Jet BD-920N Questions and request for any available info

J

JayUSArmy

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Machine: Jet BD-920N, Stock#: S21373
I've been trying to find out information specific to my machine, but the 920W keeps coming up in searches instead.

Q1) Is the W just the 220VAC version? Or are there differences between the two?

Q2) There is some "slop" in the headstock. I -think- it's a problem with the bearing closest to the chuck.. when the belt tension lever is in the loose position, I can pull up on the chuck and feel it move with an audible "chunk". My dial indicator shows 2-3 thou movement up and down. I can see what looks like a brass bearing cover move with it. There isn't a set-screw somewhere that can take up this slack, is there? I would think it would have to be shimmed. It feels solid when the belt tension is on, but I'm thinking there's no way that can hold up under load. I've been thinking I'm going to have to go through headstock tear-down, replace the bearings with the tapered ones that people on here recommend, and a complete re-calibration of everything from front to back.. which is probably a good idea anyway, as I can tell the lathe fell on its face at some point in the past(got a good price on it, esp for my area).

Q3) Could you please pass on any information, videos, channels, etc. that you've found specific to my machine? I have the manual, and I found the I'll share what I've found so far:

Awesome thread:
www.hobby-machinist.com

Jet BD-920 lathe inquiry

QUESTIONS FOR THE BRAIN TRUST: I have come across a Jet BD-920 9x20 lathe. NEED PARTS 1. Change gears. Jettools.com has them, but the entire set costs about $700. 2. Steady and follower rests. 3. Tail stock hold down nut (currently has a bolt) 4. Drive belt. The one on there is too tight. Are...
www.hobby-machinist.com www.hobby-machinist.com

Rebuilding the 9x20: An awesome step by step!
www.hobby-machinist.com

Rebuilding The 9x20

Rebuilding the 9x20
www.hobby-machinist.com www.hobby-machinist.com

Nice info on this site:

Jet 9x20 Lathe Specifications & Views

www.micro-machine-shop.com www.micro-machine-shop.com


Thanks for your time!

- Jay
 
Jay,

I'm local to you, and also an Army vet. Welcome to the forum!

It sounds to me like you need to do what every machine owner needs to do upon getting a new machine home- clean, inspect, and adjust everything. Some of these small Asian machines, Jet included, are very capable of turning out good work. It's in the machines bones, but you need to optimize everything that you can control. This will also include, in your case, re-torquing and the possible replacement of spindle bearings. Get the gibs adjusted, get your cutting tool ground correcty, set your speeds and feeds, and you'll be making chips.

I am a weirdo who only owns toys for vehicles, so I don't drive much, but I have a big shop in Bremerton and I'm offering to get you started if you need help.

-John
 
Q1 The BD-920N was a strictly 120v machine. I have one I bought new and the manual states connect to 120v, 60 cycle power supply only.
Q2 The BD-920N came with tapered roller bearings from the factory, so no need to retrofit. pontiac428 was right on in all his suggestions, especially since the lathes history is not known, except for the abuse.
Q3 Check out Steve bedair's site for info on improving the Jet 9x20 lathe. I've had one for over 25 years that I use in my business and it's still going strong. Show it some love and enjoy it.
 
Ok, sorry for the late reply.. been a rough couple days.

Anyway, @pontiac428 I would LOVE any help I can get. I'm not expecting super precision, but (obviously) I'd like to get it as good as it can get. Looking through the "Rebuilding the 9x20" manual, it looks like I can take the chuck and spindle apart to look at the bearings without removing the headstock casting. I'll see if anything can be done with the bearings or if they're munched and need to be replaced.

@Diecutter On Q1 I was asking about the difference between the 920N and the 920W, whether they're the same machine just 220v vs 110v. Thanks for the link, there is so much good info on that site!
 
Jay, is that the "Rebuilding the Asian 9x20" book that came from Yahoo Groups? It looks like a good amount of useful information. I wish he had included more detail in his setting bearing preload section, because his method is subjective, but it'll get you there. That headstock design is simple, it should be very easy to pull the spindle. Keep us posted if you get stuck.
 
JayUSArmy said:
Ok, sorry for the late reply.. been a rough couple days.

Anyway, @pontiac428 I would LOVE any help I can get. I'm not expecting super precision, but (obviously) I'd like to get it as good as it can get. Looking through the "Rebuilding the 9x20" manual, it looks like I can take the chuck and spindle apart to look at the bearings without removing the headstock casting. I'll see if anything can be done with the bearings or if they're munched and need to be replaced.

@Diecutter On Q1 I was asking about the difference between the 920N and the 920W, whether they're the same machine just 220v vs 110v. Thanks for the link, there is so much good info on that site!
Click to expand...
I was careful to only give you what I knew for sure was true. On further investigation, the site newmetalworker.com has an extensive article on the BD-920W which it says uses a 120v 60cycle power supply. Quite a good read.
 
Good news, the bearing wobble tightened up with the spindle preload. Got some fresh grease and it's good to go. I -may- have to loosen it up a hair, but it feels solid right now.
 
Took a couple of days before I stumbled over the thread. I don't have the Jet version, mine is from Grizzly. Basically different color paint. The version I have (G-1550) has a 1-1/2x8 spindle. The current version (G-4000) has M39x4. The reason I bring this up is because I wrote up a couple of modifications I made to the machine. http://www.hudsontelcom.com/9X20Gear.html All of this before I discovered this site. The write-up has been posted here, but a couple of years back. It is downloadable. . .

The spindle preload is best performed "hot". The nut is tightened snug, not tight, and the machine spooled up. Once it has run a few minutes (half hour?) the nut is tightened to just before running hot. There is a "grub screw" in the side of the lock nut, which I'm sure you've found. Make sure that's tightened up when you finish adjusting.

The change gears are M1 x 20 degree pressure angle. The gears are fairly common across the size line, pretty much all suppliers. I have a set extra from the Horrible Fright machine. They're tight but they fit well enough. The belt is a Gates 5M series. The number following is the length in millimetres. Mine is a 5M720. That does vary a little by supplier. I highly recommend a couple kept as spares.

The lead screw reversing "lever" (left hand threads) has many different versions. One for virtually every person that has made one. Mine has a low profile because of the gear head. That's the only reason to use the method. There are many better versions. It isn't well detailed, there is a large community of users.

.
 
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