# I need a replacement for the screw &  nut for the cross slide for my logan 820



## joebiplane

My   logan 820 (Early ser#  31983)  restoration is coming along and  am putting it back together.
I now notice that the cross slide can be moved back & forth about 1/8"  1/4'  in or out  especially in the center of the travel. Not against the gib but against the screw threads
I'm a hobiest and not a machinist but the major wear is in the cross feed nut  but at either end of the travel it tightens up nicely telling me the cross feed *screw *also has wear in the center of travel ( probably where it is uded the most.)
long story short I need to replace the screw and the nut.  anybody know where I cand buy a new ... Or as good as new,  one or have a nut And screw made ?
thanks,  as always
joe


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## Old Iron

I had the same trouble on my 13" South Bend and I added some thrust bearings in mine and took up all the slack. I did have a new nut and screw so I knew that wasn't the problem.

Paul


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## ScrapMetal

Jim,

Thanks for the write up, with pics even. :thumbzup:  This is something I'm going to be tackling on my SB 11" sometime in the near future and this will be of great help.

-Ron


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## bcall2043

*Re: SB cross feed thrust bearing retrofit*

Jim,

I have a SB and would like to see your thrust bearing solution.

Thanks, Benny


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## joebiplane

Jim B. said:


> While you may need a new nut and perhaps a screw the degree of play you mention cannot be ALL traced to them. If the screw were worn to a point and the nut were worn to the same degree the most play you could have would 0.050". Much more and the the slide would move totally back and forth since there would be no threads.



I took your post and went to my shop and measured the movement i have....I was waaaaaaay of the actual distance .012-.018 was i just seemed like a whole lot to me,( remember I am a neophyte Hobby machinist) sort of like having a grain of sand in your mouth....feels like a stone!
I tried your suggustion and it did help...but did not aleviate the problem.
i have looked at the nut and it does not look good indide the nut. Probably where most slop is coming from. screw look clean but neeed to be properly checked out.
there is a replacement nut for sale, on e-bay, New Manufacture and it is $48.00+/- plus $5.00 shipping. it looks easy enough to make until I looked at the price of taps for acme thread ( $ 60.00-70.00 ???)
I don't know the exact dimensions of the screw thread but appears to be 3/8'-1/2 "diameter. hopefully someone can give me the exact size and pitch. As you can tell I havn't looked DEEPLY into this matter
After 9 months of taking this beautiful lathe down to it's shadow and refurbishing it bolt by bolt I and expect to throw the switch and see it run within a week.. then i can start tweaking it.

Joe


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## Wobbles

Since the screw is steel and the nut brass, it's always the nut that wears. A guy by the user name Jayhawk (Machine Tool) is on Ebay and makes new brass cross-slide nuts. They are very accurate and very inexpensive for what you get. I bought one and like it. I think it was like $22.


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## Wobbles

I found his business card....

Jayhawk Machine Tools
Mr Mike Neville
Specializing in Leadscrew repair and cross feed nuts
913-636-6107
jayhawkman35@hotmail.com


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## gjmontll

When I restored my 1944 vintage Logan 820, I was also concerned about the play in the cross-slide and compound lead screws/nuts. I investigated replacement but other than purchasing Acme threading tools (internal and external), did not take any action. 

*Joe: When I had it torn down, I did take measurements and make sketches, here are the specifications you asked about.*

*Cross-slide leadscrew: 7/16"-10 tpi left hand Acme thread*
*Compound leadscrew: 3/8"-10 tpi left hand Acme thread*
I searched for vendors selling Acme threaded rod to meet these sizes, but found nothing. To get off-the-shelf 10 TPI Acme rod, it looks like you need to go up to 1/2". I did some less than rigorous investigation and think it might well be possible to fit a 1/2" screw and nut into the standard Logan slide. Anybody comment on this? I don't think the compound slide would tolerate the 1/2" leadscrew.

As to whether the slop is in the screw or the nut, here's what I just measured on my 820: (Measurements taken with the screws almost fully CCW (outwards from spindle), mid range, and nearly fully CW (inward). Measurements all in thousandths of inch. 
                                     CCW         Mid            CW                             
Compound slide:                7              7               6
Cross slide                        87             4               3
*Some of this slop is shaft endplay, but I conclude the cross-slide screw is badly worn (as expected) out where one would be turning fairly large diameter stock. I suspect previous owners may have replaced the nuts.

If I could get the proper Acme rod, I'd consider making a new cross slide shaft. Barring that, there's always making your own. I just love being able to use my lathe (and mill) to make its own parts. It's on my list, but low-priority for now.

 Based on the success I had in quickly, easily making a 5/16-32 UNEF tap, I'd try making the Acme tap from drill rod before buying an expensive one. 

   Greg




joebiplane said:


> I took your post and went to my shop and measured the movement i have....I was waaaaaaay of the actual distance .012-.018 was i just seemed like a whole lot to me,( remember I am a neophyte Hobby machinist) sort of like having a grain of sand in your mouth....feels like a stone!
> I tried your suggustion and it did help...but did not aleviate the problem.
> i have looked at the nut and it does not look good indide the nut. Probably where most slop is coming from. screw look clean but neeed to be properly checked out.
> there is a replacement nut for sale, on e-bay, New Manufacture and it is $48.00+/- plus $5.00 shipping. it looks easy enough to make until I looked at the price of taps for acme thread ( $ 60.00-70.00 ???)
> I don't know the exact dimensions of the screw thread but appears to be 3/8'-1/2 "diameter. hopefully someone can give me the exact size and pitch. As you can tell I havn't looked DEEPLY into this matter
> After 9 months of taking this beautiful lathe down to it's shadow and refurbishing it bolt by bolt I and expect to throw the switch and see it run within a week.. then i can start tweaking it.
> 
> Joe


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## Snag_one

www.lathe.com will get you to the official Logan parts supplier ... Logan . They have the nut , in cast iron I think it is now (my replacement 7 years ago was bronze) and I believe they have the lead screw too . But they ain't cheap ... Very few old machines are supported as well as Scott does these lathes . I must admit to making some of the parts I need myself , especially gears . 
  Actually , .012-.018 isn't all that bad . Mine probably has close to that and it'll still hold under a thou if I do my part .


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## wa5cab

McMaster lists 3/8"-10 LH precision threaded rod.  But nothing, precision or otherwise, in 7/16".

Logan probably ranks second or third after Clausing (Atlas) in continuing parts support for thier old machines.  We should where possible support these OEM's.


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