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Member postings for Craig Booth 1

Here is a list of all the postings Craig Booth 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: V-Twin 100cc Design & Build
12/04/2020 18:13:55

Today was a mix of things. Finished off 2 of the rockers in Silversteel, later to be hardened, rocker pin also from silver steel with circlips.

Made 2 of the port plates from stainless steel. I'll be silver soldering a sleeve onto these which will project into the port with an O-ring for sealing and will also allow the tubing to be soldered on.



Made the rear cam shaft housing which houses a roller bearing and has an oil seal.


And anodised the front prop plate.


09/04/2020 08:46:07

also made start on the first conrod (alu H15), with a needle bearing on big end. Small end will have a colphos bushing.





09/04/2020 08:44:32

The last couple of days has been work on the tappet guides and sleeves. I had to redesign these as I made an error in making the space available for the cam lobes to small a diameter. This has meant that I have needed to make the tappets much larger diameter 8mm diameter to meet the minimum calculated in the "cam with draw" spreadsheet I have been using. The main guides from aluminium H30 and the sleeves Colphos. Guides then anodised.





29/03/2020 19:31:40

Today I anodized the cylinder head and made the valves sleeves from Colphos. Pretty happy with the results.




30/11/2019 20:04:46

and I couldn't resist putting it together and seeing what it looked like on the plane laugh


30/11/2019 20:02:01

Hi all, well its been a few months and I been concentrating on the plane rather than the engine, but now that winters here starting to get back into it.

Finished off one of the rocker supports.


and then started on the front crankcase housing.


lump of aluminium turned and bored to shape. Main bearing will be a press fit, front bearing a push fit.


on the vertical rotary table on the mill I cut clearance for the valve sleeve and octagonal face plate.


and drilled and tapped holes for the magnet sensor



drilled the holes for fixing


18/08/2019 08:22:11
Posted by JasonB on 18/08/2019 06:53:34:

It is not just accuracy, the main reason is that a drill chuck does not hold the cutter very securely particularly when side load is applied and there is a risk of it moving. If you are lucky it will just ride up and not cut but due to the angle of the helix that the flutes follow the cutter is being pulled down when cutting, it would be a shame if this happened to a part that you had previously put a lot of work into.

I think we have all done it to start with or for the odd little cut where it's a faff to change from chuck to collet, (well at least I have) but would be worth investing in a collet chuck such as ER25 or 32 depending on what machine you have.


Thanks for the info Jason, that's something new i've learnt.

I do have a collet set that i use for the larger (16mm bit), but will look to use them for the smaller also.

17/08/2019 20:47:27
Posted by JasonB on 17/08/2019 20:44:26:

It's coming along nicely Craig and just goes to show you can hold milling cutters in a drill chuckdevil

Ignorance is bliss. I guess as a newbie I can get away with it..wink

I presume now that you've hinted that the milling bit should be held in a collet instead for better accurancy?

17/08/2019 20:39:08

more work on the head today, but first needed to get the rocker support started as I wanted this in place when I drilled the holes in the cylinder head for the valve sleeves so I would get perfect alignment.




Once valve sleeve holes where drilled, fixed the head to the rotary table to mill the flats for the inlet/exhaust ports and to drill the ports.

These ports will need to be re-drilled once the colphos valves sleeves are in place, but the head will need to be anodised first and this cannot be done with any other types of metal present.





14/08/2019 21:16:18

I didn't get any photos but when I had the stock in the lathe for the cylinders, I also parted off the 2 cylinder heads after cutting the fins. Being the same diameter it was easier to do while the stock was aligned.

Then moved to the mill to drill and counter bore the mounting holes (M4 bolts), and the 2 central holes which will be used to fix the rocker bracket. These are M3 threaded, but looking at them now I may increase to M4.

All the mounting holes are asymetric due to clearances needed on inlet and oulet holes.


Next I made a basic block to hold the head while the other operations, circlular on one side to match the head, and square on the reverse to hold it in the vice and small rotary table I have.



Fixed in the vice at 15degrees off vertical to drill the 7/32 hole for the sparkplug, tapped at 1/4-32, and counterbored to 12mm for plug wrench clearance.


Moved to vertical in the vice and used 2mm slitting saw to cut fins in the top


Then back to 15 degrees to chamfer the top edge to give plug lead clearance.



10/08/2019 21:09:37

This weekend I worked on the crankcase. Started with a big block of aluminium 76x76x65 in the lathe off centred and bored the main crank axis hole. All the other work was carried out in the mill.

The edge chamfers I will do later once the cylinder bodies are located. Now I just have 49 M3 holes to tap sad










06/08/2019 21:04:08
Posted by Emgee on 06/08/2019 09:16:04:

Hi Craig, what is the purpose of the recess in the front face of the prop driver ? I would have thought you need as much driver to shaft contact as possible with the method of fixing the drive to the shaft, also increased mounting face area for the prop, IMO a key would offer more security in operation and if also on a taper ensure concentricity of the drive system.


Hi Emgee, the recess is for the retaining nut which holds the prop driver to the shaft, the grub screws stop the rotation. Your'e right, a key would be the correct method but at the moment that is outside my experience and skill. The key and retaining nut seems to be the way most manufactured RC plane engines of this capacity appear to be fixed. I can image that this may be a part I may need to remake later in the build. Thanks for the comments.

05/08/2019 21:24:52

on to another relatively simple item. The prop thrust.


Turned on lathe with counter bore. Reversed in lathe to add 0.5mm lip so only in contact with inner race of bearing.



onto the mill to blind drill for M5 tapping holes



moved onto side to drill thru for M6 grub screw tappings (both sides) which will marry with flats on the crankshaft.



05/08/2019 21:14:41

good thing my lathe has a replicator button...wink going to be needing that a lot on this build



30/07/2019 06:45:02
Posted by Graham Williams 12 on 29/07/2019 22:10:30:

Hi Craig, this is a lovely project and superb CAD drawings, especially the fully rendered 3D images. As an engineer and keen RC aircraft fan I'm looking forward to seeing this running and flying. Do you use Inventor in a professional capacity?


Thanks Graham, I am an engineer by trade but in a different field (building services - heating,cooling, ventilation, sustainability etc). I don't use Inventor at work but was already familiar with the standard AutoCAD software so it did not take long to teach myself Inventor and is it relatively intuitive


28/07/2019 19:07:41

move to the mill to drill the bottom set of holes for bolting to crankcase and milling the octagon faces.



all that remains are the top set of holes, but think I'll leave these until later as they are non-symetrical and also mirrored for each cylinder head bolt pattern.


28/07/2019 12:30:45

parted off overlength, reversed in chuck and faced off to length.



27/07/2019 21:50:13
Posted by Rockingdodge on 27/07/2019 15:54:01:

What type and size plane are you building Craig?


Rodger, I'm drawing up plans and have it half cut out for a 1920's style racer. Its a mix hybrid between a Gee Bee R3 and Chuck Gratners Riley B design. Wingspan 100", target weight around 14-15kg

27/07/2019 13:08:08

started to make some chips. Cylinder No.1


2.5" HE30 barstock, machined down to 62.5mm OD. Fins are 1mm width with 2mm space, 7.5mm deep.







20/07/2019 19:03:26
Posted by JasonB on 20/07/2019 08:55:35:

You can get some much neater and nicer looking plug tops than those Rcexl ones

yeah, they are a bit plain, but what came with the unit. Will consider changing them but that's a long way down the track.

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