Jet 1642 alignment

[Harvey Schneider]

I Just got my new Jet 1642, and I am pleased and impressed by it. This is a big step up for me from my Fisch table top midi.
There are, however, two issues that I would like opinions on.
First, The point of the drive spur and the point of the live center misalign by about 3/32 of an inch. The question is, should I attempt to correct a misalignment of this magnitude or leave it alone. If this should be corrected, how does one adjust this?
Second, In high speed mode the drive vibrates at about 3100 RPM. I am unlikely to use this lathe at that high a speed. I understand the cause of the vibration is a "critical speed" shift from geometric center to center of mass and represents an imbalance or eccentric rotating body. It isn't necessarily a problem since it doesn't show at the lower speeds that I will be using, but is it normal for this lathe or is it an indication that there is something wrong?

I'm an engineer and I tend to obsess over little details. I do not mean to imply that I am in any way dissatisfied with my new lathe. Actually I love working at it.:)

Your opinions and advice are appreciated.

Thanks,
Harvey

[Mike Lipke]

Just picked up mine. Can't comment on the misalignment. Mine seems fine.

Have heard that the 1642 has a resonance at about 1800 rpm, which, because "they all do that" is normal.
Your rumble at 3k+, hmmmm, is your belt too tight or too loose?

[Mike Lipke]

Almost forgot.
Bought mine from Woodcraft on sale with rebate.
$1699, less 10% equals $1529, Less $100 rebate equals $1429.

Now, I see Woodcraft's normal selling price is $1399.

I'm Pixxed!

[Gordon Akin]

Harvey,

I got my 1642 a few months ago and have just noticed an allignment problem similar to yours. I am about to order some pen making supplies and am wondering if this is going to give me some problems when using a pen mandrel.

I will be following this thread for some advice also...

Good luck!

Gordon Akin

P.S. I get the vibration you mentioned around 800 rpm and somewhat less around 1700 rpm. Not enough to be a real bother, but I would sure like to have all speeds available and not have to skip these ranges...

[Dominic Greco]

Harvey,
First off, congrats on the new lathe!


The point of the drive spur and the point of the live center misalign by about 3/32 of an inch. The question is, should I attempt to correct a misalignment of this magnitude or leave it alone. If this should be corrected, how does one adjust this?

I'm an engineer (machine designer by trade) as well and this type of misalignment (0.094"!!!) is absolutely unacceptable!:eek: A misalignment of this type would make pen turning almost impossible and lead to other types of errors.

My Jet lathe was aligned perfectly right out of the box and still is to this day (nearly 5 - 6 years later). I would contact the store where you purchased this immediately and ask them for a replacement. They will need to determine if the misalignment is in the headstock (doubtful) or in the tailstock (more likely).

I assume that you checked the alignment of the head/tail stock by installing the live center in your tail stock, the spur drive in your head stock, and brought them together. Correct? I ask this in anticipation of the salesman asking you how you determined there was a problem.

I know this is going to sound weird. But are you sure that the spur center and live center are "true"? This can be determined by mounting each in the headstock and rotating them at low speed. Simply bring your tool rest up close and use that to gauge each one as it rotates. Look for little "blips" that indicate that they might be out of round. Or you can get really anal and use a dial indicator! :D

Once you've established that they are good, then you have eliminated the only logical source of error. Now you have ammunition when you talk to the salesmen who sold you this, or Jet's techs. I would go to the salesman first. If they do not perform to your satisfaction, call the manager. If that doesn't help, call Jet directly.



Second, In high speed mode the drive vibrates at about 3100 RPM. .....is it normal for this lathe or is it an indication that there is something wrong?

Funny you should mention this. I was putzing around the shop today (extracting the shot bearings in my Milwaukee RA Drill!) and for some reason decided to see what my lathe would sound like when operation at top speed. I turned it on and ramped the speed all the way up. I got a little vibration. But not enough to worry me. I have my lathe weighed down by 300 lbs of sand in a ballast box. So that eliminates a lot of the excess vibes. How much vibration are we talking about? Was it enough to make the machine walk around the shop?

Good luck. Please keep us posted on how you make out.

[Steve Schlumpf]

Harvey, first off - congrats on your new lathe! I've had mine since Nov 06 and absolutely love it.

Sorry to hear about the alignment issue. Just wondering if you checked the lathe for level - have read that level, or lack of it, affects alignment. Lots of luck figuring it out - be sure to keep us informed.

[Mike Lipke]

Yes, the bed on the 1642 is not 100% rigid, maybe 98%.

Try adjusting the feet.

[Harvey Schneider]

Hi everyone,
I was able to sneak off to the workshop for a few minutes this morning. Adjusting the leveling feet brought the misalignment to zero. I didn't think there would be that much flex in cast iron, but there is 460 pounds of it pushing straight down.

As for the vibration, I found that I can tune the frequency of it by adjusting the belt tension. It isn't enough to cause any problem when turning, so I'll just let it be.

Thanks for the helpful suggestions:)
Harvey

[Bernie Weishapl]

Congrats on the new lathe Harvey. Glad to hear you got it all fixed. Now it is fun time.

[Dominic Greco]

...Adjusting the leveling feet brought the misalignment to zero. I didn't think there would be that much flex in cast iron, but there is 460 pounds of it pushing straight down.

Harvey,
Good for you! That is some of the best news I've heard in a WHILE! I'm glad it was such an easy fix.

I never used the factory supplied leveling feet (maybe that's why I never had a misalignment problem). I built a set of trestle legs and ballast box for my Jet lathe soon after I got it home. BTW, by adding the trestle legs/ballast box, I really enhanced the performance of that lathe. I highly recommend taking a look at the article (http://www.sawmillcreek.org/articles/7/) I wrote of SMC that outline's their construction.

[Richard Madison]

For those with vibration, be sure to remove the belt and check for vibration with only the motor turning. Mine had a motor vibration at about 3/4 maximum speed. Also can sometimes be a flat spot on the belt.

[Harvey Schneider]

Dominic,
The problem isn't in the leveling feet, it's in the fact that my basement floor is not level and flat. There is a distinct roll to the concrete that caused the problem.
I like the sand box, but I think I am going to make some modifications to your approach. I want the ballast to be as low as possible so that there is some storage space for lathe accessories above it. I am also thinking of using bricks instead of sand. Concrete bricks or blocks will be easier for me to carry down the stairs and should have at least the same density as the sand. I'll let you know how it works out.
Thanks for the help.
Harvey

[George Tokarev]

Dominic,
The problem isn't in the leveling feet, it's in the fact that my basement floor is not level and flat. There is a distinct roll to the concrete that caused the problem.

Harvey

Wedges (shingles) will get and keep things firmly footed. Rubber never will. Try shifting the CG to the rear by wedging the front of the lathe a degree or so higher next time you have an out-of-balance piece.

[Kurt Whitley]

Dominic,
I am also thinking of using bricks instead of sand. Concrete bricks or blocks will be easier for me to carry down the stairs and should have at least the same density as the sand. I'll let you know how it works out.
Thanks for the help.
Harvey

Weight is good in any form, but the beauty of sand is that it can shift to deaden vibration (technically called hysteresis). Think of a dead blow hammer, or how motorcyclists put sand in their handlebars to deaden vibration.

Again weight is good in any form and the hassle of using sand may not be worth it in your situation (the Jet is pretty good out of the box); however, for people trying to get all of the goody they can from their ballast box, sand is a better option.

[Frank Kobilsek]

Harvey

I went through this when I got my 1642. Just make sure the ways of the lathe are very level both ways and the allignment will improve greatly. I didn't think that would matter as long as all four feet were firmly on the ground but my Dad kept telling me to get it right and the machine would be fine. He was right.

If that doesn't work call Jet Service. They will likily send you a new tailstock.

You are going to like this machine.
Frank

[Dominic Greco]

I like the sand box, but I think I am going to make some modifications to your approach. I want the ballast to be as low as possible so that there is some storage space for lathe accessories above it. I am also thinking of using bricks instead of sand. Concrete bricks or blocks will be easier for me to carry down the stairs and should have at least the same density as the sand.

My ballast box was sized so that the swinging basket could be used. This gave me a nice are to store some turning stuff. However, I have since removed that POC "basket" from my lathe. This has increased my useable space. I store my vacuum chuck and some assorted turning supplies on top of the ballast box

Like Kurt said, sand has the ability to deaden the vibration better. I kept my sand in the 50 lb bags to make it easier to transport (in case I needed to remove them later). But I head you about the bricks being easy to move.

[Frank Kobilsek]

Domonic,

I stand very close to the ways when deep bowl turning or hollowing. I don't have a ballast box yet. It seems that if I build it in the 'pockets' on the legs I will be kicking it with my right shin all the time. If I build the box so the it does not protrude forward (front of machine) past a vertical plane of the bed of the lathe am I creating an off balance situation with problems of its own? I hope that question makes sense.

Frank

[Kurt Whitley]

As long as you keep the weight in between the legs, it will provide benefit (though centered is ideal). If you extend the stance like Domonic did, that will go a long way towards getting good stability out of an off center ballast box.

Do you have a sliding head?
If you do, stand at the end of the lathe and instead of standing very close to the ways, you can stand inline with the spindle (much nicer for hollowing).

[Dominic Greco]

I stand very close to the ways when deep bowl turning or hollowing. I don't have a ballast box yet. It seems that if I build it in the 'pockets' on the legs I will be kicking it with my right shin all the time. If I build the box so the it does not protrude forward (front of machine) past a vertical plane of the bed of the lathe am I creating an off balance situation with problems of its own? I hope that question makes sense.

Your question makes perfect sense Frank. I built my box so that it does not interfere with standing close to the lathe. While turning I stand pretty close to my lathe as well, and I've have never had a problem with the ballast box getting in the way. Actually since the trestle legs lift the box up, it allows my feet to fit under it somewhat, enabling me to get REAL close.