Author Topic: CHUK2 - Alyn Foundry Flame Gulper  (Read 3323 times)

Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #30 on: January 21, 2020, 06:57:37 PM »
 :lolb: :lolb: :lolb: :lolb: :lolb:

Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #31 on: January 21, 2020, 10:07:41 PM »
Continued with the bearing yoke.  While it is still on the mandrel I turned down the lower edge of the rim using a profiling button tool.  I wanted the top of  the cylinder to look like a seventh fin.  I removed enough material so that when placed on top of the cylinder the two diameters were the same.  No photograph of this.  Once happy with this I removed it from the mandrel, turned it round and put in 3 jaw chuck with some thick cardboard to protect the outer rim.  Because it is only held for about 5mm depth, in order to ensure this stays in the chuck I turned a 1/2" spigot on other end of the mandrel and used this to press against the casting using a revolving centre in the tailstock.  I could now machine the top face of the bearing yoke on which the bearing block is mounted.  Without the pressure form the tailstock there is a very good chance it will fly out of the chuck.

Next step was to remove the mandrel and then bore out the centre to 40.3mm to match the cylinder bore.  This was taken very steady due to reduced hold of yoke in the chuck.  As the hole became larger it was necessary to angle the boring bar to clear the bearing block.  Whilst winding the carriage back to as to be able to measure the bore I forgot to rotate the chuck to move the bearing mount out of way and dragged the whole thing out of the chuck. :facepalm:  Reset it back in chuck and continued to bore was 40.3mm.  I needed to clean up enough of the inner edge of the bearing yoke to be able to fit the piston from this end of the cylinder (including when painted).  This meant cleaning up the inside of the bearing yoke casting for at least 33mm (just over the length of the piston).  This meant several angle changes of the boring bar to keep clearance of the casting whilst boring.  When this was done tried the yoke on the cylinder and checked the piston would pass through. It did.  :cartwheel:

Now moved back to the mill to machine the inlet valve face on the cylinder and also the inlet port.  My mounting of the cylinder was a bit Heath Robinson.  Mounted the Dividing head on the table, aligned with X axis and fitted Myford 3 jaw chuck fitted with internal jaws.  Held the cylinder by the inside top of the bore.  Had intended to use  Centering Gauge to find center of cylinder but even on Bridgeport sized machine there was not enough headroom.  Next thought, rotate dividing head till horizontal, thick end of the casting over the vice, put packing under end and at sides so could be clamped in vice and then fitted the piston.  The used laser centre finder to pick up each side of the piston in turn and then halved reading to get center.  Zeroised X-axis on DRO and then picked up base of cylinder and zeroised Y-axis.  Then faced of the port and took it down to the requisite 14.5mm from the bore.  The inlet port has to be max 40.5mm wide and 6.36mm deep and pass right through across its full width to the bore.  Used a stub drill to mark at 16.82  mm each side of x-axis center line, then drilled 6mm through to the bore.  Swapped to Clarkson chuck and fitted 1/4" slotmill.  Took this straight down through the casting in both drilled locations, then removed the area between the holes taking 1.5mm with each pass.  Amazed no breakages, and a clean hole.  :whoohoo:

Remove from mill put hone through bore quickly to clean up and then tried piston.  All okay.

Loosely assembled all bits and it now looks as though I am making progress on something for the first time in years.

Colin

Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #32 on: January 21, 2020, 10:11:33 PM »
And last couple of pics.

I picture 56 the piston can just be seen through the inlet port.  It can also be seen in pic 57 in top of the bore.

Pic 58 shows how the section of casting at the top of the cylinder has now become fin number 7.

Colin.

Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #33 on: January 23, 2020, 09:32:37 PM »
And a little bit further.

Blued up the top of the bearing yoke found center lines, drilled, tapped 2BA and then ran milling cutter round all four sides. The two back corners were hard as glass and the cutter really struggled, ended up filing them square. :(

Tidied up the front of the base below the inlet port with bullnose cutter.

Found piece of 1 1/4" square brass and decided to use this for the bearing housing. Squared up the base and top and found centres, drilled it out to 16mm, and then bored up to 25.98mm for the bearings. Checked bearing fit, slightly looser than I wanted, but at last its round and square.

Turned it the right way up and then drilled all the way through for the fixing studs,  Decided to run a 1/4" radius cutter down the two edges, then counterbored for the nuts.  Then tapped the center 5/16 x 40 ME to put in a small oiler cup.

Moved onto crankweb, linished the back and then centered in 4 jaw chuck on Myford so I could drill and bore the boss to just under 10mm diam. ready to ream it.  Once reamed I could fit it on to a expanding mandrel to turn the diameter and then face front and back.  Move back to mill and set it parallel in vice with the side with slightly less to remove uppermost.  Milled flat then turned over and repeated.

Cut a short stub of 10mm silver steel and then was able to assemble flywheel crankshaft, bearing mount and crank web.  Quite pleased with how it looks.  Fiund small piece of brass hex and turned up an oiler cup on the Cowells lathe.

Colin

Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #34 on: January 23, 2020, 09:33:53 PM »
And the next few.

Quick question for Jo. What size bearings did you use for big end and for the cam follower.

Colin
« Last Edit: January 23, 2020, 11:30:00 PM by Twizseven »

Offline Jo

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #35 on: January 24, 2020, 08:01:10 AM »
Getting on nicely  :)

Quick question for Jo. What size bearings did you use for big end and for the cam follower.

The Big end bearing is a standard common size bearing for disc drives, with 8mm OD/3mm ID bearings on the little end and on the CAM follower.

Jo
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Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #36 on: January 25, 2020, 01:26:09 PM »
Thank you Jo.

A little bit further.  Measured the offset between the center line of the cylinder and the inside edge of the crank bearing (in its housing).  I need the crank web to be total of 9.75mm to put conrod in correct position.  Needed to remove almost 8mm.   This would leave me a small boss of around 5mm for grub screw to fix web to crankshaft.

Work out that I could get a 2BA thread hole 4mm in from end of crankweb for the big end fixing.  This gives me a crank throw of 27mm and the conrod can be 120mm long center to centre.

Ordered various bits of brass material for amongst other things the cam roller bearing mount.

This morning turned down some 5mm rod to make a pair of 2BA studs.  Thought I would do this on the Cowells lathe.  Only got so far as I could not hold the turned down bar well enough in the collet chuck (Cowells early version) to cut the thread :censored:, even with the die set quite loose.  Reverted to the Myford to do this.  With studs fitted I could then fit (Loctite 638) the bearoings in the housing.  The studs act as an internal spacer for the bearings to be pressed up against, and more by luck than judgement they are flush with the outside faces.  :D

Colin

Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #37 on: January 26, 2020, 11:01:58 AM »
Jo,
When you built your engine you machined the cam initially on the lathe to give the 62mm diameter  and then transferred to the mill to get the required profile by offsetting the cam and using  boring/facing head set to give 65mm diameter cut.  What I do not understand is why you had to run the mill backwards and machine in an anticlockwise direction :headscratch:.  Could you (or anyone else who understands) please explain the reason why.  I guess there is some logical reason.

Many Thanks,
Colin

Offline Jo

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #38 on: January 26, 2020, 11:09:37 AM »
Because of the direction of the teeth on the milling cutter being used in the boring head.

Jo
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Offline Chipmaster

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #39 on: January 26, 2020, 11:34:08 AM »
Hello Colin,
You don't need a milling machine to profile the cam, simply offset it in a four jaw chuck see post 9 in my build log from 2015. I think 1/4" offset was required. The piece of paper was cut out of the plans which included an A4 page of cam profiles.

http://www.modelenginemaker.com/index.php/topic,5124.0/all.html



Andy


Online Alyn Foundry

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #40 on: January 26, 2020, 11:42:23 AM »
Good morning Colin.

You have made some rapid progress over the last few days, well done.

I've been busy with some pattern refurbishment as another run to the foundry is imminent.  :)   We're hoping to have a " NEW " engine for the upcoming event in June.

All the cams on my engines have been " hand " formed, scribed and then cut with a hacksaw. The rough face then " draw filed " down to the line. A lick on the polishing mop finishing the operation. I suppose this goes back to the days when I was building engines without having a milling machine!

Your CHUK is now reaching the " fiddlely bits " stage, looking forward to seeing how you get on.

Cheers Graham.

Online Twizseven

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #41 on: January 26, 2020, 11:53:33 AM »
Jo, Andy,

Thanks for quick responses.  Interesting that Jo's offset was 9.5mm and Andy's offset is near enough to 6.5mm.  How is the difference in offset going to affect the running of the engine?

Graham,
Yes the fiddly bits.  am waiting for some material to arrive but don't think this will be till wednesday.

Colin

Offline Chipmaster

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #42 on: January 26, 2020, 01:12:56 PM »
Colin, I guessed the offset or lift was 1/4, on reflection it was probably 3/8 to ensure the valve seals the cylinder port on the power stroke but opens enough to draw in the flame.

I set the timing for slow running on my engine


Andy

Offline Jasonb

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #43 on: January 26, 2020, 01:43:00 PM »
Colin, if you do decide to run your boring head backwards make sure it is not one that can screw off the arbor. I have a couple of bars ground for external cutting so use them and run in the normal direction, would have thought those with fancy tool and cutter grinders may have actually used them :LittleDevil:

Online Alyn Foundry

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Re: CHUK2 - Alyn Foundry Flame Gulper
« Reply #44 on: January 26, 2020, 01:52:13 PM »
The adage....

" many ways to skin a cat " comes to mind, particularly in engineering.

However, I do like Andy's solution.... Hmmm, surprised I hadn't thought of that one myself lol....