Making a bolt

May 24, 2011 48 Replies

Your new ones won't last - they're made of steel, not wrought iron.

Now if only you'd forged some iron ones up... 8-)

you could've bought some from Screwfix and mailed them over for £10. Nonetheless I admire your craftsmanship - far beyond anything I'm capable of.

The bolts are going to be painted properly, and mostly kept indoors and certainly away from the rain. Instead of being abandoned in a farmer's paddock for 20 years.

The square head has to fit into original timber holes on an artifact that is unique in the world. I try to refurbish the original parts if possible but the old bolts are too rusty.

I was thinking of welding too. Save all that lathe work.

It would certainly be easier to weld a nut on the end of some threaded rod. I haven't done welding for forty years, and in this case the final bolts might not be strong enough for the job, which is a nightmare of complicated Victorian design.

...or convert it to full CNC or add an E-Leadscrew and cut just about any thread pitch you require without buggering about with gearing or dies.

I suppose you are both joking. It's hard to tell sometimes. Here's an old bolt I fixed up for another job:

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authenticity being the important factor. There are some of us sat in the background that know what you are trying to aim for and admire your skills at coming up with the finished product, with a limited workshop containing machines that are almost as old as the equipment you are trying to re-furbish.

Keep up the good work.

Dave

Care to tell us what this nightmare of complicated design is? A lot of us would be very interested.

Dave

This typical design appears to be a horse-drawn vehicle converted to electric power.

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roof has lots of tiny windows so it's not strong. When that humungous pole with springs is added to the roof, it gets very complicated. It has long pieces of wood held on by 18 bolts.

I don't know a CL7, but the ML7 is a tiny little thing, where the only thing big about it is the pricetag. Crazy things, but that's model engineers for you. You can get a S/H Colchester for the price of a S/H ML7, and a lot more tooling included.

That's usual. You don't need many pitches, especially not for imperial work. It's generally impractical to cut metric pitches on an imperial leadscrew because either the 127 conversion gear uses up all the space on the banjo, or else the Norton gearbox won't have useful ratios in it - you need to cut 1.0mm or 1.5mm, but not 1.33mm.

It might form the best threads, but it's far from being the best way to form them. Even with good tooling, rolling threads is a PITA and no- one does it up to a shoulder.

The only time I roll threads is in thin rod, for strength. It's also nice to make a thread that's larger than the rod diameter. I have a bike spoke rolling machine and it comes in handy for a few high tension, thin wire jobs.

There's no way that single-point cutting can be said to be "easier", even if you have a capstan or an automatic. Especially not if the thread is too big to cut in one pass and you have to pick up the thread for a second cut.

bolt you showed looked to me as if it could be straightened and cleaned up to be made quite serviceable. I don't know what sort of final effect you're after, though.

BTW are you familiar with the stationary steam engine that David Harre and friends restored, at the Oratia Museum? That's a beautiful thing.

The CL7 is the ML7 with a long bed and a capstan.

I wouldn't have wanted to try to carry a Colcheter up the stairs to our first workshop and I doubt it would have stayed there if I did - the floor bounced.

...

I can't say I ever found it a chore.

Colin Bignell

While there's not a huge force on the bolts, the old rusty ones are not really good enough where safety is an issue. For brake bolts etc we would buy new high tensile bolts.

Yes, here it is being used to cook potatoes with steam:

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old duffer giving free advice, before he quotes (estimates) an exorbitant fee .. ;)

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