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Locking the table - Long Chang LC-30 mill

slow-poke

slow-poke

Ultra Member
I have one of the early Busy Bee round column mills manufactured by Long Chang Taiwan

I just enabled sensorless flux vector control on my VFD to hopefully increase torque at low RPM

I'm now trying to drill a large hole 1" at very low RPM as a test. The low RPM torque does seem improved, so much so that the table is shifting back and forth over-riding the steppers hold torque. From what what I recall I set the stepper control to only apply partial current when parked to reduce motor heat. that being said I don't think the holding torque will be high enough to hold when I'm doing heavy drilling operations so I need to lock the table.

On the RF-30 mills they have two table locking bolts for the Y-Axis, that are not on the LC30, on my LC30 there is a lock-nutted screw in about the same area, is this for locking? I assumed it was for gib adjustment. Is this a table lock or gig adjuster? Image 1

Now for the X axis, (image 2), I installed a large aluminum L bracket that provides more table surface area for when I machine a large device that I do somewhat regularly and the bracket might be hiding the x- axis lock screws or perhaps not. Any insight would be helpful.
IMG_0253.JPG
IMG_0254.JPG
 
Do you have a LC30 manual? I can't post mine as it's too large to upload. Appears to me the screws with the nut are your locking screws. The manual is not all that obvious though.
 

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Not sure if this is helpful or applicable but my old RF-45 had the classic table locks acting against the gib strip. But it had an adjustable (tapered) gib strip (note adjustment screw on the front). The thumbscrew was maybe M6 thread? Maybe they combined non-tapered gib strip (with a series of adjustment grub screws) in conjunction with table lock. Theoretically it should work as long as you back off the lock completely? I've seen other machines where they skipped the lock altogether which is worse IMO.

These gib locks are kind of cheesy at best anyways. I had the same system on my lathe but got fed up. I made a little beveled 'shoe' & inserted into the hole so it acts face to face against the gib dovetail angle when tightened. The stock configuration only sees the upper edge of the set screw. Worse is torqueing it even hand tight can chowder up the strip & physically displace the table during tightening. Not good if you are trying to hold a setting.
 

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Shall try to post my LC15 - LC30 manual here. Doesn't work for me, dang anyways!

Should anyone require a copy of said manual kindly PM me and we''ll go from there.
 
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Dusty said:
Shall try to post my LC15 - LC30 manual here. Doesn't work for me, dang anyways!

Should anyone require a copy of said manual kindly PM me and we''ll go from there.
Click to expand...

Ya, I had issues posting mine as well. Even zipped I've posted it previously.
 
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Dusty said:
Shall try to post my LC15 - LC30 manual here. Doesn't work for me, dang anyways!

Should anyone require a copy of said manual kindly PM me and we''ll go from there.
Click to expand...
Thanks YYCHM the manual download link works. I actually had a copy, but this copy is better than the one I have. They show the lock screw in the exploded drawing but in the drawing it does not look like it would lock anything. I will lock and report back.
 
Well I learned a few things today......:)

Those three screws in my original post DO lock the table. Thanks David_R8. I'm still curious are they only for locking or are they also part of the gib adjustment?

Also demonstrates the limitation of a machine this size. With the table locked and a 1" drill in the collet, I did some heavy low speed drilling with my new found torque. An aggressive pull on the z-axis and the quill and to some extent the entire head flexes about the column somewhat.

So for anyone with a VFD that does not have the sensorless flux vector control enabled (assuming your VFD supports SFVC) and would like more low speed torque it really does make a difference. I also noticed that at very low speeds the motor turns more smoothly and just sounds better.

On my Buffalo drill press the original motor was only 1/2HP. When I converted it to 3-phase, I decided to go with a 3/4HP thinking that it should be plenty, if I were to do it again I would use a 1-1.5 HP for those low speed big drill bit operations. I should mention that the belt is in the middle pulley and stays there, if I were to move it to the most torque advantaged groove 3/4HP would likely be plenty I'm just a bit on the lazy side.
 
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YYCHM said:
Here is the LC-30 manual.
Click to expand...

Side benefit for me too Craig - Thank you.

As I know you recall cuz you always do...., I have no idea what my mill drill is. But it does look sorta like an RF 30 without the belt cover and with a home-made right side up motor mount.

At some point I'm either gunna fix it up or sell it cuz I just don't use it anymore. Your manual looks quite similar and will help either way.
 
slow-poke said:
Those three screws in my original post DO lock the table. Thanks David_R8. I'm still curious are they only for locking or are they also part of the gib adjustment?
Click to expand...

My mill/drill has no dedicated lock. Instead, the center Gibb screw has a hand Lever on it to perform that function.

It's very common to have the lock be built into the Gibb adjustment like that.

So to answer your question, they are designed to be Gibb adjustments, but can also be used as a lock by adding a hand Lever to one of them.
 
slow-poke said:
With the table locked and a 1" drill in the collet, I did some heavy low speed drilling with my new found torque. An aggressive pull on the z-axis and the quill and to some extent the entire head flexes about the column somewhat.
Click to expand...
Yup, any machine has a little 'flex'...RF-30 mills just have a little more! When I was tramming my Craftex, I noticed that if I lifted the head, I could move the dial by at least a thou. To be clear, that's lifting with my hands; maybe 20-30 pounds of force. So I figure a 'spring pass' or two is a good idea...

Craig
 
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