By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale

Help

Identify my new small Portass lathe

All Topics | Latest Posts

Search for:  in Thread Title in  
peter blair20/03/2017 16:02:18
10 forum posts
8 photos

number.jpgPortassdrive.jpgGreetings all. I am new to both this site and metal lathes but I do turn a fair amount of wood with a Oneway 16" wood lathe. Last week I purchased a 'vintage' Portass metal lathe at an auction. I have been frustrated by my inability to identify it. I have searched the Portass site and the Internet without success and am hopeful that someone here may be able to help me. It is incomplete but I understand it would be capable of thread cutting if I had all the gears which I don't. I also have nothing for the tail stock, neither a live center or a drill. I would really like more information just in case I decide it is worth while or not. I did cut some brass and mild steel yesterday but I still need to do some tweaking to get the slides working etc.

badge.jpg

Neil Wyatt20/03/2017 16:32:44
avatar
Moderator
9275 forum posts
468 photos
58 articles

Have you looked here?

www.lathes.co.uk/portass/

I has much in common with the 3 1/2" centre height MkV but it appears to be too small and has the headstock and bed cast as one.

<Edit> It seems the 3" Mk5 existed with both bolt on and cast in headstocks.

I think this picture from HERE shows your lathe.

Neil

Edited By Neil Wyatt on 20/03/2017 16:39:46

Edited By Neil Wyatt on 20/03/2017 17:15:24

Speedy Builder520/03/2017 17:16:35
1059 forum posts
75 photos

the drive to the lead screw looks interesting being "belt fed" and a non positive drive. Looks like it could be a modification at some time.
BobH

Neil Wyatt20/03/2017 17:26:18
avatar
Moderator
9275 forum posts
468 photos
58 articles
Posted by Speedy Builder5 on 20/03/2017 17:16:35:

the drive to the lead screw looks interesting being "belt fed" and a non positive drive. Looks like it could be a modification at some time.
BobH

I agree, the lathe looks like it may have a couple of 'user modifications'

Neil

Muzzer20/03/2017 17:28:45
avatar
1896 forum posts
333 photos

I've had a Portass model "S" for many years, although it hasn't had any action for the last 30 or more. However, it's clear that Portass made many different variants of several different models. Yours looks right posh, having a proper apron, half nuts, cross slide and relatively solid bed. Mine lacked them. I wouldn't spend too much time trying to "identify" it beyond what you have already.

It's almost certainly got 1MT tapers in both the headstock and tailstock. The headstock bearings probably have split bronze bushes and if you overtighten the headstock clamp bolts when they become worn, you will fracture the casting (like mine), although they are repairable to some extent.

I made loads of stuff on mine when I was a teenager. It can't take massive cuts obviously but if you can grind tools (or buy inserts) with lots of top rake, you will find it can put up a reasonable show. Screwcutting might be something you do for a bet, although amassing a sensible number of change gears might take a while. You could possibly 3D print some.

Murray

Brian Wood20/03/2017 17:53:09
1103 forum posts
34 photos

Murray,

​The Myford M L 1-4 lathes were also prone to fracture of the bearing housings. The trick is to give them something to clamp down on in the split when you have the bearing adjustment about right. A pile of shims is one solution, I have in the past made a steel slipper with the bolt hole through it to retain it and lapped it down for the final setting

​I would agree with you on the taper sizes, certainly the tailstock.

Regards
Brian

peter blair20/03/2017 22:20:55
10 forum posts
8 photos

Thanks gentlemen. A lot of useful information which is greatly appreciated! For sure the drive system has been modified and is quite interesting. Including a wooden three step fully on the motor.It does have a lot of similarities to the "S" but I haven't yet seen a photo that I could easily say "that's it! Murray if your memory is any good I do have one question that you might be able to help me with. next to the 3 step pulley on the main shaft is a gear. I assume if I had all the parts this would be use to produce threads. There are a number of holes in the right side of the gear and I can easily use at least one to 'lock' the spindle. Also in this gear is where my question comes form. There is a slot headed screw that seems somehow to push the gear away from the 3 step pulley. Can you remember what it was for?

Michael Gilligan20/03/2017 22:59:22
9307 forum posts
399 photos
Posted by Speedy Builder5 on 20/03/2017 17:16:35:

the drive to the lead screw looks interesting being "belt fed" and a non positive drive. ...

.

... to a high reduction ratio worm & worm-wheel:

A nice little modification for fine power-feed yes

MichaelG.

Michael Gilligan20/03/2017 23:05:44
9307 forum posts
399 photos
Posted by peter blair on 20/03/2017 22:20:55:

... next to the 3 step pulley on the main shaft is a gear. I assume if I had all the parts this would be use to produce threads. There are a number of holes in the right side of the gear and I can easily use at least one to 'lock' the spindle. Also in this gear is where my question comes form. There is a slot headed screw that seems somehow to push the gear away from the 3 step pulley. Can you remember what it was for?

.

That's part of the 'Back-Gear' arrangement, for slow speeds ... difficult to comprehend, because the other pair of gears are AWOL.

MichaelG.

.

This page should explain, Peter:

http://www.lathes.co.uk/latheparts/page4.html

 

Edited By Michael Gilligan on 20/03/2017 23:07:14

peter blair20/03/2017 23:20:38
10 forum posts
8 photos

Thanks for the link Michael. I read it a couple of times and will need to re-read at least a couple more. The modification for the fine power feed is indeed very interesting driven by a rubber belt. It seems to work just fine but I haven't tried it while cutting. There is a gear at the back end of this drive system made of some sort of plastic which I assume was intended as a sacrificial gear. A couple of teeth were missing but I added some liquid weld and have refashioned the teeth. I doubt I will ever use it but at least it works now.

Again, I can't thank you enough for your assistance.

Michael Gilligan20/03/2017 23:29:34
9307 forum posts
399 photos

You're very welcome, Peter

... I think this short video will help

**LINK**

https://m.youtube.com/watch?v=34xmgMHjmY0

MichaelG.

peter blair21/03/2017 03:34:51
10 forum posts
8 photos

img_3918.jpgimg_3917.jpgSo this link really made it plain to me. I will just have to mess around with the back gears to get the whole thing clear in my mind. I'm pretty sure the lathe is the 3" MRK5 as Neil suggests. Here are a couple of photos of the small center for my wood lathe that I made yesterday. I did have to do the drilling on my wood lathe . .

Neil Wyatt21/03/2017 08:29:47
avatar
Moderator
9275 forum posts
468 photos
58 articles

Peter, I'm now 100% sure it's the 3" Mk5 as I linked to. For a start it's the only Portass with that 'hourglass' tailstock, there are cast in one headstock/bed versions and all the details of apron, handwheels, spindle/top.cross slide and back gear appear to agree. The only are where things are clearly different is the leadscrew which has a home made fine feed at one end and appears to have an odd handle fitted at the other.

As these appear to be rare beasts, I suggest you contact Tony@lathes.co.uk who will provide you with confirmation.

Neil

peter blair22/03/2017 14:16:12
10 forum posts
8 photos

Niel, I agree I too am sure it is a 3" MK5 with modifications. Thanks for your help!!

All Topics | Latest Posts

Please login to post a reply.

Email News - Join our newsletter

Love Model Engineering? Sign up to our emails for the latest news and special offers!

Latest Forum Posts
Support Our Partners
Ausee.com.au
emcomachinetools
Eccentric Engineering
Meridienne Exhibitions Ltd
Reeves 2000
TRANSWAVE Converters
Advertise With Us
Allendale Electronics
PaulTheCad
ChesterUK
Warco
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

Visit the Model Engineer
Exhibition website

Model Engineer Exhibition