# Total Newbie question about my 4902 feed direction.



## vt-biketim (Mar 6, 2013)

The manual says: Feed lever in upper position, carriage travel towards headstock. _Right_, but—when I engage the half nuts the motion is _away _from the HS. Is this normal for these lathes?

Tim


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## Ray C (Mar 6, 2013)

Does it have a feedshaft/leadscrew direction selector?



vt-biketim said:


> The manual says: Feed lever in upper position, carriage travel towards headstock. _Right_, but—when I engage the half nuts the motion is _away _from the HS. Is this normal for these lathes?
> 
> Tim


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## vt-biketim (Mar 6, 2013)

Ray C said:


> Does it have a feedshaft/leadscrew direction selector?



Yes, three positions. Middle=neutral, lead screw doesn't turn. Upper=moves towards HS when long. feed on apron is engaged. Lower=moves away from HS when long. feed lever engaged. I cleaned and lubed all this stuff over the last few months and it all seems to work fine, but the half nuts move the carriage in the opposite direction from the apron worm drive.


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## Ray C (Mar 6, 2013)

Sorry, hang in there and be patient.  I need to ask more questions....  When you say longitudinal feed, do you mean the cross feed?  That is, the feed you would normally use to face a plate or end of a shaft?  If so, one would not normally auto operate the carriage (left or right) simultaneously with the auto cross feed.  That's a dangerous combination and most modern lathes have mechanical lock-outs to prevent it.

FWIW:  On all the manual lathes I've used, there's usually a way to change rotational direction of the leadscrew.  When it's set to move the carriage toward the HS, the compound will move toward you (as if you were facing a piece from the center out to the edge).  I've always assumed this is a built-in safety to prevent a crash.

I'm obviously not familiar with your lathe but, I've operated a good handful of manual lathes and just trying to help out.

Ray




vt-biketim said:


> Yes, three positions. Middle=neutral, lead screw doesn't turn. Upper=moves towards HS when long. feed on apron is engaged. Lower=moves away from HS when long. feed lever engaged. I cleaned and lubed all this stuff over the last few months and it all seems to work fine, but the half nuts move the carriage in the opposite direction from the apron worm drive.


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## vt-biketim (Mar 7, 2013)

Ray C said:


> Sorry, hang in there and be patient.  I need to ask more questions....  When you say longitudinal feed, do you mean the compound feed?  That is, the feed you would normally use to face a plate or end of a shaft?  If so, one would not normally auto operate the carriage (left or right) simultaneously with the compound auto feed.  That's a dangerous combination and most modern lathes have mechanical lock-outs to prevent it.
> 
> FWIW:  On all the manual lathes I've used, there's usually a way to change rotational direction of the leadscrew.  When it's set to move the carriage toward the HS, the compound will move toward you (as if you were facing a piece from the center out to the edge).  I've always assumed this is a built-in safety to prevent a crash.
> 
> ...



Hey, Ray, thanks for taking the time. 
A Clausing 4900 series has a tumbler reverse in the HS between the spindle and the output to the QCGB. It has the three positions I've described. 

There is a leadscrew with a keyway along the entire length. Inside the apron you have a worm gear containing a sliding key transmitting drive from the leadscrew for what the manual calls longitudinal feed—along the length of the bed ways. There is a safety interlock preventing simultaneous engagement of this drive and the half nuts. The apron has three control levers: longitudinal feed, half nut engagement, and power cross slide feed. The compound only advances by hand turning the crank.

I've yet to concern myself with the power cross slide feed other than to make sure it worked when I reassembled the cleaned-out apron.

If I'm turning a bar I move the feed direction lever (tumbler lever) to the upper position as indicated in the manual, engage the longitudinal feed control on the apron, and chips fly as expected. If I disengage this feed control and engage the half nut lever, the carriage moves in the opposite direction. As far as I can tell, the only way to alter this would be to get an opposite-threaded leadscrew. I haven't cut any threads yet. Just wondering if anyone else has this situation?

Tim


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## samthedog (Mar 7, 2013)

Is the machine 3 phase, and, is the chuck moving in the correct direction? If you played with the electrical it is easy to swap two wires with each other. Ask me how I know...:whistle:

Paul.


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## Ray C (Mar 7, 2013)

Sam raises a good point...  In normal operation, as you stand in front facing the lathe, the top of the chuck should be rotating toward you.  

If that's not the issue, then, I'll either need to see pictures or the operating manual to help you further.  Of course, maybe someone here has the info you need.

BTW:  I looked-up pictures of that model machine.  -Nice!

Ray


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## vt-biketim (Mar 7, 2013)

Ray C said:


> Sam raises a good point...  In normal operation, as you stand in front facing the lathe, the top of the chuck should be rotating toward you.
> 
> If that's not the issue, then, I'll either need to see pictures or the operating manual to help you further.  Of course, maybe someone here has the info you need.
> 
> ...



Yes, 3 phase. No, not crossed up. I've done a couple of hours of turning on it since it went back together and have never run it in reverse (it's a threaded spindle, after all).


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## Buickgsman (Mar 7, 2013)

vt-biketim said:


> The manual says: Feed lever in upper position, carriage travel towards headstock. _Right_, but—when I engage the half nuts the motion is _away _from the HS. Is this normal for these lathes?
> 
> Tim



Tim, just curious,  unless you are threading you should be using the longitudinal feed lever to move the carriage.  With the feed lever in the upper position the carriage will move towards the chuck.  If you engage the half nut lever the carriage will move away from the chuck.  The half nut lever should only be used when threading- sounds to me like if you just want to feed the carriage you should be using the longitudinal or crossfeed lever to work the feeds and not the half nut.


Bob


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## Bill Gruby (Mar 7, 2013)

I'm a little late on this one but as said, if you are not threading do not engage the half nuts. They are not needed to normally cut. Yes they will reverse the direction of the carriage. ------ "Billy G"


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## Tamper84 (Mar 7, 2013)

That is how my lathe is set up. If you have the lead screw in the forward position, (with the machine running in forward btw) the carriage feed is toward the head stock, the cross feed feeds out towards the operator, and the half nuts take it toward the tail stock. When running the lead screw in reverse, (machine is still running in forward) the carriage will feed toward the tail stock, the cross feed will feed in, and the half nuts will thread toward the head stock. I thought something was screwy with mine as well. Guess not lol. But it does seem weird doesn't it. 

Chris


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## vt-biketim (Mar 7, 2013)

Thanks everybody in Clausing 49XX land. 

Bob and Billy G: it's OK, I know not to use the half nuts unless threading and I keep the dial gear swung away from the screw, as well. I really don't want to ever have to buy one of those for this thing. This was a school shop machine and was crashed a lot, but seems not to have much actual wear on it. I paid mucho $$ to Clausing for the main spindle gear b/c some kids must have tried to put it into reverse on the fly, but otherwise it was in good repair after cleaning. I gather there's been a lot of 49XX machines turning over recently and it seems the Clausing prices have been climbing accordingly. Last year I heard people say this spindle gear would be $80-90, then somebody here (architard, perhaps?) got a quote 50% higher than that, I actually paid $180. 

I went to my local machine shop guy who helped me install that new gear.  What a great resource, this man's father and grandfather before him ran this shop with water power and lineshafts in the heyday of Vermont machining. When I asked him this feed direction question he did a double take, thought about it, and said he'd never heard of a lathe working that way. :nuts:

So Chris sums it up nicely:



> That is how my lathe is set up. If you have the lead screw in the  forward position, (with the machine running in forward btw) the carriage  feed is toward the head stock, the cross feed feeds out towards the  operator, and the half nuts take it toward the tail stock. When running  the lead screw in reverse, (machine is still running in forward) the  carriage will feed toward the tail stock, the cross feed will feed in,  and the half nuts will thread toward the head stock. I thought something  was screwy with mine as well. Guess not lol. But it does seem weird  doesn't it.
> 
> Chris



I've been happily turning steel bars and aluminum tubes into bits of trash for the last week and a half anyway, but what a great relief to know it all works the way it's supposed to!


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