My name's Bob, and I rebore engine cylinders. Please see the pictures and text below where I explain how I came to do this, and the kind of machinery I use to do it with.
This is my Minimax, a wood and fabric single seat tail-dragger type aircraft that's powered by a Rotax 447 air-cooled twin cylinder 2 stroke engine.
The photo was taken just after I'd landed at my home airfield at London Colney. I'd just flown back from the Isle of Wight, where I'd been for a fly-in in 2018.
This is a hybrid aircraft using a Medway Raven wing and a Pegasus Q trike. This aircraft is powered by a Rotax 462 water-cooled twin cylinder 2 stroke engine.
The photo was taken just as I landed at Eshott airfield in Northumberland during the Fly-UK Round Britain Tour in 2016
This is my Spectrum. It is the only flying example left in the UK, and is one of only 22 ever made. It's powered by a
Rotax 462 water-cooled twin cylinder 2 stroke engine.
The photo was taken just after I landed at Boxted airfield in Essex for their annual fly-in in 2018.
Hi, I'm Bob, and I live in Borehamwood, Herts. From the photos above you can see what my hobby is. Others like to race, or to walk, or to cycle, or go canoeing, I like to fly, and to do this I own a collection of microlight aircraft. I do all my own maintenance on these aircraft, and as you can see from the photos at the top of the page, I rebore and hone the engines when necessary. To do this I have three different sized portable boring bars and matching sets of honing equipment. (See the 'Workshop Services' page for further details)
HOW I CAME TO OWN BORING BARS AND HONING EQUIPMENT
Years ago I worked for a motor re-engineering company in Bristol called Hartcliffe Engineering. Sadly they no longer exist, but I worked there from when I left school at the age of 15, until I was 21. During that time my main occupation was reboring and honing car, commercial, motorcycle and small industrial engines.
Most of this work was done in the workshop, where I used a collection of Van Norman portable boring bars. The one I normally used was the 944, and I had two of them, but I also had a 905 and a 777S for larger bores. For some engines, such as Gardner diesel bus engines, the bore size at either 4.75" or 5" diameter, and with a bore length of over 8", was so large that the Van Norman's weren't big enough to rebore them. For these I used a pair of huge static Paddon-Thomsen boring bars, and centred the block under the cutting head instead of centring the boring bar over the cylinder as I did with the Van Norman bars.
The picture above shows a Van Norman 944 portable boring bar. The 905 is just very slightly larger than the 944, but the design is identical.
The picture above shows a Van Norman 777S portable boring bar. This bar is somewhat larger than the 944 and the 905, and correspondingly heavier. (Note the lifting hook on top of the gearbox!)
The picture above shows a Paddon-Thomsen static boring bar with a large diesel engine block mounted under the cutting head.
When working in the workshop I used a Delapena Beam Stroking Honing Machine to finish the cylinder blocks I'd rebored. The picture on the right shows what they look like, and the one in the picture even has a Delapena honing head at the bottom of the honing shaft that hangs from the end of the beam stroking bar.
This was a very good tool, and was not only easy to use, but very safe as well, due to having a trigger next to one of the handles on the beam head. So if the honing stones jammed in the cylinder for any reason I could let go of the trigger very quickly to prevent injury to myself, and damage to both the cylinder I was working on, and the honing tool.
I wish I had one of those today for honing out cylinders in my workshop, but instead I use the hand tools you can see on the 'Workshop Services' page.