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Boxford Model A backlash

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JP Santos23/09/2018 15:39:09
36 forum posts

Hi all !
Over the years I always come back here for a read and a shout for help and you all always been so kind that I thought if you could help me once again...

I decided to upgrade my little southbend lathe to something with a few more capabilites and ended up with this Boxford at a very good price.
She started life as a Model C and was then converted to an A - therefore why the red colours on the gear box, apron and lead screw..

Everything works as it should and I'm looking forward to give a go at screw cutting.

However.. she has a huge amount of backlash on the cross slide...
Also on the top slide there's quite a bit of play on the turning lever (I'm sorry, I don't know all the technical terms)

I think the backlash on the cross slide is the most important as when turning any material, it jumps back.. ok you could work taking in account this, but is not ideal...

Is there a away to fix all this? I see all the videos on youtube where people set there work pieces, then turn dials to zero it and cut thous of an inch at the time perfectly, and I would like to do that, but with all this play I won't be able to...

I have taken some photos and also done a video so it's easy to see what I'm talking about as I'm pretty rubbish with the technical terms.

If there was anyone local to Newbury, Berkshire that would be willing to help me I have some bits I could trade? I have a milling attachment for a myford (was hoping it would fit the boxford but doesn't look like), a spare Boxford model C Apron and a lead screw...

btw, I use the lathe on my old harleys that range from 1951 to 1976.

thank you!
JP

Edited By JP Santos on 23/09/2018 15:39:58

Edited By JP Santos on 23/09/2018 15:41:04

Dave Halford23/09/2018 16:28:31
438 forum posts
4 photos

My Rockwell Delta 10" is just like that, however when you wind it to it's extremities of travel the backlash disappears which points to the lead screw rather than the nut being the culprit. Make sure you source the right bit :O)

Neil Wyatt23/09/2018 16:33:55
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16415 forum posts
685 photos
74 articles

That isn't a worn nut, it's badly adjusted where the spindle goes through the fixed bearing, you can see the handle and dial moving back and forth.

No wonder it jumps, winding in you will push it forwards and it will slip straight back when it starts cutting.

You need adjust the handle/dial assembly and get rid of that slop.

Neil

JP Santos23/09/2018 17:45:47
36 forum posts

Thanks for the replies gents.

I just went over to the garage to check it.

Neil, you are correct, the handle and dial move back and forth, I took it out and seems like it's due to a little gap here where I'm pointing with the allen key... perhaps put a little shim there?
or is there other way of taking that backlash off the dial? (need to find what size the little grub screws are as they need replacing as seem to start to get rounded off)

But, besides that backlash there, also seems there's more.
if I hold/push the handle forward, I still have the cross slide rocking back and forward..... perhaps a bit more tricky to get rid of this?
Done a little video to show.

Thanks for your replies and suggestions.

Kettrinboy23/09/2018 19:30:25
75 forum posts
39 photos

Once the handwheel /dial assembly is adjusted properly so that there is no movement there the crosslide will probably still move slightly due to wear in the screw and nut , on some lathes the nut is split so that you can close it slightly to take up wear , I suppose 10 to 20 thou of backlash is pretty common on a well used lathe that's about what my Harrison L5 shows but this has a split nut so I could improve it when I get round to it, how much play is too much , I would say over 60 thou is getting towards the top end of what I would live with , but with no split nut or any way to split it and close it a bit , your only recourse is a new screw and nut or a good secondhand one.

regards Geoff

Edited By Kettrinboy on 23/09/2018 19:31:01

JP Santos23/09/2018 19:55:04
36 forum posts

Sorry to sound massively dumb here, how do I adjust the wheel/dial aseembly?
as per my previous post, the only way I can see this is to shim that gap where I'm pointing at with the allen key.....but I bet there's another way I dont know?

I have a spare saddle and top slide for a Boxford and I think that one is pretty tight, so I'll see how difficult is to swap the lead screw and nut...

where would one go to buy new parts for it please? thanks!

JP

Bazyle23/09/2018 20:29:56
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4676 forum posts
186 photos

Right there's a few points that you need to get to know. The backlash comes from two areas, the fit of the nut on the screw and the setup of the bearing as you have found.
This gap is a bit tricky to adjust. In the middle of the handle is a sort of nut/screwhead with the screw going through it and two slots. You need to find a scrap of metal that fits the slot, or even an old screwdriver and file a notch in it so it can fit in the slots over the end of the screw and enable you to undo it. Next there is a grub screw in the side of the handle to undo. Remember all the Boxford grubs are imperial and using a metric allen key is what rounds them. with the handle off undo the screw in the dial so it is released too.
Now to see if the previous owner did the obvious modification. Is there a sort of top-hat section sleeve inside the dial? the original design requires you to push the dial up against the mounting while pushing back the leadscrew to clos the gap you pointed to above. Then push up the handle and lock its grubscrew,and finally lock it with that outer nut thing. Unfortunately if there is no slack then the dial rubs against the fixed mount and may rotate on the shaft losing registration. So it is a question of how much gap to leave as it is also backlash.
This leads to the top hat modification. You make a top hat section sleeve with the brim away from the operator and total length equal to the thickness of the dial. You can then assemble the parts without the dial and the handle pushes this sleeve up against the mounting and you can adjust to minimal gap. The sleeve has to be fixed to the leadscrew but with longitudinal movement. I have a small pin in the handle engaging a slot in the sleeve. When all this is working you have to bore the dial to accept the top hat and not rub on the mounting.

Martin 10023/09/2018 20:33:03
250 forum posts
6 photos

You are not looking in the right area. Look instead at the handwheel end of the cross slide screw. Unscrew the chromed slotted 'nut' (anticlockwise with something that doesn't damage the slot) Now undo the hex socket grubscrew that holds the handwheel to the cross slide screw. Now fit the handwheel to remove all slack, tighten the grub screw Refit the slotted nut.

As for spares, you are out of luck for that area of the lathe because that type of cross slide / dial was discontinued in the early 1960's

JP Santos23/09/2018 21:01:45
36 forum posts

Evening gents!!

Just got back in from the garage after reading your posts, it's sorted!

So I first done the adjustment on the dial, by undoing the grub screw (luckily I work on Harleys so it's all imperial here) on the dial side, by pushing the dial forward while pulling on the handle, then done the grub screw back in and the slop on the dial/handle was completely gone.

However.. there was still the backlash on the cross slide....
Turned to the spare apron that came with the lathe, a Model C apron, which turning it was pretty nice and tight with no backlash.

Started to taking it apart thinking I could use the whole lead screw and nut... wrong! the lead screw being from a model C doesn't have the gear that engages on the apron to give the auto cross slide...
however!
the nut was in pretty good condition, tested the nut on the lead screw that is currently on the lathe and perfect fit.

So, I fitted lead screw nut that was on the spare model C apron on the Model A cross slide and bingo! done the job.. perfect with no backlash anywhere!

thanks for the help on directing me where to look.

Next thing to look at is at certain speeds I have quite a lot of gear noise, I can't remember for sure but I think it's when at the higher speeds, if I engage the auto feed lead screw gears, it's quite noisy..

What kind of lubricant can I use on all the gears? gearbox and on the side? or should it be grease?
I have lathe oil back from when I used a Myford and needed to fill up the little oil tanks...

Bazyle23/09/2018 21:06:44
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4676 forum posts
186 photos

Part 2

Here's a useful diagram but it is really annoying that they don't tell you the threads of fixings.
It also shows the more advanced modification of fitting thrust bearings which they did on later models, but they didn't do the top hat.
Next we go to the cross-slide nut. Notice it has a cylindrical mounting boss that moves in a hole. If this is a sloppy fit then it will contribute backlash. It has a grubscrew 155 which pushes a brass slug 156 (or ball bearing) sideways against the side of the hole to lock it. Contrary to the diagram the slug should face the operator. I will leave it as an exercise for the reader to work out why.

That's it for adjustment. The nut is not split for taking up wear. The screw itself will become worn in the middle over time so that provides another source of problems.

Southbend did expect there to be backlash and if you read their instruction manual " know your lathe" there is an instruction to set the tool height above centre line contrary to the normal instruction, This upsets the purists but is very sensible on all lathes when done with some thought. Above centre there is a component of force on the tool outward which ensures the backlash is taken up.

JP Santos23/09/2018 21:11:42
36 forum posts

Thanks for that, I did find that diagram earlier, at least is good to know that if that backlash comes back I can buy a new lead screw and nut....

I will have a read on the "know your lathe manual" - it was given to me by the previous owner of my south bend lathe when I bought it. Never got to read it in details as the little lathe was in pretty good condition and I used it for basic jobs.

The Boxford now will allow me to explore more the world of lathes, specially looking forward to some screw cutting.

Bazyle23/09/2018 21:26:08
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4676 forum posts
186 photos

Part 3 but on other topics a Boxford owner needs to know.

The screw in the middle of the star wheel that engages the feed clutch is******* left hand thread********.

The grubscrew on the right of the apron that holds the halfnut engagement lever in place has another gubscrew deep down the hole,

The backgear lever on the front has a brass slipper running in a groove in the bull wheel. Check this isn't worn as the pin it pivots on will score the groove. Oil the groove even if not using backgear.

The clutch is not there to let you walk away and let the saddle thump the saddle stop which will move if you do. You adjust it to just not slip and keep your hand on the feedwheel letting it run through your fingers. As you come close to the stop you grip the wheel and slow the saddle slipping the clutch so it gently touches the stop.

Don't use grease or motorbike chain oil on changewheels as it holds dust and swarf. Use normal thin oil and use it occasionally to wash off the crud. Ditto in the apron, QCGB and leadscrews. Way oil for the ways. The apron probably leaks so put a dish under it.
Space changewheels with a piece of paper between the teeth to minimise noise.

JP Santos24/09/2018 13:16:20
36 forum posts

Hi again,

thanks for the last post, I shall take note of that advice/tips on a note pad and keep it handy.

really appreciate the help given yesterday. many thanks!

JP

Jeff Dayman24/09/2018 13:56:02
1591 forum posts
38 photos

There are a large number of spare parts available in the US for South Bend lathes, which your Boxford is based on.

You might be wise to join Practical Machinist website in USA who have a sub forum for South Bend. The guys there can probably answer any questions you may have.

Bazyle24/09/2018 14:11:51
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4676 forum posts
186 photos

Oh I forgot to mention one of the big gotchas being differences between SB and Boxford. The spindle nose diameter and tpi is the same except the SB is UNC and the Boxford is Whitworth so the facepates etc don't fit.

thaiguzzi26/09/2018 10:10:14
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555 forum posts
130 photos
Posted by Bazyle on 23/09/2018 21:26:08:

Part 3 but on other topics a Boxford owner needs to know.

The screw in the middle of the star wheel that engages the feed clutch is******* left hand thread********.

The grubscrew on the right of the apron that holds the halfnut engagement lever in place has another gubscrew deep down the hole,

The backgear lever on the front has a brass slipper running in a groove in the bull wheel. Check this isn't worn as the pin it pivots on will score the groove. Oil the groove even if not using backgear.

The clutch is not there to let you walk away and let the saddle thump the saddle stop which will move if you do. You adjust it to just not slip and keep your hand on the feedwheel letting it run through your fingers. As you come close to the stop you grip the wheel and slow the saddle slipping the clutch so it gently touches the stop.

Don't use grease or motorbike chain oil on changewheels as it holds dust and swarf. Use normal thin oil and use it occasionally to wash off the crud. Ditto in the apron, QCGB and leadscrews. Way oil for the ways. The apron probably leaks so put a dish under it.
Space changewheels with a piece of paper between the teeth to minimise noise.

I was going to reply, but Bazyle has said everything and more perfectly. +1. Keep the grease for your Harleys, it has no place on or near a lathe. Nice Shovel in the background by the way....

JP Santos26/09/2018 10:28:38
36 forum posts

Thank you
That's my 68 Shovelhead - also known as Genny shovel or Panshovel - built between 66 and 69 they had Panhead bottom ends and Shovelhead top ends

thaiguzzi27/09/2018 15:56:01
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555 forum posts
130 photos
Posted by JP Santos on 26/09/2018 10:28:38:

Thank you
That's my 68 Shovelhead - also known as Genny shovel or Panshovel - built between 66 and 69 they had Panhead bottom ends and Shovelhead top ends

Yeah i know, very very nice.

JP Santos29/09/2018 12:07:06
36 forum posts

Hi all again, was going to open a new thread to discuss something else, but probably not worth as it probably has a simple answer, so I'll try on this one instead.

I see on youtube videos people setting their workpiece, then the cross slide and then they zero it by turning the graduated dial.

I think this is very useful in order to know how much you taking out of your piece and keep consistency, but on my Boxford I can't rotate the dial, unless I undo the grubscrew - which I think it's not the correct way?

Is there a way to convert my boxford to have those graduated dials where I can turn it to zero?

thanks in advance
JP

Clive Brown 129/09/2018 14:52:03
260 forum posts
7 photos

On my ME10, the dials are friction loaded. Under the grub-screw is a small spring and a brass disc pressing on the shaft.The friction pressure is controlled by adjusting the grub-screw,(hope my memory is correct).

Sounds as if your grub-screws are over-tight. Try slackening them. It's also possible that your springs and pads are missing.

Hope that helps,

Clive

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