Deciding on material to buy and being economical

Hello

For manual machining, how do you go about choosing what materials to buy when looking at a project, and how do you make the most of what you do buy? Is there a proper method for determining the best stock shapes and sizes to acquire to create the parts most effectively and economically? How do you minimise waste when machining odd shaped pieces?

For example if I have this part (quick measurement for scale is in inches):

I am guessing you would start with a rectangular piece of flat stock the same thickness as the part, use a rotary table for the curved parts or get clever with mounting the stock on an 'axle' and rotating the part against the mill, and then mill the straight edges?

However, even if you solve the 'curves' problem, you are left with an odd shaped offcut and potential waste.

Is this all just part of the black art of machining? Finally, any recommendations for good value materials suppliers in southern UK?

Cheers!

PS apologies for any improper use of terminology, please do let me know if there are more accurate terms I should use and I will update the ol mental lexicon

Edited By Ross Lloyd 1 on 06/02/2018 22:12:54

Hi Ross it would depend on the use of the item. If it was mild steel l would possibly use a strip of steel slightly bigger than finished sizes heat the bent end and bend it round a bar in a vice and machine to size after. If it was to be made from ground flat stock (gauge plate) l would machine it as you say but save the waste to make something in the future.

David

Edited By David George 1 on 06/02/2018 22:37:13

If the specified material is nothing special, obtain some black steel flat bar not smaller than the required cross section. Heat and bend the portion that requires to be bent. Drill and counterbore/countersink (as required) the holes. The last thing I would do, quite honestly is to machine the part from a piece of plate, that's a huge waste of money, time, cutters etc etc

cheers

Bill

Hi gents

I should have said, its going to be aluminium, so perhaps the bending idea is the way to go.

You buy someone else's offcut from e-bay and then sell your smaller offcut to someone else on e-bay.

In reality the offcut goes into stock and gets used for a future project., if you are making more than one then nesting the parts will help reduce overall waste. 

Certainly would not be machining it all away, couple of saw cuts will remove most of what is not needed from flat bar or plate then you will have a minimum amount to waste as swarf and little cutter wear.

Edited By JasonB on 07/02/2018 07:42:43

As all of the above. You will see time and time again the statement " I searched through the scrap box and found this" It seems that many beautiful projects are made from mostly scrap. So a few left overs are always useful.

regards

Edited By Oldiron on 07/02/2018 08:48:44

Many, many projects are inspired by useful lumps of scrap

Different approaches:

• Minimise the material used - your example this could be bending, or angling the work to fit in a smaller rectangle.
• Maximise the size of the remaining offcut.
• Find something in the scrapbox that suits.

When buying or cutting off material I always assume I will need some extra for holding the workpiece. I always try to allow enough so I can use it for some other purpose.

When I buy cheaper materials (e.g. mild steels) up to about 1" I buy it in 3m lengths cut into 1.5 or 1m lengths.

Neil

The first thing I'd do is look at the function of the component and see whether I could either use a cheaper and more easily worked material, or redesign the shape to suit the facilites I have.

There is very little really scrap metal in the model engineer's world. (If it is, it's too small to hold, already swarf!)

It is amazing what can be made from material that is lying around, waiting to "Come in handy, one day"

A lot Fred Dibnah's materials, apparently, came from the local scrapyard, with little or no provenance.

Given that much of what we make will be lightly loaded, little used, and adequately lubricated (Road Engines and Locos possibly excepted re use and loading) there is little need for the moving parts to be fully hardened as in full scale.

"The Biggest Little Train" shows what can be achieved. Admittedly, "The Silver Lady" had regular maintenance, but still completed some 3,000 scale miles, over fairly arduous conditions, in places where a full scale loco would not have ventured. And probably contained few, if any hardened components?

We are Model Engineers, The word Engineer stems from "Ingenious", so should we be!

Howard

Plenty of "scrap" about which is of use for models and real life stuff. Some egs. - plumbing fittings, bed frame, CI lamp base, old weights. This morning my wife threw out a coffee filter thingy, she saw rubbish, I saw a con. rod for displacer on hot air engine.

Gordon W. Posted by Plenty of "scrap" about which is of use for models and real life stuff. Some egs. - plumbing fittings, bed frame, CI lamp base, old weights. This morning my wife threw out a coffee filter thingy, she saw rubbish, I saw a con. rod for displacer on hot air engine.

The other good source for materials are printers and scanners & computer cases. eg, ground round bar stock, small cogs & pulleys, flat sheet metal, bushes, springs, small screws, small nuts & bolts etc etc.

How would we home shop guys get along without scrap.

Apparently hoarding has been recognised as a medical condition.

Things like keeping stuff to 'repair later' or 'use for parts.

If any helpful soul tries to declutter my workshop *************.

Neil

I remember Fred did come unstuck with one of his scrapyard parts, the front wheel bearing seemed not to be bronze or at least not a suitable grade and ran rather hot. He seemed to win most of the time so one part going wrong is probably well worth it.

Mike

I have used a couple of ebay suppliers in the past but I try to use a local to me supplier in Alfreton, Derbyshire; (http://www.bettermetalstores.com/"

The sell small or large amounts and material can be collected.

Usual disclaimer.

Brian

Hi all, thanks for the comprehensive help as ever! It appears I already have the hoarding condition, so I am one step closer to being a true machinist.

Those 50 collected choc ice sticks WILL come in handy one day...

Cheers, I'll bank that one

Or use the spare Araldite to glue two short bits back together so you have a long one again

Araldite mixed up in those plastic lids that were kept from espresso powder, etc cans.
DaveD

empty yoghurt pots is my favourite for mixing up things.

Michael W