Stuart D10 very early model.... nuts and bolts

Hi guys, I've just bought a D10 which was in a really bad state, I must admit I didn't realise just how old this engine was till I got it cleaned up and was deciding what nuts and bolts I needed. I got stuck straight off as nothing I had was close and none of my taps/dies/parts fitted anything on it. I know that Stuart used Whitworth threads in the early days so I emailed Stuart Turner to see if they could help, the reply I got said they dont have data going back that far but that it must be 1930's or earlier.

The drain cock holes were plugged with steel bolts which look to be 3/16" but their 38TPI which does'nt match with anything I can find, same size for the plugs in the cylinder head centers which I'm guessing once had oilers fitted.

The cylinder head bolts I'm fairly sure are 3/32" x 48TPI which would make them BSW but I might be wrong !

So I'm wondering if anyone here has info that might help ?

I have ME,BA and Metric taps dies and fittings but none of them are even close.

I added a couple of before and after pics....please dont ask which ones are which

Hi John,

I wonder if Poly Models (Bruce Engineering} could tell you.

Tel: 0115 9736700.

Ron

[This posting has been removed]

Thanks Ron, I rang Poly Models who were very helpful but it looks like I have a problem with this, I think the person who built it up might have used taps and dies that he had to hand, maybe something old and obscure....like me haha

I'll drop Kieth an email to see if he has any thoughts but I might be looking at a re-tapping job (if its feasible).

I'm also thinking it might be worth a trip up the coast to a nut and bolt supplier, it's a very old established company so he might be able to help, I'll update this later, thanks guys.

Possibly 40tpi 'model engineer' threads not 38 tpi.

Neil

Similar problem back along. Cleaned out holes as best I could. Filled with JB weld and retapped BA .

Went to the nut and bolt supplier but no luck or help

I found that the long bolt in the flywheel was the same thread as the drain cocks and gave a bit more to measure, the thread is definately under 40TPI .....I held it to a 40TPI ME tap and it looks very close to 38TPI .....cant find a mention anywhere of a 3/16 38TPI thread though.

Got a reply from Kieth Appleton who also thinks the builder has used the "wrong" taps, it would have been nice to find out what they were but I guess I'll never know......got to put that aside and move on now.

Thanks for the idea of using JB weld and re-tapping, I have some very strong cleaner, tetrasomethingorother, it got banned years ago, like most things that actually worked, so I might give it a try.

The only reference I can find for 3/16" x 38TPI is in my old 11th Edition Machinery's Handbook for "American Standard Thread Forms". 3/32" x 48TPI also appears in that table.

Whether anyone currently produces threading equipment for this size I have no idea. I'm sorry this information is not very helpful.

Perhaps the original builder had taps and dies for this size from where they worked.

It looks as if your easiest option is to plug and tap in a size that you have, although it is disappointing not to be able to replicate the original builders parts.

I don't know if you are game for making carbon steel taps and dies, perhaps someone can give you some tips on how to go about it.

It is nice to be able to bring an old model back to life, very satisfying. It looks good.

Neil

Edited By Neil A on 09/08/2018 15:03:45

Thank you Neil, I've restored a few engines now and made a few from scratch, it is VERY satisfying.

I've decided for the larger tappings to gently drill out by hand and tap with ME, I might have to make up some brass sleeves/inserts but its do-able.

I need to have a think about drain cocks, I want to keep them close to the cylinders, or I might make up a pipe system with only one drain cock at the bottom. The cylinder heads might get some brass caps after re-tapping or I can MIG them in and skim them, I've never had a problem using my mig on cast.

I moan a lot and have been known to use the odd "bad word" but I love every second I spent in my workshop.

If your cleaner is Carbon Tetrachloride, it was common in the 1960s (and before) as a general degreaser. The problems with it - from memory - are that it is not good for the ozone layer, and it becomes very dangerous in the presence of hot coals, charcoal, cigarettes etc. Cigarettes are particularly bad as you will be breathing in the fumes directly - which by then will include one of the WW1 trench poison gasses (called phosgene). I expect Wiki will be able to expand on this.

Cheers, Tim

Hello John.

Stuart Turner used a 3/16" X 36 TPI thread, usually for small pipe connections pre WW 2. They had a number of standard threads of various sizes, and sold the taps and dies for these threads. They were in their catalogues. My son has these catalogues at the moment, but when he comes in I will get one and put the list in a post.

Tracy Tools stock these taps and dies, Whitworth form.

Regards. Mike Potts.

Yes Tim ! Tetrachloride, very nasty stuff, we were using it in the 70's but it was banned soon after, I have a very small quantity that came from an electrical rewinding company, it's branded under the name Semso and I think I got it in the early 80's, 30 odd years old and still removes everything including the soles from your boots !

Hi Michael, that would be very interesting to see, I read once that Stuart used Whitworth threads on very early engines which would make sense. I'll wait to see if you find the info, I would rather use original parts as much as possible though sometimes we all have to improvise.

Edited By John Horne 2 on 09/08/2018 18:28:39

If the thread was 36 TPI rather than 38 TPI it would make more sense. It can be difficult sometimes checking the thread form on small diameter fine threads. It can be quite awkward to get a thread pitch gauge into the right position.

The taps Tracey Tools have are not very expensive in carbon steel, I would certainly get a plug tap just to try if I were in your position, you might be surprised.

Neil

I finally decided there wasnt enough left around the threads for the drain cocks to do anything drastic so I drilled out the holes just enough to run in a 3/16 x 40 tap and it worked out fine, did the same to the heads and all looks good, I've had fittings into them and I'm happy to continue. Need to make some brass thumb screws for the head to blank the holes and order up some 3/16 x 40 drain cocks. The other thing that made up my mind was that I needed to fit shop bought drains so it had to be a thread suitable.

wow just seen the price of those drain cocks !