An experimental V-4 wobbler

[bezalel2000]

Nice design Tim
and good drilin
Just wondering - given that your now some what of a "expert" :bow: in deep holes, would it have been more expedient to drill the holes before you parted them off?

or all 8 ends for that matter
skewing in the collet would probably be less of an issue doing it that way. :-\

Bez

 

[spuddevans]

Thanks Bez

would it have been more expedient to drill the holes before you parted them off?

or all 8 ends for that matter
skewing in the collet would probably be less of an issue doing it that way. :-\

I did think of drilling before parting off, but these mounting holes are very close to the edge, and any deflection at all could result in breaking through the edge, so I decided to take the route of a little more trouble to ensure no breakouts.


Tim

 

[spuddevans]

Just a brief update, I found a couple of hours in the 'shop and made a start on the packing glands, or rather, the gland nuts.

I was intending making direct copies of the packing glands as designed by Bog's in the paddleducks build, but as these are quite a bit smaller I had to reconsider.

Therefore I came up with an experimental design ( at least I think it is experimental, I havent seen in used on other builds. Time will tell if there is a very good reason for that :big: )

But just like in the paddleducks plans, I am making the nuts 1st so that they can be mounted on the packing glands for theu drilling to ensure concentricity.


So I started out with some 8mm brass hex in the 3jaw




Then used the round profile tool to form a profile on one end, then centre drilled




Drilled to a depth of 3-3.5mm




Then tapped M4, I had to grind the tips off the taps, you can see an unground tap in the background.




Then part off and repeat 3 more times.

I then spent the rest of the time I had figuring out how I was going to turn the packing gland. I did make just one, just to see how and if I could make it. And just to tease you here's a pic of it with the other nuts.




These packing glands are of an inverted thread design, ie the exterior thread is on the gland, the interior on the nut. I reaslise that this is not standard, and am half expecting that it will not work quite as well as the more standard version. I have very little room for anything else on this engine, plus I expect this engine will be operating on fairly low pressure (about 5-10 psi once ran in) and so should run ok even without any stuffing in the packing glands.


Next time I will show how I turned the glands (or at least the 3 remaining ones :big: )


Tim

 

[spuddevans]

On to the rest of the Packing glands.

I chucked some 20mm brass bar and reduced a section to 13.8mm ( the required od ) and then reduced a 0.5mm bit to fit the bore on the cylinders (about 8mm)




Then I swapped over for a parting tool and turned a 4mm long section down to 4mm diameter.




Then after parting it off and making the others, I mounted a 14mm collet and reversed the glands in the chuck, then using a tailstock die holder I threaded the 4mm diameter spigot M4 as far as I could get, and then centre drilled the end to form the "V" for the packing.




Then screw on the packing nut made earlier and centre drill it





Follow up with a 2mm drill bit and drill thru both the nut and the packing gland (carefully pecking to prevent drill snappage) and make sure that you keep each nut paired with the gland.

And here all 4 are,




I then unbolted the ER32 chuck from the lathe and gripped it in the mill vice to drill the 4 mounting holes.




And here is the obligitory posed shot with a cylinder (complete with magnet epoxied in place)




Next up will be the pistons and con-rods, crank webs and crankshafts.


Tim

 

[bearcar1]

Thanks for sharing your 'travels' with us Tim, I like journeys like this.

BC1
Jim

 

[spuddevans]

Thanks for sharing your 'travels' with us Tim, I like journeys like this.

BC1
Jim

Well thank you for coming along on the journey. I am really enjoying this build, snd hopefully I will have a nice running engine at the end of it.


Tim

 

[steamer]

Nothing wrong with that packing nut. A certain 75 HP steamboat I used to run periodically had packing nuts just like it....a bit bigger :

Dave

 

[spuddevans]

Nothing wrong with that packing nut. A certain 75 HP steamboat I used to run periodically had packing nuts just like it....a bit bigger :

Dave

Thanks for telling me that Dave, I know that I am relatively new to steam engines and their design, but I had not previously come across this sort of packing nut, I was a little concerned whether it would be ok. But now you've told me that I have a little more hope that it will work ( as long as I've made it ok :big: )


Tim

 

[spuddevans]

At the past weekend I managed to get a little time to play, erm work done. :big: :big: Just a small update this time, hopefully get more done next time.


I started with some brass bar that was a bit oversize, and then drilled a 1.7mm hole in the center, to as deep a depth as I dare.




Then I blacked up the brass bar, marked off a 5.5mm length, and then tapped the hole M2 for the conrod.




Then part off at the previously marked line, and repeat the tapping, marking and parting off until you have 4. Then I cut 4 lengths of 2mm stainless steel for the conrods.




Then mount the 2mm rods in the lathe to thread each end M2. I put a little spot of tapping lube on the tip of the stainless rod ( after putting a little chamfer on the rod with a file ) and then threaded it with my tailstock die-holder.




Then I cleaned the threads, added a drop of locktite and then assembled the conrods to the pistons.




Next will be bringing the pistons down to final size to match the cylinders, and then starting on the crank-webs and crankshafts.


Tim

 

[spuddevans]

On to truing up and matching the pistons to the cylinders.

I started by mounting a piston-conrod assembly in the ER32 Chuck, but with a couple of washers to space it out from the chuck.




Then I cleaned up the end of the piston and reduced it until it was about 0.1mm oversize, then I put 2 oil-grooves in using the edge of a half-round file, just held by hand to create a shallow groove. ( very important note, any files being used on the lathe MUST have handles installed ) Then I reduced the diameter until the piston just begins to fit into the cylinder bore. ( I was advancing the cross-slide by 0.01mm each pass ) then I used some 800grit wet&dry to just polish the piston until it fitted snugly in the bore.




Repeat that another 3 times and there you go,



as each piston is matched to a cylinder, I now will try to keep them paired up, each in their own compartment.


It looks like I will have to shorten the conrods a bit, I have another part to make that will screw onto the conrod end that links to the crankpins. So until I have those parts made, and the crankshaft assembly too, the shortening will have to wait.


In view of that I thought I would make a start on the crankwebs. I chucked a piece of 20mm brass into the lathe.




Then I was rudely interrupted by my better half returning home, and so I had to go inside for some lunch. ( just think of all the things we could get done if we didnt have to eat. Would save a fortune too :big: ) So the rest of the crankwebs will be for the next update.


Tim

 

[ShedBoy]

This engine is gong to look great Tim. Love the build pics

Brock

 

[spuddevans]

This engine is gong to look great Tim. Love the build pics

Brock

Thanks very much Brock


I've been itching to get back into the workshop for over a week now, but I believe that you can get tablets from the doctors to help with that :big: :big:

I also must give credit for the design and machining order of the crankdiscs to John (Bogs) :bow: :bow: as it is pretty much an exact copy from John's Paddleducks plans, just made a little smaller.

I got a couple of hours more in the workshop today, and carried on from where I left off in the previous post.

I reduced the brass bar down to 15mm diameter.




Then parted off four 4mm thick discs.




Then I chucked each of them in a 15mm er32 chuck and drilled a 3mm hole in the centre.



I could've just drilled them all before parting off, but the drill could well have deflected during the 25mm depth, and I really wanted to make sure that the holes would be central, so I drilled them all separately.


Then I made up a little jig to hold the crankdisc blanks in order to drill the crankpin holes all in exactly the same distance from the crankshaft centre.




It has to be the easiest jig to make, just drill a 2.9mm hole, press a short length of 3mm rod into the hole, then move the mill table over by 6mm ( half the stroke length ) and lock it in place. Then pop a crankdisc on it and then drill it with a 2mm bit.




Do that 3 more times, and then it is on to machining them into somewhat balanced cranks. I put a 3mm drillbit into the central holes and a 2mm rod into the 2mm holes :doh: then using some 0.5mm shims ( some feeler gauges ) to bring the 2mm rod up a tad. Press the whole lot down onto the vice and tighten.




Then I let loose with a 14mm endmill and nibbled down to what seemed to look ok, zeroing the DRO at the bottom cut. Then turn over and repeat.




Then it was a case of removing any burrs raised, then it was on to cutting the compression slot, this is done on each crankdisc individually, so I used a vice stop. Using the same shims and 3mm and 2mm rods to align before clamping. Then I aligned the slitting saw by eye.




Then I removed the rods and slitted the slot.





Stay tuned for more updates.


Tim

 

[spuddevans]

Got the crankwebs finished off today, not that there was much to do :big:

I started by drilling and tapping the hole for the tightening screw. Then I took some 4mm stainless rod and turned a section down to 3mm to use for the central part of the crankshaft that goes through the main frame, and a section of 2mm stainless rod for the crankpin.

Then I couldnt resist assembling some bit together, and came up with this,







Next up will be the little "L" shaped pieces to connect the conrods to the crankpins. Then a little final modifying of the length of the conrods. Then the outer frames and connecting pieces. Then just a few hundred more operations and it'll be all done :big: :big:


Tim

 

[Ken I]

Tim, I see you haven't posted in a couple of months - how's this project coming along.

Inspired by your magnet idea - I've also gone and designed a V4 Wobbler.

I introduced a stagger between the opposite side banks to get the big ends to the crank. I can't see any way around it - yours are in line ?

I used the magnet in the mount attracting the trunnion boss - so I can adjust the clamping force with the clearance between the boss and the magnet - the magnet is a press fit.

Regards,
Ken

 

[spuddevans]

Tim, I see you haven't posted in a couple of months - how's this project coming along.

wow!! has it been that long. ???

I haven't had a chance to get on with this build, been working on my house, painting and other such boring stuff :big:

Inspired by your magnet idea - I've also gone and designed a V4 Wobbler.

Excellent, is there a thread on here documenting/showing it? I'd love to see it.

I introduced a stagger between the opposite side banks to get the big ends to the crank. I can't see any way around it - yours are in line ?

I have to admit that I am not quite up to speed on all the proper terms, but I think that I know what you are talking about.

On my frame, both sides are identical so that the steam ports are drilled right through from side to side.

I haven't made any more progress on the parts that connect the piston to the crank-pin yet ( are they the Big ends? ), but I envisage a part that kinda looks like a "L" with the bottom of the "L" attaching to the piston, and a hole in the upright of the "L" that the crank-pin fits through. Then with the offset created by that piece, that means I can use the same piece but reversed to fit both pistons on each side onto the crank-pin. ( clear as mud, eh!! )

I used the magnet in the mount attracting the trunnion boss - so I can adjust the clamping force with the clearance between the boss and the magnet - the magnet is a press fit.

Regards,
Ken

Are you worried that the magnet may work loose from a press fit?


Tim

 

[Ken I]

I'm not worried about the magnet working loose - the forces applied are so small compared to the interference fit.

I have not started a thread - yet - and I'm reluctant to post plans until it all works out - but I will do so.

The photo attatched is the cylinders arranged as a "flat 4" for clarity.

The crank is bolted together and runs in needle bearings.

Regards,
Ken

 

[spuddevans]

I'm not worried about the magnet working loose - the forces applied are so small compared to the interference fit.

I have not started a thread - yet - and I'm reluctant to post plans until it all works out - but I will do so.

I know what you mean about not posting up plans before having successfully got a working prototype, I am in the same boat.

I look forward to seeing how you get on with building and getting it running.

I hope to get back to my build in the next week or so, the domestic duties have started to ease off a little.

The photo attatched is the cylinders arranged as a "flat 4" for clarity.

The crank is bolted together and runs in needle bearings.

Regards,
Ken

Looks good Ken, please do post up more when you can.


Tim

 

[spuddevans]

Today I got started on the little "L" pieces that will connect the piston to the crank-pin. I found a piece of brass approx 18mm x 3.3mm x 300mm, made a rough sketch of what I wanted to achieve, and set to it.




I set it up in my vice on a parallel which was slightly thicker than the brass, so I had to use a second parallel to flesh out the brass to be gripped by the vice. Then I set up a temporary vice-stop and zeroed off the rear of the brass and the end next to the vice stop.

Then I moved to the centre of the 3.3mm width, advanced on the x-axis by 2mm and center drilled, then moved over 5mm and drilled again, repeat until 5 holes were started. Then I swapped over to drill for M2 tapping.




Once all those holes were drilled I opened the vice up and turned the brass onto it's side, pushed up against the vice-stop and tightened it up. Then I removed the vice-stop as it was in the way, and moved to the right coords and drilled 2mm holes.




Then I swapped the drill for a 4mm end mill and milled slightly more than half the thickness away.




Then I tapped the top holes M2.




and then carefully hacksawed,




then I gently hacksawed in the other direction to release them. But prior to releasing them, I cleaned them up as much as possible with a small fine file.

Then I gripped each tiny "L" in the vice and rounded over the bottom end with a file. I made 5 as I thought that would give me one to lose/spoil/have-as-a-trophy, and sure enough I did spoil one.




Here they are in place,







And that's as far as I got. I think next up will be making the outer support frames and some form of a base.


Tim

 

[Ken I]

O.K. now I see how you got around the "stagger" problem with the "L" shaped big ends.

Never look up at the mountain - just keep digging.

Ken

 

[Brian Rupnow]

So, What happened with this engine? Did it run? Is there a video?---Brian