Old portass dreadnought rebuild help

[Carl DorlingParticipant @carldorling51660]

Dreadnought lathe

[Carl DorlingParticipant @carldorling51660]

Hi all , I have just got a old portass dreadnought lathe in very neglected condition I have started to strip it down but I have got stuck with the headstock removal I can see the front two fixings but Can’t see the others has anyone stripped one down help and advise required.

[Brian WoodParticipant @brianwood45127]

Hello Carl,

I don't know Portass lathes well but I have a feeling they were rather similar to early Myfords. Headstocks on those were bolted about 2/3 rds the way along the casting below the spindle as well as having two bolts below the front spindle bearing

I suspect you will need to remove the spindle to get proper access to the middle bolt

Regards Brian

[Carl DorlingParticipant @carldorling51660]

Good evening Brian thank you I suspected it was the same as the myford but there was so much accumulation of grease and iron fillings ,I failed to see it i have re kindled my interest in restoring lathes .

[Mick DobsonParticipant @mickdobson]

Hello Carl,

I have a Portass Dreadnought and did a rebuild some years ago. Brian is correct, the third fixing is under the left hand end of the spindle pulley assembly. You can get a spanner on it from the back when you need to align the spindle parallel to the bed, but best to remove the spindle if you are doing a full overhaul. You can just see the nut in this image.

Regards, Mick

[Carl DorlingParticipant @carldorling51660]

Hi Mick, thanks my lathe has had a hard life but is very solid it’s missing a tailstock and top slide so a few challenges I will post some pics when I have stripped it down thanks.

[Brian WoodParticipant @brianwood45127]

Hello again Carl,

There were other similarities with Myford lathes, things like change wheels for example will all be 20 DP and to 14.5 degree pressure angle. The bores may not match but that is a relatively easy thing to cope with.

More importantly, you may be able to graft a Myford tailstock on to your Portass and likewise a top slide, both of which you are going to need before you can use the lathe properly

So all may not be lost and those spares are more readily found on sale sites like eBay. Take a good look at the information on Portass lathes on Tony Griffiths excellent website http://www.lathes.co.uk where you will find other interesting information.

Enjoy returning an old warrior to useful life again, it is both challenging and fun to do having recently brought an old Churchill lathe back to useful life in my workshop

Regards Brian

[Mick DobsonParticipant @mickdobson]

Hello Carl,

The change wheels are actually 16DP, not 20DP like a Myford. I have a collection of both as shown below. They don't mesh!

Here are some Portass change wheels

Regarding the tailstock problem and the suggestion of modifying a Myford, are the early Myfords an inverted V form bed like the Portass? I had a couple of ML7s over the years but they had parallel shears. The centre height of the Dreadnought is 4.5/8".

They are altogether a substantially built lathe and in many ways I prefer it to the ML7. Bigger headstock spindle bearings, longer between the bearings, larger spindle bore, larger tailstock spindle diameter and travel. The poor aspects include the short cross slide. I made a longer one and fitted new front and rear tool posts. I also modified the change gear plate to set up with more gears and enable a deeper reduction while auto feeding.

Regards, Mick

[Mick DobsonParticipant @mickdobson]

correction, 3.5/8" centre height.

[Carl DorlingParticipant @carldorling51660]

Good evening Mick, I have a home made tailstock from a myford ml4 it is constructed in three parts so I should be able to make a new base plate it’s not a through bore type but it might do for a while, I have stripped more parts of the headstock in preparation of the spindle removal hopefully it’s not badly worn also do you have any idea what other lathe gears I can use as trying to get portass gears would be nye impossible cheers

[Mick DobsonParticipant @mickdobson]

Hello Carl,

If there are no change wheels with the lathe then anything similar that can be adapted may be the only answer.

As you say the Portass ones could be hard to track down as a complete set. Myford gears are easier to obtain, but at 20DP are smaller. This could be a problem since the mandrel diameter on the Dreadnought is probably bigger than the Myford and has a 30T 16DP gear fitted. I am not sure what a Myford has but it is probably too small to fit the Portass mandrel, unless you were to make a stepped adaptor of some type and a home brew set up to mesh the tumbler reverse. It could get a bit clumsy, having said that most things are possible.

Here is the Portass arrangement, albeit with a modified change gear bracket to take a couple of extra studs.

Plenty of Drummond lathes about and change gears do crop up occasionally. I parted with some a couple of years ago. It is a pity the car boots and auto jumbles are all shut down at the moment.

Regards, Mick

[Carl DorlingParticipant @carldorling51660]

Hi Mick, thanks for the pics I have stripped out the headstock today the spindle is scored a bit but it will polish up ok, also the 30T gear is worn so I might look for possible replacement can I ask did you recut the spindle thread to accept myford chucks or did you use an adapter.

[Mick DobsonParticipant @mickdobson]

Hello Carl,

My lathe originally had the 9TPI thread which is a bit of an oddball when trying to buy proprietary items such as screw on chucks.

I turned the mandrel thread off (gulp, a bit risky!!) and machined up a threaded collar that was good fit on the freshly turned mandrel diameter. The chuck register on the adaptor was left slightly oversize. I welded the collar to the mandrel then turned the register to true size. I can now fit Myford chucks and accessories which are easier to obtain from the usual suppliers.

Regards, Mick

[Carl DorlingParticipant @carldorling51660]

Good evening Mick, I have just been stripping the old girl down the lathe I mean lol, and she's a bit more damaged than I thought nothing that is unfix able but a lot of work as you say they are solidly built was yours in good condition or a basket case like mine.

[Mick DobsonParticipant @mickdobson]

Good evening Carl,

My Dreadnought was in a bit a state when I got it, covered in oily swarf and wood shavings, but it seemed to be complete, apart from a missing countershaft. I stripped it down and sorted what needed fixing, various missing screws and everything mal-adjusted. There was an old 3 jaw chuck bolted to a face plate that had been turned with a register to locate the chuck, also a quite chunky 4 jaw. I could see the potential so thought it would make a good 2nd lathe to my larger Chester Coventry.

Fortunately the mandrel bearings were in good condition and the bed ways generally ok. After I had rebuilt it I actually sold off my ML7 in preference. Then I did the other mods mentioned earlier, including the mandrel 'Myford' thread, the new cross slide and the change wheel plate extension. Thinking next about somehow making the saddle rear guide a bit longer, although I have already added more gib adjustment screws to the standard set up.

I hope you can rescue yours, there aren't too many Dreadnoughts about.

Regards, Mick

[Carl DorlingParticipant @carldorling51660]

Hi Mick , thanks for the information I have been busy today taking all the years crud of the lathe and assessing the task , so for the parts that require work or replacement are the leadscrew nuts headstock bearings and possibly the spindle small back gear bull gear leadscrew rear bracket wear in bed minor plus the headstock was cracked on the front clamp I have drilled and threaded a repair on this so lots to do .

[Carl DorlingParticipant @carldorling51660]

Hi Mick, I have noticed several differences on my lathe compared to any others I can find photos of ,apart from the headstock split main bearings the leadscrew rear carrier is a separate casting not the same as others that are part of the bed casting ,this along with the main items of the lathe being stamped with the number 5 leads me to believe it’s a very early one do you have any idea when portass started making the dreadnought cheers

[Mick DobsonParticipant @mickdobson]

Hello Carl,

I don't know when Portass started making the Dreadnought, although according to the very useful website **LINK** there were several different models all called a Dreadnought, so perhaps yours is one of the less well known versions?

My lathe is stamped at the right hand end of the bed on the top of the shear with 'LP 8454'. Other parts also have '54' marked on. Could be 1954 as the year?

Regards, Mick

[Carl DorlingParticipant @carldorling51660]

Thank Mick, that makes sense

[Carl DorlingParticipant @carldorling51660]

Sorry should be (thanks)

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