Author Topic: Two Cylinder Engine  (Read 53240 times)

Offline Roger B

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Re: Two Cylinder Engine
« Reply #390 on: May 08, 2022, 05:54:38 PM »
It's getting there  :)

I had to drill and tap a new grub screw hole in the sector as the original was inaccessible. Some trials suggested a suitable profile which I filed on the sector and then added a return spring to the rack. The first trials were good so I set up a quick load trial. The load is a resistance back with a maximum load of 1 ohm. This means I just need to measure the current and square it to get the output in Watts. The meter has a full scale of 15A. I was able to run up to 9A so 81W and could both accelerate under load and add and remove the load without stalling  :) The video is a bit messy but hopefully you can see what is going on  ::)

Best regards

Roger

Online Kim

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Re: Two Cylinder Engine
« Reply #391 on: May 08, 2022, 08:54:57 PM »
That is very cool, Roger!  :ThumbsUp: :popcorn: :popcorn:

81W seems pretty respectable for a little fuel-injected engine! :)

Kim

Offline Roger B

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Re: Two Cylinder Engine
« Reply #392 on: May 10, 2022, 08:12:26 PM »
Thank you  :) I think the real output is somewhat higher but I can't measure it at this time  :headscratch:
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #393 on: June 05, 2022, 05:33:22 PM »
As the MFA motor was not capable of fully loading the engine I found another motor in my 'rescue' collection that will hopefully have a more suitable characteristic. Some quick trials showed that this was not quite capable of starting the engine on 12V and due to the larger diameter I decided to mount it on the end of the existing MFA motor and hanging off the end of the baseboard. The coupling I have has a 1/4" bore both ends which suits the MFA motor. The new motor has a 6mm shaft so I needed to bore and sleeve the coupling. With some thought I bored and reamed it out to 11.5 mm as I had a suitable reamer and I can then turn a piece of 12mm stock to suit. I drilled the grub screw hole in the sleeve to 6mm as clearance so both parts would be held by one grub screw and I didn't need Loctite (experience says this will be changed more than once  ::) ). I now see why Jason choose 24mm bore as he can use 25mm stock for the pistons rather than turning 30mm down to 25mm.
The mounting plate was clamped to the face plate ( Dodgy Set Ups are Us) drilled 13.5 mm and then bored 28mm to suit the motor.
Best regards

Roger

Online Kim

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Re: Two Cylinder Engine
« Reply #394 on: June 05, 2022, 07:53:33 PM »
Silly question, but what does MFA mean here?

Thanks,
Kim

Offline Roger B

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Re: Two Cylinder Engine
« Reply #395 on: June 05, 2022, 08:39:39 PM »
Kim, not a silly question, just a European one. MFA is a supplier of model drills, motors, gearboxes, etc.

https://www.mfacomo.com/index.html

I have tried to use available motors as my loads rather than random things I have in my rescue box so others can hopefully follow/copy.
Best regards

Roger

Online Kim

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Re: Two Cylinder Engine
« Reply #396 on: June 05, 2022, 08:54:24 PM »
Ah, Thanks Roger!  That clears it up for me. :)

Kim

Offline Roger B

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Re: Two Cylinder Engine
« Reply #397 on: June 12, 2022, 01:48:41 PM »
The fixing holes were drilled in the plate and the support arms were drilled and tapped M5. It was all then assembled and set up for a quick test.  The characteristics of this motor/generator are completely different. I was getting around 60V at full speed without a load and around 30V at 3A on load but then the engine started spluttering and stalling, it would idle but not rev. I tried adjusting the fuel rack setting but without success  ::) Removing the timing gear cover showed the problem, lots of brass/oil emulsion and a completely worn excentric strap  :toilet_claw:
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #398 on: June 12, 2022, 02:02:50 PM »
Brass was obviously not a suitable strap material for the speed/load requirements of this injection pump. The excentric on the horizontal engine injection pump shows no signs of wear after significant running, but it barely reaches 2000 rpm whereas this one will exceed 8000 rpm.
I decided to try a case hardened steel version together with case hardening the excentric. This was roughed out of 2mm strip with a hacksaw, rounded on the Proxxon mill and cleaned up with some filling. It was bored directly from 6mm by taking shallow radial cuts. I was doubtful about opening it out with a 12mm drill first due to the risk of snatching. I am using the 4 jaw SC chuck as that was on the lathe at the time.
After hardening and cleaning up it seemed to run freely so I reassembled the engine and gave a quick trial. It runs again  :) however I need to readjust the rack/throttle relationship.
Best regards

Roger

Online crueby

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Re: Two Cylinder Engine
« Reply #399 on: June 12, 2022, 03:47:35 PM »
Hi Roger,
Are the two pieces different types of steel? If the same, is there a risk of the two galling together, or does the hardening prevent that issue?
 :popcorn: :popcorn: :popcorn:
Chris

Offline john mills

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Re: Two Cylinder Engine
« Reply #400 on: June 13, 2022, 12:12:27 PM »
Hi
I worked in industry on metal working machines as apprentices we were told you don't run similar metals together but wire bending machines were all driven by cam rollers and pins same hardened and ground some nitrided slides were lined with ground stock hardened and ground all sliding faces only one had a free loading bush of aluminium bronze as long as lubrication kept working gave good service if lubrication failed then turning blue and wearing away when they stopped turning.
John

Offline Roger B

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Re: Two Cylinder Engine
« Reply #401 on: June 14, 2022, 09:02:28 AM »
I believe that both hardened steel and cast iron don't tend to gall when run together.
The highest loading in a conventional IC engine is the camshaft - cam follower interface. These are almost always surface hardened steels however without adequate lubrication they will rapidly fail. A number of the additives in 'High Performance' motor oils are to help this interface.
Best regards

Roger