Repair advice, please!

As shown in the photos below, my D-W has developed a crack in the motor/head tube support. 'The Gods' were with me, in that I had a steel tube of a very close matching inside diameter which I have mangled into approximate shape.

Question is - which is the best/most 'do-able' fixing method. I have 2 stick welders and a Lidl's mig jobby, but have never welded anything! 2 part epoxy used to be touted as suitable to repair diesel crankcases and screw attachment would be limited by the thin underlying structure.

Suggestions gratefully received.

TIA

rgds

Bill

Bill

Plenty of joint area there which helps.

I've done satisfactory repairs to cast iron with ordinary stick welder rods using the old fashioned, field expedient, puddling approach. The basic process is to create a nice wide Vee in the joint area for easy access and lay down multiple, thin layers of weld metal using a thin rod at the lowest practical current. During cool down the weld area should be aggressively peened with the chipping hammer. Once you have a reasonable build of weld metal you can finish off with a more usual, but still small, size rod and current. Still can't do it in one hit, two or three layers on a joint like yours I'd say, and aggressive peening during cooldown remains essential.

My practice is to do the small rod build up bit first then leave for an hour or so to ensure its all properly cooled down.

Theory is that the initial multiple thin layers pretty much isolate the joint proper from any carbon migration and associated brittleness. Aggressive peening stretches the weld surface minimising stresses due to contraction.

All goes much better with a good inverter welder than with a buzz box because you can reliably operate at lower currents. I'd have just Vee'd out the original crack and stuck it together. But I've done it before a time or three and my little Fronius welder is really good.

If you have a choice use the most ductile breed of ordinary rod you can find. Never, ten thousand times never, use "proper" cast iron welding rods. These must be used on preheated castings and the instructions followed exactly. I recall a friend being given a couple of such rods which he used with disastrous results. Stuck together OK but massive lumps everywhere and harder than a woodpeckers beak. An angle grinder would barely touch the stuff. Knowing him he'd got hold of something really exotic for super-strength repairs.

Clive

Many thanks, Clive, for a most comprehensive reply. On a personal level, the major caveat is that I have NEVER welded anything and mid-eighties manual skills and sight aren't the best basis for learning!! If we weren't still in lockdown, it would prbably be worth hiring in a competent welder. The chopped-up tube 'patch' I saw as an alternative but needing reliable high strength attachment methods - hence the 2 part epoxy thought.

Ron Moody's Fagin probably sums it up nicely ..."I think I'll have to think it out again!"

rgds

Bill

The only time I was involved with cast iron welding (steam loco cylinder) the advice was to use nickel rods, pre heat the casting and then after welding cover it up to let it cool slowly. As it turned out the box of rods was so expensive we could probably have sent it to a specialist. However it held for 30+ years until the cylinder was replaced for other reasons

I don't see that lockdown stops you getting a competent welder in...England allows for journeys for work and with only one of you in the hobby shed you're keeping your distance. Any concerns about the welder contaminating your shed could be resolved by staying out of it for a few days after his visit. Of course it would be better to move the D-W outside but a major chore solo.

I know that if I was faced with the same issue here I'd have a word with my local agri engineers and they'd almost certainly sort it (but then I've spent lot of money with them over the years). Agri engineers seem pretty flexible chaps due to the nature of the stuff they have to sort and where they have to sort it..

I have a lot of respect for epoxy and I'd expect it'd probably work with the huge surface area involved under your cover

Another option would be to create a bunch of split-collars-with-bolts out of, say, 15-20mm steel and layer them between the original lugs in addition to the epoxy while it all sets up. You might even get away with large hose-clips if the tube is emptied and the gap wedged to close up the cracks during epoxy-set.

Final though is to create a similar solution as you have but with it's own lugs and bolts that are a sliding fit through the originals. It'd probably take an acetylene torch to do the bends

pgk

Stupid question, what is a D-W?

Adrian

Dore Westbury

I had an old-style Myford countershaft unit that had completely cracked across one arm. I took into college and the welding instructor SIF bronzed it - producing a very strong (but not exactly pretty) repair. As I think I've related before - he did swear a great deal during this process (which was something he did a good deal of anyway) but I gathered it didn't go that smoothly at first and that possibly I wasn't his favourite student either...

From what I recall - it was a two part process - he first heated the part up to red-heat, let it cool somewhat and then reheated and brazed it - all using Oxy/A of course. A highly skilled man.

Regards,

IanT

Edited By IanT on 25/05/2020 13:33:14

The inherent tendency to crack under cooling stresses due to material brittleness, made worse by carbon migration, inevitably makes cast iron repair rather tricky. Especially when taking into account oil absorption, cast iron tends to be slightly porous, on older items of machinery. Not to mention free carbon in really old or really cheap samples.

But for minor repairs there is a tendency to overthink things. The professionals use pre heat and special rods, or sif bronze, to get a good reliable result fast. They have the experience and skills to get it right too.

If you take your time and work carefully the puddling technique works fine providing the job isn't too big and you don't have ambitions for high tensile loads. Personally I avoid anything likely to take significant tension by design. If the one piece part broke then odds are a weld won't do better, maybe not as well. Do remember that back in the day puddling was an officially approved technique. But its dog slow and has some limitations of application. So if you have preheat and slow cool facilities its not viable.

Darned if I can recall what the first job was but the second attempt was a similar fracture to yours on the banjo pinch bolt of a SouthBend Heavy 10 many, many years ago. Worked just fine. Still in one peice when I sold the lathe 10 years later.

Clive

Thank you Duncan,pgk and Ian.

pgk's agri eng route has possibilities being in rural Norfolk. It would be much more feasible if I were a 'Big Cheese 'spad'.

Ian - your experience is what gives me pause for thought!

The 'quality engineering' solutions suggested above would be nice but my lifetime addiction to 'good enough for Government work' standards is urging me down the epoxy (maybe modified with small securing screws) route.

Back to thinking!

rgds

Bill

Interesting post about the challenge of welding cast iron.

All my occasional MMA welding has been done with a vintage oil-filled Oxford welder (20-110 amps, AC only) and I have sometimes wondered whether a modern inverter machine would be a worthwhile improvement. Can you comment on the advantages of the inverter over the old machine?

Your Dore may have had the clamp made too slack for the tube, hence the over tightening.

The thing with cast iron rods is there are several types, all have a percentage of nickel between 90% and 99.5%. The lower % makes them cheaper but the resultant weld goes very hard. Weather preheating would stop that I cant say.

I've found cast iron welding easier (less sticky) than normal rod welding and once you get a good layer of nickel rod on both sides you can get away with a switch to steel rods.

Use 99% plus.

Personally I would carefully consider remaking the clamp in the correct size from steel tube and weld new ears on it.

There is always metal stitching not sure how easy it is to buy the metalock stitches

Could be worth giving them a call.

As a rank amateur stick weilder I have used both the Lidl transformer and the inverter welders

The inverter welder gives off almost no smoke compared to the transformer one and is far more reliable

The transformer one tripped quite a lot, the inverter hasn't missed a beat

They were like night and day for me

Sparking up seems to depend a lot on the rods, I always do a pre-heat sparkup because most of my runs only last a few seconds and I need a first time start

On important welds I've seen short bits of scrap tacked on at the end so you start up on the scrap and run onto the important bit, then cut the bit of scrap off when you've finished

I don't know the answers, but are Dore-Westbury castings still available, and how much would just the broken one cost - It is not that big??

Thank you very much gentlemen - all good advice and food for thought.

Nick C3 - I believe they are out of production (used to be Hemmingway kits)

rgds

Bill

A final thought for you. I have been looking at pictures of D-W and the MkII seems to have a thicker angular casting. It looks that it could be machined out of a solid block of CI. Could be an answer if all else fails.

This site has a picture of it **LINK**

Adrian

Thank you again, Adrian. That link is quite interesting and the D-W head/motor support shown is definitely intended for serious work!! Unfortunately, I have an 'Eliza's bucket' situation!! Even if I had the skills (very doubtful) to manufacture the item, my machine to make it is the one requiring repair!!

I note, however, on a different, current thread, discussion on the merits of Devcon/JB weld etc. which would have considerable personal appeal and which I had seen, initially, as strong (pun intended) contenders. There has been no enthusiasm on the forum, in that direction, so far.

I have emailed Araldite's website for their view on such application and await their reply.

rgds

Bill

I welded this vice, if you look where it says England, going diagonally up to the machined surface, the whole front of the vice snapped off (not me, I pulled it out the skip at work) it was a nightmare, I wouldn't do it again for love nor money.

I think brazing is the way to go.

Edited By Pete. on 26/05/2020 20:38:14