Possible'Way' issue with my new PM1440BV

ezduzit said:
This is a Chinese machine, right?
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Yes, they are Chinese made.
Let's not start a issue with Chinese quality here.
I can remember a time when we used to fight the same issues with American made machine tools, too.

Most any new machine tool will have small issues like this when new, regardless where it was made.
Best thing we can do is help the OP identify the problem and relay this information back to QMT so they can either send out a replacement part and tell their manufacture to pay attention to small details like this on future orders, so it doesn't happen again.

Ken


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Although I never had this issue, I can envision some cosmoline perhaps caked on the pinion rack. Use a bright flash light and get down and inspect the rack and pick out any debris you might see. New machines are coated pretty good to prevent corrosion. Hopefully this is the issue. On my lathe the pinion gear is almost center of the carriage and never really crosses the gap section of the bed. I have never had to remove the gap but the pinion rack is pinned to the bed leaving no adjustment. It has always been smooth since new, but I cleaned it machine thoroughly. Mine is Chinese made.

It should run smooth thought the travel. Like was mentioned, check the key slot running down the length of the feed screw for burrs as well.
Good luck and hope its a simple fix.
 
I have a very similar 14x40 & can suggest one thing to check. In fact I'm working on a remedial solution right now so wish me luck & I will report back with pictures. I suspect your lathe power feed might be similar principle to mine but without seeing your parts manual I'll describe mine & you can compare/decide.

There is a power feed rod that comes off the headstock. It has a keyway milled down its length. The rod threads through a worm gear in behind the apron which slides along this keyway. The worm gear translates rod rotation to another helical type gear/shaft & that moves the carriage similar to the manual crank wheel. There is probably some sort of bracket or block that retains the worm in position. The feed rod is supported on the headstock side by a stub shaft (and typically clutch) & on the tailstock side via the bearing block.

Now, if this worm gear is not exactly axially concentric with the feed bar on the fixed ends of the lathe, then there is potential for friction in the carriage movement that has nothing to do with the ways or gap (although these should be checked too). For example with the carriage mid lathe, the power bar may actually be bowing under tension a bit through the carriage so you may not notice it here, it seems to slide smooth. But if you approach say the HS & the fixed bearing is high/low or in/out, this axial discrepancy builds up & causes what appears as tension or constrained movement. Alternatively, if you have a certain random spot but not necessarily near the HS/TS (fixed bearing extremities), then you could have a kinked power feed bar or something amiss in the keyway that is similarly holding things up a bit

About the only way is to isolate is to pull the power bar out & see if the carriage traverses smoothly through the range without it in place. If it dramatically improves then you know something is up somewhere with the power feed driveline assembly.

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Another thought. If you are feeling resistance or partial holdup near the headstock... I would have to say in a very specific spot... it could be related to a short segment of the rack which is bolted separately onto the lathe bed related to the removable gap section. If this has shifted then the pinion teeth would not track on it the same relative to transitioning off the main long rack. Its been a while, but I don't think my short rack is pinned or anything, just cap screws in holes.

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tjr6257 said:
I've got a question for you experienced machinist; my new 1440BV has rough spots on the ways for the carraige. From one end to the other it moves very smoothly except for two spots of maybe three inches or so where it tightens up then it's fine then tightens up again then good again right at the chuck end. It's not supper tight but definatly noticeable. Matt tells me it will wear in in time. This is my first new lathe and any other older lathes I've used never had tight spots like this. It is bothersome to me and I want to know if this is an issue I should be concerned about while it's still under warranty. Any thoughts would be appreciated. Tim
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The real question here is whether you are advancing the carriage with the hand wheel or with the feed screw or with the lead screw when you notice the tightness. The answer to that question would pare down the list of potential issues a lot.
 
I think he indicated that he feels it when he manually advances the saddle. That means it could be the rack and pinion, feed rod and key, or the ways. Until something is taken out of the equation anything other than an obvoius problem is going to be hard to pinpoint. As far as the point of origin....I don't see where that makes much difference. Where I have a problem is when a seller has a potential problem brought to his attention and he responds "it will wear in". I'm guessing the OP dropped some serious coin (at least in my world) on this machine. I would be more than a little POd by that response. JMHO
 
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