# Better Gibs for mini lathe



## moditwell (Jan 22, 2021)

I have decided to dump the factory gibs and make brass ones for the compound and cross slides. The new gibs are machined accurately to have maximum contact area with only one side of the dovetail. The new gibs performed so well that only very light touch to the set are required. Put a bit more force and it becomes tight. The new gibs have totally transformed the mini lathe, it has become  very rigid but still allow silky smooth movement when cranking the handle, it's very smooth! Parting operations are no more nightmares. Here are some pictures


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## Danuzzo (Jan 22, 2021)

Very nice. In the photos, Looks like a significant dimensional difference, at least in one dimension. Pleased that it worked out so well for you.


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## rleete (Jan 26, 2021)

Stupid question time: how do you mill at an angle like that?  Adjustable vise?


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## SmithDoor (Jan 26, 2021)

The gib looks good. 
The problem maybe in the dovetail or screw.
1) What is the nightmares. 
2) What is the dovetail angle. 

Dave 



moditwell said:


> I have decided to dump the factory gibs and make brass ones for the compound and cross slides. The new gibs are machined accurately to have maximum contact area with only one side of the dovetail. The new gibs performed so well that only very light touch to the set are required. Put a bit more force and it becomes tight. The new gibs have totally transformed the mini lathe, it has become  very rigid but still allow silky smooth movement when cranking the handle, it's very smooth! Parting operations are no more nightmares. Here are some pictures


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## kop (Jan 26, 2021)

I had a conversation with Joel (if that needs an explanation-ask) 
The result was new cross and compound gibs for my MK II Atlas.
The lapping of the gibs was a work out. 
Remove the lead screws and assemble first the cross and then the compound.
Remove the obvious high spots, damage, abuse, and begin adjustment and lapping. 
Apply compound, adjust, stroke, stroke some more, wipe, check, adjust, lap, ~wash , rinse , repeat. 
Hours later with a serious case of arm pump, the likes of which I haven't had since an abortive attempt at motocross racing in the '70's. 
The improvement is immediate and dramatic. I now have a usable lathe. 
The previous maintenance was the spindle bearings. 

In all the mods and maintenance were not only effective but necessary.


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## davidyat (Jan 27, 2021)

*Rleete, there are NO stupid questions, only stupid answers.
Grasshopper*


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## moditwell (Feb 11, 2021)

rleete said:


> Stupid question time: how do you mill at an angle like that?  Adjustable vise?


Use a dovetail cutter.


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## moditwell (Feb 11, 2021)

SmithDoor said:


> The gib looks good.
> The problem maybe in the dovetail or screw.
> 1) What is the nightmares.
> 2) What is the dovetail angle.
> ...


 Parting operation is a nightmare.
Dovetail is 60 degrees


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## matthew-s (Feb 12, 2021)

moditwell said:


> Parting operation is a nightmare.
> Dovetail is 60 degrees



very neat.Can you share your work holding approach for securing gib while machining the dovetail? It’s a small, thin, part to machine.

fettling of the compound is on my to-do list.


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## SmithDoor (Feb 12, 2021)

matthew-s said:


> very neat.Can you share your work holding approach for securing gib while machining the dovetail? It’s a small, thin, part to machine.
> 
> fettling of the compound is on my to-do list.


I make a jig to cut the angle in flat bar.
Tapper jibs are more fun after cutting the then I bolt the flat bar in cross slide and the use side zero out the slide then cut the taper very slowly. Some time you to true up the other side first.
Some times on old lathes you see holes drill in cross slide on taper jib side this where how made a new taper jib

Dave


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## matthew-s (Feb 12, 2021)

SmithDoor said:


> I make a jig to cut the angle in flat bar.
> Tapper jibs are more fun after cutting the then I bolt the flat bar in cross slide and the use side zero out the slide then cut the taper very slowly. Some time you to true up the other side first.
> Some times on old lathes you see holes drill in cross slide on taper jib side this where how made a new taper jib
> 
> Dave



Thanks - that makes sense.
I'm guessing you have a tilting vise, and set it up perpendicular to the table?


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## moditwell (Feb 12, 2021)

matthew-s said:


> Thanks - that makes sense.
> I'm guessing you have a tilting vise, and set it up perpendicular to the table?


Only machinist vice, not tilting type.


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## SmithDoor (Feb 12, 2021)

matthew-s said:


> Thanks - that makes sense.
> I'm guessing you have a tilting vise, and set it up perpendicular to the table?


The last time I had Bridge Port mill and  made the vise jaw for jig and till the head.

Dave


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## Charles Lamont (Feb 12, 2021)

moditwell said:


> The new gibs performed so well that only very light touch to the set are required. Put a bit more force and it becomes tight.


Years ago the revered George Thomas pointed out that relying on setscrews bearing on dimples in the gib is less than ideal, because as soon as you move the slide there is a tendency for the screws to ride up the dimples. He advocated the addition of a dowel with a firm to tight fit. I have so recently done this to the topslide of my lathe that I have not tried it out yet. (The lathe is currently being stripped down to almost the last nut and bolt for its 48-year service).


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## goldstar31 (Feb 12, 2021)

Charles might I respectfully endorse the comments which are still available in GHT's Model Engineer's Workshop Manual.
Again, respectfully, GHT used a peg through the gib to anchor the gib and there was  a further little lock. screw of 2BA which was on  the vertical slide. Mine, is on an old Perfecto vertical slide as I could not afford a Myford one.
 Idly commenting further Ian Bradley of him as an individual and  also as Duplex with Dr Norman Hallows added extra gib screws in his Myford top slide and illustrated in his Book on the Myford.

I'm guessing but the machine was the ML7 as the Super 7 has a different top slide  lock.

Thank you for jolting my memory.

Best Wishes 
Norman


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## KenC (Feb 12, 2021)

The problem with the gibs on my mini lathe is that the edges were sharp and the edges needed to be removed, but more significantly the gibs were slightly bent. Now corrected the mini lathe still has the original gibs.


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## goldstar31 (Feb 12, 2021)

I see ArcEurotrade in Leicester are still selling brass replacements  complete with new gib screws


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## moditwell (Feb 13, 2021)

Charles Lamont said:


> Years ago the revered George Thomas pointed out that relying on setscrews bearing on dimples in the gib is less than ideal, because as soon as you move the slide there is a tendency for the screws to ride up the dimples. He advocated the addition of a dowel with a firm to tight fit. I have so recently done this to the topslide of my lathe that I have not tried it out yet. (The lathe is currently being stripped down to almost the last nut and bolt for its 48-year service).



Use more set screws to distribute the load across the gibs. This way you will have less problems.


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## ignator (Feb 14, 2021)

SmithDoor said:


> I make a jig to cut the angle in flat bar.
> Tapper jibs are more fun after cutting the then I bolt the flat bar in cross slide and the use side zero out the slide then cut the taper very slowly. Some time you to true up the other side first.
> Some times on old lathes you see holes drill in cross slide on taper jib side this where how made a new taper jib
> 
> Dave


Dave, I have to repair the taper gib, with my current compound slide top. It uses a 55 degree dove tail, I just got the cutter in the mail yesterday. There are two issues with the current compound, the top is not flat, even though it has a ground finish. Where the T-slot is, it's raised above the rest of the compond top slide, this raised area was scraped to make it look like a precision flat surface, I have no idea what they were doing with this 2004 manufactured lathe, other then I've determined that every incorrectly manufacture component was not thrown away but made into the lathe I have now. Anyway, where it is ground goes up hill from the T-slot drop down edge, to the crank end.  And I recently put a sine bar on the side to attempt to set the angle precisely, but the side is not parallel with the slide dovetail. So I'm going to re-machine the dovetail to be parallel with the side, (or the side to be parallel with the dovetail). The current trapezoidal gib is tapered, so I assume I need to do as I think you indicated, and clamp that in place to machine it parallel to the opposite dovetail, so it will slide without binding. This compound uses a screw on each end of the gib to adjust it for correct fit. This adjustment range was already exceeded as the screw that pushes the gib ran out of its travel, and I made a spacer that fit under this flange head screw to push the gib farther.


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## SmithDoor (Feb 14, 2021)

ignator said:


> Dave, I have to repair the taper gib, with my current compound slide top. It uses a 55 degree dove tail, I just got the cutter in the mail yesterday. There are two issues with the current compound, the top is not flat, even though it has a ground finish. Where the T-slot is, it's raised above the rest of the compond top slide, this raised area was scraped to make it look like a precision flat surface, I have no idea what they were doing with this 2004 manufactured lathe, other then I've determined that every incorrectly manufacture component was not thrown away but made into the lathe I have now. Anyway, where it is ground goes up hill from the T-slot drop down edge, to the crank end.  And I recently put a sine bar on the side to attempt to set the angle precisely, but the side is not parallel with the slide dovetail. So I'm going to re-machine the dovetail to be parallel with the side, (or the side to be parallel with the dovetail). The current trapezoidal gib is tapered, so I assume I need to do as I think you indicated, and clamp that in place to machine it parallel to the opposite dovetail, so it will slide without binding. This compound uses a screw on each end of the gib to adjust it for correct fit. This adjustment range was already exceeded as the screw that pushes the gib ran out of its travel, and I made a spacer that fit under this flange head screw to push the gib farther.


Sound great any photos 

Dave


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## ignator (Feb 14, 2021)

SmithDoor said:


> Sound great any photos
> 
> Dave


I don't mean to hijack this post, but here are some youtube links of video of the compound issues;


So the original assumption about the slide not running straight was wrong, it's a hollow ground into the top, as figured out later and spliced and shown in spliced in video.


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## ignator (Feb 19, 2021)

ignator said:


> I still need to test the sine bar angle set against a test bar chucked into the spindle chuck. I have a zero set, and of Bison brand that has very small radial runout. If you own a cheap import lathe, buy a decent chuck for it.


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## matthew-s (Feb 19, 2021)

Ohhhh THAT "mini" lathe!  No wonder I could not follow - I have a 7x16. You are in a totally different class of machine than I am!


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## woffler (Feb 19, 2021)

I made some of leaded bronze bearing material came in a rod , for my 9x20 been in use for years now with  no problems my originals looked like bad bananas and were always coming loose or to tight in spots and i had to resurface some of the slides as they had high low spots i scraped them in smooth as a baby's butt.


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## ignator (Feb 19, 2021)

matthew-s said:


> Ohhhh THAT "mini" lathe!  No wonder I could not follow - I have a 7x16. You are in a totally different class of machine than I am!


I started with a 10x24 bench lathe (Jet brand) back in 1976. In 2004 I purchased a new 18x40, but it never was a catalog item at Grizzly. It was internet online purchase only, and I could afford it. I think they imported a half dozen of these. They probably got them for scrap iron price, as I can see every incorrectly made part was assembled into these. I wanted a lathe with a large bore hole. I fix broken stuff, and this lathe at least turns stuff true (with good chucks), but everything else is an issue. The tailstock point's off to the right of the spindle. And that don't appear to be fixable. When you watch a drill wobble as it finds center, and you know you just adjusted that with the 60 degree morse taper mounted centers, I scratched my head, and figured it was a long drill problem. Then I stuck a alignment bar in the tail stock, and swept it with an indicator to see it not parallel to the ways (about 0.012 in 10 inches). I used my bridge crane to lift the top off the tailstock, you can't correct that, as it's machined channels that controls that alignment. I got a  real bargain with this..........
And you can see, I have to fix them as I find them.
This all started with the original head stock adapter, not fitting in the tapered hole of the spindle. The specifications for the lathe, say that the taper is #6 MT. But that is smaller then the 80mm hole through the head stock. So after posting on metal working sites, I found out it is a 90mm metric taper. This is common in Europe, as it is a DIN standard. 
I measured it to be machined wrong, it seemed like it fit, but it would 'rock' in the headstock.  So the adapter was hardened tool steel and needed to be ground with a tool post grinder. That lead to being able to adjust the compound to an accurate angle. And after having much difficulty getting it to the 20:1 angle (40:1 half angle) of the taper, the compound issue needed to be fixed. 
I did get it (the adapter) reground last week. And I found the spindle bore to have issues as well, as the taper has a hollow in it's middle area (another scrap part saved!). Now the adapter fits very tight, and takes a bit of hammer force from a brass solid rod to remove.


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