Flexispeed Mk 2 Restoration – Final Questions (Hopefully!)

[Andy_HParticipant @andy_h]

The restoration of my recently acquired Flexispeed Mk 2 lathe is progressing well, and now in the reassembly and adjustment stage. I have a few remaining points on which I would appreciate some advice.

I am not very good/knowledgeable with imperial threads so these questions come out of ignorance rather than laziness!

1) The headstock pulley grub screw is missing. But the grub screw in the back gear wheel (or more correctly, the bull wheel) fits the pulley. It measures 0.25" diameter but what thread is it?

2) The gib adjuster screws on the saddle include locking nuts. But the cross slide and top slide only have adjuster screws. I'm thinking it might be a good idea to replace those with longer screws and add locking nuts. What thread size are these? Or is this a bad idea anyway?

3) I have polished the gib strips in the saddle and slides. What's the right thing to do with these – should they be oiled or run dry?

4) Still on the subject of gib adjustment. Obviously these shouldn't be so tight the saddle (or slides) won't move! But just how tight should that adjustment be? I seem to be having trouble adjusting to the point where I believe there is no play without being what I think is tighter than it should be.

Andy

[Andy_HParticipant @andy_h]

[bernard towersParticipant @bernardtowers37738]

to find the TPI lay against a imperial rule and with a mag glass check tooth count over a known distance and if say 1/4' was used multiple by 4 =TPI. if pulleys are cast odds on they will be Whit.

[Neil AParticipant @neila]

This question was asked a few years ago in 2019, search the forum for Flexispeed and you will find it.

I can only answer for my Flexispeed 2 lathe that was bought from the Norfolk Lathe and Tool Co in the mid 1970's, as this lathe has been made by a number of manufacturers there may be variation in the threads that were used.

On my machine the thread in the three step pulley is 1/4 x 20 UNC. The grub screw is a dog point 3/8" long.

On my machine the gib threads for the saddle, cross slide and top slide are all the same, they are:

For the adjusting screws (outer two screws) 6 – 32 UNC (nominal OD 0.138&quot. The grub screw is a cone point 5/8" long. 1/4" AF hex lock nut.

For the locking screw (centre screw) 4 – 40 UNC (nominal OD 0.110&quot. This is a cap head screw 3/8" long under the head.

I have always oiled the gibs on my machine. It can be difficult to get a consistent tightness on the gibs on the Flexispeed, they were not an absolutely precision lathe. The assembly instructions did give advice on easing any tight spots by carefully using a smooth cut file on the gib side of the dovetail. But I would only do that if you are confident you know what you are doing and then only as a last resort. I still have a tight spot on my Flexispeed so obviously I did not attempt it, too long ago to remember now.

I hope that this helps with your machine, there can be variations, particularly on a second hand machine where you do not know its history. Someone might have modified things to suit their own equipment. Just go carefully.

Neil

[James AlfordParticipant @jamesalford67616]

I bought a spare saddle for my Flexispeed. It was clearly from a different era, manufacturer or had been modified as the gib screw threads were different on each.

James.

[Andy_HParticipant @andy_h]

Posted by Neil A on 16/08/2023 17:48:17:

This question was asked a few years ago in 2019, search the forum for Flexispeed and you will find it.

Thanks for the reply Neil. I've found that old thread (excuse the pun!) https://www.model-engineer.co.uk/forums/postings.asp?th=144241

[Andy_HParticipant @andy_h]

A few months ago I posted several threads related to restoring a newly acquired Flexispeed Mk 2 lathe and had lots of useful replies – thanks.

So an update for anyone interested (e.g. James A).

Although delayed by other projects it has progressed quite well. Photo attached.

– Now fully reassembled.

– Equipped with a new brushless DC motor with variable speed control.

– Fitted with a new M14x1 3-jaw chuck by means of an adapter allowing the original spindle to retained unaltered.

– All mounted on a custom made cabinet (albeit with the motor mount being a temporary measure for now).

I’ve used it for a recent clock repair job and find some “fettling” is required.  Cutting performance is poor. I think the main culprit is the drive belt.  Having tried a couple of solutions I’m hoping the one currently on order (8mm Optibelt VB) will be the solution.

The other problem was, what I originally thought was a tailstock misalignment problem. But it’s actually a problem with the MT0 Jacobs chuck (retained from my now departed Flexispeed Mk 1). That causes the drill to be off-centre (below) by at least 0.5mm.  SO the next challenge will be to some how fit a new short MT0 to that chuck.

So, not quite “there” yet but reasonably positive and worth the effort.

Andy

PS I pondered whether it was correct to reply to a previous thread or start a new one – so may have picked the wrong option!

[Neil AParticipant @neila]

I think that you have made a really nice job of restoring the Flexispeed. It looks almost too good to use now. I like the cabinet that you have mounted it on, I hope that you keep it that clean in the future. My machine is positively filthy, I’ll have to see about giving it a clean after seeing yours.

Sharp tools are the order of the day for the Flexispeed, also only machine material of known specification. Free cutting steels, brass CZ121, aluminium HE30, gunmetal and most grades of cast iron, provided there are no chilled areas, work well. I never had a lot luck with phosphor bronze and some grades of stainless steel, also parting off was something that I tried to avoid.

The drive belts on the Flexispeed are a bit of a problem nowadays, the original pulleys were machined to take an old “A” section belt which was 3/8 inch x about 7/32 inch deep, the modern equivalent the “Z” section is 10mm x 6mm, which I have found to be a bit too deep when trying to go to the largest pulley, not really enough clearance between the pulley flange and the headstock casting. I am loathed to take a file to the casting, I have considered machining new pulleys to use a Poly-Vee belt to make speed changes easier, but so far it’s only an idea.

I think you were correct to carry on with the original thread, it keeps all the information together as well as showing the progress of your project.

Neil

[James AlfordParticipant @jamesalford67616]

That looks really good and puts mine to shame. It will interesting to hear how you get on with it.

Like you, mine tends to suffer from a slipping belt between the headstock pulley and the counter-shaft. Mine is caused by the jury-rigged tensioner moving. Once I stop this, with a new nut and bolt, it should be fine.

James.

 

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