Boxford CUD change gears, feed speeds and levelling.

[Ian Rees 1Participant @ianrees1]

[Ian Rees 1Participant @ianrees1]

I've got myself a Boxford CUD, serial number suggests that it dates from around 1959. I'm not sure if it's had a hard life or if it just hasn't been looked after terribly well. The more I look at it, the more I want to totally strip it down and do a full restoration! Anyway, that's another topic. I've got a lot of questions to ask so I'll start with the ones in the title.

After much searching, and exercising parts of my brain that haven't seen action in a long time, I believe I've answered my first question myself. I wanted to know about finishing feed speeds using the leadscrew on the CUD. The plate on the machine says the finest thread setting is 160tpi. The spec sheet I found on the internet says the CUD is available with 10 feeds (as well as all the screw pitches) from .0063" – .0156". I've assumed that the measurements are distance per spindle revolution and my limited maths says that 160tpi is very close to .0063" per rev. Am I right?

Can the feeds be slowed down any more than this or is this ok for a finishing feed?

Next up, the change gears. This lathe was in a bit of a state when I got it, luckily what looked like a little rust on the bed turned out to be dried on grease and oil so that cleaned up ok. Unfortunately the tooling that came with it was in need of thorough stripping, rust removal and oiling. I cleaned up all the change gears yesterday and logged down all the different ones I got with the machine. I was wondering if anyone can tell me if this is a full set or not. Here goes..

First all the ones with the smaller, keyed bore.

16t (x2), 24t (x2), 32t (x2), 36t (x2), 40t, 44t, 48t (x2), 52t, 54t (x2), 56t (x2), 60t, 80t

The ones with the larger, non keyed bore are.

80t, 54/18t and 72/18t.

Finally, the levelling issue. I tried a little simple turning on a 1" piece of bright mild bar, it's not a proper test I know but I was taking small cuts along the length and then decided to measure it. The end nearest the chuck is coming out smaller by 0.11mm over a distance of around 4". This doesn't sound acceptable to me. My spirit levels are too basic for this sort of job and I'm struggling with what to use as wedges, I don't like the idea of wood as the humidity can be a bit changeable in the workshop.

It's sitting on concrete but the workmanship involved in the floor leaves a lot to be desired. If anyone has any hints or tips on levelling a lathe, I would love to hear them

I'd better stop rambling there, thanks for reading

[Thor 🇳🇴Participant @thor]

Hi Ian,

Congratulations with your "new" Boxford. Levelling a lathe has been discussed here before, and on Harold Hall's website you will find a good guide on lathe setup. Even if you don't have a machinists level you should be able to get your lathe to turn more parallel than now after reading Harold's guide. I first used a fairly course level when setting up my lathes, then I used Harold's method ( and got better results than you reported).

Thor

[Anonymous]

Correct, the pitch of a 160tpi thread is 0.00625".

That's possibly a little coarse for fine feed. As standard I use 4 thou per rev for finishing, but I suspect I am at the upper end of what most modellers use?

Andrew

[BazyleParticipant @bazyle]

You seem to have loads of gears, probably more than normal. I don't know if there is a definitive list of what the standard list is but if you look at the screwcutting charts on the Yahoo group for Boxfords you can see what ones are used.

If you think about it 160 tpi with the leadscrew pitch of 8tpi means you are getting 160/8 revs of the chuck per single turn of the leadscrew. ie the gears are giving you a 20:1 reduction. So you just need to look at the gears you have and make a train that provides say an extra 2 or 3 to one ratio. You may need to make an extra stud to hold the gears and then may not be able to fit it on the banjo. If the latter then you will have to look out for a bigger gear, like a 100 or the 127 needed for exact metric screws.

Levelling. You didn't say if the test was between centres or just in the chuck. If in the chuck that is pretty good and more the chuck than the lathe bed. Between centres it could be more the alignment of the tailstock set over. For packing up the feet use bits of plastic eg packaging, CD cases, shop signs (Got a few bits of the latter after high winds)

Floor: if really rough it might be worth making small pads where each foot will go just using cement/sand  1/2 in thick 6 in square giving you the opportunity to give them a nice flat top so you can feel the packing has a stable interface.

Edited By Bazyle on 30/12/2015 12:30:19

[Ian Rees 1Participant @ianrees1]

Thanks for the replies, especially the link about levelling.

The test piece I did was just held in the chuck, if I look carefully at my (very basic) spirit levels, I seem to be detecting a very slight twist in the bed. The Boxford and South Bend manuals both suggest levelling the cabinet rather than the lathe bed feet. I think I'll make sure all 4 bolts are torqued to the same level and then use some plastic wedges to see how good I can get it. This may remove my fears about bed wear as well (something I forgot to mention in the original post).

The lathe had to come apart into two big chunks (cabinet and lathe) for transport. After trying to get the cabinet as level as possible, everything had to be moved when, during the initial motor testing, there was a big bang and we tripped one of the RCDs on the consumer unit. We eventually re-wired the parts that needed it and changed the motor start capacitor and it all works fine now. I also made sure the mating faces of the bench and lathe were cleaned before everything went together but I may have bolted one end down tighter than the other.

This has all been very exciting for me so I've probably done everything in the wrong order and I'll need to go through it all and check everything properly.

[RichardSParticipant @richards31161]

Ian

The keyed changewheels go on as either stud or screw gears.
The compounds and the 80 idler go on the banjo.

The "standard set" of change wheels appears to have been:
	16, 24, 36, 40, 44, 46, 48, 52, 54, 56, 60, 80,
	72/18 (4:1) compound,
	80 idler (with boss).

so you have some to swap/sell for other potentially more useful ones.

You have a 54/18 (3:1) so you can get down to about 0.002"/rev (480 TPI) with the chain:

16 – 54/18 – 72/18 – 80. It does all fit on the upper arm of the banjo.

If you need to cut metric threads then a 100/127 compound is the best solution. However those are hard to come by and often expensive when found.

Come and join the Boxford Lathe group on Yahoo if only for the useful info in the files and photos.

[Steve PaveyParticipant @stevepavey65865]

Before you get involved with levelling the lathe it's worth checking the tailstock is adjusted correctly.

As for feed rate, I seem to remember it is possible to substitute a 100t gear for the 80t in the gear train recommended for the 0.0063" feed – obviously it is a bit bigger but it just allows the cover to close. I'm nowhere near the workshop at the moment so I can't check this, but I'm pretty sure this is the setup I normally have on mine when I'm not cutting a thread.

[Ian Rees 1Participant @ianrees1]

Thanks Richard, it seems I'm missing a 46, although I'm not sure how important that will be, I'm not expecting to do much screw cutting. Some of the gears do look a bit different to others and some even have S&B cast into them, I'm guessing they may be from a Smart and Brown, who also did a version of this lathe. During my late night googling sessions I have found lists of gears that were included with these lathes, and I seem to remember some sizes were repeated but, as with all my internet searching, I can't find the same information again.

One more question, should the gears have a washer between them and the nut? There's various washers in the rusty old Oxo tin that the gears came in and one washer that came off the leadscrew that has been (rather badly) filed out so it fits over the key. There was also a stepped washer on the stud and I'm assuming the stud gear that meshes with the tumblers, as well as the tumblers, are left as they are and not to be fiddled with?

A point to remember, this total gear count includes all the removable gears from the lathe as well as the spares.

[RichardSParticipant @richards31161]

The 46T changewheel is only used for 11 1/2, 23, 46, 92, ..

The Boxford, Smart Brown, Hercus are all copies of the South Bend see the write up on http://www.lathes.co.uk/boxford/

Bookmark the above URL on the inside of your eyelids.

Don't worry too much about what gears came as standard, more important is that you have the gears to cut the threads you need.

> should the gears have a washer between them and the nut?

On my lathe there is a washer (well more of a short spacer) on the stud, ensures the nut does not come in contact with the gear on the idler. For the end of the leadscrew many use a spare changewheel as a spacer. The idler/compounds have a washer.

The only duplicate changewheel needed is 32T, and then only for 8TPI.

On a Mk I you can not close the changewheel cover with a 100T on the leadscrew.

[AjohnwParticipant @ajohnw51620]

There is a keyway along the lead screw that provides the feed not the lead screw thread that is for screw cutting.

One mine that has a gearbox min thread pitch is 224 and that give a feed rate of 0.0015" per rev. The ratio between the two will always be the same. There is usually a chart on the machines some where that shows both. Probably inside the change wheel cover. There may be photo's about on the web even off a SouthBend.

The feed is engaged with a black knob that sticks out of the saddle that screws in and out. It's actually a clutch arrangement so that the saddle can be run up to a rigid stop. It might even stop you wrecking the machine if you managed to engage both feed and screw cutting which is a no no – just one or the other.

I think Harold mentions the real reason for levelling the bed – if you haven't got a high precision level there isn't any point – other than suds trays overflowing of it's at a stupid angle.

You would do well to google for Know Your Lathe and also join the Yahoo Boxford group to obtain parts lists with breakdowns.

Sometimes the bearings need adjusting – first job if you are going to set the machine up. I do that by running the machine at around 500rpm for 20min and feeling the heat on the inside of the spindle under the rear bearing plus what it does when I turn.

The parts list shows Boxford's way of setting them on new machines but usually grease added over the years and wear prevents that from working and they need to be a bit tighter. Searching the yahoo group will bring up various views.

Boxfords are set up via turning once that area is ok – the 2 rings method with light cuts then staining the bed at the tails tock end to correct their sizes. Then the tailstock is set up. This is only intended to correct maybe a thou or error maybe a bit more. Any more from bed wear has to be put up with. The lathes are very precise as they come and this just finesses them. The method is detailed in know your lathe but I would use a bar well over 1" dia, also for checking taper and bearing tightness via plain turning. They also mention levelling the lathe but it really is a red herring. If a precision bubble is used it can be used to check for bed wear and twist – within limits but the myth persists. An ordinary spirit level is enough to make suds run out of the tray rather than leave puddles.

Oh do check that the head fixings are tight. These lathes are often moved by dismantling them and it's best to bend up a combination spanner to tighten or even check them. The ring end may need filing down a bit and don't go for a very long one as some of the spanner will foul on the gap between the bed rails.

John

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Edited By John W1 on 31/12/2015 15:58:35

[AjohnwParticipant @ajohnw51620]

This what a suitable spanner needs to look like

I would tell you the size but it's another thing I have yet to find again. You can check for fit at the change wheel end.

John

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[Ian Rees 1Participant @ianrees1]

Thanks for the replies. John, the only thing I have to pull you up on there is the keyed leadscrew, the C model doesn’t have this feature and relies on the leadscrew itself for both screw cutting and feed, also, there is no feed on the cross slide.

I’ve had to strip the headstock now due to drive problems.

[AjohnwParticipant @ajohnw51620]

Interesting I thought they all used the keyway in the lead screw for the feed apart from some of the very early ones which were rear drive. A,B or C and UD, under drive. I hadn't realised the C lacks it.

To be honest I never use the power cross feed on my ME10, it needs too much variation of feed rate and I'd rather do that by hand.

My rear bearing inner was extremely tight on the spindle. If you got your spindle out easily yours probably isn't tight. I have wondered if this is down to a bearing changes and fitting what people usually use rather than the separate outer and inner rear that can be bought at great cost. The fit seems to vary lathe to lathe.

The other thing I found when I bought and used the lathe was that the bearings needed adjusting but every time I did some heavy work they loosened again, especially opening up holes to 1" from 1/2" with a drill. All I can put it down to is the front cone not being fully home. Eventually they stayed adjusted. I did see something direct from Boxford years and years ago about making sure that the front inner was fully home against the shoulder too.

I use ArcEuro's high speed moly grease by the way on the head stock gears and the bearings. It doesn't need much on the gears just a smear. It stays there. Around 1ml or so evenly smeared on the bearings is likely to be about right. Too much isn't a good idea. Oil is the best thing to use on the change wheels as swarf is less inclined to stick to it – the lead screw too.

John

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[Ian Rees 1Participant @ianrees1]

I did start using some standard grease I’ve got lying around but I do have a couple of different moly greases.

I’m in the process of seeing if Boxford can help me out with the parts I need, then I expect I’ll have plenty of questions for the rebuild.

[BazyleParticipant @bazyle]

In the underdrive models it is ok to use grease on the backgears because there is a cover to prevent ingress of swarf. The Boxford 'know your lathe' book, page 18 in mine, says "any good quality bearing grease as used in garages" so no need to get obsessed with it.

Bearings also grease (1cc on build and sparingly after) per the book although some other makes, especially new far eastern models use oil but the Boxford isn't trying to go fast with an undersized motor so the drag of grease is not important.
I mention this because many lathes, not just Boxford, use the same grease nipples for oil and grease points and people get confused and there is mixed advice on the web. On some lathes the headstock 'grease nipples' are in fact for oil so reading the manual can help.

Everything else gets " light machine oil SAE 20" but 15 to 40 is fine. If you are at a show sometime and find a spare tenner at the end get some slideway oil which has small but non essential advantages.

Don't forget to oil the pulley inside bearing surface and backgear layshaft tube inside.

[Ian Rees 1Participant @ianrees1]

I've read the lubrication advice in the book many times, I'm quite picky about using the right oils and greases for the right places. I'm OK for grease and I bought some slideway oil online, it's ISO 68, designed for slideways but since then I've seen different advice saying things like the countershaft bearings and leadscrew oiling points may need something different, ISO 32 I think someone mentioned.

I would like to know if the 68 slideway oil is going to be all right for everything or if I need to order a litre of something else for the faster spinning bits?

[AjohnwParticipant @ajohnw51620]

If you go onto the Boxford site they have a spares section complete with prices last time I looked. Downloading the parts list pdf off the Boxford group may help you navigate that. It's somewhere in the files section. It can help a lot with strip downs and rebuilds.

The other aspects really are just adjustments. Slides and bearings. There has been a lot of discussion on bearing adjustment at times. You can try the boxford method first but from what I can gather many find it leave them too loose so go their own way. I'm always reluctant to be very specific on that as what works for me might wreck some one else's lathe and my idea of what warm means is likely to differ to others. What people must do is to check what happens when the lathe is run at max speed. I initially check at around 500 rpm and to be honest don't use max speed much at all.

John

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