Author Topic: The Oliver Tiger Mk III - a 5cc Version  (Read 15482 times)

Offline Neil-Lickfold

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #105 on: March 08, 2019, 11:40:20 PM »
I use the ramp down feature.  Stops in 0.2 seconds. I have the ramp start and ramp stop set the same. The micro switch is on the foreward stop. So only reverse direction can be enabled on the motor start. I leave the 1/2 nut engaged until the thread is completed. I have the micro switch on an adjustable thing to get the stop length correct.

Offline Ramon

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #106 on: March 09, 2019, 10:34:11 AM »
Hi Neil, thanks for the info :ThumbsUp:

I do have vfd on the lathe but having done this method for so long and with very little likely to require it in the future I'll 'stick to what I know' - besides - me an electrics don't exactly go hand in hand ::)

Tug

"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline strictlybusiness1

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #107 on: March 09, 2019, 04:08:20 PM »
Ramon,

I see that you are still doing beautiful work! Keep it up!!

Jim Allen

Online sco

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #108 on: March 09, 2019, 06:43:29 PM »
I use the ramp down feature.  Stops in 0.2 seconds. I have the ramp start and ramp stop set the same. The micro switch is on the foreward stop. So only reverse direction can be enabled on the motor start. I leave the 1/2 nut engaged until the thread is completed. I have the micro switch on an adjustable thing to get the stop length correct.

0.2 of a second is pretty quick - would be worried about the chuck unscrewing! Think I'll carry on with the leadscrew dog clutch lever but thanks for the suggestion.

Simon.
Ars longa, vita brevis.

Offline Jo

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #109 on: March 09, 2019, 06:54:07 PM »
I would be more concerned about the low cycle fatigue stresses generated in the shafts by such fast slow downs  :paranoia:

Jo
Enjoyment is more important than achievement.

Offline Ramon

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #110 on: March 09, 2019, 07:22:03 PM »
Jim - it's good to see you looking in and for your endorsement.

What I do pales into insignificance in comparison to your sterling workmanship but it's real nice to know that someone like yourself can enjoy it - thanks indeed  :ThumbsUp:

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Neil-Lickfold

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #111 on: March 10, 2019, 12:13:37 AM »
0.1 seconds will unscrew the chuck. At0.2 seconds it never does
Unscrew. But it also takes actually longer than 0.2 seconds to stop.

Offline Ramon

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #112 on: March 12, 2019, 04:26:43 PM »
Ken (Croft) - further to your PM

Unfortunately I am not able to scan only copy. For your info though - and anyone else who may be interested to read it......

Having checked through my folders the article on CIS you refer to was not published in Model Airplane News as I thought but in the Strictly I/C magazine. I have copies on many of Georges writings from MAN but they mainly refer to glo engines and predominantly for C/L speed and aerobatic usage.

The near four page CIS article was featured in the February/March 1989 issue of SIC. I believe they are still available but if you have any problems PM your address  ;)

Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Ramon

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #113 on: April 23, 2019, 10:38:40 PM »
Hello Guys,

I see that quite a few have looked in over the last few weeks no doubt to see if any further progress has been made. Well, I regret to say, unfortunately there's not ::) however it has not been forgotten :)

Just to say then that this project has not been abandoned in favour of another modelling distraction but, as previously mentioned, I have found myself with some major changes in the garden and this has been occupying virtually all my time. A whole new area has suddenly become a viable proposition from a growing point of view and work to make this happen has been ongoing since.

I won't pick these engines up again until I'm well on top of this unplanned distraction but though it is now likely to be awhile rest assured, they will very much be in the forefront of any return to the confines of 'tha ol shid'. My intention is still to have them ready for the Forncett ME Day in October   ;)

In the meantime, thanks for looking in and enjoy the summer :)


Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Tennessee Whiskey

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #114 on: April 23, 2019, 11:41:56 PM »
From modeling to land baron  :lolb: :lolb:

Whiskey

Offline Ramon

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #115 on: April 24, 2019, 07:52:39 AM »
Ha - at around sixty feet by thirty I hardly think so Whiskey  :Lol: but it's been neglected and in deep shade for so long it's taking it's toll on the old bones  :old: Might be able to grow the odd lettuce or two when all's done though  ;)

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Ramon

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #116 on: June 08, 2019, 11:28:24 PM »
Hi Guys,

At last I have something to report  ::)

Having just seen how many have looked in since the last post I can only say thank you for your interest, whoever you are, and an even bigger thank you for your patience  :o

So, with the garden distraction now on top of to a stage where it can be picked at in coming weeks I should be able to get some continuity on the remaining parts.

The main outstanding items left to do are the piston/liners, crankshafts, con-rods and needle valve assemblies.

Three pieces of freecutting EN1a were cut for the liners


First off was to establish the bores. These were drilled thru 5, 10 and 16 mm diameter for a 17.74 finished bore


These were then held in soft jaws - for boring to size and facing one end. This end was marked to ensure that when replaced on the mandrel for turning the outer diameters the marked end would be the lower end - any slight taper usually occurring from a boring operation assisting in the lapping process to achieve a slightly tapered bore. A plug gauge was turned to ensure the bores were similar for fitting to the expanding mandrel for later turning. I have long considered it much more easier on subsequent machining to establish the bore first then carry out all other work on a mandrel. The main reason for this is the potential for distortion particularly on thin walled liner sections - if held in a three or four jaw chuck even the lightest nip will show high (low?) points when the lapping begins. By leaving the wall thickness as large as possible this virtually eliminates that potential.


A previously used mandrel was turned to size. As said so often before these are so easy and quick to make. Expansion is by a caphead socket screw which has been turned to a 60 degree taper to match a deep centre drilled hole. The lightest nip on the screw providing a really firm grip for all subsequent operations - accurate removal and replacement too.


All three liners were roughed to within .2mm first


Then finish turned to dimensions against a fixed stop


Utilising an old ground block a simple fixture was quickly made for holding the cylinders for cutting the exhaust ports


A silver steel cutter, previously made for another engine which happened to be the right thickness and diameter, was pressed into service and all twelve ports were cut with ease. No coolant was used as it has previously been found that doing so tends to create swarf clogging and subsequent broken cutters. Low speed and feed is just fine and the cutter still has plenty of life left


With the exhaust ports cut and deburred the liners were set back on the expanding mandrel to cut the transfer ports
These were plunge milled using a 2.5mm diameter cutter then opening with a 3.5 diameter.


Incidentally, in order to hedge off any possibility of galling, the mandrel had been relieved beforehand to clear the internal burs created by this op


Last op was to turn the taper and debur the ports - the liners are now finished ready for lapping which will be done later after the pistons are made.


Well that's another step forwards - I hope that's of interest and has been worth the long wait. Next up is to get the crankshafts done

I've enjoyed my garden time but it's good to be back  :)

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline vcutajar

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #117 on: June 09, 2019, 05:10:10 AM »
Nice to see you back Ramon.

Vince

Offline Roger B

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #118 on: June 10, 2019, 12:54:19 PM »
Excellent   :praise2:  :praise2:

At the start of the liner machining you are using a 4 jaw SC chuck. Is there a reason or like me because it was on the lathe at the time and would do the job?
Best regards

Roger

Offline Ramon

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Re: The Oliver Tiger Mk III - a 5cc Version
« Reply #119 on: June 10, 2019, 10:08:33 PM »
Thanks Vince, hope you are well - do you have a new project?

Roger, no, no reason just that  the three jaw had soft jaws in and would be used for the next op. I have to say though that I bought this cheap SC four jaw purely to hold the odd square section as opposed to the normal 4 jaw. It's proved to be a very accurate chuck and gets used more and more as a first option. I'd certainly buy another over another 3 jaw.

A start has been made on the crankshafts and all the initial rough turning is now complete. Turned from EN24t the three blanks were first reduced to 16mm dia shafts then held in a collet block to mill away the surplus around the crankpin. This could of course be done on the lathe but I prefer to do it thus


The embryo cranks


The pins were roughed to .5mm plus and the rear face of the web cleaned up. The fixture, made many years back, is ideal for this op allowing, within it's limit on the face plate, an infinite crank throw.


Set in the soft jaws the shafts were reduced to plus .5mm on diameters. Roughing these En24 shafts is one of the rare occasions that the Myford sees a tipped tool.


Ready for the final ops


With the shafts now ready for finish turning this was the time to machine those front bearing housings on the cases so that the shafts could be test fitted as finished. A new expanding mandrel was made for this op to ensure co axial alignment. The case is locating on the main bearing diameter and being clamped (by expansion) inside the shaft hole.


With these done it was time to set up to finish the shafts. First they were held in a collet and a centre put in the web face then this little drive plate was pressed into service yet again, the centre pin being skimmed at 30 degrees to ensure concentricity


Ready for the off in the morning :)



We've had some real good rain today so there was only place to be  :) Looks like it will be more of the same tomorrow :D.

As before I hope this is of interest - I can only assume it is  :-\

Regards from the 'Ol Shid' - Tug
« Last Edit: June 10, 2019, 10:13:42 PM by Ramon »
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)