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View Full Version : 9X20 auto feed question?



Bob Fisher
07-31-2012, 07:54 PM
The auto feed on my 9X20 Is difficult to release on a deeper cut. Is this a common problem with these lathes, or is mine unusual? Of course I can always use the Logan, but for some things I prefer the Jet since it has so many tool holders and form tools. Anybody else experienced this condition? Bob.

bobw53
07-31-2012, 09:39 PM
You should blow out the gears and some other stuff pretty quick. That's what happened to mine. Ordered some parts up from Grizzly, and guess what, some of the
parts on the JET are different than the Grizzly, especially down in the apron. The gears are really not much better than compressed dirt. I ended up with
a pile of grizzly parts I couldn't use, I'd say 80% of them were the same though. I guess it depends on what assembly line in what factory on what day
the lathe was made.

I'd take it apart now, see what's going wrong, what you can fix here and now, and order up some spare parts, because if I remember correctly, Jet parts
took a while to get.

I can't help you much more than that, I got rid of it about 4 years ago.

Bob Fisher
07-31-2012, 10:37 PM
Mine is an older Jet, made in Taiwan sometime in the 80's. Quite nicely finished for a 9X20. Been like that since day one however. Wouldn't be the first apron I took apart though. Bob.

loose nut
08-01-2012, 09:09 AM
My 9 x 20 does the same thing, they are hard to disengage, the deeper the cut the harder it gets. Maybe that is a warning on over stressing it, I don't know, I try and avoid it by taking lighter cuts.

Bob Fisher
08-01-2012, 04:08 PM
I guess I should take the apron apart to better understand how it works, there may a fix that could help.I posted on the 9X20 site, but no help. If I manage to improve it I will post. Thanks, Bob.

Arthur.Marks
08-01-2012, 06:09 PM
This may very well have nothing in common with your problem, but I once owned a Jet 9x20. It is pretty much the "standard variety" as found nowadays, so it is much newer than yours. Anyway, I was having trouble with my feed lever engaging very clunky. I'm not sure how else to describe it. Upon investigaton, the bushing the gear rotated on which the lever engaged was held in place by one simple socket head screw. It had worked itself loose from the vibraton of using the lathe. Once I snugged that up, the gear properly aligned again. The lever worked much better. I'm not sure what yours is like, but the current designs are shockingly simple mechanically inside the apron. They make a South Bend look like a mastery of invention :) Please don't get me wrong, that is not meant as a slight of hand against them. It is moreso meant as an encouragement to investigate the apron. Mine was my first lathe ever. It intimidated me until I realized it was so basically constructed.

uncle pete
08-01-2012, 09:17 PM
Bob,
Since I don't own the same lathe, then these are a semi educated best guess on my part. I'd be willing to bet that once you get that area stripped down you'll find more than a few areas where some re machining will do a lot to help. Normally these areas are..............less than poorly done as far as smoothly finished, deburred, and tight tollerances on the internal areas and parts. Normal screw cutting doesn't involve heavy cuts. Those non screwcutting passes do preload the half nuts against the flanks of the leadscrew. I've read about a few crashes where the user couldn't get the half nuts disengaged in time to avoid that crash on these types of lathes.

I certainly don't know as much as I'd like to about it, but a secondary reason for those feed rods on the more complicated lathes might also be for more than a reduction in wear and tear on a lathes leadscrew.

Lack of or the incorrect lubrication could be another reason?

Pete

danlb
08-01-2012, 11:04 PM
The 9x20 uses half nuts for threading, but uses a sliding gear on the lead screw (keyed to a slot in the same lead screw) to power the auto feed gear train. The gear train reduces the speed by quite a bit.

Is the gear pushed into the other by the action of the lever? There is a PDF that shows the apron internals. Might it be simply a matter of lubing the shaft that the gear rides on so it slides easier under pressure?

Dan