Welded/fabricated engine ‘castings’

[Mick BaileyParticipant @mickbailey28509]

<p style=”text-align: left;”>I started building a vacuum engine many years ago and constructed the main frame from welded steel plate. The welds were full thickness and then ground and radiused. The finished result was better than I hoped for, with just a few surface imperfection that wouldd be filled with JB Weld.</p>
At the time I used MMA but now have a MIG setup that would be an improvement. I suppose TIG would be even better.

It strikes me that this is an inexpensive method to use for a medium size model, but searching for pictures of examples made by others doesn’t turn up anything.

I was thinking of using this to make up the main bed, water jacked etc for a hit-miss engine. Has anyone here used this technique?

[JasonBModerator @jasonb]

I’ve been known to do a bit although my welding (stick) is not particularly good. 1/3rd scale Ruston Hornby. Smaller details like bosses on the feet and bearing housings were silver soldered on to single pieces of steel before welding and dressing. Final machining as a “casting” after all the hot work.

1/5th scale casting for IHC vertical

1/4 Scale welded version

Steam engine A frame and box bed. I had the main parts of the A frame laser cut then bent and welded them

Bed and crankcase welded again some detail soldered on and there is a bit of carbon arc brazing in there too. cylinder and hopper soldered.

[JasonBModerator @jasonb]

Hopefully this will take you to the album with the Ruston photos in it which shows the stages from pieces of plate to completed “casting”

There are a couple of published hit & miss engines that are mostly welded fabrications, the Finney which was in Model Engine Builder Magazine and the J & E which was and may still be about on the net.

J & E Plans

Reg Ignol’s site used to have several of his fabricated engines but the detailed images have not been archived so I won’t post a link

[Mick BaileyParticipant @mickbailey28509]

That’s impressive work and just the thing to rekindle my interest in continuing with this route. I wish now that I’d kept up my BOC oxygen rental for my oxy-propane setup. I think that Sifbronze would be even more straightforward than welding and is easier to create smooth fillets with a minimum of grinding/filing.  It’s the one thing that I really miss. However, as I now have a decent MIG setup I’ll settle for that, though recently I’ve been doing a lot more MMA and it’s a little easier to reach inside awkward spaces.

I did wonder though if there’s any need to stress relieve the fabrication. Perhaps if the major machining and shaping is performed prior to welding any distortion will be corrected upon final machining, assuming no major cuts or reshaping are needed.

Another thought is to cut out the parts with a plasma cutter and templates. My 30A unit works quite well up to 5mm, and with 3mm and below the cut only needs a superficial cleanup. It’s certainly quick and fairly accurate. What I like about a fabricated  construction is that it’s a rapid way to get the main superstructure built at a fairly low cost.

[JasonBModerator @jasonb]

I tend to think of fabrication as making your “pattern” from metal and sticking it together with weld/solder/epoxy rather than wood glue. You then skip the casting part of the process. So are left with a fabricated “casting” that can then have the critical surfaces and features machined.

I’ve not found the need to stress relieve anything I have made as the final machining operations after fabrication are only removing a small amount of material any movement is unlikely to happen. I’ll typically leave 1mm on a surface which is a lot less then you tend to have to remove from a casting which can be 3mm plush draft. But if you had the option to heat the whole welded fabrication then it would do no harm.

It is possible to braze with MIG and also tig with the right wire, maybe not quite the same method as building up a fillet with oxy but I would have thought a few runs of braze would build up a fillet that could then be blended and smoothed a lot easier than welding. Also less chance of geting it too hot and having the pool of braze drop on the floor.

Plasma and a linisher or sanding/grinding disc in an angle or air grinder would soon clean up the parts, weld is a bit more forgiving than silver solder if there is the odd small gap.

 

[JasonBModerator @jasonb]

Couple of old threads on HMEM that inspired me with the welded fabrications.

1/2 scale Advance Rumley

1886 benz

[Dave HalfordParticipant @davehalford22513]

One problem with mig welding is the result is harder than the parts though it does let you recover mistakes with a blob of of weld and a trip to the grinder.

These parts were 30a Plasma cut from 3mm steel

Assembled as a geared drum below. The small inner ring was welded in 4 places to the rear geared outer disc

The thin large ring was bolted and glued before gear cutting to give 5mm gear width

No distortion occurred.

If you follow good mig welding practise it will be fine. If you start at one end and just weld to the other things will move due to the shrinkage.

In full size (six foot dia) Burrell cast these, how they kept them flat I have no idea.

[Nick Clarke 3Participant @nickclarke3]

Not quite the same model but in volume 139 of ME the Late Don Young did a short series on fabricated locomotive cylinders.

[DiogenesParticipant @diogenes]

I believe Find Hansen fabricates all his models, i.e. I don’t think he uses any castings at all..

https://www.youtube.com/@boksermotor/videos?view=0&sort=dd&shelf_id=1

[noel shelleyParticipant @noelshelley55608]

Unless your MIG has ample power you may have welds that will look fine but have no strength, MMA if it looks bad it will be ! Minimum 180A and not a cheap one for this sort of work. BOC accounts the rental is by the month so may not be too bad, and if your used to brazing and still have the gear it might be worth going back to it. If you have oxygen then with a clean propane nozzle you can cut thick plate with ease, 1/2″ and 3/4″ are no trouble.  Noel.

[JasonBModerator @jasonb]

As I said my stick welding is not good but how strong does it need to be.?

My engines run without falling apart but I would not want to weld up anything on my cars.140A Machine Mart inverter jobbie.

[noel shelleyParticipant @noelshelley55608]

Both BOC with the Autolynx and Migatronic both saw fit to give 180A for either 0.6mm or 0.8mm wire for the repair of vehicle bodies, MOT welding. 3mm is fine and IF you know what your doing even 6mm but it requires more skill than some would realise.  For the OP I would say stay with MMA, You will need Argon for MIG or TIG. Gasless MIG I would not even consider. My £60 inverter for MMA is unbelievably good, almost as good as the £550 one, but the 375A MIG machine is best and only cost £25, the gas costs me more !

Jason, Your welds look passable and as you say they hold, that’s  all that matters. MIG can be very dangerous in unskilled hands, trust me, I know ! As for stresses, if the “casting” is not to big put it in a bonfire or living room grate and then leave buried in the ashes till cold. Noel.

[Grizzly bearParticipant @grizzlybear]

Jason,

Your fabrication is a work of art.

I’ve always admired them.

You are thinking outside of the box, or in your case, the casting.

Bear…..

[Mick BaileyParticipant @mickbailey28509]

My MMA machine is a 180A Peerless unit I bought new in Australia. It performs well with 2.5mm rutile electrodes. For MIG I use argon mix with a modified SIP migmate. The cylinder is rental-free but the gas still works out to be quite expensive. A plasma cutter repaced the oxy-propane setup which was mainly used for cutting sheet or thin plate.

[Perko7Participant @perko7]

Just following up on a comment from Nick Clarke 3, does anyone have more details on the fabricated cylinders described by Don Young. I’ve looked up Volume 139 in the ME index but can’t work out which issues contain the cylinder fabrication details. Any other information on where I could find descriptions for fabricated cylinders would also be very helpful. For context, I am building a 5inch gauge Queensland loco with outside cylinders and inside steam chests, cylinders are 32mm bore and 56mm stroke. Planning to build cylinder assemblies from steel and will be a combination of silver-soldered and bolted construction. Thanks in advance.

[JasonBModerator @jasonb]

Can’t help with that one Perko

But having placed an order with M-machine yesterday which included the material for a fabricated cylinder destined for  a future project the cost savings that can be made are quite considerable so worth doing the sums before you order that next casting.

The engine will be 30mm bore x 56mm stroke and has quite a large diameter and thick back cover so 50mm cast iron bar would be needed. Sufficient bar to make the cylinder, 2 end covers, Valve Chest, Chest Cover, port face etc cost £16

Compare that with the smaller but common 1″ x 2″ Stuart cylinder and associated parts bought as spares which would cost £103.

Fabrication is a no brainer in this case. A Bronze & Brass soldered cylinder as above still comes in at around half the Stuart price if I went down that route instead of using iron. Other parts can still be a good saving for example a fabricated 180-20mm dia flywheel will work out about half that of a 7″ Stuart casting

 

[JasonBModerator @jasonb]

Maybe this will help with which issues you need to be looking for

[Clive FosterParticipant @clivefoster55965]

From the perspective of a modern neophyte the ready availability of self adjusting “synergic” inverter welders at “affordable if I save up a bit longer” prices has made getting started with MIG welding vastly easier. Leaving it up to the machine ensures that the current settings and wire feed rates are reasonable for the job in hand so you can just concentrate on moving the torch correctly. So only one thing to work on when the weld is less than ideal.

So different to the bad old days when affordable welder meant something like SIP or Clarke from Machine Mart et al with a confusing array of switches to set power and an all too frequently dubious wire feed drive. I rapidly gave up and sold my SIP MIG after a few bad experiences where inadequate wire feed interacting with overly cheap power control design made it all too difficult. Trying to remember whether it was left hand switch up and right hand down or both down for the current setting being just the final snowball down the back of my neck of an all round bad experience.

Never did, and still don’t, get the MIG is easier than MMA thing. Once I’d twigged that MMA isn’t a drill substitute I soon learned to do decent jobs on most things. Even on thin materials.

Lucking into one of the then fairly new Fronius compact inverter welders at a fraction of its (entirely justified) eye-wateringly high new price was just the icing on the cake. In those days its performance and control, especially on thin materials, was a revelation. Fully the equal of the big oil cooled  boxes from Oxford et al that (probably) produced their own local gravitational field distortion as well as doing a real good job of holding down the floor. But in a box small and light enough to sling over your shoulder and carry up a ladder!

Twenty years on a decent commodity import equivalent is pretty close in performance. Obviously avoiding the bottom of the range uber cheap ones. I’m told the Parkside ones occasionally seen in LiDL are decent but next step up from a proper welder supplier is noticeably better and not far short of the old Fronius.

The modern automatic welding helmets are amazingly good too. So much easier than old style fixed lenses. Mine is an older, high end, Speedglas that was then head and shoulders above the DIY level ones that were trickling onto the market. £300 to properly care for my eyes was a bargain in my view. These days the commodity, mid range, ones are pretty much as good at less than 1/3rd the price.

I guess we’ve all seen the YouTube videos of wonderfully neat welds produced by running a laser welding head down the joint and wondered fake or £££££. UK  supplier price tags from around £10,000 up for 2 kW devices are reassuringly £££ for something that should work. But when AliExpress starts at maybe £500 for same style, different colour, boxes you have to wonder.

A fibre laser is actually an inherently inexpensive device if you have a factory set up for quantity production.

Having done a fair bit of work with lasers in the past and being involved in figuring out how to do things safely in experimental set-ups I find the idea of letting these things out into the hands of any Tom, Dick or Harriet with a few £ to spare somewhat worrying. High power laser beams bouncing all over the shop isn’t a good thing. Most especially not when you see the de-rusting YouTubes showing a narrow beam scanning across an object clearly a yard or more from the projector. Short focus, quickly diverging beam would seem safer for welding as the power density rapidly falls off with distance. I’ll bet the manuals say nothing about the importance of a good safety screening set-up. If AliExpress is to be believed the screening needed for safe open air work will cost more than the welder.

Clive

[Perko7Participant @perko7]

Thanks JasonB, that’s exactly what I wanted. Cheers.

[noel shelleyParticipant @noelshelley55608]

I take my hat off to anyone who can weld properly with a cheap SIP or Clarke MIG machine. Inverters have put reasonable MMA machines in the hands of the 13A brigade and given them a sporting chance of avoiding voltage drop or the RCD dropping when the transformer is plugged in. Trying to get the heat when it’s just not there is to ask for trouble , one sees it here where the weld does not flow, or penetrate well. If one wants to ” fabricate ” castings then power is what you need, to give a nice fillet and avoid poor penetration that may lead to leaks Etc.  The auto dim helmet I found good for TIG but for MMA the lightness of old flip down was better. As for those who may spend £100s or even £1000s on gear but will not buy the gas for a process because of the bottle rent (£130 for a BIG gas bottle for 12 months, or pro rata )- there’s no hope. Give up and take up knitting ?

Jason, thanks for the reference to the Don Young articles, I will take a look later.

Ah well. Noel.

[Mick BaileyParticipant @mickbailey28509]

The SIP Migmates can be made into a decent welder by changing the wire feed supply, the biggest failing being the motor feed being taken directly from the torch, so there’s an interaction caused by the varying voltage drop. I installed a decent sized transformer and 25A bridge rectifier to give a separate motor feed. Also the wire feed control PCB can be modified to give a more useful operating range.

The feed rollers need a support to give a better grip on the wire. I also installed a Eurotorch socket and separate gas solenoid.

Overall I’m really happy with the weld quality and depth of penetration and the machine is simple and easily repaired. The only thing these days is the weight.

 

 

 

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