I have an opportunity to buy a Jet milling machine from a customer of mine. He found out I was interested in machining as a hobby and he is downsizing his personal shop and doesn't need two mills. It's dirt cheap. In fact, if I can't get it fixed it's free. He fools with machinery all day at work and he simply doesn't feel like tearing it open to see what's wrong. He also has a nice Bridgeport right next to it, so motivation is low. He just wants the space back.

The bad: it knocks quickly, but softly in reverse. It is nice and quiet in forward though. While in reverse and knocking if you fiddle with the brake you can make it a little better or a little worse depending on how you wiggle the handle. The noise seems to be in the front pulley assembly, not the rear one under the motor. I have never been inside a milling machine before. I know it's silly, but any ideas? Anyone familiar with this sound in any mill, or its fix? How often do you guys use reverse anyways? I can't ever remember using the reverse on my bench mill.

Even though the mill may end up being free (or at least cheap) it's going to cost a bit to get it moved, I will have to get another 3 phase converter, wire in a new run from the panel, etc. Then if it's something major I have to move it out again. Or I could get it knowing it may only ever run properly in forward.

What do yall think? Risk it being an easy fix and bring it home or pass?

The rotary table and indexing head do not go with it. It comes with no tooling.
The power feed works, but whatever the box with buttons and switches near the bottom does not work.

You can always make it direct drive with a VFD if it's not something fixable. You can pull the head off easily wherever you put it. I'd fo.

Double tap

+1 to the VFD's, we wont be doing anymore converters at our place!

I'd grab it.

It's beautiful.

After some really high quotes for getting it moved my neighbor down the road got me in touch with his friend who moved it on a rollback for $150. Not bad.

When I got it in the shop I removed the entire head so I could get it on the workbench and start tearing it apart. As luck would have it, the knocking noise was coming from a broken brake shoe, which is a simple fix. Every revolution the pulley was trying to grab the broken pieces of brake pad and the busted shoe that was being held outward by spring pressure.  After contacting Jet and finding out they no longer have parts for this mill I ordered a set of BP brakes hoping they would fit, but they didn't. Not having many options, I did what any respectable person would do - I JB welded it back together.  

I cut up an old belt and glued it on as a brake pad. Since it's now running on a VFD I can control the spindle braking speed and only use the brake to hold the spindle to tighten the drawbar.  Works perfectly and it runs nice and quiet. Everything has to be squared up and I still have to tidy up the wiring to code and mount the VFD, but she's ready to make chips again.

The machine is surprisingly tight for its age and can still deliver more than my skills can extract at this point in time, but this will be so much better than my mini mill. I thought about giving it a bath and a paint job. Maybe down the road.

Awesome! I built an external controller for my VFD.  Just used networking cable and buttons, lights, and potentiometer from a commercial panel I bought on eBay.

While the commercial life may be over for a cracked casting hobby use is just starting.

Think of it as well broken in.

Get a 240 V input VFD and hook it up.

Pics?

Look on the mill table...

Found one.



Can't find any, HSRacer asked too. It's an hour and a half away in my old garage still, haven't relocated it or the mill.  


Basically just toggle switch for forward and reverse, start button, emergency stop, and a light, plus the potentiometer for speed control.

I went overboard because I had the stuff and it was a fun little project.

 I have a VFD for an old Bridgeport project that's been in mothballs for a while.  I'd like to build a remote panel if I ever get around to it.  

Got a pic of the repair? The ring with the crack looks like aluminum?

It was a little frustrating at first, just trying to comprehend the information in the manual. I over think stuff too, so that doesn't help. But once I started figuring out what it wanted, it wasn't a big deal. A good example: does it need to be a push button or does it need to be a constant switch. And can I use a constant switch instead of a push button. Another frustrating thing was that one of my two VFDs didn't say that it will convert single phase to 3 phase. All I could do was hook it up and see.

I used network cable as it wanted at least the potentiometer wire to be shielded. Maybe some more, it's been a while.

A search like this helped: Ebay

The commercial quality stuff is night and day above anything else. It's interesting seeing how serviceable the button is also. My Westinghouse VFD is substantially better build quality than the China one, but both work fine.

NOOOOO... that's like nails on a chalk board.

Did you consider having it TIG welded? A competent TIG welder should have made nice work on repairing that... if the JB weld doesn't hold the whole thing is not contaminated and will be significantly more work to repair properly.

That being said, nice mill!

Definitely look into a VFD. And depending on which one you get you will certainly want to remote mount it. That's something I'm very close to doing with my VFD. It's a Hitachi; great VFD, excellent cooling. Did I mention the excellent cooling? The fan sounds like a jet-engine. Being "dumb" I mounted it on the swing-arm the carries my DRO. So I always have a jet-engine singing right at face level only a few feet away... it's extremely annoying and just as soon as I get time it's getting moved inside the column with remote controls mounted by the DRO.

The VFD is in the second picture of the mill.  It's on the table.  The black box with glowing red numbers on the front. Y'all are blind.  

The brake isn't very important to me.  The VFD controlls spindle decel and I can adjust it.  The brake is only used to hold the spindle for tightening the drawbar right now, which can actually be done just by dropping it into the backgear.  

It's not perfect, but it works for me.

Buy a rotary table and make a spare.  
Nice mill.

I don't think you realize how much of a true PITA that will be (dropping it into backgear just to hold the spindle), not to mention that isn't a true "lock". Also, using electronic braking (there is a difference between controlled decal & braking) on a motor that isn't rated for it can cause damage to the motor.

The pic took a while to load.

I hope you got a 240 V input.

Yes, it's 240. I tried the 120v input on my SB lathe just for giggles but didn't like it. The 120v input ones only go to 1hp and this mill is 2hp. Next month I may get an identical one for the lathe because I can notice the 30ish % loss I'm losing in my static converter.

This VFD is a Teco L510.

Now you just need some DROs.
I made my own ~12 years ago by using quadrature scales, linear encoders, some free software and an old laptop. It really made machining stuff a lot easier.

Kharn