Ordering the right material…

[jps1982Participant @jps1982]

I’ve decided to build a Webster I/c engine as my first project. I’m trying to buy all the right materials but quickly find myself unclear on what exactly is the right stuff…

E.g. the plans call for ‘aluminium alloy’ in 5/16 and 3/8 for the baseplate and main frame pieces.

Somewhere like https://www.aluminiumwarehouse.co.uk give options of 1050/5251 and 6082. Metals4u has 5083 to throw in another grade… Not sure if any of those = ‘aluminium alloy’?

Looking at Brass I have seen CZ108, 124, 130rades for starters

I assume other metals will have similar levels of choice…

Any advice on where to get started figuring this out?

[Mike HurleyParticipant @mikehurley60381]

When you say ‘first project’, how much machining background do you already have? An IC engine is not an easy thing to build correctly and a thorough understanding of the characteristics of materials to be used is essential.

Experienced engineers will already have a general idea of best practice, and will simply research areas they are not familiar with. There isn’t really a one-size-fits all answer to your question, although I’m sure other members of the forum will advise where they can, but I’m surprised that whatever plan you’re working from doesn’t give specifics.

Standards for materials define many, many critera, such as workability, machining finish, stress tolerance, wear characteristics etc etc . For non critical parts, many guys simply use whatever they have already lying around.

[noel shelleyParticipant @noelshelley55608]

The trouble is the company you mention is really an industrial supplier who will be less likely to offer help and also may want to supply in industrial quantities. Since what you want to build is not saftey critical I would not worry to much, each grade will be formulated for a particular job in industry. EG brass and bronze are both copper alloys but with very different specs brass can suffer zinc loss, bronze does not. I would buy a copy of model engineer and try some of the suppliers in there. Good Luck Noel.

[FulmenParticipant @fulmen]

1050 is pretty much pure (and hence soft). 5251 and 6082 are both high strength alloys (which is what you usually want). Do pay attention to the temper as this determine the actual properties of the alloy. Here are a bit more info:

https://www.azom.com/article.aspx?ArticleID=2805
https://www.azom.com/article.aspx?ArticleID=2813

The TLDR is 6000-series T6, it’s the most common structural alloy with good all-round performance.

[JAParticipant @ja]

Look at M Machine website. They have an interesting few pages on steel selection. Aluminium is not too difficult: castings are generally horrible to machine while something like HE30 is nice.

As you have discovered a lot of spec.s from different sources cover the same metal. It is really an afternoon with Google.

Surely this is an article for the ME?

JA

PS. By the way, this is not a “Beginner’s Question”.

[JasonBModerator @jasonb]

The Webster is a common first IC project particularly in the US and you can be a bit flexible with some of the materials, others should be adhered to.

6082-T6 would be my choice for the frame and 95% of other aluminium parts found in most model engines. You may find some of the ME suppliers list this as HE30

For Brass I would go with CZ121 which is not too soft and machines nicely.

Anything on the drawing that calls for Drill Rod will be Silver Steel in the UK.

CRS is Cold Rolled Steel which is  a bright mild steel such as 230M07 (EN1A) and for the built up crank I would suggest using PGMS which is precision ground mild steel

Bearing bronze would be SAE660 or in smaller sizes Colphos is reasonable to machine

The 12L14 for the cylinder is a leaded steel 230M07pb or EN1Apb but my choice would be to go for iron GR17

M-Machine would be my choice of supplier.

[JasonBModerator @jasonb]

To be fair to the Webster drawings they do give more specific material requirements where needed.

The frame which is not critical is just spec’d as “Aluminum Alloy” whereas something like the conrod is spec’d as 6061-T6 (The common American version of UK 6082-T6

[SillyOldDufferModerator @sillyoldduffer]

Jason has given specific recommendations,  but a more general way of doing it is to search the web and check what the material’s specification says about machinability.

For example, Aalco say: ‘In the T6 and T651 temper, alloy 6082 machines well’.

Phrases in the spec like “free-cutting” are good, but avoid anything that mentions ‘work hardening’, or any other hint of poor machinability, unless there’s a special reason for using it.  (Copper doesn’t machine particularly well, except it’s other properties outweigh that when making Boilers.)

Alloys of the same metal vary wildly, so it pays to check.  Of the US 1000 to 7000 Aluminiums, only alloys in the 6000 series have specifically good machinability, and though many of the others do machine, bit tricky, some are vile; I believe the entire 1000-series are all too soft to machine well.

Dave

 

 

 

[JasonBModerator @jasonb]

2011 T3 and 2014 (old HE15) can be very nice to machine, not just the 6000series

The problem with suggesting Google is that if the drawing just says “Aluminum Alloy” and as a beginner you don’t know what you actually want property wise it is hard to know if what you find is what you need. You will also end up with a load of info on American spec material that is not going to be much use if buying in the UK or ROW when you want an “AluminIum Alloy”

[JasonB]

On JasonB Said:

2011 T3 and 2014 (old HE15) can be very nice to machine, not just the 6000series

The problem with suggesting Google is that if the drawing just says “Aluminum Alloy” and as a beginner you don’t know what you actually want property wise it is hard to know if what you find is what you need. You will also end up with a load of info on American spec material that is not going to be much use if buying in the UK or ROW when you want an “AluminIum Alloy”

This is where I come unstuck with the different grade numbers across the globe, is there a list of comparisons from one side of the planet to the other

[JasonBModerator @jasonb]

There are plenty on the net such as this. Aluminium is not too bad as the 1-7000 series numbers are used in most places unless you are working to a DIN Drawing

Note 2014’s old BS code was FC1 for Free Cutting!

[Lee RogersParticipant @leerogers95060]

Straying a wee bit off topic but that’s a good heads up on 6061 T6. It is silly expensive in the UK and the only reason to use it is the availability of thin wall tube and sheet that you can’t get in UK spec 6082 T6.

[Anonymous]

Some years ago I machined a number of aluminium alloy discs for a client to test out an electrochemical coating process. I machined discs from 2, 5, 6 and 7xxx series alloys. As I recall they all turned easily with an aluminium specific insert. Strangely some of the 7xxx series discs got pretty warm when hand tapping a M4 thread in the periphery.

The 1xxx series is pure aluminium and only available in the UK, as far as I am aware, in sheet/plate form. It’s great for bending but awful to machine. It has all the machining characteristics of warm fudge.

The alloys 6061 and 6082 are not equivalent, 6082 contains up to 1% manganese, 6061 contains less than 0.15% manganese.

Andrew

[Author]

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