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Logan 10" rebuilding

Not much to take pictures of shimming the rack. I added 0.017" to bring it where it felt right.
I wanted to get the gearbox mounted to get the leadscrew to its new home.
Sadly, this meant addressing the wear and damage in the gearbox.

This lathe had a hard life. I didn't have a second lathe or time to fix this originally, so I filed the gears and avoided using the feeds. The shafts and bushings had a large amount of wear which resulted in excessive backlash and damage to the soft steel gears.

The tumbler lever had a chicken shit repair previously so I fixed that too.
I drilled oil points for each bushing and will add oil cups.

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I bought a pile of gears off eBay a couple years ago after finding a seller with a lot of nos/good used. . I had forgotten all about them. The little gears for the compound gears obviously were too short. But the price was right - around $15 ea.

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You have to fix the inside corner of the dovetail on your cross slide. Your gib is touching the bad surface where it is not flat all the way to the inside corner of the saddle. You really need to put your saddle up in the mill and with a dovetail cutter go in there and cut out all of the positive metal that is preventing the gib from lying flat against the dovetail.

You can tell that you used a hacksaw blade and tried to clean out the corner. But the hacksaw blade missed some of the metal that needs to come out.
 
Mounting the feed box was pretty straight forward. There was already enough movement in the bolt holes to accommodate the lower position. The feed box originally did not sit hard against the bed - I had .030" between the bed and feedbox at the correct height. I used the existing dowel holes enlarging them from 1/4" to 5/16". The rear leadscrew bracket was not doweled. I added 2x 1/4" dowel pins to make future removal and install straight forward.

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"fitting" the new gearbox with timesaver lapping compound.
The compound gear on the input shaft had a lot of run out. Maybe 0.015" or so. It had previously been repaired, but the new gear was fitted off center. Alas I had to pull it out and repair it as it was going to damage the rest of the gears.

Brazing the compound gears it's critical to have no excess braze at the joint as it will create interference. The brazing paste worked perfectly for this.


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The cross slide screw was in bad shape. The threads for the handwheel were non existent and it was bent.
I cut off the damaged section and welded a new piece on.

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I guess I welded a piece of silver steel on as it broke clean through the HAZ after gently coming to the end of the cross slide travel...

I took a break before I lost my temper, hence the reason I am here. Oh the joys of old machinery
 
You have to fix the inside corner of the dovetail on your cross slide. Your gib is touching the bad surface where it is not flat all the way to the inside corner of the saddle. You really need to put your saddle up in the mill and with a dovetail cutter go in there and cut out all of the positive metal that is preventing the gib from lying flat against the dovetail.
Here's a photo of something similar, this is the tailstock for a cylindrical grinder, I had to move the tailstock down to match the workstock so needed more corner clearance. This is after milling and grinding but before scraping:

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Usually when the cross-feed screw is bugered up on the end, the rest of the screw is more than likely well worn. I usually make a new cross feed screw rather than patch up the existing one.
 
You have to fix the inside corner of the dovetail on your cross slide. Your gib is touching the bad surface where it is not flat all the way to the inside corner of the saddle. You really need to put your saddle up in the mill and with a dovetail cutter go in there and cut out all of the positive metal that is preventing the gib from lying flat against the dovetail.

You can tell that you used a hacksaw blade and tried to clean out the corner. But the hacksaw blade missed some of the metal that needs to come out.
There is plenty of clearance. It doesn't look like it in the photo because of the angle I took it on. I was trying to show the contact pattern of the gib, not the clearance in the groove. Sorry my hacksaw groove isn't a fancy pants milled groove.
 
A guy can also use the side of a hand scraper to cut relief for a gib. Haven’t used this technique on anything larger than a B-port but works ok. Easier to cut this way in the middle of a groove than with a saw.

Ballen’s method is prettier :-)
 
Potential solutions;
  • Flat spot the gib and use a flat set screw,
  • Ball bearing or ball point set screw to let the gib rock to where it wants to be?
  • Potentially it's from the gib surface being high in the middle and rocking? it looks like this in the photo with the cross slide turned around.
  • A tighter/closer fitting gib? The gib I made was certainly tighter before I filed half of it away to ensure it wasn't hanging up in the groove.
  • Drill/tap new set screw holes that land in the center of the gib - I think this is the only way that's going to work. As it doesn't make sense to me that pushing the gib in on the top third is going to result in a contact pattern that says differently.




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With the cross slide turned around;

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I did notice the gib contacting the top and filed it the gib more, but no change.

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When I replaced the gibs on my cross slide table, I made them tall enough that they were firmly seated against the top of the moving section and bridged between that surface to the flat bearing surface of the bottom fixed part. In other words, they were tight at the top and flush with the bottom, constrained so they could only move to tighten or loosen the gap. I imagined that the gib should just be an extension of the slide and perfectly fill the gap to make an ideal dovetail joint and shouldn't initially require the set screws to apply any preload to get a tight sliding fit. Obviously in the real world the wear that you have may make that difficult, but the gaps I'm seeing with your parts just seem like room for that gib to tilt and shift making trying to properly fit it more difficult and inviting movement and uneven contact and wear.

The homemade gibs I replaced were way undersized height wise and despite being scraped in and having well formed bearing points for the set screws, were a hot mess that could never stay properly adjusted and (I believe) constantly rocked and repositioned when the slides were moved. The constraints provided by matching those top and bottom surfaces really seemed to help in my case.
 
Posts like these are such great resources for people like me who are trying to learn. Thank you for the detailed posts and good work!
 
I never had much luck with the hacksaw treatment on dovetail inner corners. After a few go around I always just use a woodruff key cutter to get in there. These days I don't bother with the hacksaw to start anymore.
 
Echoing all the comments on scraping, something I doubt I'll ever tackle. Rank amateur with a Logan I've had a lot of fun with. Your thread was pointed out on the Logan group site. Lost of admirers.

Some comments and thoughts on the Logan cross slide and the screw you needed a break from.

The lack of a thrust bearing on the cross slide is an often discussed topic, and Scott Logan once talked about some of the things they had considered. None were put into production. A new screw and nut will often still have ~.02 - .2 backlash because this slop can only be taken up with the nuts that also secure the dial. So it just can't be tightened down. Some just put in an o-ring. The cross slide covering up the index mark is another issue.

Most common solution for the back-lash is to fit thrust bearings, but from what I've seen the only real viable method is to cut a well in the screw "bushing." And then figure out how to tighten the screw against the thrust bearings. I've never seen a solution I wanted to try. Maybe something in the cross slide idler screw cavity.

Am looking forward to seeing what you consider.

After semi-solving that problem, most fit larger dials for old eyes, there are a couple of YouTube examples. But if you don't extend the screw, the cross slide movement is impacted. For the dial, my thought is to simply use a Brideport type dial and make a replacement dial carrier with a smaller hole for however the cross slide screw is extended. Not expensive, a decent dial lock with no thumb screw and the option of a direct read dial. If you happen to have a set of Hardinge dials, they look really nice.

Two options for the screw.

Make a longer cross slide screw so the threads can be the length needed to tighten against the thrust bearings. 7/16" LH 10 tpi Acme can be hard to find.

Make an extension as was once used by Steling, a commercial accessory that simply clamped over the factory bushing. I have also seen extensions silver soldered on, but the appropriate Lock-tite could be argued for. For the Steling, the orginal shaft had to have a flat filed on the end for the set screw of the shaft extension. After my, limited, experience with a 10EE I'm inclined to use a socket to fit over the orginial screw and secure it with a taper pin. The one on my 10EE feed rod dog clutch apparently worked for the past 67 years without a problem. Over kill, but the extension could simply be made to fit the Bridgeport dial carrier.

Hope this wasn't some boring amater rambling on about the obvious.

Ron
 
The cross slide backlash is correctable, it just takes a bit of modification.

The nut on the left is what you set the backlash with. It rides against the added washer shown in the "exploded view".

The dial then rides on it, bored out to fit.

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And a pretty simple one at that! Thank you. Really. Amazing what others can see that becomes a "Blinding Flash of the Obvious" as was said in my former profession. How deep did you run your thread?

Thoughts on using a thrust bearing? Recent move, the set with the washers has gone missing, but something like the picture?

There are two different cross screw bushings with the index mark. You have the hex style, the other is shown in the parts illustration without a hex and is tightened with a pin spanner and is what's in my picture. By using a pin spanner hole rather than a hex, your dial carrier/backlash adjuster can be made on the same lathe by locking the carriage and doing the work with the compound.

Reference information below as a simple FYI for those who stumble across this in the future. From the Logan parts manual. The cross slide screw illustration is from a Logan sales catalog, a quick paste of the dimensions.

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The thread was not super long, there is only so much thread length on the shaft.

Nothing stops a person from using a thrust bearing, assuming one can find a bearing to fit. The dial assembly could act as the shroud for it, if not too deep. Otherwise you will have to take out and machine the "spigot" that screws into the casting (#689 above).

I'm not sure there is a benefit from that. There are other backlash sources, worn screw/nut, loose attachment screw holding the nut to the slide, etc.

Plus, the Logan cranks are not 100% balanced, so it may tend to turn with vibration, requiring some sort of brake to hold it....
 
Thanks, just seeking opinions from others who know a lot more than I do. Appreciate the thoughtful input off-topic from your awesome scraping job.

Too little friction is something to consider. Now I wonder if maintaining a minimal friction is another reason for the 10EE cross slide screw friction screw.

7/16" ID bearings are a standard size, Monarch uses it on the anti-operator side of the cross slide screw where it attaches to the taper cutter. Acetal is always an option.

The screw illustration cut/paste was part of a review of other Logan cross slide screws with longer overall lengths. The stock one I pasted in just happened to be right next to the standard parts. Some kind of a shaft extension like Stealing did so a larger dile can be mounted outboard of the cross slide is typical.

Most people working on this have already replaced the nut and often also the screw and have moved on to something like you have done looking for a reasonably simple solution to reduce the shaft mount slop.
 
Thanks for sharing the cross slide handwheel bearings/dial information.

I made a complete new screw. It was a pain in the ass. I do not have a traveling steady and my monarch cuts .002 taper close to the chuck. Next time I'll be silver soldering the handwheel section on! The keyways I cut on the lathe hence the imperfections with the drilled end reliefs
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Re spotting and scraping the gibbed side dovetail. It was in-fact high in the middle which was part of the issue with the gib.
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Initially I wasn't going to put oil points on the saddle, but after Ballen suggested it I thought it would be the right thing to do. I used 1/4" cups from mcmaster
Cutting the oil grooves was not fun. I used a cut off wheel to get them started straight and a carbide burr to finish the profile. They look best from a distance!

I don't think I'll add oil cups to the cross slide as there isn't a good place to put them due to the compound rest. Plus there wasn't a lot of wear on the cross slide ways.
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I made ANOTHER gib. This time zero clearance. It now has good contact. Though I think once it wears in a bit it will start riding at the top again. Oh well.
Drilling the set screw holes as Richard suggested, the gib threads would get chewed out, so I used an undersize drill bit and wrapped it with shim stock to protect the threads.

While I was there and going above and beyond I drilled the gib dowel pin hole out and made a lock screw.
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Mainly I wanted an excuse to make some crispy knurls. Hehe. I used a #2 taper pin for the handle, and made a bronze pin w/ 60* beveled end to match the dovetail angle for the gib lock screw to press against.
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Nearing completion - onto the compound. I already had scraped this. It was pretty straight forward.
There is damage to the screw, handwheel is not original and too small to be cutting any respectable tapers.

The cow print tray my girlfriend gave me makes for cutesy arrangements.
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I went back and forth on making a new nut and decided to do it. The alignment wasn't great with the screw and was prone to binding. Plus the OD of the nut was mutilated.
I don't care for how Logan built these. There should be a spotted hole for the compound nut set screw, plus a tapped hole for pulling the nut out for compound disassembly.
I know it's due to the lathe being made for a price point, but I would consider that to be minimum build quality. Maybe I am just spoilt from the monarch.

I did not have a 3/8x10 tpi acme tap. Nor did I really want to be spending money on one for a one off job that's not paying. Making a new nut with the tap would be straight forward. Without it - a little bit more messing around to secure alignment. I made some drill bushings for the compound screw bore, using that to pilot the drill and 1/4" reamer.

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I then used the reamed hole in the nut blank to dial it in with the 4 jaw. The carriage on the monarch is pretty flogged out but the tailstock is pretty close as I line bored it last year to fit a new quill - which is nice for things like this.

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Don't be scared :P
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Marking the compound dial for graduations - there wasn't any on there.
One day I'll make a fixture for doing this. It wouldn't even be that hard - I am not sure why I insist on marking out the lines and then stamping them freehand with a chisel. I kind of like the challenge, but it's a pain in the ass. I'm sure someone out there has a universal type stamping jig they'd like to share pictures of.

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That's it for now. Initially, I only planned on scraping the lathe, but that is kind of pointless when the rest of it is worn out/damaged. I hope this is not too off topic for the scraping forum.
 








 
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