Member postings for Mick Dobson

I found the technical report to very interesting, but since when was torque measured in Ft/lbs?

This is a meaningless unit, since torque is defined as force applied at a standard radius and should of course be written as lbft. For ease of visual interpretation it can sometimes include a dot or dash, such as lb.ft or lb-ft. The lb part can even be expanded to lbf denoting pounds force, so then torque is expressed as lbf.ft.

I think our American cousins write it the other way round, as ft.lbs, but not as the version shown in the report.

I reconfigured the starter circuit on my NuTool 12 speed pillar drill by using a foot operated HD micro-switch. This is contained within a robust die cast box and I find this a much safer way to operate the machine without having to fumble for the stop switch in an emergency. Still going strong after about 35 years.

I had a similar problem with the too-fast feed rate on my Chester Coventry 0632A lathe, which is basically (I think) identical to Warco GH1330. My lathe is from 1997 when Chester machines were painted green, the same as Warco. Now of course they are painted grey.

I managed to use gears from the existing set of change gears and arranged a compound gear drive such that the gear ratio was modified by a factor of 2.62 slower than the original set up. I had to make new studs for the gear sets as well as a slight modification to the gear quadrant bracket. The slot in the bracket was lengthened by 7mm in order to just accommodate the gear stud next to the spindle driver gear.

The pictures show the set up, plus a very rough sketch of the layout, which is often how things are made in my workshop! Note that the feed selector lever has to be positioned opposite to as originally marked to drive the saddle or cross slide the correct way.

This may also fit LatheJack's GH1330 lathe

The oil price was just as high in 2008, at over $130 per barrel, similar to the rates now. But I don't recall the pump prices being anywhere near £1.70 per litre back then. A definite whiff of consumer rip off?

**LINK**

Colin,

if you have trouble sourcing the 5-40 fasteners, there is also the 1/8" x 40 TPI ME (Model Engineer) thread, if this could be incorporated in your application. The ME threads use 55 degrees thread angle rather than the 60 degrees in the case of UNC.

It has diameter 0.125". Often used in US designs.

**LINK**

Ian,

Your £5k or perhaps a little more will get you a Royal Enfield Constellation, Big enough for two up riding, not too heavy, a bike with real character. They have a very gutsy engine and it was at one time the biggest displacement parallel twin (692cc) when the competitors were at 650cc. Plenty of spares back up too.

Good luck In your search, Mick

On my Portass lathe with flat belt drive I arranged the motor and countershaft plate to hinge at the bottom. The belt tension is set by use of a car handbrake lever with ratchet and a link rod to the countershaft plate. Easy to de-clutch or change speed on the fly.

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,

The mandrel bearing arrangement is different to my lathe, which has separate bearing caps and two fixing studs each, rather than the split cap with single pinch bolt on your lathe. Is it definitely a Dreadnought? The bed should be cast with the lettering Dreadnought below the headstock area. Unless of course they changed the headstock design at some point?

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

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

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

Hello Carl,

For your question regarding the bull wheel. Yes it is 16DP, same as the change wheels.

Regards, Mick

correction, 3.5/8" centre height.

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

Hello Carl;

The bull wheel has 75 teeth.

Regards, Mick

Hi Carl,

I'll have a look tomorrow after work.

Regards, Mick

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

Mine is the Chester equivalent, badged as a Coventry lathe but basically just the same as a Warco 1330. Bought new in 1997, so now reaching 24 years. It is even painted green from when Chester and Warco had the same colour scheme!

The lathe has been a very good machine all told, accurate and reliable, although some of the headstock gears were rusty even when new. I suspect it sat on a container ship for while before I got it. Chester never responded to my request for a replacement at the time, but apart from being a bit noisy in one particular speed (300rpm) it hasn't affected the performance.

I added a further reduction gear at the feed screw banjo bracket to enable much finer feeds, also fitted DRO to X and Y, and have built up a good stock of QC tool holders. On the wish list is 3 phase motor + VFD.

If you venture to remove the gap bed piece be careful to replace with care. I did this for some traction engine rear wheels (that is why I bought it in the first place) but it went back ok after judicious use of the soft mallet.

Regards, Mick