Material for engine block.

[Steve CrowParticipant @stevecrow46066]

[Steve CrowParticipant @stevecrow46066]

I want to make a model engine block from 1" square bar stock.

I've made a couple in the past from bright drawn EN3 but I would like to make this one out of aluminium, like the original. The cylinders will have liners.

My problem is I've never got on with aluminium. I get an unpredictable finish and it sticks to tools. Also I have many M1.6 and 12BA holes to tap and I'm not sure that the threads would cope with a lot of assembly/dismantling.

My only experience has been with 6082 and I realise that other grades are available (2011 sounds good) but I don't fancy my chances of getting my hands on a small length of square stock.

Which brings me to cast iron bar. I've not machined cast iron since the first year of my apprenticeship 40 years ago. Would it be suitable for a job like this? I believe it can be quite messy and I've got a kitchen table workshop so it might not be ideal.

Any ideas or suggestions welcome.

Steve

[Martin ConnellyParticipant @martinconnelly55370]

The best tooling for aluminium alloys is polished. I have sometimes taken a risk with milling cutters with a black oxide finish but find that new cutters can clog within a few minutes of use as the aluminium doesn't flow away properly even with cutting fluid on the cutter. Polished inserts for aluminium alloys are available now. Cast iron can produce dust as opposed to shavings. If you have dust covers for the area and exposed parts most of it will stay near the machine. Pick up the waste with a magnet in a plastic bag and turn the bag inside out around the waste to bin it.

Martin C

[JasonBModerator @jasonb]

I've made several crankcases out of 6082 and not had problems with threads stripping out. As Martin says polished inserts and uncoated milling cutters are best with some lubrication such as paraffin.

2014 (HE15) would not be far off 2011 and can be had in 1" square by the inch from the likes of M-Machine

[Jon CameronParticipant @joncameron26580]

I would use 2014 Ali, as Jason suggests, parrafin for lubricant could be used, but i've always found WD40 works really well for Ali, and so long as the cuts aren't too aggressive. The tool can be kept lubricated with a squirt every so often. It also seems to help with keeping the Aluminium from cold welding to the tip of HSS as youve found happens. Not sure how well it works with the likes of insert tooling but seems to work very well for me on my old ML4 with HSS tooling. It can also be bought by the 5ltr bottle with a convenient spray bottle which is easy to fill up with a funnel, from various sellers on e-bay.

Regards

Jon

[JAParticipant @ja]

I doubt if a tapped 12BA. hole will last in aluminium. Can you use a plain hole with a nut and bolt? Always the best option but can be difficult to assemble. Otherwise look at using inserts, brass or better still steel. You will have to make your own out of bar. You should have no difficulty tapping 12BA into mild steel. I have yet to break a 12BA tap (I have destroyed a 12BA die but that is another story).

JA

[Oily RagParticipant @oilyrag]

Somewhere I have a 'block' of Hiduminium RR56 and a similar block of RR58 as sample blocks from piston forgings. I would estimate the block as being about 2 " square and probably 3" length. They were 'forged' into blocks from ingot slugs.

RR58 is equivalent to 2618 specification. This in heat treated form is 26/28 tons/sq in stress at 3% elongation. I'll dig around some to see if I can find it – let me know if you are interested.

[old martParticipant @oldmart]

The harder stronger alloys always machine best, using really sharp, honed HSS or the inserts made for aluminium which are also sharp. I use a little AC90 spray and never let the metal get dry.

[Steve CrowParticipant @stevecrow46066]

Another potential problem is I will be drilling/boring out the crankcase and sump out of 2 pieces bolted together. This picture should give you an idea of what I mean…

The green line is the outline of the 1" square bar and the sump will be made from 3/4 x 3/8 (or 20mm x 10mm) bar stock.

If I were to make the two pieces of different materials, would I run into problems drilling and boring? I should imagine a drill would want to wander into the softer of the two?

If anyone has experience of a situation like this, please let me know.

Steve

[JasonBModerator @jasonb]

Drill will likely wander into the soft material but as you are going to finish it by boring that should not matter, could always drill will an end cutting milling cutter which should be less likely to wander.

Could you get it out of a single piece of round? really depends on whether the joint is needed for assembly or if you are just trying to save metal.

[Steve CrowParticipant @stevecrow46066]

I'll be boring and drilling on a Sherline lathe and the hole is 12mm dia and 50mm long so I think I'll struggle to hold a big enough end mill in the tailstock.

If I can find the headroom on the mill I see that Arceuro do a 10mm 45mm long end mill that I could get away with.

The joint is for assembly so I can get the con rods on the crank.

[JasonBModerator @jasonb]

As you will only be using the milling cutters to get upto a size that your boring bar will fit I can't see why you could not come in from each end so a long series mill would not be needed as you only want to go full depth with the bar.

What material were you thinking of for the bottom half? If just another grade of aluminium it should be OK but something like steel/ali would wander. Also what engine is it based on?

[Roger BParticipant @rogerb61624]

I have used this material, EN AW-2007 AL CU Mg Pb F37, for crankcases and cylinder blocks. It is available up to 40mm square in 200mm lengths. It's a German company and appears to offer shipping to the UK for €6.99.

**LINK**

I don't know how the prices will compare to UK suppliers.

It turns well with specific inserts for aluminium. I have used threads down to M1.4.

[Steve CrowParticipant @stevecrow46066]

Thanks Roger, I shall have a look at that.

Jason, due to my method for holding the piece, I can only drill from one end.

I would prefer for both parts to be the same material, I'm just sounding out ideas.

It's a 1/12 Cosworth DFV V8, 7.2mm bore, 5mm stroke.

[Oily RagParticipant @oilyrag]

"It's a 1/12 Cosworth DFV V8, 7.2mm bore, 5mm stroke."

Fantastic! are you going to do the cam drive by geartrain as per the original, if so I would love to see how you do the compound spring gear. Also are you intending to replicate the 'bomb' in the centre of the vee banks? The quil drive to the bomb was an indicator of if the engine had 'kissed' the valves. If the quil was not true then the driver had over revved the engine – time for an engine change!

I used to work on those engines in the 70's and 80's, Originally in F1 and then later as F3000 engines, Also the DFL in 3.3 litre capacity for Le Mans 24 hrs and the 2.7 litre DFT's for Indy car racing in the USA.

Concerning my earlier post I have been looking for that forged sample block that I have (it is really annoying as I could lay my hand on it right away about 2 weeks ago but have 'put it somewhere safe' during my workshop 'Lockdown deep clean'). I did find the test results for VHN indents on several samples which shows the average Vickers number to be 126. This converts to 400Mpa TS. If I find it you are more than welcome to have it!

Edited By Oily Rag on 10/06/2020 14:00:57

[Steve CrowParticipant @stevecrow46066]

Posted by Oily Rag on 10/06/2020 13:38:35:

If I find it you are more than welcome to have it!

Thank you for your kind offer but I will pass on it. It's a bit big for my requirements and machinery.

I won't be attempting the quill drive and I don't even know what a "bomb" is! Maybe you can educate me.

In fact, the gear train isn't strictly scale, more "inspired by". My model will be running on compressed air and will be two stroke so there is no reduction between shaft and cam. Here's a drawing.

As you can see, this is a simplified version designed to resemble the original. This is with mod 0.5 gears, if I can cut mods 0.33 or 0.25 gears it would be more realistic.

It is good to hear from somebody who has worked on such an iconic engine and it's derivatives. I have never even seen one in the flesh.

Cheers

Steve

[Oily RagParticipant @oilyrag]

Here is the front end drive with a close up of the compound spring gear and the torsion sheeves, earlier gears (upto about 1978) had the sheeves (torsion bars) displaced axially, this is the first photo, as the rev capability increased to 14,000 this became a problem so the sheeves were displaced radially as in the 2nd close up photo here.

I later worked on an V10 F1 engine that in its early form could snap the nose off the cams within 1 hour of running on the test bed. We instrumented the engine up and found a +/- 15 degree of crankshaft to cam position variation due to the immense torsionals. As a development engineer I had originally commented to the designer that the cam drive should have been up from the rear of the crank. We overcame the problem by modifying the drive to the cams via a quill drive from the front mounted gear which was isolated from the camshaft (mounted on a needle roller) – the quill drive was then taken to the centre of the cam (well between cylinders 3 and 4).

All the Cossies were beautifully designed! and a treat to work on – much was derived from the Merlin as Duckworth (partner to Mike Costin in the Cosworth business) was an ex Rolls Royce engine man. The crank nose gear was a tapered fit on the crank and required a 12 ton press to disassemble.

The 'bomb' was the ignition distributor mounted in the centre of the vee and driven from the front geartrain. It was called the 'bomb' because of its uncannily resemblance to an item of air launced ordanance!

If you have any questions I'd be happy to answer them – if I can still remember!!

Edited By Oily Rag on 10/06/2020 15:03:06

[Steve CrowParticipant @stevecrow46066]

Thanks, all interesting stuff! I didn't know about the Rolls Royce connection.

I'm trying to find any scraps of plans and drawings on the web to help me with this. Do you know of any sources?

[Oily RagParticipant @oilyrag]

I can ask around some contacts to see if there are any drawings still available.

One of the RR Merlin carry over features in the engine was the use of 'O' ringed stand pipes between the head and block in place of a head gasket. The other was the end feed oil system into the crankshaft so that the oil did not cross through the main bearings into the crank to feed the big ends. It allowed the DFV to run with very low oil pressure – 2.5 Bar at 10,500 rpm. The later Judd developed engine used by Keke Rosburg in his championship winning year revved to 14,000 on the same oil pressure! The BRM V8 used a similar low pressure crank design but achieved by low depth drillways in the main bearing journals.

I have some documentation but it is more to do with setting up the Lucas mechanical fuel injection system and the later Lucas 468 electronic digital system and other oddities like the chopper discs and hall effect pick ups and the fuel pumps (which were gear type mechanical units). I do have my personal log book notes from running engines on test beds and from race support notes with items concerning exhaust system dimensions, camshaft references (such as DA 10, DA 102, DA 88 etc.,) and valve MOP's for differing characteristics.

I think there is a lot of stuff on the web concerning the DFV and all its derivatives (DFL, DFT, DFR) and some stuff about the FVA (Four Valve Assembly – a 4 cylinder Formula 3 engine) which of course led to the DFV (D = Double FVA). Try a search for 'historic DFV F1' or contact Race Engines magazine – they did a comprehensive write up of the DFV (but I disagreed with some of their timelines and some facts had been overlooked)

Keep me informed of your progress I will follow this with interest. In the meantime I'll talk to some of the 'old boys' to see what is available drawing wise.

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