An experimental V-4 wobbler

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stirling lad:
keep in mind that these magnets drasticly and permanently lose thier pulling power when they get heated to much,, you might be able to use that in your favour if pulling power is an issue later........just a thought...

....Mike...

spuddevans:

--- Quote from: stirling lad on June 10, 2011, 09:57:05 PM ---keep in mind that these magnets drasticly and permanently lose thier pulling power when they get heated to much,, you might be able to use that in your favour if pulling power is an issue later........just a thought...

....Mike...

--- End quote ---

Good point Mike, and one I will file away just in case I have too much attraction ( a problem I have never personally suffered from in the past :lol: )

At the weekend I managed to get a little time to play, erm work done. :lol: 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 :lol: ) So the rest of the crankwebs will be for the next update.

Tim

spuddevans:
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 :lol:

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 :lol:

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 :lol: :lol:

Tim

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