Most difficult part first

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It depends whether you are a beginner or not.

I try to make parts in order that they can be fitted together. That way I can size parts for fit and they don’t get lost over time after assembly. But it all depends on what you are making, something like a clock requires most pieces to be assembled in one go.

More often that not I will start making some of the smaller simple parts of the next engine while the previous one is being finished off as it beats twiddling your thumbs while the paint dries etc. This also seems to make a project come together faster as you can start to assemble the bigger more complex parts as they are made if all the small fixings, bushings, etc are ready to fit. It is also useful when I feel like a bit of workshop time after work to just pick a simple part or two that does not need too much thinking about or leaving the machines set up as a long machining sequence can't be completed in one sitting.

However sometimes I will tackle what I feel is the most testing part first particularly if it is one that I may be fabricating or cutting from solid where the original may have used castings. If I can't make the major part then I have not wasted time and materials on the small bits.

Normally I prefer to build in logical assembly order, modified by availability of time and materials. The sum bother of making several easy parts fit together might exceed that of making one awkward bit. And if the difficult part is made wildly out of sequence, it might be a long time before discovering it doesn't fit or is riddled with errors. Very upsetting. Don't ask how I know...

Before starting I assess how difficult each project stage might be, walking away if anything is too challenging at the moment, including time and money. A couple of times it made sense for me to tackle the hard bits first to develop the skills needed or to understand new techniques. As learning carries a high failure rate, I've found it more economic to build skills up step by step. Others make better progress being thrown in at the deep end.

May depend on your personality, I'm with my hero Homer Simpson who said: 'If at first you don't succeed, it's not worth trying!'

Dave

As old mart says, it depends on your machining ability. If a beginner, start on something simple and not expensive to build up your skill level. Cheaper to make again if something goes wrong.

When starting my traction engine, a machinist who had built his own engine advised me to start on the wheels first as these were fairly straight forward and required a number of different skills. (Turning, milling, drilling, rolling plate, welding). They were also something which could be completed on their own and give me a sence of achievement.

Paul

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For me it depends on the project and the type of parts I'll have to make. If there are several simple parts required in multiples, I don't want to have all the interesting work to do at once, then a load of tedious repetition components.

So I try to distribute the 'smarty-pants' operations through the project so there's a pattern of interesting work to look forward to whilst doing any humdrum stuff. Sometimes that might mean splitting the operations on a particular component where I'd have to change setup in any case. For example, I might finish bore a cylinder, put it aside and make some spacers or fasteners, set up and mill the ports in the cylinder, drill and tap the stud holes, do some more dull bits, then set up to drill long, angled steam passages or suchlike.

Edited By Mick B1 on 04/08/2019 15:12:23

I only have the one model to date, the 0-4-0 and I started with the wheels and worked up, just seemed logical that way and I am doing the same with the class 22, bogies and chassis first.

I do make myself a list of parts/jobs in sequence but some items jump the queue if I already have material on the shelf etc. If I had a part to produce which I knew was going to be difficult or I had some doubts over it I would definitely begin with that.

Ron

As an aside to this, when I statrted with Leica you are introduced to the T2 Theodolite. This is an optical theo. that reads both sides of the optical circles. Conventional overhaul was to start at the bottom and work your way up to the last part which was the reading Mirometer which allowed one to read both sides of the vertical and horizontal optical systems.

As we became profficient we were able to start on any part and I found it was easier to do the Micrometer bit first as it was used in all the process to follow the setting up. It is quite a complex operation centering the circles and placing reading prisms at the right distance and setting all of them set to position with a Dioptre tube where the Pupil through the instrument was centered. The vertical and horizontal pupils brought together at the Micrometer.

Average overhaul time about 12/13 hours and cost in the 80's about £400.

By far the most important is to find the drawing dimensional errors first !

Then at least you know you are not wasting your time making stuff that will never fit.

+1, but I also try to keep all the turning bits together, then all the pieces that require milling; two separate machining sequences.

George.

Comments deleted since they were not directly relevant.

Sorry

Edited By JA on 04/08/2019 18:13:17

Sort of... it can be really motivating if you know you've done the hardest bit, but it can also mean you've 'solved the challenge' and lose interest.

My Jovilabe is still waiting for me to work up the courage to attempt a 10" diameter gear.

The 'ancient engine' is 90% complete and waiting for me to lost PLA cast the brass crosshead that has been 'drying out' since October

Neil

If I started a job doing the easy part first my Dad gave me hell for saving the hard part for last. If I started the hard part first he gave me hell that, too.

I think there is logic in starting with the easiest part first. As you work through the progressively harder parts you gain confidence and proficiency. What you learn on the simpler parts may give you some insight into ways to set up the difficult part.

I think there's a lot in that. Many or most projects are assemblies that require the parts to have the correct relationship with each other. Unanticipated outcomes in making some of the simpler parts might influence how you approach the more complex ones, or even cause you to mark up the drawing with a modified or restricted dimension - or you might consider whether to remake the simpler one if the knock-on effects are too undesirable or difficult to resolve.

In the end, most of our projects probably need to be considered holistically rather than as just a collection of logically separate parts. After all, lots of detail ME drawings aren't toleranced the way production drawings would be, with every dimension bearing limits to ensure fits within an acceptable envelope - we have to use judgement and experience.

As many have already said it all depends. There usually is a 'preferred' place to start on a build with all other things being equal (materials, tools, equipment and skills). Many projects have one componant which is the basis for everything else. With Traction engines this would be the boiler as everything else 'hangs' on it, for a clock it would be the plates.

The hardest part would vary between builders dependent on skill and equipment. I have heard model car builders who started on the tires with the reasoning that if they could not make a very good job of scale tires there would be no point in building the rest. Others may take the view that 'something will turn up', either their skill level will improve or some new technique would appear.

Doing the hardest part first can have a downside as well as an upside. If you fail to make a really good job the whole thing may be scrapped whereas if that item was the last to be made you have all the incentive of not wasting the effort you put in to all the rest of the project so you just set to and make a better version.

My 5 inch King loco was started nearly 30 years ago now with the clear intention of it being a long, long project. My circumstances have changed enormously since I made the frames. Initially all I had was hand tools and a decent pillar drill, closely followed by my first lathe.I also had little space and next to no spare cash or time. Now I am in the position of having a very well equipped good sized workshop, lots more cash and time and the expirience of making many smaller projects so my skill levels are greater than they were. At the time of starteing I thought I would have to build the boiler (for me probably the msot challenging bit) now I can afford to have one made.

So in all I think it is important to have some idea of how all the problems can be overcome or at least the belief that it is possible but that it's not absolutely necessary to do the difficult bit first. However it as absolutely imperitive that a start has to be made somewhere which I would say is the most important thing.

Using the Apollo program as a timely example the Americans didn't know how they were going to get to the moon but they believed they could, that it was worth doing and the made a start with a clear goal in mind.

regards Martin

First job I always read and then re-read the drawings so that I am familiar with how the parts affect each other and where possible check that dimensions on the drawing will mean that parts will fit together. In a previous life I carried out complicated modifications to aircraft structures, it is surprising how many drawings for aircraft parts have wrong dimensions on them, and these are supposed to have been thoroughly checked before being signed off. Any drawing can have an error, better to find it before you cut metal.

Dave W