Help identifying Portass Sheffield Dreadnought Lathe

[Michael Richards 2Participant @michaelrichards2]

Hello all,

My late step-farther was an engineer who also had hobbies building kit cars and home renovation. I have inherited his garage full of tools and machines but I am having difficulty identifying some. He has a Portass Sheffield Dreadnought leathe I am unable to find information about anywhere so I am hoping someone might be able to I.D. the model or point me in the right direction.

The lathe is roughly 41iches/105cm wide by 17inches/44cm tall, believed it was bought in the UK where it currently is, only other markings are: "55" on the gear", "6 taper Made in U.S.A." on a part that looks like it holds the drill bit and "M3" on the larger metal holding tool across from it (sorry I dont know the part name). I have attached some pictures of the lathe and can attach more if needed.

thank you.

[Michael Richards 2Participant @michaelrichards2]

[not done it yetParticipant @notdoneityet]

I am unable to find information about anywhere

Lathesdotcodotuk seems to have more than enough information to enable you to get very close to the information you are asking for.

 

Edited By not done it yet on 06/09/2020 07:53:52

[Michael GilliganParticipant @michaelgilligan61133]

Posted by not done it yet on 06/09/2020 07:52:51:

[…]

Lathesdotcodotuk seems to have more than enough information …

.

Greetings, Michael

You may indeed suffer ‘information-overload’ if you are not familiar with the equipment, or that site:

This would be a good page to start your investigation: **LINK**

http://www.lathes.co.uk/portass/index.html

MichaelG.

[Clive FosterParticipant @clivefoster55965]

Michael

That is almost certainly a bench mount "Green List" Dreadnaught 3 5/8" x 20".

Fourth picture down on this page :- **LINK**

Probably the definitive version and most common. Generally considered to be a tough, durable and, by the standards of the day, accurate machine. Albeit a little on the crude side being of old fashioned design with few refinements. Mr Portass preferred to get the basics right and keep the price affordable.

Looks smart and pretty standard except for the flat belt pulleys being converted to Vee belts. Its worrisome to see that it appears to have short Vee belt drive direct from the motor without an intermediate speed reducing countershaft. Unless the motor is a low speed version or one with its own speed reducing gearbox built on the machine may well have been run too fast for its bearings leading to serious wear.

Clive

 

Edited By Clive Foster on 06/09/2020 09:54:46

[Michael Richards 2Participant @michaelrichards2]

Thank you everyone! Yeah I have been going through information overload with all the machines I'm not used to but have enjoyed learning about them.

The links have helped a lot and now that I know which model I have I can do more research.

I will have to investigate this Vee belt situation do thank you for pointing this out to me.

[Clive FosterParticipant @clivefoster55965]

Michael

So far as speeds are concerned the Dreadnaught was originally developed as a treadle driven machine for use with carbon steel tools so high speeds in the modern manner were neither practical nor useful. Even with the massive flywheel and considerable step up drive ratio of the standard Portass treadle assembly there are serious limits as to how fast a normal mortal can treadle for long periods. Carbon steel tools are easily overheated if driven too fast.

Generally a top speed in the region of 500 to 700 rpm has been found satisfactory when arranging electric motor drive for older machines with that style of headstock bearing. Although apparently modest 700 rpm is "book" speed for steel of around 1/2" diameter and light alloy of around 1" diameter using HSS tooling so ajob needs to be quite small before any benefit could be gained from higher speeds.

Most folk find it more important to arrange a decently low bottom speed for screw cutting, 30 – 40 rpm perhaps, and let the top speed fall where it will.

Clive

[Mick DobsonParticipant @mickdobson]

Hello Michael,

I have a Portass Dreadnought which is my second lathe used for odd jobs and one-offs. Having said that it is a very well built and solid machine from the era and in fact I prefer some aspects of it compared to the Myford ML7 I had for about 15 years.

The Portass has a bigger, longer headstock spindle with larger plain bearings compared to the Myford. The tailstock barrel is similarly larger than the Myford with a longer travel. The cross slide is a bit on the short side so I made a new one and fitted sturdy front and rear toolposts.The original top slide can be fitted when required. I also modified the headstock spindle to accept Myford type threaded chucks, faceplates, collet chucks etc. Parts are more easily obtained compared to the Portass thread.

The pulleys are flat belt, using a water pump belt from a Cummins diesel engine. The countershaft pivots on a plate that is tensioned by using a car handbrake lever and ratchet, so that speed changing can be done on the fly.(safety first!). I also extended the change gear plate and added more studs to enable a deeper reduction to the leadscrew when in auto feed cutting.

A good sturdy machine, I hope you enjoy fixing it up.

Mick

[philip bissellParticipant @philipbissell99747]

hi i also have a dreadnought lathe i think a model 5

am looking for a three jaw chuck any body know what thread it is. its about 1" EITHER BSF OR WHIT

regards

phil

[Brian WoodParticipant @brianwood45127]

Hello Philip,

The lathes.co website lists a Model 5 spindle nose thread of 9 tpi x 1.122 inches with a bore of 3/8 inches. It will most certainly be an imperial thread.

It might pay you to visit Tony Griffiith's superb archive, he has a lot of information on Portass lathes for you to look at.

http://www.lathes.co.uk

Regards Brian

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