on using studs instead of bolts

[johan]

I'm here with another stupid question. If this project goes on longer there will be enough of these to start an other part of the forum...

So I'm drawing myself into a knot on this engine casing and the original is put together with lots of studs. To hold the side covers with the bearings of the crank axle, to hold the inspection covers, to hold the stuffing glands, etc. A quick count get me at 142 pieces in assorted size of M3 and M2.5.

Now I have to fix these in parts that will be 3mm thick, some in 5mm thick. Now I have no idea on how to fix these so I can tighten the nuts when I put everything together. I will have to drill through the parts and then thread them, in 3mm thick material there just isn't enough meat to the part to thread a blind hole with M3 thread (even not for M2.5).

- I cannot screw them in to the bottom of the hole as there will be no bottom.
- there is no space to put a kind of ring onto them that will butt against the main part it is screwed in. And that will not secure it when I undo the nut that is on it.
- using loctite? This is for the engine block of a steam engine, loctite isn't very good at higher temperatures. And if I have to use a version that will withstand unscrewing the nut, will it be possible to replace a stud without a lot of trouble? (like heating everything up above the temperature for the loctite, removing all of them etc etc)
- solder is another option but then again, how to replace one?
- I thought about putting in a bolt from the "other side" but that is not very secure when you screw the nut on. Unless of course you fix the bolt with loctite or solder but then I end up in the same problem when replacing a stud. This is also not possible in every place.
- likewise doing something like drilling a hole in one side and when that is in the threaded hole, giving it a whack to "rivet" the stud in place. Again a possibility but against the idea of using studs.

[jasonb]

If you make proper studs by threading both ends of round bar you can control how far into a hole they will go by how long you make the thread. Screw them in until they go tight. It takes a bit of time to get the hang of it so they all end up with a similar amount of stud sticking up above the nut.

[johan]

Ok, I understand. When the piece you put on using studs is thick enough I can see this. Like the covers holding the bearings of the crank axle. But I'm not so sure when the cover plate of an inspection hole is just 1mm thick. You need to end up with something like 0.75mm without thread! That is watchmaking for me.

Love your cylinder block, really looks the part. What size are the studs in that photo?

[jasonb]

5BA so close to M3

Regarding tapping shallow blind holes. Grind off the point of your taps, many have a point that is used when they are ground but it doe snothing except stop the tap going right to the bottom of a hole.

I have also gone over to Spiral flute taps which will cut a full thread most of the way down a hole and you only need the one tap. Easy to get hold of in metric sizes.

For thin items I tend to thread the whole of the length and then loctite a nut onto the end (648 which is high temp) and then use that like a bolt. These are only fitted at the final stage after painting as I use cap head screws for ease of use during building as they are easier with a ball ended hex driver than mucking about with spanners.

[johan]

This gave me a very cold shower and put a good stop on the "detail creep". I know myself well enough that I won't be making 146+ studs in that size. So this means going back to the drawing board and find a more simple engine. Or just use bolts. Maybe a couple of studs where it is visible and where I'll need to remove a part more frequently.

It also reminded me I'll have to drill and tap 146+ holes.

[JonL]

Everything is just one little job at a time. You can do this as long as you do what I forced myself to do: understand that you won't be making components every minute like a production line.

[jackrae]

If you want to simulate studs with nuts you could use hex headed bolts and maching a little off the top face of the head leaving a little bit to simulate the end of the stud. A pain to do 146 times but as others have indicated "it ain't a race" You could make a special tool (in effect a hollowed out counterbore) to do the complete job with one movement of the tailstock

[johan]

Thanks for all the ideas and advise. Just 2 things:

1: I know myself and I do know that if it will take 5 years it will never get done. My electric loc is after 10 years still waiting of having a number painted on. (It works so why bother?) That is just me.

2: Everything considered you won't see a thing of this engine! Even if I open the inspection hatch to it you will not see more then the top and half of that is covered in insulation. On the other hand... knowing it "isn't right under it" is going to bugger me. So I have to balance that off point 1.

I should just get on with it and continue drawing the plans. At the moment I'm finding things that can be more of a blocking issue than using studs or bolts. Like if that boiler will give enough steam or if that engine will even be able to pull myself down the track...

[chris vine]

One thought to add for you:

If you quietly and not too slowly get on with your build, you will get better and quicker at making things "just right". Don't go back and over complicate the build or remake things you are not 100% happy with.
Then go on and do another build using your new level of skill etc.

If you keep going back, nothing gets finished!!

All best
Chris

[mbrown]

Isn't the psychology of our hobby fascinating! It teaches us an awful lot about ourselves which must be why model engineers are generally such well balanced and decent folk.

Malcolm

[johan]

Ok, this was very helpful. I need to take some time off and reconsider the project. It is too easy to draw in 3D things that are (for me) impossible to make. So I have to take a couple of steps back, see what is achievable (both in work and expenses) and go that direction.

It means work has to be redone but at least it is just virtual work. The time spend is real. But probably small compared to the time that would have been spend if I had gone the path I was on.

Jul 3, 2024 21:22:52 GMT mbrown said:

Isn't the psychology of our hobby fascinating! It teaches us an awful lot about ourselves which must be why model engineers are generally such well balanced and decent folk.

Malcolm

I'm not so sure about the "well balanced" part, after 2 sessions my psychologist might disagree with you.