Possible'Way' issue with my new PM1440BV

T

tjr6257

Registered
Registered
Joined
May 26, 2017
Messages
17
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
 
Matt tells me it will wear in in time.

That's not the sort of thing I want to hear after I just dropped a bunch of cash on a new machine. Is it possible that he missed a few spots when he was prepping it for delivery? The only thing I could imagine "wearing in" would be some protective coating that wasn't completely removed.
 
My pm1440gs has the same issue. Having spent alot of time looking at it, it does appear when the carriage and it's gear cross over the joint for the gap is where the issue is on mine. Though I have run a dial indicator over the joint and the rack gear connection and the appear fine. I cannot see the gear as it goes over the rack gear at that point, my thought is in my case that is where the issue is...

1) is the rack gear piece that goes where the gap is a little larger in size? I tried to change its location but it is pinned to that
2) the gear on the carriage should not be part of the issue, the carriage works fine on the rest of its travel.

I do believe it has something to do with the rack gear, the gap, and the pinion gear on the carriage. I took delivery of my machine in late July early August, mine may be better, it's not as nice as the rest of its travel

Rich
 
Thanks guys for the responses. I should clarify my post now that I read it again. I didn't mean the ways had visible rough spots on it, it looks visibly and to the touch, smooth and consistant for it's length. I meant that it feels rough or perhaps tight is a better word in it's travel in those spots when cranking the hand crank and, I will add, it feeds smoothly when using the feed screw, I don't see any slow down in it's feed rate. I wonder if there's an easy way to disengage the pinion gear in the carraige and push the carraige by hand to see if it's the ways or the rack? And by the way Richl, this problem is not at the gap joint, it's 8-12 inches away (approx). Tim
 
Pinion to rack or saddle to ways wouldn't matter to me. My issue would be having the seller tell me that it would wear in over time. I don't think I want something that has to wear before it feels smooth.
 
Let me know if you find anything, it might be the same for me, just that mine is where it is, and I am chasing after the wrong thing. In a remorse kinda way, it's good hearing others have a similar machine with a similar issue.

Happy hunting!
 
Have you looked at the keyway in the feed screw/rod. I don't know if it has seperate feed and lead screw. If it had a tight spot in it, that might give some resistance as the key in the worm gear slid through it.
 
Worth looking into Chuck, I'll take a look toworrow
 
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.
Click to expand...

Just a check:: You did clean the ways really well--like washing it down with WD and a tooth brush, wiping clean with cloth, and then manually lubing it with a clean chip brush and way oil?
 
Chuck K said:
Have you looked at the keyway in the feed screw/rod. I don't know if it has seperate feed and lead screw. If it had a tight spot in it, that might give some resistance as the key in the worm gear slid through it.
Click to expand...
I think Chuck has hit the nail on the head!
I've seen a similar thing happen on a larger new lathe many years ago. The OD of the feed rod had places that were slightly oversize from centerless grinding that wouldn't allow the reverse pinion gear in the apron pass over this area. Look for dull spots on the feed rod, if equipped, and leadscrew. What to do for it? Not much, unless you want to remove the affective part and file/polish those areas until the mating parts will pass over. Personally, I wouldn't worry about it, unless it's so tight, you almost have to force the carriage to move over these areas. Measure the OD's of the feed rod every inch or so and see if you get a slight diameter change. A half thousandth can cause problems, so take careful measurements. Without knowing the factory tolerances of these items, be difficult to determine of anything was out of tolerance. All you will be doing is making an observation of your findings. Of course, a person needs to get into the apron and measure the ID's of the mating parts, too, for comparison.

Last, if the rack pinion seems to get tight in these areas, loosen the screws holding the gear rack to the bed and see if it loosens the tightness of the gear to the rack. Pull the rack completely off the bed and try. This could at least rule out one of the possibilities if the problem still exists.

Ken
 
You must log in or register to reply here.
Back
Top