Forgotten engineering techniques

[Larry Coleman 1Participant @larrycoleman1]

I have started this thread to try and document engineering knowledge forgotten over the years by evolution.

Things like how to soften the end of a morse taper drill ( water annealing )

How to drill a one inch hole in sheetmetal with a new drill.

[Larry Coleman 1Participant @larrycoleman1]

What do you know that we don,t

[Neil WyattModerator @neilwyatt]

here's one small tip that can be useful, if you want to heat one end of an item without overheating the other, stick it in a potato!

Neil

[Hamish McNabParticipant @hamishmcnab62554]

I have been puzzling for a few days as to how to soften a morse taper and here it is first in the knowledge base. So how do you soften it and then harden it?

Edited By Hamish McNab on 09/01/2015 22:42:26

[“Bill Hancox”Participant @billhancox]

Download old books from here, just click on one of the four headings and download books to your hearts content. Select at the side PDF, if you want that, or any other type if needed

**LINK**

John

John.

Thank you for these links. Blessings upon you. May moths never infest your woolens. I love reading old publications, particularly the make-do fabrications and repairs using materials at hand. Those chaps had the presence of mind to share their knowledge and experience by having it printed.

Cheers

Bill

[Larry Coleman 1Participant @larrycoleman1]

Well many years ago I had a box of No 3 Morse taper drills.

My hobby lathe was No2 and so was my drill and an old fellow said to me why don't you turn them down. So I heated them up to a nice cherry red and packed them in lime to anneal them but they were still very hard to machine. I contacted him and asked him how to soften them.

He came over and heated up the taper part only to cherry red and left the drill in the vice. he took out his box of matches and rubbed a match down the taper and it went black. To hot yet he said. Then he did it again and again until the match went brown. He quickly dropped the drill into a tin of cold water.

When I placed the drill in the lathe chuck I then machined it with high speed steel very easy it was soft.

He explained to me that that was the temperature the metal crystals change state. Much to my surprise it worked and I have never forgotten the process.

To reharden it you heat it to cherry red and immediately drop it into a bath of cold oil and I use car sump oil. then temper to light blue.

Larry

Edited By Larry Coleman 1 on 10/01/2015 01:26:48

[Larry Coleman 1Participant @larrycoleman1]

Now how to drill a one inch hole in sheet metal with a new drill and get it round.

I worked in a sheet metal shop for years and although we had a room full of presses and punches i was asked to drill a one inch hole in a sheet metal cabinet made from 16 gauge and the hole that existed was half an inch.

so I got the big slow speed hand drill and a one inch drill with the end machined down to fit the chuck. I quickly started to grind the drill cutting edge to a very sharp taper and I removed the forward rake to prevent grabbing. The head toolmaker came out and asked me what the hell are you doing. I explained what I was try to achieve. He took the drill and resharpened it back to the way it was and proceeded to the cabinet. He set the drill up in the chuck and then took a cotton rag from his back pocket then he ripped of a piece about four inches square and folded it twice. He then placed the drill on it and pressed the trigger. I stood back expecting all sorts of bangs & clunks but the drill went through with no chatter and drilled a reasonable round hole.

The rag practice was used quite often even in the lathe when you drilled out internal metal of a die after a pilot drill.

Caution:: If you drill sheet metal on a dill press do not hold it with your hand and make sure you clamp it securely.

Try it it works

Larry

Edited By Larry Coleman 1 on 10/01/2015 01:57:16

Edited By Larry Coleman 1 on 10/01/2015 02:45:53

[“Bill Hancox”Participant @billhancox]

Posted by Larry Coleman 1 on 10/01/2015 01:25:31:

Well many years ago I had a box of No 3 Morse taper drills.

Larry

Thanks for that. A truly wonderful story. I would definitely say the old fellow was a "competent person".

Bill

[Larry Coleman 1Participant @larrycoleman1]

Yes Bill

As much as what I have said sounds strange it works and there must be other techniques out there we don't know.

Try the rag theory it does work ! You do not have to remove the front rake on the drill.

Larry

[Larry Coleman 1Participant @larrycoleman1]

As soon as I can I will describe what spotting screws are, but I will have to take some pictures of them first.

Have you ever tried to drill screw holes to line up with blind threads already drilled in a pattern by measuring and marking them on the new plate you are trying to replace.

Also we should mention what toolmakers buttons are, and I will take pic's of them later and explain there use.

Cylinder squares should also get a mention.

Larry

[Larry Coleman 1Participant @larrycoleman1]

By the way lads I am venturing into casting brass parts and my knowledge of that is about one out of ten. I am building a smelter at home and I am in real Tiger country.

Can anyone tell me how to get the mold sand to set hard. I have been told to mix the sand with Molassas and bake it.

I also have a solid carbon crucable and I am wondering if it will work.

Can you make molds from plaster of paris? for alloy and brass only or will it explode.

Totally lost for knowledge.

Larry

[Danny M2ZParticipant @dannym2z]

G'day all.

When reading my well thumbed copy of 'Model Aero Engine Encylopædia' the section on building an engine mentions using tallow to prevent parts sticking when attempting precise fits (piston to cylinder).

So I hunted down a wild pig with a .444 Marlin lever action to obtain the tallow for a mate who makes smoked sausages and ham from pigs, he rendered me some tallow as part of the deal.

Apart from the smell, it is perfect for the job. In fact, I have never found anything better!

* Danny M *

Edited By Danny M2Z on 10/01/2015 04:03:55

[Larry Coleman 1Participant @larrycoleman1]

Danny

That is interesting. Where does the lard come from and have you tried Goanna oil. Suprisingly it will penetrate glass.

Goanna oil is what is used in bleeding bolts. Where you have a pin in a crane that takes maximum loads they are prone to fine cracks. So they drill a hole in the centre removing the fulcrum point and fill it with Goanna oil and red die then weld the dye in. Now the dye will penatrate fine cracks and on inspection if you see red oil the bolt is cracked.

Larry

[Danny M2ZParticipant @dannym2z]

Posted by Larry Coleman 1 on 10/01/2015 04:56:56:

Danny

That is interesting. Where does the lard come from

Larrry

The lard comes from the pig, Best to make sure it's dead first,. If you have seen 'Dirty Harry' and his .44 magnum the case is 1 inch long. So double it to 2 inches and add a 200 grain hollowpoint Hornady then you have a.,444.

I hunt a bit but noway is the tucker allowed to suffer, I respect what food comes to the table and never dreamed of shooting a goanna. I thought that they were protected. Feral introduced pests like rabbits and foxes and pigs are enough to keep me happy. We have more feral camels than Saudi Arabia btw.

* Danny M *

Edited By Danny M2Z on 10/01/2015 06:56:19

Edited By Danny M2Z on 10/01/2015 06:57:33

[Larry Coleman 1Participant @larrycoleman1]

Yes I think your right they might be protected but you can buy bottles of it at most pharmacies. It is also used for rubbing into joint strains as a liniment.

So for those who don't hunt can you uses bacon fat or fat from pork roast.

What I actually meant was what part of the pig do you get it.

Larry

Edited By Larry Coleman 1 on 10/01/2015 08:12:28

[Ed DuffnerParticipant @edduffner79357]

Here's a quirky web site I found a while back detailing lathe design and specification.

**LINK**

Ed.

[Larry Coleman 1Participant @larrycoleman1]

That is an excelent link and I liked the tree lathe. Thanks Ed !

I remember operating a lathe driven from a line shaft with flat leather belts. It was a WH&S nightmare but it worked well. On the fine cuts you jammed a bit of wood against the spindle to reduce the slop in the bronze bearing.

Larry

[Larry Coleman 1Participant @larrycoleman1]

Now lets get on to cylinder squares.

Now from time to time you will have to check if your square is correct. So you put square on to another square and it shows an error so which one do you believe is right.

The best way is to make a cylinder square if you look at the picture basically its a cylinder but it must have two requirements.

The cylinder must be parallel within tenths.

The dia and the ends must be machined in one setting.

If both parameters are carried out it will stand perfectly square.

Simple and effective.

Larry

[Larry Coleman 1Participant @larrycoleman1]

The cylinder square

[Ian S CParticipant @iansc]

You can also get a tub of Lard in the Super Market, in the local Super Market here, it's along side the butter, and similar spreads.

Ian S C

[Ady1Participant @ady1]

The best resource for "old stuff" is those old circa 1900 books which can be downloaded as a pdf

They have all the old systems which are still relevant to craftsmen and hobbyists, metal spinning and pattern making for example

The big advantages of a pdf file are you can search the entire publication for a few key words in 30 seconds which at our time of life is handy, (we're all on a tight timescale nowadays!) and you can also view a pdf file on any gadget you like

I have also found that if I turn my computer screen on its side I now have a giant A4 page with which I can look at entire pages and review a publication in far less time while sitting back with a coffee in one hand

[Ed DuffnerParticipant @edduffner79357]

Tallow should be available from electrical wholesalers (where Sparky's get their cable and conduit etc) It's used as a cutting grease for threading conduit by hand. Possibly another forgotten or dying technique.

Re: solidifying casting sand. There are a few youtube videos, here's one using CO2 and sodium silicate.

**LINK**

Ed.

[Larry Coleman 1Participant @larrycoleman1]

Thanks Ed

Someone told me to use sugar or molasis then bake it. After the casting just wash the sand with water.

What I am searching for is a method that does not require the purchase of expensive bonding agents.

Larry

[AndyPParticipant @andyp13730]

Larry

Google for recipes for greensand, at its simplest it is just sand, bentonite and water, depending on where you are bentonite can be easy to find (drilling contractors or farmers suppliers are possibilities) or not.

For small castings and especially where more details is required I like Delft clay which is an oil bonded mix that I haven't managed to replicate yet largely because the sand is very fine, more like a silt if I remember my college soil mechanics properly.

It is possible to cast in plaster of paris, a club member did so for a dome for a 5" gauge Heisler in a plant pot on his drive but I admit I always use proper investment powder. If experimenting please remember that molten metal + moisture = PAIN and that can include the moisture remaining in apparently dry and set plaster – a normal investment casting flask will do a 4 hour or more cycle up to 580 deg C before pouring metal.

Lots of good web resources for home foundry.

Andy

[Speedy Builder5Participant @speedybuilder5]

It seems sacrilege, but I have a few old engineering books which I have advertised here and elsewhere some which are over 100 years old with no interest. Such as Reed's Engineers handbook All about marine steam) – available USA for 4$ UK, £8. , Model Power Boats 1940. By the time you add on postage, nobody is interested. Should I just dump them in the bin ??

BobH

[Author]

Posts