Chinese Mill Problems

[ironsanctuary]

I have a Chinese mill that is about 20 years old. When I got it, it had not been used much. My problem is that the head turns on the pillar no matter how tight I make the two clamp bolts. Has anyone else had this problem?

[jackrae]

Sounds like the bore is larger than the column - one of the problems of buying a "cheap" machine

If you want the head permanently fixed into one position you could smear the column with locktite or similar before raising the head into position and tightening just short of maximum. Once the loctite has set you can further nip up the locking bolts.

The alternative is to rebore the head to permit the insertion of a shim sleeve.

Jack

[brozier]

You might get away with slipping some shim material between column and head.

Another thought might be to drill through and pin the two together.

Cheers
Bryan

[metalworker]

Try checking that the gap where the column clamps is large enough, it may be that the column cant close up enough.

[steam4ian]

G'day Iron whatsit

Get Dr John he has a Chinese mill and doesn't seem to complain about it; he would if it were no good ;D.

Give him a PM.

He claims to be a bit ascerbic by is basisclly a good bloke for a Scott.

Regards
Ian

[drjohn]

What is it with you Ian - you're always getting a fish-slap in my direction ;D

Ironsanctuary, as metalworker said, maybe the available gap for squeezing the column is insufficient, in which case, short of drilling the casting and putting in a couple of grub screws to fix it, you might well be stuffed, and even that won't give you the accuracy. Short of taking the headstock off and making a bigger gap for tightening (that is if the casting hasn't already fractured), you have a problem.

20 years ago, Chinese stuff was junk, rather like Japanese stuff after WWII, but unlike the west who have rested on their laurels, nowadays, stuff from China and Japan are pretty good. Won't be too long before the west set their standards by the Eastern quality.

DJ

[jasonb]

May also be worth checking the thread length on the bolts is sufficient, they may be tightening into the threaded hole before pulling the joint closed, washer under the bolt head would cure that.

Jason

[steam4ian]

G'day Dr John

It must be because we live in the same hemisphere, out east.

I endorse your comments about Chinese equipment.
I get fed up with some on another group that complain about the mini lathe. Truth is that you can't get much tooling for the price of the lathe; a reasonable 4" rotary table will cost above half. The quality is improving.

I think it is high time the west woke up to what is going on, I hope this GFC is the call.

Regards
Ian

[steam4ian]

G'day Iron whatsit

Take care with over tightening as you may finish up busting a casting or stripping a thread. If the shaft were smaller I suggest you knurled it

Short of the problem being inherent in the design it most likely simply solved if you take things apart and have a good look. There may be a gib missing or out of place.

Understand how it works, don't presume. I made a good name for myself early in my career by getting equipment to function properly in the steel works. It had been "fiddled" to get it going but never commissioned so I studied the gear to find what the designer had intended then made it do it. Sometimes there is a design weakness but armed with knowledge you arrive at a proper fix not another botch-up.

Regards
Ian

[engineernut]

Just a thought but are the two tightening bolts both for tightening?
I knew of a mini lathe/mill that had two bolts on the tail stock. One was for tightening but when you screwed the other one in it opened the gap so one could move it. Obviously the tightening bolt had to be slackened off first. I was told of someone who broke the casting through not doing this correctly.
On this lathe/mill they had two bolts as mentioned above but also three for column and lathe saddle. Two bolts for tightening and one for opening gap up.
Just a thought. ;D