# clausing 111 carriage backlash



## magu (Dec 19, 2014)

Hello all! I have lurked around the site for a long time without signing up; eventually I signed up but never started posting. About this time I bought a clausing 111 which I have been monkeying around with for 6 months or so. (See picture below)

I have gotten somewhat comfortable with basic cutting on the lathe, but anytime I am trying to do anything but create scrap metal (I.e. working towards a dimension) I have found that I have a major problem: backlash. I usually try to mitigate thks by pulling aginst the diection of motion to preload things, but I would much rather fixthe problem properly.  

The main carriage travel is atrocious,  however, I havent figured out a good way to measure that yet, so for this first post I only have numbers for the cross slide and tool vise. 


I measured the movement in two different pieces. First, while loading the carriage against the lead screw I measured how much i could move the handle and screw in and out. Next, holding the lead screw I measured how much the carriage would move. 

For the main cross travel slide I found .030" movement of the screw and .023" of the carriage.

For the tool vise I found .016" in the screw and .016" in the carriage. 

My guess would be that the screw movent can be fixed by tightening or shimming the fit of the handle area to the carriage it pushes, but does anyone have any experience or recommendations on this or the rest of the backlash? I am hoping it is as simple as replacing the bronze nuts.

Thank you all for your attention and comments.


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## 34_40 (Dec 21, 2014)

Good to see you here and a great machine to boot.   I have a 108 and mine has the cast iron legs and no clutch mechanism.

I'll be watching for an answer as I may try the same repair/replacement on mine and gain some accuracy.  But I have a hunch you're already knowing the correct answer.

Thanks for the post too.


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## wa5cab (Dec 22, 2014)

Magu and 34_40 (please sign all posts),

I've never actually had my hands on a Clausing 100 Series or 4800 Series machine.  But the first thing that I'll say is that backlash in the carriage feed, cross feed and compound feed is just a way of life in any engine lathe.  You learn to always approach the final setting of either feed screw from the same direction, CW if doing OD turning or facing, CCW if doing boring.  If you overshoot your desired setting, you run the screw back out (or in) past the setting and then try again.  Although high-dollar machines do exist with zero backlash controls, they are uncommon and quite expensive.

That being said, when new, backlash on your machines was probably around 0.010" on the cross feed and compound feed and a bit more on the carriage feed.  0.030" is excessive and may indicate a need for a new feed screw and/or feed screw nut.  However, there are two sources of backlash.  One is the necessary running clearance between the feed screw and nut.  It cannot be zero or you would be unable to turn the screw.  The other is end float in the feed screw.  This can be reduced to nearly zero (probably 0.001" to 0.002") by proper adjustment of the feed screw.  Neither manual that I have tells how to do this but looking at the two exploded view drawings of the carriage assembly, it appears that the crank in both cases must be internally threaded.  In which case, the adjustment is made by loosening the crank on the screw, tightening the hex nut slightly (probably one or two flats) and re-tightening the crank and checking the end float and feel.  The objective is as near to zero end float as you can get without the crank being difficult to turn.

To adjust the cross feed end float, run the cross slide to the rear of the carriage until you run the nut off of the screw.  Then push the slide another eighth of an inch.  Adjust the hex nut and handle for best feel and minimum end float.  Then pull the slide toward you and re-engage the screw and nut.  The compound is built differently.  The nut is stationary in the swivel, not in the slide.  And I don't know whether there is clearance in the underside of the slide to allow you to run the screw out of the nut or not.  If there is, it will be with the slide all the way towards you.  If there isn't, then you will just have to do the adjustment less conveniently.

Once you have the feed screw end floats near zero, check the backlash again.  You do not need any special tools to do this.  Turn the crank until Zero on the dial lines up with the fiduciary or witness mark.  Then turn the crank gently in the opposite direction until it stops.  The reading (or the complement of the reading) is your end float.  If it is under 0.015", rejoice.  If not, replace the nut.  If it is still over 0.015", replace the screw.

Robert D.


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## 12bolts (Dec 22, 2014)

Dont get hung up on the backlash. Think about the cutting forces and the direction they will be opposing, and cut in from that direction. When you wind back out, just go past your end point by half a turn and then come back in to your zero point and take the next cut from there. All machines will have some backlash, you just need to get in the habit of dealing with it, then it is no longer a problem. The carriage especially is not a fine tolerance part for small cuts. Just move it to position the tool in the right spot and lock it down. The only time you should be leaving it loose is when you are using power feed, and then the leadscrew will deal with the backlash for you.

Cheers Phil


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## magu (Dec 25, 2014)

Thanks Robert and Phil. 

It sounds like I will have to learn to accept at least some of this. I have been coping with it as you mentioned or by loading the tool with my free arm as I move the tool. I understand that some backlash is a necessary evil, but this I find it annoying. 

I tightened up the end float on the tool holder before we left home for the holidays, I will try adjusting the end float on the cross travel according to your instructions when we get home. 

Perhaps from here the next step will be to get new nuts and see how much they tighten things up. I would presume that the brass (bronze?) nuts should have much more wear than the lead screws.


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## magu (Dec 25, 2014)

On a somewhat related note, how much should be considered acceptable for the carriage travel down the bed? I have approximately 20 degrees of free movement before the backlash comes out of the gears and lead screw.


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## fast freddie (Dec 25, 2014)

magu said:


> On a somewhat related note, how much should be considered acceptable for the carriage travel down the bed? I have approximately 20 degrees of free movement before the backlash comes out of the gears and lead screw.



all of us deal with backlash, that's part of being a machinist. it does not keep you from doing precision work. do you have a friend who can show you how to work the backlash ?


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