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Diesel fuel in the engine explodes - it detonates as opposed to simply deflagration burning - this imposes enormous shock loads. Shock loading doubles stress loads. Hence considerably larger bearings and stronger piston and crank designs than petrol. This will be particularly relevant for sizing...

Oooohhhhhh - pictures please - now you've got my interest piqued. Mentally I'm picturing something like a Morgan V-Twin but noisier and way cooler. You can't just drop something like that into a conversation. Can't wait. Regards, Ken I

This is a hexagonal mount ER32 collet chuck I use for milling hexagons :- I just open the vice rotate the hex shank and continue - accurate enough for spanner flats and hexagons. An a lot easier than mounting the dividing head or rotary table. See also my thread on using such a cheap and...

I've posted this before... High speed drilling, sensitive drills? These are what I use for very small holes :- The upper one uses a DC motor, Dremmel collets or chuck (5/16" 40 ME thread) - the whole thing floats in that it is free to rotate and slide in the MT3 shank. It uses a Mabuchi motor...

I normally drop a piece of solder (just cut with side cutters) into the hole - the grub screw compresses it like a liquid and it holds well. Regards, Ken I

Steamchick - "feeling of confidence that my thumb was right" even that can set you up for a hard landing - I couple of years back I designed a machine with a conveyor of two hollow pin roller chains with 20mm diameter rods bolted between them with M4 cap screws (all that would fit) - since it...

Absolutely correct ! Huge differences for small changes because of ^4 Regards, Ken I

minh-thanh - yes I'm an engineer and I have studied things such as strength of materials and structural design plus years of experience in breaking things. So while it may be obvious to me it is not always so to others - I've also had the salutary experience of lecturing to students which maybe...

See :- materials - torsionload. Standard strength of materials calculations - for a shaft in torsion its to the 4th power. Bending 3rd power, tension or compression 2nd power. So without doing any calculation of actual stress then an 8mm vs a 6.9 is (8^4) / (6.9^4) = 1.8070 or 80.7% stronger...

Minh-Thanh, I have attached a file on steel manufacture. I wrote this specifically for customers who bought "cheap" welding wire - it's cheap for a reason and that reason is generally not good. There are many ways ranging from cheap and nasty to excellent. Look at the...

I'm going to ask a really dumb question - but only because I made this mistake myself. Are you trying to start the engine in the right direction - wrt cam timing set up ? The fact that it won't even pop bothers me. Is the cam set for clockwise or anti-clockwise rotation ? Above comments on free...

Indeed - re prior two comments..... Rule #1 - never trust a drilled hole (where possible) Rule #2 - bore before reaming (where possible) As in this sequence from my 6-Shooter Elbow Engine :- This posted over 10 years ago. Regards, Ken I

The can of worms rule "the only way to reclose an opened can of worms is to use a bigger can" I also forgot to mention that gun drilling normally has a whole bunch of intermediate guides for the long drill which can suffer from "crippling deformation" (as per Euler - Rankine) which will cause...

I have been hearing that all my life and agree there is no difference - however when drilling a long hole in say a milling machine, the tiniest tramming error produces a large error at depth - but that's an accuracy issue rather than something related to the physics of machining but I would...

Some tips on deep drilling. Make sure your drill is perfectly sharpened (equal cutting edges). Use a spotting drill (rather than a centre drill) to start. Your start must be perfect or you are going to wander. If the hole is large enough - pre-drill and bore the start. You can extend drills - as...

Having spent most of my professional life designing one-off machines I have seldom bothered much with tolerancing except where necessary. This has carried over into my model engine designing and building. The following caveat appears in my drawings and build notes :- All dimensions are...

I had the reverse experience - one of my suppliers had to sell up his toolroom in a hurry - he offered the entire stock to the various dealers and got pretty much the same crappy offer - he asked me if I was interested in matching their best price - I did. See :- I Bought A Toolroom ! I...

If you can't fix it hide it ! The toolroom I was working for at the time bought a brand new (and very expensive) Swiss jig boring machine and set it up in its' own air conditioned room. It was given over to the tender mercies of a toolmaker who had developed multiple sclerosis and worked mostly...

I try to adopt the "two bites of the cherry" approach. I make the parts in the sequence most easy to correct on the subsequent part - I then strive for perfection - a personal triumph every time I mike up after my final cut to find I'm spot on. If not I'll fix it on the mating part. Screw that...

Steamchick, you might like to hear about my further problems and (accidental) improvements. Although I got it running it was not as it should be - it turns out it had been dropped and was misaligned. Anyway I resoldered the displacer but it did not run as it should and I ended up overheating...