part again and cleaned up the rear surface with a 1/2" end mill.  I used an 8 degree angle block to set the part tot the specified angle from the drawing.



And here's the part on the drawing so you can see how it compares at this point to the isometric view.



Repositioned the part yet again in the mill vise and chewed away most but not all of the material that needed to be removed from the interior of the part.  In particular I was careful to stay away from the rear of the part as that will need to be cut away at an angle. 



And here's the part with most of the material from the interior removed.



Since there's a radius called for in the bottom corners, I decided to plunge in as shown in order to create those radii.  And then clean up the remaining material on the bottom and sides.  I thought that this might eliminate the inevitable chatter when trying to shove an end mill into a corner.



Then I reoriented the part in the mill vise and used a 4 flute end mill to bring the bottom and sides to dimension. 



In this pix you'll see the start of where I went wrong.  I thought I had calculated the depth of the plunge of the end mill when I formed the radii in the corners so that when the back was cut at an angle, everything would blend together smoothly.  I was wrong!



The part is reoriented in the mill vise as shown.  I put an 8 degree angle block under the part to match the angle previously formed on the back.  The idea was that this ball end mill would remove the material on the interior back and would blend the edges and corners together. 



You can see what actually happened.  Somehow I plunged in too deeply and I simply couldn't clean up the interior rear corners.



After crying in my beer, I decided that there was nothing to do but proceed.  Here I've reoriented the part 8 degrees from vertical in preparation for creating the 1/2 round opening at the rear of the part.  Note that this radius doesn't start at the top surface but about 1/2" lower, but interestingly the center of the radius is at the top surface.  I noted at least one other builder missed this and had to notch out the back to clear the connecting rod when it rotates.  Here I've found the centerline in y but I'm visually lining up in x as there was really no other surface to reference from. 



Then I used my boring head to advance the cut until I had the radius formed as per the drawing.  That all went well.



And here's the part laid on the drawing.  It matches well except for the terrible eyesore in the bottom rear corners.



Next I turned the part on it's side and milled the features on the right side, first using a 1/2" end mill to remove most of the material and to create the relieved area that will mate with the front frame.



Since the drawings call for a .032" radius at the base of the raised features, I purchased a 3/16" end mill with an .032" corner radius and used it to bring the raised area to the final dimensions.  I'm not sure that this was necessary as afterwards you really can't see the radius.  So if I were to do it again, I'd not bother with this step.



The interior corners kept bothering me so I tried to fix it up a bit.  I smeared some JB weld in the corners and at the rear and then tried to use a small ball end mill to clean it up.  I was somewhat successful, but if you look closely it's still ugly.  What I should have done was to wait until this part was complete and then use Bondo as a filler with some sanding to smooth things out.  That would have been much faster and probably better in the end. 



So now onto the other side.  I placed the part in the mill vise on some large parallels as you can see along with a 123 block between the part and the movable vise jaw in order to hold it securely.  I also blued up the surface and scribed some layout lines to double check myself.  Note that I located the upper right corner and set the DRO to 0/0 at that point as the reference for work on this side.



Then I milled away most of the material with a 1/2" end mill.



Then I changed over to the corner radius end mill and brought the two raised features to dimension.



And finally I used a 1/2" end mill to reduce the height of what will be the cam boss to the height spec'd in the drawing.



And this pix is actually a bit out of order but you can now see how the 3 major frame components will all go together, sooner or later!



There's still some work to be done on this part and it has to be joined to the front frame, but that's all for today.

Enjoy!

Mike

MIke
Wichita, KS, USA

Online Kim

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Re: Farm Boy #876 - Mike's Build
« Reply #20 on: September 26, 2022, 05:15:39 AM »
More great carving there, Mike!  :popcorn: :popcorn:

Sorry about the miss on the hole depth there.  Math can backfire on you sometimes... I try so hard, but sometimes miss the calculation for some reason.  To help prevent this I try to calculate things in two ways.  If they don't match, I need to figure out what I did wrong!  But all too often I forget, or I just think it'll be close enough.  Often it works out, but sometimes, it really bites me!  But you have a good work around for it.  And by the time it's painted, no one will ever notice it!

Kim

Offline Roger B

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Re: Farm Boy #876 - Mike's Build
« Reply #21 on: September 26, 2022, 11:08:49 AM »
Thank you for the information  :)

I use the 55° DC.., style tips and also use the Aluminium types for finishing steel. I was interested in the radius tip for the parting/grooving tool you were using for profiling. The maximum tool size I can use is 10mm so I will have to see what is available.
Best regards

Roger

Offline mikehinz

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Re: Farm Boy #876 - Mike's Build
« Reply #22 on: September 26, 2022, 04:00:11 PM »
More great carving there, Mike!  :popcorn: :popcorn:

Sorry about the miss on the hole depth there.  Math can backfire on you sometimes... I try so hard, but sometimes miss the calculation for some reason.  To help prevent this I try to calculate things in two ways.  If they don't match, I need to figure out what I did wrong!  But all too often I forget, or I just think it'll be close enough.  Often it works out, but sometimes, it really bites me!  But you have a good work around for it.  And by the time it's painted, no one will ever notice it!

Kim

Kim, thanks for the kind words and sympathy!  I do try to double check my calcs, but for the life of me I don't know exactly where I went wrong on this.  Maybe I failed to zero the quill DRO???  I'm just not sure.  But as you say, Bondo and paint can cover a multitude of sins!!

Thanks!

Mike
MIke
Wichita, KS, USA

Offline mikehinz

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Re: Farm Boy #876 - Mike's Build
« Reply #23 on: September 26, 2022, 04:19:43 PM »
Thank you for the information  :)

I use the 55° DC.., style tips and also use the Aluminium types for finishing steel. I was interested in the radius tip for the parting/grooving tool you were using for profiling. The maximum tool size I can use is 10mm so I will have to see what is available.

Roger, I took a quick look thru the various catalogs I have and it looks like for the small'ish tool shank size you have, you can use only up to the 2mm size groove/turn/profile/part tools.  That may be a too small a radius for you.  Just for your reference I found this tool holder from Shars, although I note that you're located in Switzerland, so you'll likely have to find a different supplier.

https://www.shars.com/products/indexable-cutting/cut-off-and-grooving-tools/3-8-x-1-2-external-cutoff-grooving-turning-tool-holder-right-hand-2-mm-mgmn

I do like the MGMN style of inserts and tool holders as they work very well and can serve multiple functions.  But with my tool holder max size being 5/8" I'm limited to 3mm maximum insert width for either grooving or profiling. Interestingly I tend to use the 2mm grooving tool the most as it parts off very well and easily creates grooves as needed.  But it can only part up to about a 1" OD so sometimes I have to revert to the "P" style HSS cutoff blade in an Aloris tool holder.

Good luck on finding what you need!

Mike

MIke
Wichita, KS, USA

Offline Don1966

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Re: Farm Boy #876 - Mike's Build
« Reply #24 on: September 26, 2022, 05:06:17 PM »
Wow! Nice work and craving …. :Love:


 :cheers:
Don

Offline Bearcar1

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Re: Farm Boy #876 - Mike's Build
« Reply #25 on: September 26, 2022, 11:46:24 PM »
Nicely done!!! Whew! a lot of steps but WoW!! what and end result.... VERY Good!..


BC1
Jim

Offline mikehinz

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Re: Farm Boy #876 - Mike's Build
« Reply #26 on: September 27, 2022, 01:20:05 AM »
Finally I'm at the stage of working on the 'smaller' bits.  They're not necessarily less complex to machine, but at least they're smaller! 

First up are the crankshaft bearing caps.  These are pretty straightforward.  I brought a couple of small pieces of 1/2" Al bar stock to size as seen here.



Then located and drilled qty 2 #18 holes in both pieces as seen here.



And here are the 2 caps on the drawing.  Note that the edges are not yet rounded over and there's not a half of a hole in either of them yet!! 



Next is the crankshaft bushings.  I had some bearing bronze (SAE 660) round stock on hand and quickly turned the OD and then drilled and reamed through .001" over .375" as per the drawing.  I deviated from the drawing in that I made the non-governor side the same length as the governor side.  I did that because I need to fit a disk on the non-governor side that will hold a magnet and became the ignition timing.  So I need a bit more room on that side than Mr. Howell originally called for.  My method isn't as elegant as what Howell specified, but it has the huge advantage of making the ignition timing completely independent from the exhaust cam timing.



And here are the 2 bushings on the drawing.



And with those parts made it's time to create the threaded holes on the rear frame for the caps and for the camshaft.  Here I'm tapping the camshaft securing hole with a spiral flute 4-40 tap.  Note that I've already drilled and tapped the locations that will bolt the bearing caps.  After having purchased a number of spiral flute and spiral point taps, I regret purchasing any conventional hand taps.  Clearing the chips out either forward or backwards makes life much, much easier when tapping.



And here's the rear frame with the bearing caps bolted down.  You can see the ugly JB weld that at least partially covers up my earlier screw up on the rear frame interior.



Now comes a critical operation.  First I carefully located my reference edges and then moved to the center location of where the crankshaft will go.  First I center drilled and then drilled thru the top hole 31/64".  In the pix I'm using a long center drill to locate the hole in the 'bottom' of the rear frame/cap assembly.  I did the OoO this way to to try to make sure that the two holes were aligned as accurately as possible.  I'd of course locked the table in x and y right before i commenced drilling.



Then I drilled thru the lower location with a 1/4" drill and here I'm using the 31/64" drill to bring the hole to almost the required dimension.



And finally, I'm running a .500" reamer thru both sides to (hopefully) get the holes accurately aligned and to size.



And now, because I'm an old, mistrusting skeptic, even though I never unlocked the table, I used a DTI to be absolutely sure that the spindle is still exactly over the hole for the crankshaft.  The reason I wanted to be sure is that this now becomes the reference for the camshaft hole location. 

I do want to caution anyone building this engine that Howell's drawing for the camshaft hole location seems to be slightly in error.  I took the pitch diameters from the gears and recalculated the camshaft hole location and it turns out to be more than a little off.  so I moved the camshaft hole location 'forward' a bit in order to get the distance between the gears properly spaced. 



Then after locating the camshaft hole using the DRO and my corrected distance, I center drilled, drilled and then reamed for the camshaft.  I think I actually reamed it .251" just to have a bit of clearance when assembling.



Then to check if I managed to get things right, I installed the bushings and the caps and than ran a piece of 3/8" drill rod through both sides.  By some miracle it passed thru both bushings and actually turned rather nicely!!!!   I felt pretty good about this as this is definitely something that will prevent a successful build if you have the crankshaft in a constant bind.  Plus you'll note I put a pin in the camshaft location just to check the fit. 



So the only op remaining is to do a bit of rounding on some of the edges as per the drawing.

Here I'm rounding the upper rear corner of the frame using a corner rounding end mill.  This is actually a bit tricky as the assumption when using these end mills is that you're working on a 90 degree corner.  The trick here is to NOT cut as deeply as you otherwise might.



Here I'm starting to round over the corners of the bearing caps and the mounting area just below them.



And here's the rear frame completed with the corners rounded and the bearing caps installed.



And that's it for this series of operations.  Next up will be assembling the front and rear frames permanently, but that's a post for another day.

Enjoy!

Mike

PS.  If anyone wants to know the distance between the camshaft and crankshaft locs and what my correction was I'll be happy to post it here.  Just let me know. 
MIke
Wichita, KS, USA

Offline mikehinz

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Re: Farm Boy #876 - Mike's Build
« Reply #27 on: September 27, 2022, 04:43:01 PM »
Now that all three frame parts are completed, there's one more big step, that being to join the front and rear frames together permanently.  I followed JE Howell's exact process as it seemed entirely reasonable to me.

First I needed qty 4 flat head 2-56 shcs.  I had some longer ones in stock from a previous project so I cut them off with a cutoff blade in my flex shaft tool and then cleaned up the ends on the belt sander so that the threads would start properly.  Here's a before and after with a British coin for comparison.



Then I mounted the 2 frame pieces in the mill vise using some parallels and packing and a large C clamp to hold everything together and aligned properly.  Then I drilled and tapped 4 locations as per JEH's drawing.  I carefully tapped using a spring loaded follower and tiny tap wrench.



Next was countersinking the 4 drilled/tapped locations with an 82 degree countersink tool.  I went deep enough to make sure each of the heads was below the surface of the part.  The only way I've found to really get the depth of a countersink correct is to sneak up on it using the quill stop to slowly advance the depth and then try the fit of the shcs after each pass. 



And here's what the engine looks like with all 3 major pieces assembled.  This is a major milestone and it is really starting to look like an actual engine!



Next is actually joining the pieces permanently.  Here I've mixed up a small batch of JB Weld and applied it liberally to both surfaces.  To get the screws into place, I used the large clamp to draw the 2 halves together and then installed the shcs when the holes matched up.  Then I wiped off the excess epoxy that squeezed out of the joint. 



The next day, after the epoxy cured, I drilled at 2 locs from the top as per JEH's drawing. 



Next I liberally coated 2 small brass pins with epoxy and shoved as much as possible into the two holes and tapped in the brass pins until they bottomed out.  I wiped off the excess epoxy and here's the final result. 



I'm pretty confident that between the 2-56 flat head screws, the epoxy and the brass pins, those 2 frames halves will never separate!  It felt good to get to this point!

Enjoy!


Mike
MIke
Wichita, KS, USA

Online Kim

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Re: Farm Boy #876 - Mike's Build
« Reply #28 on: September 27, 2022, 05:04:26 PM »
That does look very secure!  How deep did you make the pin holes?  Seems like the pin hole might cut through the screws you were using to hold it together if the pin hole went very deep.

But I'm sure it's a very solid connection regardless.

Kim

Offline Admiral_dk

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Re: Farm Boy #876 - Mike's Build
« Reply #29 on: September 27, 2022, 06:14:34 PM »
A very fine result so far - so I can see why you are happy with the parts shown  :ThumbsUp:

If you haven't admitted up front that this isn't a Live Build - I would seriously wondered if we are witnessing someone faster than Chris and his Elves  ;D     :cheers:

Per