Author Topic: Tangler's Air Cooled Farm Boy  (Read 6150 times)

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #45 on: August 21, 2019, 09:53:18 AM »
My intention had been to use the Denford/Sherline mill to make the cam - it should be a simple profiling job.  Sadly the mill has not been playing ball.  I've been driving the mill from a laptop via a USB to serial converter which seems to lead to communication errors.  I'm currently in the process of  resurecting an old XP desktop which I had been hoarding because it has a parallel output which could be useful for  Mach 3.  It doesn't have a serial output so I'm waiting for Ebay to provide me with a PCI serial card.

Rod

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #46 on: September 12, 2019, 06:20:32 PM »
Sorry for the delay, hassle with the CNC mill (still bust) and the acquisition of a sailing dinghy for playing in Christchurch harbour have distracted me.  Also, I've been hosting my pics on the Coppermine Lister forum.  Although this was a generous offer, you may have noticed that the resolution and image size is not great and the bulk upload feature seems to be arguing with Flash.  So, I'm now trying to use Flickr...

Fabrication of the governor mechanism continues.  This little assembly needs a pivot with 2 arms at right angles - one holds the ball and the other actuates the catch lever spool.  The pivot was drilled for 2 off 1/8"  holes



Jerry calls for the bits to be assembled with silver bearing soft solder.  I'm more comfortable with hard silver solder so here they are anointed with silver alloy brazing paste.  The steel supports were roughly turned down ( horrible sticky steel ) to a diameter to ensure that the arms were parallel to the base



They were then warmed up with a torch 'til the solder flowed



The outboard end of the balls have little brass mounts for the spring.  The drawing shows a plain shank to be Loctited in place.  I prefer a thread which will be screwed 8BA and Loctited in the correct orientation



Once threaded this was held in a little fixture that is just a hole threaded 8BA.  I have a few of these of various sizes made from Precision Ground Mild Steel so that they can be re-used in a collet chuck.  First chamfered



and the round end finished with a hand graver



The flats were then milled and the hole drilled using the toolpost miller



The pivot pins are 3/32" and I decided to retain these using 3mm E clips so the pins were grooved using my modified hacksaw parting/grooving tool from a Len Mason Design



These bits now need to be fitted to the flywheel and the next step will be to make the flywheel collets and machine the matching tapers in the flywheels themselves



Cheers for now,
Rod






Offline Don1966

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Re: Tangler's Air Cooled Farm Boy
« Reply #47 on: September 12, 2019, 09:02:14 PM »
Real nice work Rod and love the use of your various tools. ...... :ThumbsUp:



Don :cheers:

Offline DavidLloyd

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Re: Tangler's Air Cooled Farm Boy
« Reply #48 on: September 13, 2019, 12:48:17 AM »
Excellent Job Rod,

DavidLloyd

Offline Craig DeShong

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Re: Tangler's Air Cooled Farm Boy
« Reply #49 on: October 04, 2019, 01:35:43 PM »
Very nice Rod.  I've been silently following along.  Past time to comment.  I just love your work!
Craig

Offline Brian Rupnow

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Re: Tangler's Air Cooled Farm Boy
« Reply #50 on: October 05, 2019, 01:09:13 AM »
Tangler--You are doing marvelous work. I am following.---Brian

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #51 on: November 04, 2019, 06:30:10 PM »
Thanks for the kind comments chaps.  Sorry it's been so long.  DeltaTango came to visit and Sally and I had a holiday in Norfolk where we  took in the Forncett ME show and met up with a few more MEM guys.  I've taken my Denford/Sherline CNC mill to near Melton Mowbray to be converted to Mach 3.  The 3d printer has finally been persuaded to behave and I've managed to print some stands for my Pultra collets:



We now have a new desktop PC which was specced to deal with Fusion 360 and is really quite whizzy.  I've also done a little bit of organisation in the tool storage area:



Anyway, back to the Farm Boy.

The flywheels are located on  tapered collets.  I'm making these back to front so that I can leave the topslide at the same angle to cut a matching taper in the flywheel.  It will also make drilling the holes in the flange easier.





Another thing I've done recently is to make a simple direct indexer for the 60 tooth Myford bull wheel.  I wanted one that was quick to attach but still allowed the belt cover to sit properly.





Now it's very quick to mount the toolpost mill and index for 3 clearance holes and 2 threaded holes for extraction jacking screws



These still need to be slit but I want to wait until I've cut the tapers in the flywheels to the right size.  I used the collets as a Jig for drilling the location holes in the flywheel



The flywheels were mounted in the 4 jaw and roughly centered with a length of 3/8" pgms in the tailstock chuck



And then set up properly with a DTI



The taper in the flywheel was then turned so that the collet had a 25 thou allowance for tightening against the crankshaft.





That's all for now.

Rod




Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #52 on: January 22, 2021, 11:35:47 PM »
Sorry about that, I just popped out to do some woodwork.

Before going any further I thought I ought to lap the cylinder bore to size since the head has a spigot that fits in the bore and there are some chatter marks to remove.



The lap is just lump of ally with  tapered bore on a tapered mandrel.



The initial lapping compound is some valve grinding paste that I inherited from my dad and was probably bought to keep a pre-war Vauxhall on the road back in the 1950s.  The tub has a coarse and a fine end.  The coarse paste removed the chatter marks after an hour.



30 mins with the fine end has left some work still to do before moving on to some finer carborundum powder



More to come soon (promise!)

Stay well,
Rod




Offline deltatango

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Re: Tangler's Air Cooled Farm Boy
« Reply #53 on: January 23, 2021, 01:55:21 AM »
Rod, Good to see some more progress. It's good to see some new posts from you.
David
Don't die wondering!

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #54 on: January 27, 2021, 11:56:55 PM »
Hi David,

Back in the metal work fold now!  Sally and I are keeping well away from people - just one weekly trip to the supermarket and a daily walk down to the sea or round the marsh so plenty of time in the workshop.

Still some work to do on the bore of the cylinder.  I took the large scratch marks out with a 3 stone hone but I think the bore needs to be a bit smoother for an elastomer O ring.  The aluminium lap seems to be wearing away much quicker than the c.i.  so I may have to investigate something more sophisticated.

Now that the bore is (pretty much) to size I've started on the cylinder head - turned in the lathe with the locating spigot fitted to the bore.  I kept a small centre mark from the lathe to locate in the milling machine.



I used the DRO to locate and spotted the holes for the studs to fasten the head to the cylinder and removed the head from the mill to the pillar drill for the 4BA clearance holes (no quill on my mill) then returned the head to the mill using two clearance size drills to relocate the head in the vice



I spotted the 2 holes for the valve guides and milled the pocket for the spark plug with a ball nose end mill.  I'm using close(ish) metric and BA equivalents to the original drawings.



The head was returned to the 4 jaw in the lathe and I picked up the cenrtres for the valve guides with a wobbler



and then drilled, bored and reamed to size



I decided to make a jig for the next step which was to drill the spark plug hole at a 20 degree angle.  Easy to do as I already had the coordinates for the stud holes




Then tapped 4BA



The jig was set up in the vice at 20 degrees.  Jason will be amazed that I'm using my special aluminium magnet again!  The angle gauge has a V slot on the base so in order to get it to sit on the cylinder head between the bolt heads I used a round steel bar and there was enough magnetic flux to stick the bar against the hold down bolts.



The spark plug sits in a pocket that should be 7/16" diameter.  I have to be careful here because anything bigger risks breaking into the holes for the valve guides.  The only 7/16" milling cutter I have is this rather old fashioned 6 flute one and I didn't fancy my chances of starting a clean hole with this so I used a 12mm 2 flute mill to start and then finished off with the old cutter
The drawing gives the dimensions to get  the hole in the right place...



...but it was still a relief to find that the result was near enough in the correct location.  I tapped the hole for the plug and it seems to fit






I didn't plan that job terribly well.  I changed my mind several times about how I was going to do it so ended with several redundant transfers from machine to machine but got there in the end.

Stay well everyone,

Rod


Oops.  Seem to be having a problem with the pictures.  I'll try and sort it out tomorrow

Update:  Was using Flickr to host but that didn't seem to want to play so now trying Ondrive - I think I've got it sorted  :hammerbash:





« Last Edit: January 28, 2021, 09:38:21 AM by tangler »

Offline Jasonb

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Re: Tangler's Air Cooled Farm Boy
« Reply #55 on: January 28, 2021, 12:14:05 PM »
Good to see you back at the swarf making and pics are showing up fine.

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #56 on: January 29, 2021, 05:54:58 PM »
The valve guides are bronze and require a 1/8" reamed hole.  I was fortunate to find in my collection an unused reamer still with the protective coating so that should be good for bronze.




Spotted then drilled 7/64" before reaming (this picture especially for Allen Smithee  :) )





Turned around in the jaw and clocked in for turning the tapered top



Here they are pressed into the head



Cheers,

Rod

Offline tangler

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Re: Tangler's Air Cooled Farm Boy
« Reply #57 on: February 24, 2021, 11:42:06 PM »
I've been round the houses several times looking for an easy to use and free hosting/embedding for my pictures.  All the sites I've tried (Flickr, Google photos, Dropbox, Onedrive) seem to make it labour intensive to generate an embed code and it doesn't always seem to work.  So I am back with Coppermine.  Loading one photo at a time is a pain but at least I've found out how to display the photos at a decent size.  I have to confess you almost lost me from any more postings this afternoon I was that frustrated.  I wonder if that is one of the reasons that this site is not generating much traffic these days?

Anyway, I've been making the piston.  It starts with a simple turning job with groove for the ring which, as I have mentioned elsewhere, is oversize for a 1/8" section Viton O ring.

Milling the internal features and gudgeon (wrist) pin holes was more interesting.  First to align the piston axis to the mill so I know where I am with the DRO.  Then I used a 1/2" endmill to widen the access for the con rod.



The gudgeon pin doesn't float but is held in place by a couple of grub screws which I drilled for  M3



I have a set of stub drill for most of the tapping sizes I use a well as sets of jobbers from 1mm to 10mm in 0.1mm steps so I could use one each of these to align the piston on the dividing head to drill the gudgeon pin hole.



I turned a plug to steady the piston and drilled and then reamed the hole



The design calls for a hole for a pipe to allow oil to get to the little end bearing which is probably unnecessary but which I think is a rather sophisticated touch.







Thanks for looking in.  I'm still here - just :)


Offline cnr6400

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Re: Tangler's Air Cooled Farm Boy
« Reply #58 on: February 25, 2021, 12:02:30 AM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

Offline Jasonb

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Re: Tangler's Air Cooled Farm Boy
« Reply #59 on: February 25, 2021, 07:14:15 AM »
Good to see you back on this one. Not seen the pipe before but just a hole is quite common often with a shallow oil groove at the same point along the piston.

Yes it has been a bit quiet, anything to make it easier for people to post would help, maybe lifting the small image size limit would make it easier for some to attach images though I do prefer them posted within the text rather than all at the end.