Could not have put it better myself.

As an example the question of a missing pulley casting came up on MEM forum last week, someone dropped me in it saying I could CNC a pattern. I saw the post and within a few mins had put up an image of the pulley. Turns out the person has a 3D printer so a couple of mins more work adding machining allowance and draft angles and The pattern was ready to export as both STL and STP files which I e-mailed to him. He was printing within half an hour having processed the file through Prusa's own slicer software.

Also last week I sent someone else a complete assembly of a Stuart Victoria, waiting to see how that comes out printed with a Resin Printer

Gary, having used Alibre for over 10 years I have a lot of files that I do still go back to and I'm also quite happy and conversant with Alibre so don't really want to go with something else.

F360 in it's non commercial form is fine for the small amount of CAM that I use it for and as I also tend to use Alibre for my work as well as using DXF and DWG output for hobby use it would mean having to pay for F360 too. At the moment I opt for the yearly maintenance for Alibre Professional and that is less than the more expensive yearly F360 licence would not really be worth paying for both.

I will do the odd tweak of an imported STP file in F360 such as filling in a hole so the CNC does not try to machine it out or as I have done on this bed part model the shape of the stock.

Ches, as David says I find a pdf output the best way to share my drawings with others and they also go to our editors for publication in the mag. This will give you an idea of the output. Though for my own use I tend to just pull the dimensions off the 3D model and sketch them out onto a scrap of paper in most cases.

The main bearings started life as two pieces of bronze that were milled to overall size before being drilled and reamed 5mm

I then used the CNC mill to shape the tops to profile. As the flute length of the 3mm cutter I was using was 8mm was the same depth as the stock I did not quite run the adaptive and contour cuts to the full depth of the material.

They were then mounted onto a simple arbor so that each side could have 1mm turned off just leaving a raised boss around the hole, I used a CCGT insert with 0.8mm tip radius to leave a nice internal fillet.

A piece of steel bar was faced, drilled and reamed 5mm and then transfered to the CNC to have both the outer profile and the recessed areas milled away as well as drilling the offset hole for the crank pin.

After sawing the crank off from the end of the bar it was Locteted to a length of 5mm PGMS and when set the end was faced back to thickness while holding the shaft in a collet, this gets the face perpendicular to the shaft regardless of any misalignment there may be in the Loctite joint

The two cylinder end covers were worked on either end of a short stub of 30mm cast iron bar

And then after sawing in half the external faces were machined, here the one for the piston rod end has had a rough boss turned which will be shaped into an ellipse later.

My largest 28mm 5C collet in a block held the covers while they were drilled 2mm for the studs and tapped M1.6 for the gland.

I also made a start on the valve chest, machining some cast iron to overall size, drilling and counterboring for the valve rod and it's gland and also tapping M1.6 for the gland studs.

Two glands were turned from bronze bar and then screwed to their respective parts which were then machined as one. The CNC makes a good job of machining true ellipses and combined with a cutter with 1mm corner radius leaves a nice fillet in the internal corners. Most of the images of existing engines I found had the gland boss horizontal rather than vertical as shown on the General Arrangement so I set mine out the same as it is easier to get to the studs at either side than having one tucked down at the bottom of the engine

Usual adaptive and two contour passes to finish

Thanks for the comments

I'm not keen on the "+" shaped reinforcing ribs that Stuarts used on the valve chest cover as they look out of place on a small freelance engine and are not done that well anyway so I opted for an elliptical recess to tie in with the shape of the glands and to keep things similar also turned a round recess in the cylinder end cover rather than the conical protruding one Stuarts used.

The eccentric strap is shown completely split in two with a pair of bolts holding the two halves together but as it's a simple beginners engine I decided to use a design like that use don the 10 series engines with a single split and pinch bolt which allows some take up for wear if needed. I started out with some brass that was bored (big end) and reamed (small end) as well as thinning the smaller end from 4mm down to 3mm on the manual mill

A couple of top hat bosses allowed the part to be held down while the CNC did it's thing of my usual adaptive path to remove the majority of the waste, two contour passes to finish the outer profile and then a scallop on either side to form the tapered elliptical section of the rod.

The strap could then be used to gauge the size of the eccentric

Which was then offset in a small 4-jaw to be reamed and have the boss turned down to the required diameter

Not being a fan of bright bling on engines rather than use gun metal for the cross head I went with cast iron. After machining up a lump to the required size it was held in the small 4-jaw to Turn the boss on the end

Before milling the various features so it would run in the guide bars and take the end of the conrod

I previously drew up a flywheel and did the CAM for the One-One which used the Progress flywheel so it was just a case of sawing off another bit of bar and CNC machining another flywheel for about 1/10 the cost of a casting.

I did not take any pictures of the various rods, pins and guide rails as they are all fairly straight forward turning jobs so next post we will see what I looks like with a lick of paint.

Martin. that is my old lathe chuck that does not get used much on the lathe now and the jaws were done in the lathe.

On both the lathe and mill I tend to use them more for the fact they provide a backstop for shallow work rather than for concentricity and in this case just clocked the part in with a dti in the spindle

This set of jaws have only been machined for approx 35 and 60mm diameters by just over 1mm deep for each and I use them the most as they will hold anything from 25 to 75mm dia quite firmly if you don't go too mad with DOC

Looks like I'm going to have to run it up again and get the tacho out so see what speed it needed to start levitating

I think one reason this one stays fairly well grounde dis that unlike the cast original which would likely have beed hollow I left the base solid which dampend any vibration.

I suppose the counter balanced shape of the crank web is there mostly to counter the in out movement of the conrod, cross head, piston and piston rod but will add some up and down imbalance as the speed goes up. The verticals seem to want to jump about a bit more whether that is due to the moving parts or simply the fact that they have a smaller footprint and tend to be a bit more top heavy I'm not sure.

Build was spread over about 5weeks looking at the dates of the photos, I don't tend to start writing up a build until the engine has been test run. I do tend to have a few projects on the go at once and would have been painting and assembling the James Coombes when I started making this one. And while this has been getting painted I managed to get another engine that has been sitting about for a while completed and test run.

While I was taking the photos of the Progress replica I thought I would take a quick group shot and video of the three Stuart replicas. They have all been quite enjoyable quick builds fitted in between larger projects and are all good runners.