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8th Sep 2019, 10:12 AM #1New Member
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HELP with HAFCO AL336D Lathe - leadscrew gears.
Hi all, just starting with the Hafco AL336-D lathe, and to my disappointment yesterday found that I am unable to engage one of the leadscrew gears. Specifically - gear selection is made via 4 dials on the front of the quick-change gearbox, with most of the position selections being ok - engaging the leads crew to move the carriage for turning and threading etc.
Please see the below images for the 4 gear selector dials - with particular note to the “S / M” dial that does not engage in the “M” position.
When selecting the “M” position on the upper right dial, the leadscrew simply disengages, so that I can with everything switched off rotate it by hand even though it should be engaged. Once the lathe is switched on and run, and I engage the half nut, the carriage does not move as the gear that should be selected at this position is not engaging. Hence as the carriage does not move, I am unable to for example thread at 20 tpi. The “M” position on this dial selector seems to correspond with coarse thread pitches and moves the carriage (or should do) quicker than the “S” position - hence I can only do very fine threading.
This is obviously very frustrating. Though I am a noob In terms of lathe use, I am pretty sure I am not omitting something here in the gear selection process, but am happy to be corrected. Alternatively I would appreciate hearing from anyone who may have had this some trouble before - and fixed it, or from anyone who could either recommend pulling the gearbox down or otherwise in an attempt to rectify this issue.
This is a lathe that I purchased from a guy who bought it but never used it as he didn’t know how to, and it had all the packing grease still on it - obviously done no work, so I would not have expected this issue on an as new lathe.
Any help or suggestions would be greatfully received.
Thanks, Mark.
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8th Sep 2019, 05:48 PM #2Novice
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- Aug 2009
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- Sydney.
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Hi Mark, I have the AL 330A which is a similar layout.
The only thing I can suggest at the moment, is to try rocking the chuck back and forth while turning the selector knobs to try and engage a position. The "M" position might not be exactly where the arrow is pointing and it can often take some fiddling back and forth to lock any of those knobs into the right spot. I just go through this process automatically now.
You might find that the position you want is quite a way from the labelled position.
Let us know how you go.
Michael
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8th Sep 2019, 07:33 PM #3
Hi Guys,
My Myford has a selector which in the middle position disconnects the drive from the gearbox and chuck, so sometimes I have to rotate the leadscrew in order to select a gear. I have a calibrated hand wheel on the end of the leadscrew so the carriage can be fed by hand when the half nut is engaged and the gearbox disengaged.
HTH.Best Regards:
Baron J.
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8th Sep 2019, 07:49 PM #4Senior Member
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- Jun 2012
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- melbourne
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I have one of those too. That dial usually won't go into place unless you are rotating the gearbox by hand. The top left lever, the smaller of the three selects the gearbox direction. Straight down is neutral with clockwise one side and counterclockwise the other. In your photo it looks like it might be pushed too far to the left which is another neutral. With the change gear cover off, rotate the motor pulley by hand as you try to select m on the dial. Ifits not that, I have some photos somewhere of inside. It's possible to put the cover on and get the symptoms you indicate
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8th Sep 2019, 08:34 PM #5Member
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- Nov 2009
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- australia
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Just got to ask this question --------- HAVE YOU READ THE MANUAL ?
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8th Sep 2019, 08:49 PM #6Senior Member
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- Jun 2012
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- melbourne
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The manual doesn't even tell you how to turn it on. I had tcheck the Internet cos all I could do was find the jog button and I felt sure you shouldn't have to hold a button down while cutting
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8th Sep 2019, 09:03 PM #7New Member
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8th Sep 2019, 09:07 PM #8New Member
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Thanks Michael. I spent about an hour fiddling with settings and rocking the chuck back and forth while trying to get the gears to engage yesterday. No luck unfortunately, but will give it another go tomorrow morning when I get home from work (doing nights). At this point it’s worth another go before dismantling the thing. 👍
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8th Sep 2019, 09:10 PM #9New Member
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8th Sep 2019, 09:58 PM #10New Member
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Hey sossity, so I managed to give your suggestion a go just now - put the upper left small gear lever selector into the neutral position - that isolates the motor / upper gear system from the lower leadscrew / feed gearbox. That makes it possible with the cover off the left side of the machine to rotate the change gears by hand - they are the power input r this lower gearbox. Doing so makes it easier to make gear selections. As before, I can select the S position, and when doing so the feed output shaft locks up / engages within the gearbox and so rotating gears by hand results in the feed output shaft turning (given other gear selectors are also engaged). When I move the S / M selector into the M position and I have jiggled it around through it’s hole range of rotation (and do get a click in the extreme clockwise part of its rotation corresponding to the M position) - there is not engagement within the gearbox at all - as if there is actually no fear there at all, and I can independently rotate the change gears by hand and the feed output shaft at the same time - even in opposing directions simultaneously - that is not supposed to happen. Could there be a missing gear ???? Just to clarify, it is the feed output shaft that is not engaging - sorry - not the leadscrew as initially noted.
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8th Sep 2019, 10:15 PM #11Senior Member
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I'm not near the lathe just now but I'm not sure you have anything wrong. One of those shafts is used to drive the cross slide or saddle under power for making cuts. The other shaft looks like a big thread and it drives the saddle when doing a thread. I think that's what the s/m switch changes between. If you get the lead screw engaged with the s/m switch then you might not see the lead screw turn when rotating by hand cos some threads are very fine. Maybe I'm not understanding the issue though. Only one of those shafts should be engaged at a time I think. I could be wrong, my memory plays tricks on me. I can check things tomorrow if it helps
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8th Sep 2019, 10:55 PM #12Senior Member
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I'm a bit confused as to which shaft isn't rotating. There are two shafts under the saddle, one is threaded and one has a slot long its length. The one with the slot will move the saddle under power if you select the correct lever position on the saddle. This moves the saddle fairly fast, or you can switch it to move the cross slide. You don't use the half nuts to move the saddle, that is only for thread cutting. For that to work, the threaded shaft needs to be rotating, not the slotted one. I usually leave the gear cover off, and If i want to change the position of the S/M knob, I make sure the gearbox is selected and just turn the motor pulley by hand. Then it doesn't matter what gearing its in, you can always turn the pully fairly easy. If you dont mind geting your fingers all greasy, you can do what you did and turn the gears. I can't remember if the S/M switch should be at S for cutting a screw or M for machining. Thats how i remember it and its usually wrong from memory. Whatever way round. i'm sure you will figure it out. Íf your threaded rod or leadscrew is not turning, then it might have been run into the end stop and sheared the pin that feeds the shaft. Id say that was unlikely because there is still enough friction to turn it by hand. I think the leadscrew is actually on a clutch as well.
So, if its not just finger trouble with the levers,, here are two pictures showing what else can go wrong.
the first shows the gears on the back of those four knobs. The second you can see what those gears go onto, the rack gears that will slide sideways to change the function of the gearbox.
Where I show two yellow arrows, you can see two protrusions out the back of the rack gear. Those protrusions need to fit over either side of the selector dog. If they are not aligned, turning the know will not allow you to select between screwing or machining because it won't be moving the selector dog thingy.
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8th Sep 2019, 11:13 PM #13Senior Member
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Just for clarity, in your own picture, the black metal lever on the saddle is for selecting the saddle to move under power when you want a controlled cut at an even speed. You can push it up or down to select saddle or cross slide power. The silver handle on the saddle is the half nut selector. You need to make sure the back lever is in neutral again, you can't select drive to the saddle and then select the half nuts. i think something will give if you try that.
So, work out which combination of levers makes the threaded shaft (leadscrew) turn and use the half nuts to cut a thread. OR use the S/M knob to select the slotted shaft (so now the threaded shaft doesn't turn from memory) and then you use the black lever to either make the cross slide move or the saddle move. Sorry, you might know all that already.
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8th Sep 2019, 11:17 PM #14New Member
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Thanks Hanks heaps for the pictures and further information - that really helps understand what should be going on (though it actually isn’t ding what it’s supposed to).
You are correct - it’s not a problem with the threaded leadscrew- that’s doing what it should. It’s the slotted feed rod that will not engage when the S/M dial is in the M position. You may be on to something noting that the dog thingy should be moved by the selector to switch between the screwing and machining gears. It may well have a problem in its alignment or something as it will only engage a gear in the S position - not the M position - in the M position the slotted rod just free spools by hand and does nothing when the machine is running. When in the S position, the change gears on the side are mechanically linked to that slotted rod and move together driving the cross feed or horizontal travel of the saddle - sorry if my terminology is a bit screwy as I’m only starting out with this.
On consideration of this, and looking at the photo you have kindly given of the fear assembly with the front cover removed, I am thinking it might be necessary to remove that front cover to investigate what is going on in there. What would you think about that idea ? Are there any important points to note if I go ahead and do that ?
Your assistance is greatly appreciated.
Regards,
Mark.
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8th Sep 2019, 11:21 PM #15Senior Member
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I found a better picture that shows which each of the rack gears has to engage with. If you take the cover off, they can move and you won't know where they were. Thats what happened to me. Try not to move them. move all the knobs to clockwise extreme and then they should be like this to fit together
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