Series 1 knee tough to raise

[AlfromNH]

It seems like the knee on my mill is getting harder to crank up, lowering it is easy. What are the first things to check?

 

[Monostre]

Hey,

I don't have a series 1 but a Lagun FTV-3, which is very similar in construction. On the fly I could think of the following points to inspect:

- The lifting mechanism is driven by a gearbox to a trapezoidal threaded spindle, which lifts the knee. The spindle and the gearbox could have a problem (e.g. lubrication etc.). On the downward movement the weight of the knee and table helps to lower the knee, thus the movement feels easier. If you have a crane you could lift the knee, remove the screws on the nut (connection to the base) and try "in the air" to see if the mechanism works properly in both directions.

- The gib could be damaged / bent / loose. If I remember correctly the gib is inserted and positioned from the top with a screw. The screwhead sits in a recess of the gib and pusitions it in the dovetail guide (to allow adustment of the play). Because of this the play in the dovetail could change during the upward movement, if the gib is too loose on the screwhead.

I hope this helps at least a little bit.

 

[AlfromNH]

Thanks Monostre, I'll have a look at the gib. Since it seems to have come on gradually I want to say it's a lubrication issue rather than damage. This machine is fairly new to me and I'm still learning my way around it both in use and maintenance

 

[Firstram]

How is it lubricated?

If it has zerks, pump in copious amounts of oil while moving up and down!

If it has a one shot, loosen the 2 hoses and pump the oiler to confirm flow. If you don't see oil, there's your problem. If its flowing, pump in copious amounts of oil while moving up and down!

What ever you do, don't lower the knee all the way down. It could get stuck due to dirty and dry gibs.

 

[Janderso]

What ever you do, don't lower the knee all the way down. It could get stuck due to dirty and dry gibs.

Do you speak from experience? I never would have thought of it.

I would add, maybe someone packed the oil fittings with grease? Very common.

 

[AlfromNH]

The machine has a one shot oiler and i pulled the line off the knee and confirmed there's oil flow.

I found when lowering the knee it would drop in steps, so now I'm working on adjusting the gib, while manually applying oil as I raise and lower.

The manual says there's a gib screw on the bottom as well as the adjustment screw on the top, but mine has no screw on the bottom, see pic. Note: pic is backwards, this is the left/ gib side

 

[Firstram]

Do you speak from experience? I never would have thought of it.

That's a problem Richard King pointed out somewhere, make sure they are kept perfectly clean. The absolute bottom of the dovetails are often coated in dried oil and dirt. The bottoms also never see wear. Just like a carriage lock gets tighter toward the tailstock. The knee gib can only be loosened by pulling up on the notch in the top. If it's wedged, the notch will break off!

He went on to describe the fix. You drill a large hole through the base under the gib, lay the mill on it's back and drive the gib up with a tight fitting steel bar!

A month or two ago, some one on PM wedged their mill table by over traveling with the power feed. He got it out but, a missed hammer blow broke a chunk out of the saddle!

I would add, maybe someone packed the oil fittings with grease? Very common.

Absolutely! I do think stripping a mill down is a good exercise for a new user!

 

[MrWhoopee]

First thing I'd check is the calendar. Everything gets gradually harder (except you know). I'd swear the stairs in my house are getting steeper and longer.

 

[Firstram]

The machine has a one shot oiler and i pulled the line off the knee and confirmed there's oil flow.

I found when lowering the knee it would drop in steps, so now I'm working on adjusting the gib, while manually applying oil as I raise and lower.

The manual says there's a gib screw on the bottom as well as the adjustment screw on the top, but mine has no screw on the bottom, see pic. Note: pic is backwards, this is the left/ gib side
View attachment 475742

Bridgeports only have a screw on the top.

You can raise the knee all the way up to the stop screw and scrub the lower dovetails on the column. Then lower it 2/3rds of the way down and stick a 2x4 between the base and the front edge of the cutout in the knee.

Gently lower the knee and the 2x will support the front edge and counteract the cantilever forces. Center the table and move the saddle centered or slightly behind the lifting screw. Now you can pull the knee gib out to clean it and the upper dovetail on that side.

Be aware the entire knee and table assembly is only balanced on the screw. The dovetails won't let it fall out but, it will move around a little! You can use a 1" ratchet that goes form each end of the table around the column to add stability.

I had the same issues with my knee as you. I cleaned and lubed it like I just described, while it did help, it still shuddered on the way down. A full teardown and cleaning was needed to make it go away. I'm glad I did because I found filth packed everywhere.

A one shot oiler doesn't always get enough oil in there with 1 pump! Pump it until oil is dripping if the mill has been sitting for a long time.

 

[benmychree]

Another thing about one shot oilers is that the metering fittings get clogged up and need replacing in time.