9 x 20 Jet, HF, etc.. Chinese models Lathe upkeep and mods

[PremalChheda]

I made some very minor mods to my Jet BD 920 that were very necessary, and also became aware of some necessary upkeep to prevent problems in the future.

Thanks to Brad Pohlmann for the advice on this first mod. I will post some pics and go into more detail at a later date.

I replaced the original bolt that clamps the tailstock down with a modified carraige bolt and added a spring and additional nut to hold it steady. I also ground the edges and surfaces smooth on the bottom plate so it will not stick when slightly tightened for guiding the tailstock by hand on the bed. Without the modification, the tailstock would stick when slightly tightened and moved by hand.

The last few months my cross slide feed was sticking a little and I thought it was just an adjustment. I could not get it to run smooth. The last time I dissassembled it I found that the area where the lead screw touches the assembly was wearing and there were bits of metal shavings. GREASE THIS AREA OFTEN!

I am going to do a few more minor modifications to get by until I can upgrade the lathe next year.







Here is the part that needs to be thoroughly greased. The one on the left is the old one. I figured out it was worn due to a combination of no grease, gib adjustment, and leadscrew nut adjustment.

[PremalChheda]

Also grounded the threads on the bolt so the spring would not stick.

[Alden]

Thanks for posting that Premal. The more I use my Jet 920, the more I want a real lathe
Theres probably 50 things I could (should) do to this lathe to make it more user friendly. But its much easier just to complain about it.

[PremalChheda]

It does the job, but after using a real nice emco super maximat super 11 (ferarri), it feels like im driving a beat up 1985 toyota corolla.

[Alden]

It does the job, but after using a real nice emco super maximat super 11 (ferarri), it feels like im driving a beat up 1985 toyota corolla.

Exactly. I've never driven the ferrari, but I know how this Toyota handles
I dont have any choice for now. Until I have a workshop with concrete floors instead of wood, this is about as good as I can get.

[Tyler]

Good thread Premal. Thanks!

As an intrresting note, I bought a new Jet Bd920 about two months ago. The tailstock now has a spring on the tailstock bolt factory installed.

[ToddJohnson]

We converted one of ours to a cam lock. It requires some grinding and welding, but worth it in my opinion. Jody uses a ratchet wrench where the rack is soldered to the nut. Basically, he created a ratcheting nut for his tailstock. The tailstock mod--whatever it is--is a must for hand drilling.

TJ

[PremalChheda]

Just added the pictures of the worn out facing. I got the new one in today and sanded it smooth and applied a liberal amount of grease.

Todd,

The cam-lock sounds interesting. How long did it take you to install?

[PremalChheda]

This site has a nice selection of mods for 9x20 and smaller lathes. The two things I use from them are the quickchange tool holder and the hold down plate for the compound.

http://www.a2zcorp.us/
Here are some of the 9x20 items I upgraded.
Hold down plate - has 4 bolts instead of 2. I also got the tnuts for it because the factory bolts stripped over the years.
https://www.a2zcorp.us/store/ProductDet ... uctID=3833

Tnuts and bolts
https://www.a2zcorp.us/store/ProductDet ... uctID=5648

https://www.a2zcorp.us/store/ProductDet ... uctID=4285

Quick change tool holder - should fit the 9x20 bolt. I did not have to make any adjustments for mine.
https://www.a2zcorp.us/store/ProductDet ... oductID=19
Replacement nut
https://www.a2zcorp.us/store/ProductDet ... oductID=33

I have no affiliation with a2z, just a happy customer.

The links above are not linking correctly. Copy and paste to get to the individual product pages.
Here is all the 9x20 items.
http://www.a2zcorp.us/store/SearchDispl ... D3E106E624}

[smokindawg]

Here is a link to a site with many good mods for the Jet and it's copies.

http://bedair.org/9x20camlock/9x20project.html

[caskwith]

I am a member of many engineering type forums and one of the best bits of advice I think they all give about the chinese made lathes is don't think of them as great lathes, think of them as a kit that can be turned into a great lathe.

[PremalChheda]

Thanks for the heads up on the lathe forum and Steve Bedair's site. I remember looking at Bedair's site quite some time ago, and now that I know a little more, I may try out some of those mods. The new lead screw and ball bearing look to be a huge improvement.

[PremalChheda]

A few weeks ago, upon the recommendation from Thomas James, I made a little delrin washer/spacer that fits onto the cross slide lead screw in front of the stop. It removed most of the play and made it much smoother. I also did an overhaul on cleaning and lubricating which helped quite a bit with the smoothness. There is less than 10/1000 play in the cross slide now, where before I had 20+/1000. I also made one for the tail stock, and will be making another soon for the top slide and a pair for the worm gear.

However, the new 12x36 just blows the 9x20 away in precision and smoothness.