general ways adjustment

[SamIAm]

All,
after spending some time behind my newly acquired lathe atlas 10
Im not to impressed happy with my saddle/crossfeed compound "feel"
they don't look overly worn. but it seems like if I adjust the gigs so that they are free and smooth
then I have too much play under any load. conversely if I tighten them up the the play is gone.
But then I have to get out the persuasion bar to crank the hand wheels (an over exaggeration but you get the drift)

So should I leave em loose and only tighten /lock em down when needed or leave em as is.

or am I off entirely and need to re examine them and perhaps re visit lapping them in.
surprisingly their made from steel and not brass is this common?

Advise?

Sam

 

[pdentrem]

Are you feeling a difference as you move away from the headstock? The ways being flat is a bit of an issue but not as bad as some would lead you to believe. Have you checked the ways for difference in thickness and width?
On my Atlas I had to settle on a fit that allowed me to do the job in the area that I was working. Re-adjust as required. I found that lube was required and I made some brass strips that slide a bit easier than the steel on cast iron gibs.
I have seen others that used springs (Belleville washers) to supply a part of the pressure on the gibs. Might be something to try.

 

[SamIAm]

Are you feeling a difference as you move away from the headstock? The ways being flat is a bit of an issue but not as bad as some would lead you to believe. Have you checked the ways for difference in thickness and width?
On my Atlas I had to settle on a fit that allowed me to do the job in the area that I was working. Re-adjust as required. I found that lube was required and I made some brass strips that slide a bit easier than the steel on cast iron gibs.
I have seen others that used springs (Belleville washers) to supply a part of the pressure on the gibs. Might be something to try.

The saddle portion isn't so bad its reasonably smooth up until I get more than half way down the bed.
The cross slide is smoother near the furthest portion and tighter as it gets near the center of the swing.
and the compound well its just to loose or too tight... I suspect Ill need to lap it in.
Also as you have prob seen I figured most of the contention was in the cranks. so I changed them out to include thrust bearings.
while this helped and the handles are nice and smooth. it feels like I need longer handles to compensate for the resistance.


any chance you have some pics of your brass inserts?

Sam

 

[swatson144]

If you haven't already disassemble them and clean them.

On the cross and compound slides of most lathes there are usually one or more set screws to move the gib inwards (often 3 in a row down the length of the way). I adjust them and the sliding gib (if so equipped) to get a reasonable easy operation. While adjusting them you'll likely find one that makes a world of difference. I back that one out a little for ease of cranking and use it as a pseudo lock when needed. So facing a shaft the compound is tight and the cross is loose. Then to cut a short taper on the shaft the compound is set loose and the cross is set tight. It's just my way of working with older machinery without adding to the wear by lapping etc. Works for me as long as I can get the results I need out of a machine.

Steve

 

[pdentrem]

The saddle portion isn't so bad its reasonably smooth up until I get more than half way down the bed.
The cross slide is smoother near the furthest portion and tighter as it gets near the center of the swing.
and the compound well its just to loose or too tight... I suspect Ill need to lap it in.
Also as you have prob seen I figured most of the contention was in the cranks. so I changed them out to include thrust bearings.
while this helped and the handles are nice and smooth. it feels like I need longer handles to compensate for the resistance.


any chance you have some pics of your brass inserts?

Sam

You have the same typical wear that all older lathes have. All the work usually gets done in the first few inches.

Afraid not as I have since sold the lathe, but they are just flat stock that I draw filed the 30 degree angles on the top and bottom. The adjustment screw pockets are just a touch with a 3/16" end mill. The saddle bearing plates again were just flat stock and the gib at the back of the saddle same. Simply just Chinese copies of the steel ones.

As you adjust the bolts keep moving the saddle, compound whatever as you tighten one at a time. Basically you want the same amount of tension/play at each one. I replaced the center one on the compound with a wingnut style to allow easy locking of the compound when needed.

The saddle when it left the factory would of had shims that allowed for changing the bottom plate fit. Are there any still there?

 

[SamIAm]

So facing a shaft the compound is tight and the cross is loose. Then to cut a short taper on the shaft the compound is set loose and the cross is set tight.

Steve, I have had it completely apart and thoroughly cleaned.
Im not sure what you mean by quoted part above.
Also are you suggesting I not Lap parts due to the lapping it self is wear in it self?

As you adjust the bolts keep moving the saddle, compound whatever as you tighten one at a time. Basically you want the same amount of tension/play at each one. I replaced the center one on the compound with a wingnut style to allow easy locking of the compound when needed.

The saddle when it left the factory would of had shims that allowed for changing the bottom plate fit. Are there any still there?

Great idea on the wing nut. quick and easy. perhaps Ill turn a knurled nut of sorts. Also yes, my saddle still has the shims on the bottom plate.

making the replacement gibs out of brass should help slow down future wear right. what about brass on whatever metal this is?
I think I read somewhere they brass on cast is not good? or is it that my gibs are made of cast material so no problems..

Also thanks for the suggestions thus far!

Sam

 

[pdentrem]

The brass bearing plates and gibs just become wearing parts that have to be maintained that is all. It is softer than the casting so the wear is only on the brass. Currently it is steel on iron. Yes they will and are lapped already due to the wear etc.

Swanson was talking about that on certain operations you can lock down one direction of motion, thus reducing the slop and vibrations in the lathe. Since you are only moving one axis at a time.

 

[swatson144]

Steve, I have had it completely apart and thoroughly cleaned.
Im not sure what you mean by quoted part above.
Also are you suggesting I not Lap parts due to the lapping it self is wear in it self?

Sam

You tighten the slide you aren't moving on the cut reducing the slop. You loosen the part you are moving just enough to be comfortable. Pretty much the same as the wing nut thing.

I'm pretty sure I wouldn't use brass to replace the cast iron gibs as it seems to just be a lap to me, accelerating future wear on the cast iron ways. A lap is simply a softer material that the abrasive embeds itself into and removes metal from the harder surface.

Lapping on a lapping block to flatten the gibs would be fine IMO. Since it isn't a sealing surface you could even use sticky back abrasive sheet on a flat plate. I can see no way to have proper control if you try to grind the parts together. In this case grind means rub the mating parts together with abrasive which is often confused with lapping.

Proper adjustment of the gibs can make a world of difference.

Steve

 

[SamIAm]

Ok then,
looks like I'll take it apart and revisit the mating surfaces.
so something like 800 wet dry paper to start? on the insert that is.

Sam

 

[swatson144]

Ok then,
looks like I'll take it apart and revisit the mating surfaces.
so something like 800 wet dry paper to start? on the insert that is.

Sam

You'd want to blue it and see what you have to deal with first. The blueing of sliding surfaces isn't overly complex but some imagination is needed. You are simply trying to find out exactly what is going on and making sure you address the problem and not make it worse. I'd take the compound off and inspect the gib. lay a drill rod into the dovetails (all 3 sans gib) and get a better idea of what is going on. If you have a real straight edge with 30° angle you can use it to blue.

I still don't recommend lapping or grinding because there is no good way to fix the previous grinding (wear) that causes your problem. The wear is normally caused by the sliding surfaces only being used on part of the travel for years.

If your gibs are most of the wear you can make new ones. If they are bowed don't try to straighten as they will break and the bow makes no difference. You can buy cast iron from most any of the online venders. ie http://www.speedymetals.com/pc-4253-8387-34-x-1-12-gray-cast-iron-class-40.aspx so as not to turn your cross slide into a lap.

I'm thinking the atlas has straight gibs so you can mic them down the length and it should be the same thickness down the length. Some lathes have tapered gibs which are wedge shaped and have an adjusting screw on each end to wedge them in as needed for adjustment. Tapered gibs should be a true angle.

Steve