Newbie question

Hello everyone,

Thanks so much for all of the great help. Just as a lurker I have picked up an incredible amount of knowledge from this site!

I have recently acquired a nice heavy 10, vintage 1958.

Everything on the lathe works as smooth as silk except the cross slide. It feels like the gears do not mesh smoothly. I took a look at the cross feed screw, it has a slot cut in it which could be the cause.

And, if it makes a difference, it is equiped with a taper attatchment.

Does this seem normal to you guys?

Thanks,

Glove

http://www.wswells.com/projects/tj_schmidt/10L_taper_Revival.pdf


This is the best answer I could find you. tommie

Thank you Tommied,

So I am correct in assuming that the cross feed should be as smooth as the carriage and compound rest feeds?

If so, should I get a new crossfeed taper screw, the repair described may be a bit optimistic for my current skill level.

I don't have answers, but it might help the regulars to help you if you could clarify whether your problem is in the screw (feeding manually) or in the gears (power feeding) - it is not clear whether you mean "It feels like the gears do not mesh smoothly" metaphorically, or literally...

Presumably you do have power cross feed with a taper attachment? In which case the first (or last from the transmissions perspective) gear is the one on the cross feed screw which meshes with the one that sticks up from the apron to transfer the drive. If someone has had the saddle off (4 big screws that are usually bound up solid and take a lot of effort to slacken) it is possible they didn't get the screw gear and the apron gear meshed properly when re-assembling (I've done it, but quickly worked it out), I would expect this just to lock the cross feed up solid, but if the saddle was not screwed down properly (look for a gap between it and the apron) then these gears may be touching but not meshed? Chock up your apron before investigating the screws, if you undo them it will otherwise only be supported by the leadscrew and you may bend it.

If it's not that and it is definitely gear related you might need to look at stripping the apron - it might be worth it to de-gunk the insides anyway, mine was full chips and old oil turned to grease.

If it's not the gears but the screw, maybe withdraw the screw and nut (again I'm sure this is a different operation with a taper attachment than I am used to) and check them, there are often replacement nuts for sale on ebay so if it is just a nut problem it may be quite easy to sort out. You mention a slot in the screw - I have no idea where this is or if it is likely to be a problem, but it is worth inspecting the threads - if they are very worn you might feel a stronger case for replacing it.

I presume the cross feed gib is adjusted properly and you are not simply experiencing it binding and causing the slide to jump when it frees itself? Depening on the age there may be a number of screws down the tailstock side of the slide that adjust it (parallel gib), or one locking screw on the side, and a big cheesehead screw accessible from the end which can pull or push a tapered gib to adjust it.

Finally of course, I guess you have taken the chipguard off (if possible with a taper attachment or does it replace the guard?) to make sure there isn't a big mass of curly chips wedged under it causing the problem?

Good luck troubleshooting!

Thanks Jim

the rough feel of the cross feed is in manual operation. It literally feels like the slot in the cross feed screw is not meshing properly with the gear in the slide each time it comes around as it is rotated.

Since this is my first South Bend lathe, I really just need to know if this is normal or if I should expect silky smooth operation of the cross slide.

Thanks for your help.

It should be smooth. The slot in the screw doesn't engage with any gear, it slides in and out only when the taper attachment is in use. You may have a problem with the crossfeed gear in the apron meshing with the gear on the front screw.(maybe a bad tooth damaged in assembly)
Ted

It might help to take a look at some of the parts diagrams on Steve Wells' website:

Saddle
You have the top type of screw with taper attachment, but in eiher case, when feeding by hand the screw moves the cross slide by drawing the nut (item 58 or 59) which is bolted to the slide backwards and forwards. I can't think why that mechanism would produce a feel like badly meshed gears, it should be as smooth as the compound screw.
Where the label for item 11 (or 12 or 13) points to the front screw part, it shows the gear cut into the screw for the power feeds.

Apron
Item 23 (which is included with item 22 if buying a replacement, you order part 22) is the crossfeed gear which meshes with the gear cut into the screw. If feeding by hand it should just turn freely (as long as cross feed is disengaged) because you aren't actualy driving anything through it, but as Ted says, if either gear is damaged it might cause a bump or something as a damaged tooth passes. One of my suggestions above is that because this gear sticks up above the apron to engage with the cross feed screw, it is possible if the saddle and apron have been separated to not line it up properly when putting it back together. The problem should be immediately obvious and easy to fix, but it could be some numpty didn't work it out, forced it and broke a tooth or more, or as I say, if the saddle isn't down tight on the apron, it may not yet be aligned.....

Good luck stripping and dismantling - it looks like the screw for the taper attachment is in 2 parts, it sounds like your problem is with the gear and front screw, in which case as long as the threads on the rear screw are OK you shouldn't need to replace the entire screw. If it is a broken gear and you are handy at brazing you will find threads here about repairing gears if replacements are difficult to find.

Thanks guys

Looks like a teardown is on the menu for the weekend!

I will update with the findings.

Glove

Teardown Complete

Hey guys,

After tearing down the crossfeed I figured out that my problem has nothing to do with the crossfeed screw, but with the power feed gears.

The gears pictured are not meshing together well, the feel kind of gritty as if they were off size slightly, my guess is it is from 50 years of use.

So, I could replace the gears in question, but since I have the whole apron off, I thought it would be a good idea for someone who knows what they are doing to go through it and bring it back to origninal tolerances.

Is there someone you guys would recommend for this job?

Thanks,

Glove

Doesn't look exceptionally nasty, but does look like someone in the past didn't reassemble the apron/saddle properly - can't think how else only one end of the CF gear would be chewed up and the rest look fine. Seems it was probably sitting at an angle instead of seated down properly so just the corners of the teeth engaging one end of the splines.

First thing is probably to try filing any burrs off the teeth and and splines, then reassemble it making sure it is properly aligned and the saddle seated properly and see how it feels then. Kind of looks like someone already had a go at the taper(?) pin that secures the CF gear....

Also to check - are the felt wicks all present in the apron for getting the oil to the gears? I can't recall if we should be able to see any in that photo or not - the blanket hides the one for the gear shaft. The gear itself I think is parlty lubricated by splashing from sump (there is a thing a like a gear which is sort of loose with the clutch assembly whose job it is to splash oil about), and partly from above - one of the oil screws under the cross slide drips oil onto the screw near the splines.

Does this picture help?

Thanks for your help Jim, are you talking about the wick in the center right?

It looks ok, but I did not see any others.

Can dirty felt wipers make things feel rough if they are overly saturated with dirt?

Gloveman said:

Thanks for your help Jim, are you talking about the wick in the center right?

It looks ok, but I did not see any others.

Click to expand...

Yep that's one of the wicks, I seem to recall (my lathe is a 13 so may be a slightly different layout of wicks) that both those extra holes were used somehow in routing a wick. Also from that upper reservoir I think there should be one that runs directly left and into the slot on the underside of the shaft you took the CF gear off of, to lubricate the plain bearing - most of the shafts on the lathe have a groove with a felt wick laying in them!

Not associated with this particularly but still on the subject of apron felts, there should be one running a round about path in throughthe bottom sump and through the bearings for the worm gear. I forget exactly how it runs, Ryans 13" rebuild has pretty good descriptions though.

Actually looking at Ryan's photos, he routed the felt for the gear shaft different to what I just described.

As for dirty felts being the cause of the rough feeling, I don't know - those look cleaner than mine did, but then my apron was brimmed with chips and grease formed from years of oil and coolant...

I couldn't find felts in the UK so used paraffin (kerosene) wicks, they work fine.

Mystery solved!

Today I deburred all of the gears, cleaned them, oiled them and loosely put everything back togehter, I though I was a genius when the cross slide worked as smooth as silk.

That was until I tightened the saddle down on the apron. The problem was back just as before. So, I loosened up the bolts and everything was smooth again!

What is happening is the saddle is literally crushing the gears together when it is tightened down. There is a metal gasket between the saddle and the apron that is either too thin, or the saddle should not be tight to the apron.

I could get some thicker gasket material and make things work, seems like I need about .050 additional clearance to make everything smooth.

What do you guys think?

Glove

Normally, there is not gasket(shim) between the apron and saddle. Is there a letter and number stamped on your crossfeed gear?(the one in the apron)(example: P10 or M20 or ??)
Does the gear hit all the way acrossed its face, or only on the corner? If only on the corner, it might be hitting the radius left by the hob. Blueing the crossfeed screw(gear portion) will show where it is hitting.
How well does the gearbox, leadscrew, apron, and bracket line up?
Ted

Yes,

it is stamped "M10"

Everything seems to line up well.

It looks to me like the edge of the gear is not aligning up the whe teeth in the cross feed screw. Losen the set screw on the gear shaft and slide gear as close to the front of the apron as possible without the small gear rubbing. also check the thrust bearing on the crossfeed screw worn thrust washers can cause the cross feed screw piece to set to far back and cause the edge of the gear teeth to hit the crown of the teeth on the cross feed screw.

Thank you

I want to thank everyone who helped with advice and questions that got me thinking.

After trying everything suggested as well as some of my own ideas, i took the easy way out.

I cut a .045 shim out of gasket material and installed it between the apron and saddle. The cross slide now operates as smooth as silk.

Thanks again!

Glove