Rod’s Hoglet

[Roderick JenkinsParticipant @roderickjenkins93242]

The valve guides are brass. I turned the OD for a press fit in the head in the 3 jaw and then parted off, dialled in the 4 jaw and drilled and reamed through

The returned to the 3 jaw (now that concentricity is not so important) to cut the spring seat and taper

My valves are stainless steel turned down to a 5/32" shaft and then grooved for a 3mm E clip

The heads are relieved to 1/8" and the seats turned to 45 degrees. They will be ground in later

4 valves, all very nearly the same

Rod

[Roderick JenkinsParticipant @roderickjenkins93242]

I need 4 rocker arms. The idea was to make them as a lump then saw it up into 4 pieces. First drill for the pivots

Then mill to half depth

and round off the protuberance

And slit

3mm hemispherical socket for the push rod end

Springs were wound in 22SWG piano wire at 10 tpi

I cut the valve seats with my trusty D bit valve seat cutter with a guide the same diameter as the valve stems

Valves retained with a collar and a 1.5mm E clip

A bit of hand work was required on the rockers to make them more presentable

The tappets also need a hemispherical seat – possibly the only acceptable use of an end mill in a drill chuck

The push round ends need to be hemispherical. I made a form tool by drilling a 2.9mm hole in some gauge plate, milling the excess away then hardening and tempering

One end threaded for adjustment and the other Loctited in place

A gratuitous picture (for Neil) of the hardened and ground dowel pin for the crank pin being trimmed

After Loctiting the cam shaft drive gear to the cams, the holes for the ignition triggering magnets need drilling. An elephant foot indicator found the peak of the central cam and the GHT Headstock Dividing Attachment was turned to give the -120 degrees and +39 degrees spacing

Drilled with my tool-post mill/drill

And that's pretty much all the mechanical bits of the engine done

Just need to wrestle with the carburation and ignition now

Thanks for dropping by

Rod

[Grenville HuntParticipant @grenvillehunt47315]

Fantastic work Rod, keep it coming.

Gren.

[Howard LewisParticipant @howardlewis46836]

Excellent work, Rod.

Envious of your skill and patience.

Howard

[Craig BrownParticipant @craigbrown60096]

Engine looks superb. Some top notch photography too

[Roderick JenkinsParticipant @roderickjenkins93242]

Kind words. Thanks guys.

Spent a couple of hours making a starting dog that keys onto the drive side of the crankshaft

I think I've made it to drive in the right direction!

Rod

[GrahamSParticipant @grahams]

Thanks Rod , some excellent and timely inspiration for machining setups there, especially the rockers!

After a break I am just starting the pistons, then onto the valve gear.

Have you settled on a carb yet? The design OS1A seems to be unobtainable , as is the OS21A Andrew Whale used.

[GrahamSParticipant @grahams]

Pistons machined using the Rod method, all went well apart from the last stage machining out the relief for the little ends of the con rod. I couldnt get a good enough grip in the vice even with very light cuts ( I may well have not been applying enough grip in the vice – scared of squeezing the pistons out of shape ), so used the three jaw chuck in vertical mode in the mill instead which worked well.

Trial assembly shows it turns nice and smooth, and lots of compression with the O rings fitted.

Can I ask what the design 0.125 hole in the centre of the wrist pin button is for ? Seeing this has given me the thought of using a small countersunk screw through this hole into the wrist pin each side to secure the buttons on. Then I can strip it down easily if required.

Also what is the thinking on lubrication after assembly for the little and big ends of the con rods? Has anyone attempted any form of lubrication in this area for between runs ? I am aware it is a demo engine only designed for short runs, but I am happy to do extra work to be able to lubricate these areas, if it is possible. I am toying with an oil hole through the big end boss of the blade rod and through the bearing to to lubricate the crankshaft, placed so it is accessible through the frames between the rods.

The Rexcel V twin ignitions are back in stock at Just Engines if required.

 

Edited By GrahamS on 28/02/2023 18:16:48

Edited By GrahamS on 28/02/2023 18:17:19

[JasonBModerator @jasonb]

The holes in the buttons stop them getting pushed outwards by pressure against the cylinder. There is no real need to secure them with a screw. Anther common way to do them is to turn the button like a shallow domed head rivit and have a small hole in the end or right through the wrist pin and make them a light push them into that. Nylon can be used instead of brass/bronze.

If you have used the oilite bearing as per drawing it should not need much in the way of lubricant. Small drop with a needle oiler between runs will be ample and just turn the engine upside down to put a drop on the wrist pins

Any 4 or 5mm bore RC carb should do the job

[ianjParticipant @ians]

Hi Graham.

Can you just confirm the "Just Engines" web site that shows the V twin ignitions are available, because when I look it says they are out of stock.

Just Engines

Ian

[Roderick JenkinsParticipant @roderickjenkins93242]

There has been a slight hiatus in my Hoglet completion since I seem to have mislaid the Hall effect lead and have had to order another from Just Engines, which has now arrived. Seems to work OK on 6V, One of the plugs sparks when the magnet is passed over the sensor and, with the magnet turned around, the the other sparks . Just need to find a good way of mounting it.

Rod

[GrahamSParticipant @grahams]

Posted by ian j on 28/02/2023 19:03:11:

Hi Graham.

Can you just confirm the "Just Engines" web site that shows the V twin ignitions are available, because when I look it says they are out of stock.

Just Engines

Ian

Hi Ian

Thats the correct link, unfortunately it looks like they have run out of stock almost immediately !

I would give them a call, very friendly and informative. I started calling them before Christmas when they were out of stock then and was given a lead time when they were expected – back then mid Feb. I get they feeling they hold very little stock which makes sense given the quantity they must sell. They also sell separately the magnets and plugs if needed.

Graham

[GrahamSParticipant @grahams]

Posted by Roderick Jenkins on 28/02/2023 23:19:55:

There has been a slight hiatus in my Hoglet completion since I seem to have mislaid the Hall effect lead and have had to order another from Just Engines, which has now arrived. Seems to work OK on 6V, One of the plugs sparks when the magnet is passed over the sensor and, with the magnet turned around, the the other sparks . Just need to find a good way of mounting it.

Rod

Dont know if you have seen this Rod, Andrew Whale produced a drawing of his sensor attachment ( dont know if its the same type of sensor) and made it available on Youtube.

[ianjParticipant @ians]

Graham.

I followed your advice and gave them a call. The ignitions are in stock ( web site just not updated) Got one on the way and the fun trying to get the engine to run starts then !!

Thank You

Ian

[GrahamSParticipant @grahams]

You are welcome Ian and good luck with the test runs – keep us updated !

Have you settled on a carb yet ? I know next to nothing about model carbs. Jason has kindly suggested any 4 or 5mm bore carb will do , but so far no luck finding anything.

[JasonBModerator @jasonb]

You could always make one, Malcom Stride's one for the Bobcat & Jaguar is 5mm bore

[Roderick JenkinsParticipant @roderickjenkins93242]

This is the carb that I made according to the Matador drawings. It seems to be quite flexible since it has run my Matador, my 10cc side valve four stroke and the Wyvern. If it works I'll make a version that suits the Hoglet rather better than this lash up.

This is a prototype Hall probe holder

Needs a re-design to fix a couple of silly mistakes and improve the aesthetics but it is functional. Tomorrow I will have a go at getting the Hoglet to fire up. Don't hold your breath.

Rod

[GrahamSParticipant @grahams]

Good luck with the test run Rod, and lots of pics ( and vids? ) please.

[Roderick JenkinsParticipant @roderickjenkins93242]

That Hall probe holder didn't work. It needs to be able to rotate through a larger angle, which means that the crankshaft timing gear screw needs to be flush with the gear which means disassembling the engine to remove the half shaft – glad I didn't Loctite it!

Redesign of the Hall detector meant using the die filer to make a D shaped hole

I think this design is a bit more in keeping with the overall look

I'll try again tomorrow (minor domestic crises permitting)

Rod

[Dave WoottonParticipant @davewootton]

Lovely work Rod, been watching this with interest for some time, thought I should show my appreciation, good luck with the test run, I'm sure it will all be fine judging by the workmanship displayed.

Much more interesting than the current debate about industrial spoons and metrication!

Dave

[Roderick JenkinsParticipant @roderickjenkins93242]

 

 

It took a bit of fiddling about, the timing is still not quite right, it's blowing back a bit through the carb but, hey, it goes

 

Rod

Edited By Roderick Jenkins on 10/03/2023 21:43:29

[ianjParticipant @ians]

Well done Rod, it looks and sounds fabulous, You must be very pleased with the end result.

I must revisit mine as I now have the ignition. To be honest I've been holding back to see how you got on.

I need to make a starting dog and Hall sensor attachment. I've made the Jerry Howell two jet carb. (made two as the

same carb is used on his V4 engine which I need to get back too as well!)

Ian

Edited By ian j on 10/03/2023 22:59:21

[HopperParticipant @hopper]

Posted by Roderick Jenkins on 10/03/2023 21:42:46:

It took a bit of fiddling about, the timing is still not quite right, it's blowing back a bit through the carb but, hey, it goes

Rod

Edited By Roderick Jenkins on 10/03/2023 21:43:29

Chuffs away very nicely. Well done!

Based on full sized Harley V-twin experience, spitting back though the carb is most likely lean mixture.

Spark timing too retarded can also cause it due to weirdness associated with the "waste spark" that fires on the exhaust stroke on the other cylinder, but 45 degrees late due to the cylinder spacing — so can end up sparking at or a bit after TDC as the intake stroke is starting. If there is enough mixture in there already it can cause a hiccup. (Technically known as a "carb fart".) Not sure if this attribute of a full sized V-twin with one carb transfers down to model scale but may be something to fiddle with and see.

[JasonBModerator @jasonb]

It's going well Rod.

[GrahamSParticipant @grahams]

Excellent , well done. I would be very pleased with that.

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