Building the V-Twin “Kelsey”

[Mark EasingwoodParticipant @markeasingwood33578]

Thank you Jason.

Mark.

[JasonB]

On JasonB Said:

Must admit I had missed your second comment as it fell between two postings and we don’t get the warning hear that other posts have been made while typing. Though we don’t seem to get many comments on builds here a syou probably know from your own posts.

 

Like you, I do wonder whether it is worth posting, as many here seem to want to talk about other things other than engineering.

 

[Michael Gilligan]

On Michael Gilligan Said:

Great stuff, Jason

I regret there is no hope of me building one, but I shall be following with great interest.

MichaelG.

Still here … Viewing and learning

There is plenty of ‘skills transfer’ opportunity in your beautifully documented build.

MichaelG.

[JasonBModerator @jasonb]

Those following along that like to read the whole book and enjoy the build up to the cliffhanger ending should look away now.

If you are the type that just look at the cover and skim through the synopsis at the back then this is for you.

Kelsey took her first steps this afternoon. I had enough parts made to give here a whiff of air and off she went with out drama. Only one screw in each cover for now and I left of the gland nuts which would be an option as Stuarts don’t use any. Seems quite happy to start in either direction with a fairly small flow of air and at 10psi. Just the regulator/reverser left to make. As I said at the beginning plenty of time for anyone to get theirs made before Xmas.

[Andrew CrowParticipant @andrewcrow91475]

Very nice Jason always interesting to watch how quickly you produce an engine that works well and looks good.

Andy

[andyp123Participant @andyp123]

I’m watching with great interest, my day job has taken over a bit at the moment but to follow this step by step is great teaching.

Thanks, Andy

[DalboyParticipant @dalboy]

That runs nicely, can’t wait to see the end result. If it was to run in a boat for example, I presume you would use the brass option as you have stated in the plans.

[JasonBModerator @jasonb]

Yes the brass is the better option if the engine is going to be put to use.

[JasonBModerator @jasonb]

Before completing the recessing of the faces life can be made easier if the overall shape is machined beforehand so that the finished edges can be used to take sizes from.

Start by applying some marking blue or get the Sharpie out. With the piece of metal stood vertically on a flat surface (Porcelain tile in my case) put the shank of your 6mm drill into one of teh holes at the base of teh “Y” shape, rest a square up against it and lightly scribe a line, repeat for the other one.

Using the same two holes but this time with something whicj will give you a 45degree line scribe the two edges of the “y” I just used a school type plastic protractor.

Lastly use a top hole to mark where the cut out comes to.

Holding the work in the vice the top recess can be milled out to the required 45mm from the bottom. Use the hole sto guide your depth and don’t go too far sideways and cut into the 3mm radius fillet that should be left.

The remaining two corners can be sawn out as the material can be used for some of the smaller parts, cut about 1mm away from the line.

Back into the mill vice and with some packing in the top mill the lower vertical edge to the line/hole. Put the stop in place and then the part can be flippe dover to do the other side. I did these cuts at the full 12mm depth moving over approx 0.25mm per pass.

To do the other angled edges the vive is best set at 45degrees, I don’t tend to use the swivel base on mine, instead I just bolt the vice to the table with clamps as the slots are unlikely to line up with the holes in the base of the vice. The 45deg protractor can be used again placed against a jaw and a block of metal to run the Dti against.

First long side being cut, again using the full edge of the cutter

Then up the other way to do the other side

Sliding the part out the vice a bit and with the top packer in use again the two small areas at the ends of the top cutout can be machined.

Cont…… after dinner!

[JasonBModerator @jasonb]

Attension can now turn back to completing the recessing of the front face. Blue or sharpie around the two cylinder port faces then mark lines 25mm from the the tops of the “Y”. A ruler and scriber is good enough for this.

Using the 45deg set square progect the short angled edges down to meet th elines at 25mm from the top. This defines the two rectangular areas that do not need machining.

As the vice is still at 45degrees, it is just a case of clamping the work so it sits a bit above the vice jaws, the top packer will be needed again and then touching off on the flat area around the crankshaft boss to set the height of the cut. Then just work your way over the surface until just the turned boss and the two cylinder port faces are left. The 6mm cutter is fine for this and as the cut is only 0.75mm deep you can make each step-over 4-5mm wide.

Might as well try the two bits together and get an idea of what the engine will look like.

Th elast job fort now on the standard is to blank off the various passages that were drilled in from the sides. You can cut a couple of rough squares from some of the waste material or use some round stock if you have it to hand.

held in the 4-jaw I turned the square down to 4mm dia, then turned a short 3mm diameter spigot on the end to fit the holes. Saw off tho leave a head and make another five. Having a head stops the plug getting pushed in two far and interfering with other holes. For the two holes that plug the angled surfaces I just used 3mm diameter and filed the ends to 45deg

I used J B Weld to bond the plugs in place but a high temperature Loctite such as No 648 will also do. Once set file of the protruding heads and excess material.

That more or less completes the standard, rounding off of edges is best left until later if you want that “cast” look.

Hopefully some of the following bits will go a lot faster but at least you will have the most complex part of the engine out of the way.

 

 

 

[Adrian R2Participant @adrianr2]

Making the plugs from brass might add a bit of interest for a display model, invites the admirer to contemplate the complexity inside.

[JasonBModerator @jasonb]

Funny enough I had considered doing a less traditional looking engine with maybe just small chamfers to all the edges, stainless cap head screws, squarer cylinders and actually leaving small heads on the plugs.

With any of these engines the builder can do what they like in the way of looks provided the basic mechanics work, anyone for Purple anodizing?

[Adrian R2Participant @adrianr2]

Well there’s an idea – a cabin fever type competition over the winter months, entries to be featured in the magazine, maybe a supplier would provide a voucher for best execution and/or interpretation of the design?

 

[JasonBModerator @jasonb]

There is an idea “Best Dressed Kelsey” entries to be in by end of March 2026.

This is her sister Barbie!

[JasonBModerator @jasonb]

One thing I forgot to describe on the standard is doing the oil hole as I had machine dthat out of sequence.

Mark a line 18mm up from the bottom on the regulator side of the standard. Then hold is by the bottom of the “Y” at 45degrees. Touch the far side and then move in 14mm so the spindle is central to the part. Put something with a point into your chuck and move the Y axis until it is pointing at the 18mm line.

Change to a 3mm milling cutter and plunge down to create a pocket to hold a little oil, approx 3mm deep measured centrally will do.

Change to a 1.2mm drill or whatever you have around that size, the 1.6mm for tapping the M2 holes will do and drill through into the 6mm crankshaft hole.

[JasonBModerator @jasonb]

Rear Bearing

Just to show that it can be done without a mill I used a vertical slide to do some of the initial milling of this part on the lathe.

From the spare piece of 1/2″ x 2″ that you sawed off but a piece a little over the required 24 x 10 x 16 and then machine to those sizes in the vice. Start by using a dti on the vertical slide’s table to check it is true acoss the lathe and then mount your vice and check that the fixed jaw is parallel again using the di against it as you move the cross slide in and out.

Start by reducing teh thicknes sto 10mm, taking similar amounts off opposite sides, then machine the other two faces to arrive at the 16mm height.

Lastly trim the ends to length, I used the edge of the cutter at full 10mm depth making sure to move the work upwards against the downwards moving teeth of the cutter.

The main 6mm hole can be done first. In much the same way as the standard wa smachined locate the bottom and end, here I am using an edge finder that is run at around 500rpm and the work brought up to the side of the 4mm diameter end. You will see any wobble in the tip reduce as you get closer and then the tip will suddenly kick off to one side. Stop feeding at this point and reset the handwheel dial. Now feed in a further distance equal to half the diameter of the edge finder’s tip and the lathe axis will now be inline with the edge you were finding. Repeat for the end.

You can now wind the vertical slide up 10mm and the cross slide in 12mm and proceed to spot, drill 5.8mm and ream the hole 6mm.

Remount the work with the bottom facing the chuck, find the edge and end again and this time move up 5mm and over 5mm then 19mm to spot, drill 2.5mm and tap the two holes M3

The Block could be left this rectangular shape or the top domed as follows

 

[JasonBModerator @jasonb]

Hold the block in the (now) mill vice and arrange some for of stop, I often use this small one that clamps to the top of the vice jaws. With the 6mm milling cutter mounted touch down on the top surface and reset the dial/dro. Then move to the left side and touch off on that end of the work. Lower the cutter 3mm and using say 1mm wide passes, cut in a distance of 6.8mm.

Turn the work around and do the opposite side to match.

then locate the rear face and left hand end, move in 5mm and over 12mm and make a deep spot drill hole approx 3mm across to form the oil pocket. Change to the small 1.2mm drill and drill down until you break into the 6mm hole.

Those that have made some of my other engines will be familiar with this method of forming a radius on parts.

Slip the 6mm drill bit shank into the hole and let the drill rest on the vice jaws then bring down the 6mm milling cutter which will level up the part so that it can then be clamped in the vice. Zero the Z axis dail and then raise the cutter clear.

Now loosen tehvice and slightly rotate the work and retighten the vice making sure the drill is still resting on the jaws. lower the cutter down and take a cut off the top. STOP the machine reposition the work at a bit more of an angle and cut again.

keep repeating this cut & rotate and you will slowly see the curve appear made up of a series of small flat facets. Just be careful not to cut into the two flat areas either side

The last job is to lightly blend the facets into one another with a fine file. I tend to use 6″ long files for most of the work on these size engines and a couple of needle files to deburr the smaller parts.

Again the bearing could be left as it is or you can do similar to what was done on the standard and turn down the sides to just leave a projecting boss around the crankshaft hole.

The 4-jaw can be used again to hold the bearing but a better bet is to make a small arbor which won’t risk crushing or marking the part in the 4-jaw. To make the arbor take a piece of 8-10 or 12mm diameter bar, face the end and then turn down say a 5mm length to snugly fit the hole in the bearing block. Drill and tap for a screw, in this case M3.

With the addition of a small washer the part can then be held on the arbor to turn off 0.8mm from each side leaving a raised diameter of 10mm.

Keep all these off arbors and filing buttons as they can be used again and again on future jobs.

 

[DalboyParticipant @dalboy]

Looking good Jason. I have a box which I use to keep all the jigs and filing buttons in, I am sure if I throw one away that will be the one I need next.

[JasonBModerator @jasonb]

Crankshaft Assembly

The crank pin is just a case of sawing off a piece of the 3mm Silver steel and facing the ends to bring it to overall length.

I used 6mm Precision Ground Mild Steel (PGMS) for the crankshaft but 6mm Silver  Steel would be another option but not quite so nice to machine. As these tow rods tend to be very close to size they are a better fit in reamed holes than a piece of bright mild steel would be. Saw off some material and face the ends leaving the length a mm or so longer at this stage. I use collets quite a lot but a 3-jaw chuck will do if that is what you have.

The crank can be turned on the end of some 25mm cast iron bar, this is usually a bit oversise so skim the OD down to 25mm but it does not matter if you end up a little under, then face the end.

If you touch off the tool against the end and OD then the handwheels can be used to size the 6mm length of the spigot and its 12mm diameter.

Saw off the part machined crank and then hold by the 12mm spigot to face the end, leave it about 4.5mm thick for the moment.

Then spot drill, drill 5.8mm and ream 6mm right through.

Clean the hole and one end of the shaft with solvent and then Loctite together, I use 648 as I have a big bottle an dit does for most jobs. Set aside to really go off, I usually leave it overnight.

Now holding by the 6mm shaft the crank can be turned to it’s final 4mm thickness going right across the end of the shaft so they are flush and the face is then true to the shaft.

Without removing the work from the chuck move the whole lot over to the mill. Locate the centre and then offset 8.5mm to spot, drill 2.8 and ream 3mm. If you are using a hand reamer advantage can be taken of it’s long tapered lead in by not reaming all the way to full diameter. Stop a bit short so the crank pin enters about half depth, this will make for a tight press fit later.

The crank could be left round but I have shown a token balanced shape. Set the shaft horizontal on parallels or packing in the vice and with the shank of a drill in the crank pin hole arrange some packing to get the approx angle and mill the first flat.

Th evice can then be loosened and th ecrankshaft rotated so teh drill bit is resting on the opposite side. This will give a symmetrical shape when the second flat is cut.

The last bit of machining is to add a small flat for the Flywheel grub screw to bear against. Slip the shaft into position and mark a line approx 7mm from the edge of the bearing block.

Holding the shaft in the vice so it sits above the jaws eyeball the middle of the 6mm cutter to the mark on the shaft and mill a flat 0.5mm deep.

Lastly the Pin can be Loctited into its hole. If you were able to leave the hole tapered then the mill vice makes a good press to squeeze the pin into place.

 

 

[JasonBModerator @jasonb]

Ran out of room for the last image of the Crankshaft

[Roderick JenkinsParticipant @roderickjenkins93242]

Jason,

Great stuff.  Even better than “Building a vertical steam engine from castings” 😄

Cheers,

Rod

[JasonBModerator @jasonb]

I’ve not read that one😎

[JasonB]

On JasonB Said:

Lastly the Pin can be Loctited into its hole. If you were able to leave the hole tapered then the mill vice makes a good press to squeeze the pin into place.

 

 

The George Thomas method for this was to drill very close to size then use a hand reamer but not go all the way through with the tapered section of the reamer, leaving a tight spot at the end.

Andy.

[JasonBModerator @jasonb]

Same as what I hopefully said

” If you are using a hand reamer advantage can be taken of it’s long tapered lead in by not reaming all the way to full diameter. Stop a bit short so the crank pin enters about half depth, this will make for a tight press fit later.”

[JasonB]

On JasonB Said:

Same as what I hopefully said

” If you are using a hand reamer advantage can be taken of it’s long tapered lead in by not reaming all the way to full diameter. Stop a bit short so the crank pin enters about half depth, this will make for a tight press fit later.”

My apologies, I must have missed that.

Andy

[Author]

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